Radar device, radar signal transmission method, and radar signal processing device

Abstract

To improve the detection accuracy of a target in a radar device.SOLUTION: A radar device includes: multiple transmission antennas which include a first transmission antenna that forms a first beam, and a second transmission antenna that forms a second beam that is different from the first beam; and a transmission circuit which performs multiple transmission of a transmission signal applied with a phase rotation amount corresponding to the combination of a Doppler shift amount and a code series from the multiple transmission antennas. Combinations in which at least one of the Doppler shift amount and the code series is different are associated with the multiple transmission antennas respectively. The first pattern of the Doppler shift amount and the code series assigned to the first transmission antenna is different from the second pattern of the Doppler shift amount and the code series assigned to the second transmission antenna.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This disclosure relates to radar equipment. [Background technology]

[0002] In recent years, research has been progressing on radar systems that use short-wavelength radar transmission signals, including microwaves or millimeter waves, which can achieve high resolution. As a radar system, for example, a configuration has been proposed in which the transmitting unit, in addition to the receiving unit, is equipped with multiple antennas (array antennas), and beam scanning is performed by signal processing using the transmitting and receiving array antennas (sometimes called MIMO (Multiple Input Multiple Output) radar) (see, for example, Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-211388 [Patent Document 2] U.S. Patent Publication No. 2022 / 0066012 [Patent Document 3] Japanese Patent Publication No. 2008-304417 [Patent Document 4] Japanese Patent Publication No. 2014-119344 [Patent Document 5] Japanese Patent Publication No. 2020-204603 [Patent Document 6] Japanese Patent Publication No. 2022-92247 [Non-patent literature]

[0004] [Non-Patent Document 1] J. Li, and P. Stoica, "MIMO Radar with Colocated Antennas", Signal Processing Magazine, IEEE Vol. 24, Issue: 5, pp. 106-114, 2007 [Non-Patent Document 2] M. Kronauge, H. Rohling, "Fast two-dimensional CFAR procedure", IEEE Trans. Aerosp. Electron. Syst., 2013, 49, (3), pp. 1817-1823 [Non-Patent Document 3] Direction-of-arrival estimation using signal subspace modeling Cadzow, JA; Aerospace and Electronic Systems, IEEE Transactions on Volume: 28 , Issue: 1 Publication Year: 1992 , Page(s): 64 - 79 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, methods for detecting targets in radar systems (e.g., MIMO radar) have not been sufficiently studied.

[0006] Non-limiting embodiments of this disclosure contribute to providing radar devices that improve the accuracy of target detection. [Means for solving the problem]

[0007] A radar system according to one embodiment of the present disclosure comprises a plurality of transmitting antennas, including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, and a transmitting circuit that multiplexes a transmission signal to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is assigned from the plurality of transmitting antennas, wherein each of the plurality of transmitting antennas is associated with the combination in which at least one of the Doppler shift amount and the code sequence is different, and a first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from a second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna.

[0008] These comprehensive or specific embodiments may be implemented as systems, devices, methods, integrated circuits, computer programs, or recording media, or as any combination of systems, devices, methods, integrated circuits, computer programs, and recording media. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, the accuracy of target detection in a radar system can be improved.

[0010] Further advantages and effects of one embodiment of this disclosure will be made apparent from the specification and drawings. Such advantages and / or effects are provided by several embodiments and features described in the specification and drawings, but not all of them are necessarily provided in order to obtain one or more identical features. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram shows an example of Time Division Multiplexing (TDM) transmission. [Figure 2] A diagram showing an example of Doppler Division Multiplexing (DDM) transmission. [Figure 3] A diagram showing an example of unequal-interval Doppler multiplexing transmission. [Figure 4] A diagram showing an example of a multibeam transmitting MIMO radar. [Figure 5] This figure shows an example of Doppler multiplexing in a multibeam MIMO radar. [Figure 6] This figure shows an example of Doppler multiplexing in a multibeam MIMO radar. [Figure 7] Block diagram showing an example of radar system configuration. [Figure 8] This diagram shows an example of a transmitted signal when using a chirp signal. [Figure 9] A diagram showing an example of a chirp signal. [Figure 10] This diagram shows an example of a transmitted and received signal when using a chirp signal. [Figure 11] A diagram showing an example of setting the Doppler shift amount. [Figure 12] A diagram showing an example of a received signal in Doppler multiplex transmission. [Figure 13] A diagram showing an example of a multibeam transmitting MIMO radar. [Figure 14] A diagram showing an example of setting the Doppler shift amount. [Figure 15] A diagram showing an example of a received signal in Doppler multiplex transmission. [Figure 16] A diagram showing an example of setting the Doppler shift amount. [Figure 17] A diagram showing an example of setting the Doppler shift amount. [Figure 18] A flowchart illustrating an example of Doppler multiplexed signal separation operation. [Figure 19] Diagram showing an example of a transmitting antenna configuration. [Figure 20] A diagram showing an example of a multibeam transmitting MIMO radar. [Figure 21] A diagram showing an example of MIMO antenna configuration and virtual receiving antenna configuration. [Figure 22] A diagram showing an example of encoded Doppler multiplexing. [Figure 23] A diagram showing an example of a multibeam transmitting MIMO radar. [Figure 24] A diagram showing an example of a multibeam transmitting MIMO radar. [Figure 25] A diagram showing an example of a multibeam transmitting MIMO radar. [Modes for carrying out the invention]

[0012] [About multibeam radar] For example, there is a method of configuring a MIMO radar using multiple transmitting or receiving antennas with different directional characteristics (or simply referred to as "directionality") that have different main beam directions (hereinafter sometimes referred to as "beam direction," "transmitting beam direction," or "receiving beam direction") (see, for example, Patent Document 1 or Patent Document 2).

[0013] Examples of multiple different directional characteristics of a transmitting or receiving antenna include directional characteristics with the same beam width but different beam directions, directional characteristics with both different beam directions and beam widths, or directional characteristics with the same beam direction but different beam widths.

[0014] In the following, a MIMO radar that uses multiple transmitting antennas with different directional characteristics (for example, transmitting antennas that form different beams) will be referred to as a "multibeam transmitting MIMO radar." Here, a multibeam transmitting MIMO radar includes multiple transmitting antennas with different directional characteristics. Note that a multibeam transmitting MIMO radar may also be configured to include one or more transmitting antennas with the same directional characteristics.

[0015] Furthermore, in the following, a MIMO radar that uses multiple receiving antennas with different directional characteristics (for example, receiving antennas that form different beams) will be referred to as a "multibeam receiving MIMO radar." Here, a multibeam receiving MIMO radar includes multiple receiving antennas with different directional characteristics. Note that a multibeam receiving MIMO radar may also be configured to include one or more receiving antennas with the same directional characteristics.

[0016] Similarly, in the following, a MIMO radar that uses multiple transmitting and receiving antennas with different directional characteristics as described above will be referred to as a "multibeam transceiver-MIMO radar" (or multibeam MIMO radar).

[0017] For example, examples of multiplexing transmission methods for MIMO radar using multiple transmitting antennas include time division multiplexing (TDM) transmission (e.g., Patent Document 3) or Doppler division multiplexing (DDM) transmission (e.g., Patent Document 4).

[0018] Time-division multiplexing (DPP) or Doppler multiplexing (DPP) can separate reflected waves corresponding to transmitted signals from multiple transmitting antennas using an allocated transmission time or Doppler frequency domain. On the other hand, in DPP and DPP, the detection range of the Doppler frequency tends to narrow as the number of transmitting antennas increases. For example, in DPP and DPP, the detectable Doppler frequency range is -1 / (2Nt×Tr)≦fd<1 / (2Nt×Tr), and the detection range of the Doppler frequency narrows inversely proportional to the number of transmitting antennas. Here, Nt is the number of transmitting antennas, and Tr is the transmission period of the transmitted signal.

[0019] [About coded Doppler multiplex transmission] Patent Document 5 (for example, Figure 1 of Patent Document 5) discloses a multiplexing transmission method that combines Doppler multiplexing and code multiplexing (hereinafter referred to as "encoded Doppler multiplexing transmission" or "Coded DDM").

[0020] For example, Figure 1 shows an example of the assignment of transmission Doppler frequencies and codes when transmitting a radar transmission wave (e.g., a chirp signal) at each transmission period Tr, using two Doppler multiplexed signals (e.g., Δfd1, Δfd2) to three transmitting antennas (e.g., Tx#1 to Tx#3) with orthogonal codes of code length Loc=2 (e.g., code#1, code#2).

[0021] The phase rotation based on the code is performed, for example, by cyclically repeating the operation of applying it to the chirp signal with a transmission period of code length Loc × Tr (2 transmission periods (2Tr) in Figure 1). In this case, the phase rotation based on the Doppler multiplexed signal is kept constant during the transmission period of code length 2 (2 transmission periods (2Tr) in Figure 1) in which a code of code length 2 is applied. For example, the phase rotation based on the Doppler multiplexed signal may be applied with a variation every 2Tr transmission period.

[0022] For example, in Figure 1, the assigned transmit Doppler shift amounts are set to Δfd1 = -1 / (4Tr) and Δfd2 = 0 [Hz], respectively. For example, since the transmit Doppler shift amount Δfd1 is applied every nth transmission cycle, a phase rotation Φ1(n) = ΔΦ1 × (floor(n / Loc) + 1) is applied to the radar transmit wave (chirp signal). Also, since the transmit Doppler shift amount Δfd2 is applied every nth transmission cycle, a phase rotation Φ2(n) = ΔΦ2 × (floor(n / Loc) + 1) is applied to the radar transmit wave (chirp signal). Here, ΔΦ1 = -π and ΔΦ2 = 0. The Doppler multiplexing interval is Δf d = 1 / (4Tr). Also, for orthogonal codes with code length 2, for example, code#1=[1, 1] and code#2=[1, -1] may be used. In Figure 1, for example, for transmitting antennas Tx#1 to Tx#3, DopCode#1=(Δfd1,code#1), DopCode#2=(Δfd1,code#2), and DopCode#3=(Δfd2,code#1) are assigned and transmitted as coded Doppler multiplexed signals combining Doppler multiplexed signals and codes, respectively. Also, floor[x] is an operator that outputs the largest integer not exceeding the real number x.

[0023] These simultaneously multiplexed signals are received by a radar device (e.g., a received signal processing unit). The radar device performs Doppler frequency analysis on the received radar reflected wave signal using separate Doppler analysis units (e.g., V-FFT#1 and V-FFT#2) to separate the multiplexed transmitted signals into transmission periods of code length, for example, the received signal for each odd-numbered transmission period and the received signal for each even-numbered transmission period. Based on the output of the Doppler frequency analysis, it performs code multiplexing and Doppler multiplexing to separate and receive the multiplexed transmitted signals.

[0024] Here, the radar device (e.g., the Doppler analysis unit) uses a received signal with a transmission period of code length (Loc=2 in Figure 1) (2 transmission periods (2Tr) in Figure 1), so Doppler frequencies exceeding ±1 / (2 Loc Tr) (±1 / (4Tr) in Figure 1) are detected as aliased. Whether or not the radar reflected wave received signal contains components in the aliasing frequency range is determined, for example, using an encoded Doppler multiplexed signal (DopCode#4=(Δfd2,code#1) in Figure 1) which is a combination of an unused code that is not assigned to a transmitting antenna and a Doppler multiplexed signal, as disclosed in Patent Document 5. For example, whether or not the radar reflected wave received signal contains components in the aliasing frequency range is determined by utilizing the fact that the received power of the code multiplexed and Doppler multiplexed signals is approximately at the noise level for an encoded Doppler multiplexed signal which is a combination of an unused code that is not assigned to a transmitting antenna and a Doppler multiplexed signal.

[0025] In this way, the radar device makes the code multiplexing number between Doppler multiplexed signals uneven, transmits multiplexed signals from multiple transmitting antennas, and detects the received signal level to detect the presence or absence of aliasing signals. This expands the Doppler frequency range (maximum Doppler) in which the Doppler frequency can be detected without aliasing to ±1 / (2Tr), and also enables the identification of the transmitting antenna.

[0026] For example, Figure 2(a) shows the received Doppler signals when the coded Doppler multiplexed signal shown in Figure 1 is separated by code#1 and code#2, respectively, when the target's Doppler frequency fdtarget=0. As shown in Figure 2(a), the received Doppler multiplexed signal separated by code#1 has a Doppler multiplexing interval Δf between Δfd1 and Δfd2. d High reception levels are detected at two Doppler frequencies with matching Doppler frequency intervals, and the radar system can determine these components as the received signals of Tx#1 and Tx#3. Also, as shown in Figure 2(a), in the received Doppler signal separated by code#2, one Doppler frequency with a high reception level is detected, and the Doppler multiplexing interval Δf between Δfd1 and Δfd2 for the detected Doppler frequency is also detected. d The received level of Doppler frequencies with matching Doppler frequency intervals is approximately the noise level. From this, the radar system can determine that one Doppler frequency component with a high received level is the received signal of Tx#2. Furthermore, the radar system can determine the target's Doppler frequency because the deviation from the Doppler shift amount at the time of transmission for each transmitting antenna is the Doppler frequency of the target.

[0027] Furthermore, for example, Figure 2(b) shows the received Doppler signals when the encoded Doppler multiplexed signal shown in Figure 1 is separated into code#1 and code#2, respectively, when the target's Doppler frequency fdtarget = -1 / (2Tr). As shown in Figure 2(b), the received Doppler signal separated by code#2 has a Doppler multiplexing interval Δf between Δfd1 and Δfd2. d High reception levels are detected at two Doppler frequencies with matching Doppler frequency intervals, and the radar system can determine these components as the received signals of Tx#1 and Tx#3. Also, as shown in Figure 2(b), in the received Doppler signal separated by code#1, one Doppler frequency with a high reception level is detected, and the Doppler multiplexing interval Δf between Δfd1 and Δfd2 for the detected Doppler frequency is also detected. dThe received level of Doppler frequencies with matching Doppler frequency intervals is approximately the noise level. From this, the radar system can determine that one Doppler frequency component with a high received level is the received signal of Tx#2. Furthermore, the radar system can determine the target's Doppler frequency because the deviation from the Doppler shift amount at the time of transmission for each transmitting antenna corresponds to the target's Doppler frequency.

[0028] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit (e.g., V-FFT#1 and V-FFT#2) will observe the folded Doppler frequency. In this case, the actual Doppler frequency differs from the Doppler frequency detected in the Doppler analysis unit (V-FFT#1 and V-FFT#2) by 2π phase over the transmission period of 2Tr. Therefore, a phase rotation of π is added between the detection time difference Tr between V-FFT#1 and V-FFT#2. Consequently, the radar device can determine that aliasing has occurred when the received signal of Tx#2 is determined in the separation of code#1, as shown in Figure 2(b).

[0029] By separating and receiving such encoded Doppler multiplexed signals, the radar system can estimate the Doppler frequency of the radar reflection within a Doppler frequency range of ±1 / (2 Tr). Thus, by transmitting encoded Doppler multiplexed signals, the detectable Doppler frequency range is expanded to ±1 / 2 Tr. For example, compared to Patent Documents 3 or 4, the detectable Doppler frequency range is expanded by Nt times.

[0030] [Regarding the application of coded Doppler multiplexing to multibeam MIMO radar] As described above, unlike the MIMO radar using Doppler multiplexing (e.g., also referred to as "coded DDM"), in the MIMO radar using coded Doppler multiplexing, some Doppler frequency regions are not allocated to the transmission signal, and the MIMO radar performs a separation process of the Doppler multiplex signal (hereinafter referred to as "coded Doppler multiplex separation") for estimating the Doppler frequency of the target based on the received power of the received Doppler frequency of the reflected wave from the target after code multiplex separation.

[0031] Therefore, when applying coded Doppler multiplexing to a multi-beam transmission MIMO radar, the following can be assumed.

[0032] In a multi-beam transmission MIMO radar, for example, a phenomenon may occur in which the received level of the reflected wave varies greatly depending on the beam direction (or transmission beam direction) and the target direction. In a multi-beam transmission MIMO radar, the received level of the reflected wave from the transmission antenna may vary greatly between the case where the beam direction and the target direction coincide and the case where the beam direction and the target direction do not coincide. Therefore, when performing multi-beam transmission using coded Doppler multiplexing in a multi-beam transmission MIMO radar, if the difference ( or ratio) in the received level of the reflected wave between multi-beams in different beam directions is large, Doppler multiplex separation by coded Doppler multiplexing may become difficult. When Doppler multiplex separation becomes difficult, the detection performance of the target in the MIMO radar may deteriorate, or coded Doppler multiplex separation may be incorrect, resulting in Doppler estimation error or deterioration of the angle measurement performance.

[0033] Hereinafter, an example in which Doppler multiplex separation becomes difficult in a multi-beam transmission MIMO radar to which coded Doppler multiplexing is applied will be described.

[0034] For example, the case of a 4Tx MIMO radar including two transmission antennas in each of two beam directions will be described. For example, the number of transmission antennas corresponding to each of the two beam directions is represented as "N TxBeam#1 " and "N TxBeam#2 " (N TxBeam#1 = N TxBeam#2=2).

[0035] For example, as shown in Figure 3, we will describe a multi-beam transmitting MIMO radar that uses two of the four transmitting antennas Tx#1 to #4 to form two different transmitting beams (TxBeam#1, TxBeam#2) in different directions. In Figure 3, the transmitting beam (beam direction) of Tx#1 and Tx#2 is referred to as TxBeam#1, and the transmitting beam (beam direction) of Tx#3 and Tx#4 is referred to as TxBeam#2. Furthermore, for example, the directional characteristics of the receiving antenna may be omnidirectional, or they may be nearly uniform within the field of view (FOV) covered by multiple transmitting antennas with different directional characteristics.

[0036] For example, for four transmitting antennas Tx#1 to #4, the Doppler multiplexing number N is as shown in Figure 4(a). DM =3, code multiplex number N CM This section explains the case where a Doppler multiplexed signal encoded using =2 is assigned.

[0037] For example, if the target direction is target direction (1) as shown in Figure 3, the direction of the reflected wave corresponding to the radar transmission waves transmitted from Tx#1 and Tx#2 that form TxBeam#1 coincides with target direction (1). Therefore, as shown in Figure 4(b), the reception level of the received signal corresponding to Tx#1 and Tx#2 that form TxBeam#1 (e.g., the reflected wave reception level) is relatively high. On the other hand, if the target direction is target direction (1) as shown in Figure 3, the direction of the reflected wave corresponding to the radar transmission waves transmitted from Tx#3 and Tx#4 that form TxBeam#2 does not coincide with target direction (1), and target direction (1) corresponds to the directional null direction of TxBeam#2 (hereinafter also referred to as the null direction). Therefore, as shown in Figure 4(b), for example, the received signal levels of the received signals corresponding to Tx#3 and Tx#4 that form TxBeam#2 are lower than the received signal levels of the received signals corresponding to TxBeam#1 (Tx#1 and Tx#2). For example, the received signal level corresponding to TxBeam#2 differs significantly from the received signal level corresponding to TxBeam#1, and depending on the null-direction beam directivity characteristics of TxBeam#2, it may be more than 10 dB lower.

[0038] Furthermore, for example, if the target direction is an intermediate direction between the beam direction of TxBeam#1 and the beam direction of TxBeam#2, and the beam widths of both beams, which are approximately 3dB or 6dB, overlap in the area direction (for example, the target direction (2) shown in Figure 3), then the reflected waves corresponding to the radar transmission waves transmitted from Tx#1 and Tx#2 that form TxBeam#1 and the reflected waves corresponding to the radar transmission waves transmitted from Tx#3 and Tx#4 that form TxBeam#2 will be received at similar levels, as shown in Figure 4(c).

[0039] Furthermore, for example, if the target direction is the target direction (3) shown in Figure 3, the direction of the reflected wave corresponding to the radar transmitted waves sent from Tx#3 and Tx#4 that form TxBeam#2 coincides with the target direction (3). Therefore, as shown in Figure 4(d), the reception level of the received signal corresponding to Tx#3 and Tx#4 that form TxBeam#2 (e.g., the reflected wave reception level) is relatively high. On the other hand, if the target direction is the target direction (3) shown in Figure 3, the direction of the reflected wave corresponding to the radar transmitted waves sent from Tx#1 and Tx#2 that form TxBeam#1 does not coincide with the target direction (3), and the target direction (3) corresponds to the null direction of TxBeam#1. For this reason, for example, as shown in Figure 4(d), the reception level of the received signal corresponding to Tx#1 and Tx#2 that form TxBeam#1 is lower than the reception level of the received signal corresponding to TxBeam#2 (Tx#3 and Tx#4). For example, the received level corresponding to TxBeam#1 differs significantly from the received level corresponding to TxBeam#2, and depending on the beam directivity characteristics of TxBeam#1 in the null direction, it can be more than 10dB lower.

[0040] For example, in the case shown in Figure 4(c), the received level of the reflected wave corresponding to the radar transmitted waves from Tx#1 and Tx#2 forming TxBeam#1 is approximately the same as the received level of the reflected wave corresponding to the radar transmitted waves from Tx#3 and Tx#4 forming TxBeam#2. Since the code multiplexing number between Doppler multiplexed signals is non-uniform, the multibeam MIMO radar can determine, based on the received levels of these received signals, which transmitting antenna the detected Doppler frequency peak corresponds to in the coded Doppler multiplexing transmission. Also, in Figure 4(c), the Doppler frequency fd of the target reflected wave can be determined to be within the range -1 / (2Tr)≦fd<1 / (2Tr).

[0041] On the other hand, in cases like those shown in Figure 4(b) or Figure 4(d), it is difficult for a multi-beam MIMO radar to determine, based on the received signal level, whether the received level of the reflected wave corresponding to the radar transmission wave transmitted from Tx#1 and Tx#2 forming TxBeam#1 has decreased (for example, in the case of Figure 4(d)), or whether the received level of the reflected wave corresponding to the radar transmission wave transmitted from Tx#3 and Tx#4 forming TxBeam#2 has decreased (for example, in the case of Figure 4(b)), because the Doppler frequency of the target is unknown. For this reason, it is difficult for a multi-beam MIMO radar to determine, based on the received signal level, which transmitting antenna the detected Doppler frequency peak corresponds to in the coded Doppler multiplexing transmission. Therefore, multi-beam MIMO radars have difficulty separating Doppler multiplexed signals, making it difficult to determine the Doppler frequency fd of the reflected wave from the target (for example, called the "target reflected wave") within the range of -1 / (2Tr) ≤ fd < 1 / (2Tr).

[0042] Thus, in encoded Doppler multiplexing, the encoded Doppler multiplexing separation process is performed on the premise that the received levels of the reflected waves corresponding to each transmitting antenna are similar, and that the received levels of the Doppler multiplexing intervals that are not Doppler multiplexed are sufficiently low, at the level of noise. In multibeam transmitting MIMO radars that use encoded Doppler multiplexing, as shown in Figures 4(b) and (d), the premise for the separation process of encoded Doppler multiplexing may break down (the received levels corresponding to some beams may decrease), which may lead to errors in the encoded Doppler multiplexing separation process.

[0043] Non-limiting embodiments of this disclosure describe a method for improving the detection performance of a multi-beam MIMO radar using coded Doppler multiplexing.

[0044] Hereinafter, an embodiment according to one example of the present disclosure will be described in detail with reference to the drawings. In the embodiment, the same reference numerals are used for the same components, and their descriptions will be omitted as they would be redundant.

[0045] The following describes a radar system configuration in which the transmitting branch simultaneously sends out different multiplexed transmission signals from multiple transmitting antennas, and the receiving branch separates each transmission signal for reception processing (for example, a MIMO radar configuration).

[0046] Furthermore, the configuration of a radar system using frequency-modulated pulse waves, such as chirp pulses (also known as fast chirp modulation), will be described below as an example. However, the modulation method is not limited to frequency modulation. For example, one embodiment of this disclosure is also applicable to a radar system using a pulse-compressed radar that transmits pulse trains with phase modulation or amplitude modulation.

[0047] Furthermore, the radar system performs Doppler multiplexing, for example. In addition, the radar system encodes (for example, CDM (Code Division Multiplexing)) a ​​signal to which different phase rotations (for example, phase shifts) equal to the number of Doppler multiplexings have been applied in Doppler multiplexing transmission (hereinafter referred to as the "Doppler multiplexed transmission signal") and transmits it multiplexed (hereinafter referred to as "Coded Doppler Multiplexing").

[0048] [Radar system configuration] The radar device 10 in Figure 5 includes a radar transmitter (transmitting branch) 100 and a radar receiver (receiving branch) 200.

[0049] The radar transmission unit 100 generates a radar signal (radar transmission signal) and transmits the radar transmission signal at a defined transmission period (hereinafter referred to as the "radar transmission period") using a transmission antenna unit 109 (for example, a transmission array antenna) which is composed of multiple transmission antennas (for example, Nt antennas).

[0050] The radar receiver 200 receives the reflected wave signal, which is the radar transmission signal reflected by a target (not shown), using a receiving antenna unit 202 (e.g., a receiving array antenna) which includes a plurality of receiving antennas 202-1 to 202-Na. The radar receiver 200 processes the reflected wave signal received by each receiving antenna to perform signal processing, for example, detecting the presence or absence of a target or estimating the arrival distance, Doppler frequency (e.g., relative velocity), and direction of arrival of the reflected wave signal, and outputs information related to the estimation results (e.g., positioning information).

[0051] The radar device 10 may be mounted on a moving object such as a vehicle, and the positioning output (information regarding the estimation result) of the radar receiver 200 may be connected to an electronic control unit (ECU) (not shown) such as an advanced driver assistance system (ADAS) or an autonomous driving system that enhances collision safety, and used for vehicle drive control or alarm call control.

[0052] Furthermore, the radar device 10 may be mounted on a relatively high structure (not shown), such as a roadside utility pole or traffic light. The radar device 10 may also be used as a sensor in a support system to enhance the safety of passing vehicles or pedestrians, or in an intruder prevention system (not shown). The positioning output of the radar receiver 200 may also be connected to a control device (not shown) in a safety support system or intruder prevention system, and used for alarm call control or anomaly detection control. However, the applications of the radar device 10 are not limited to these, and it may be used for other purposes.

[0053] Furthermore, a target is an object detected by the radar device 10, and includes, for example, vehicles (including four-wheeled and two-wheeled vehicles), people, blocks, or curbs.

[0054] [Configuration of radar transmitter 100] The radar transmission unit 100 includes a radar transmission signal generation unit 101, a phase rotation amount setting unit 105, a phase rotation unit 108, and a transmission antenna unit 109.

[0055] The radar transmission signal generation unit 101 generates radar transmission signals. The radar transmission signal generation unit 101 includes, for example, a transmission signal generation control unit 102, a modulation signal generation unit 103, and a VCO (Voltage Controlled Oscillator) 104. The following describes each component of the radar transmission signal generation unit 101.

[0056] The transmission signal generation control unit 102 sets, for example, the transmission signal generation timing for each radar transmission cycle, and outputs information regarding the set transmission signal generation timing to the modulation signal generation unit 103 and the phase rotation amount setting unit 105 (for example, the Doppler shift setting unit 106). Here, the radar transmission cycle is denoted as Tr.

[0057] The modulation signal generation unit 103 periodically generates a modulation signal, for example, a sawtooth-shaped one, based on information regarding the transmission signal generation timing for each radar transmission period Tr, which is input from the transmission signal generation control unit 102.

[0058] Based on the modulated signal input from the modulated signal generation unit 103, the VCO 104 outputs a frequency modulated signal (hereinafter referred to as, for example, a frequency chirp signal or chirp signal) as a radar transmission signal (radar transmission wave) as shown in Figure 6 to the phase rotation unit 108 and the radar receiving unit 200 (mixer unit 204, which will be described later).

[0059] The phase rotation amount setting unit 105 sets the phase rotation amount to be applied to the radar signal for each radar transmission period Tr in the phase rotation unit 108 (for example, the phase rotation amount corresponding to coded Doppler multiplex transmission) based on information regarding the transmission signal generation timing for each radar transmission period Tr input from the transmission signal generation control unit 102. The phase rotation amount setting unit 105 includes, for example, a Doppler shift setting unit 106 and a coding unit 107.

[0060] The Doppler shift setting unit 106 sets a phase rotation amount corresponding to the Doppler shift amount to be applied to the radar transmission signal (e.g., chirp signal) based on information regarding the transmission signal generation timing for each radar transmission period Tr.

[0061] The encoding unit 107 sets a phase rotation amount corresponding to encoding based, for example, on information regarding the transmission signal generation timing for each radar transmission period Tr. The encoding unit 107 calculates a phase rotation amount for the phase rotation unit 108 based on, for example, the phase rotation amount input from the Doppler shift setting unit 106 and the phase rotation amount corresponding to encoding, and outputs it to the phase rotation unit 108. The encoding unit 107 also outputs information regarding the code sequence used for encoding (for example, each element of an orthogonal code sequence) to the radar receiving unit 200 (for example, the output switching unit 209).

[0062] The phase rotation unit 108 applies a phase rotation amount input from the encoding unit 107 to the chirp signal input from the VCO 104, and outputs the phase-rotated signal to the transmitting antenna unit 109. For example, the phase rotation unit 108 includes a phase shifter and a phase modulator (not shown). The output signal of the phase rotation unit 108 is amplified to a specified transmission power and radiated into space from each transmitting antenna. For example, a radar transmission signal is multiplexed from multiple transmitting antennas by applying a phase rotation amount corresponding to a combination of Doppler shift amount and orthogonal code sequence.

[0063] Next, an example of how to set the phase rotation amount in the phase rotation amount setting unit 105 will be described.

[0064] The Doppler shift setting unit 106 sets the Doppler shift amount DOP ndm Phase rotation amount φ to impart ndm The settings are configured and output to the encoding unit 107. Here, ndm = 1 to N DM N DM This is the number of different Doppler shift settings, and will be referred to as the "Doppler multiplexing number" below.

[0065] In the radar device 10, encoding by the encoding unit 107 is used in combination, so the Doppler multiplexing number N DM The Doppler multiplexing number Nt may be set to a value less than the number of transmitting antennas Nt used for multiplexing. DM The value must be 2 or greater.

[0066] Doppler shift amount DOP1, DOP2, ~, DOP N_DM ("N_DM" is "N DM As for the Doppler shift amounts (which can also be expressed as "), for example, equally spaced Doppler shift amounts may be set, or unequally spaced Doppler shift amounts may be set. Each Doppler shift amount DOP1, DOP2, ~, DOP N_DM This is used in conjunction with encoding by the encoding unit 107 described later, for example, 0≦DOP1,DOP2,~,DOP N_DM <(1 / TrL oc ) may be set to satisfy the following conditions. Alternatively, Doppler shift amounts DOP1, DOP2, ~, DOP N_DM For example, it may be set to satisfy equation (1).

number

[0067] Also, for example, Doppler shift amounts DOP1, DOP2, ~, DOP N_DM The smallest Doppler shift interval Δf in between MinInterval The following equation (2) may be satisfied. Note that the Doppler shift interval (also referred to as Doppler multiple interval or Doppler interval) is the Doppler shift amount DOP1, DOP2, ~, DOP N_DM It may be defined as the absolute value of the difference between any two of the Doppler shift amounts. Here, Loc represents the number of code elements. For example, Loc represents the code length of the code used in the encoding unit 107.

number

[0068] Also, each Doppler shift amount DOP1, DOP2, ~, DOP N_DM Phase rotation amount φ to impartndm For example, it may be assigned as shown in equation (3) below.

number

[0069] Note that the intervals are equal and Δf MinInterval When the following Doppler shift amount is set (hereinafter referred to as "equally spaced Doppler shift amount setting"), the Doppler shift amount DOP ndm Phase rotation amount φ to impart ndm For example, it can be assigned as shown in equation (4) below.

number

[0070] Note that the minimum Doppler shift interval Δf MinInterval The narrower the interval, the more likely interference between Doppler multiplexed signals is to occur, increasing the likelihood of reduced (e.g., degradation) target detection accuracy. Therefore, within the range where the constraints of equation (2) are satisfied, it is preferable to widen the interval of the Doppler shift amounts. For example, when the equality holds in equation (2) (e.g., Δf MinInterval = 1 / (T r N DM L OC )) can maximize the spacing in the Doppler region between Doppler multiplexed signals (hereinafter referred to as "maximum equally spaced Doppler shift amount setting"). In this case, the Doppler shift amounts DOP1, DOP2, ~, DOP N_DM The phase rotation range is N, which is between 0 and 2π. DM The system is divided into equal parts, and each part is assigned a different phase rotation amount. For example, the Doppler shift amount DOP. ndm Phase rotation amount φ to impart ndm It is assigned as shown in equation (5) below. Note that angles are expressed in radians below.

number

[0071] In equation (5), for example, the Doppler multiplexing number N DM When = 2, the phase rotation amount φ1 = 0 that imparts the Doppler shift amount DOP1, and the phase rotation amount φ2 = π that imparts the Doppler shift amount DOP2. For example, each Doppler shift amount DOP ndm The phase rotation amount φ that imparts ndm They are equally spaced.

[0072] Note that the Doppler shift amounts are DOP1, DOP2, ~, DOP N_DM The assignment of phase rotation amounts to which the Doppler shift amounts are assigned is not limited to this method. For example, using a phase rotation amount assignment table, the Doppler shift amounts DOP1, DOP2, ~, DOP N_DM For the phase rotation amounts φ1, φ2, ~, φ N_DM (However, "N_DM" is N DM (Equivalent to) may be assigned randomly.

[0073] Furthermore, in setting the amount of equally spaced Doppler shift, Δf is given by equation (4). MinInterval = 1 / (T r (N DM +N int )L OC By setting it to ), the following equation (6) may be used to set the amount of phase rotation. Here, N int It takes an integer value.

number

[0074] The encoding unit 107 receives N from the Doppler shift setting unit 106. DM Phase rotation amounts φ1,~,φ that impart individual Doppler shift amounts N_DM For each of them, one or N CM The encoding unit 107 sets a phase rotation amount based on multiple orthogonal code sequences of one or fewer units. The encoding unit 107 also sets a phase rotation amount based on both the Doppler shift amount and the orthogonal code sequences, for example, an "encoded Doppler phase rotation amount" that generates the encoded Doppler multiplexed signal, and outputs it to the phase rotation unit 108.

[0075] The following describes an example of the operation of the encoding unit 107.

[0076] For example, the encoding unit 107 has a code number (e.g., code multiplexing) N consisting of the code length Loc. CM It is preferable to use a code sequence with low or no correlation between its elements; for example, an orthogonal code sequence can be used. Note that the code elements constituting the orthogonal code sequence are not limited to real numbers, but may also include complex values.

[0077] Below, N consists of code length Loc. CM Code a sequence of orthogonal codes ncm ={OC ncm (1), OC ncm (2), ~, OC ncm It is written as (Loc)}. OC ncm (noc) is the nth orthogonal code sequence Code ncm This represents the noc-th sign element in the array. Here, noc is the index of the sign element, and noc = 1 to Loc.

[0078] The orthogonal code sequence used in the coding unit 107 may be, for example, a Walsh-Hadamard code. The coding unit 107 has a code count of N. CM A predetermined code length L capable of generating multiple orthogonal code sequences. OC An orthogonal code sequence is generated using this method.

[0079] For example, N CM When = 2, the code length Loc=2 for the Walsh-Hadamard code is 2, and the orthogonal code sequences are Code1={1,1} and Code2={1,-1}.

[0080] In the encoding unit 107, the ndm-th Doppler shift amount DOP is input from the Doppler shift setting unit 106. ndm When encoding a Doppler multiplexed signal using this method, the code multiplexing number (hereinafter referred to as the encoded Doppler multiplexing number) is "N DOP_CODE This is denoted as "(ndm)". Here, ndm = 1 to N DM That is the case.

[0081] The encoding unit 107, for example, encodes the Doppler multiplexing number N when encoding a Doppler multiplexed signal. DOP_CODE (1), N DOP_CODE (2), ~, and N DOP_CODE (N DM The sum of the Doppler multiplexing numbers N is equal to the number of transmitting antennas Nt used for multiplexing. DOP_CODE The (ndm) is set. This enables the radar device 10 to perform multiplex transmission in the Doppler region and the coding region using Nt transmitting antennas (hereinafter referred to as coded Doppler multiplex transmission).

[0082] Furthermore, the encoding unit 107 uses, for example, an equal-interval Doppler shift amount setting, including a maximum equal-interval Doppler shift amount setting, to encode the Doppler multiplexing number N. DOP_CODE (1), N DOP_CODE (2), ~, N DOP_CODE (N DM Regarding ), 1 or more N CM The settings may include a range of up to 1 different coded Doppler multiplexing numbers. For example, the coding unit 107 may set the code number N for all coded Doppler multiplexing numbers. CM Instead of using individual Doppler shifts, use at least one Doppler shift amount DOP. ndm Corresponding encoding Doppler multiplexing number N DOP_CODE (ndm) to N CM Set it to a value smaller than one. Therefore, the Doppler shift amount DOP ndm In multiple combinations of and orthogonal code sequences, at least one Doppler shift amount DOP ndm The multiplexing number (encoded Doppler multiplexing number) N is determined by the orthogonal code sequence associated with it. DOP_CODE (ndm) may differ from the coded Doppler multiplexing number associated with other Doppler shift amounts. For example, the coding unit 107 sets the coded Doppler multiplexing number for Doppler multiplexed signals to be non-uniform. This setting allows the radar device 10 to individually separate and receive signals transmitted by coded Doppler multiplexing from multiple transmitting antennas over a Doppler range of ±1 / 2 Tr, for example, by aliasing determination processing in the reception processing described later.

[0083] In the m-th transmission period Tr, the symbolization unit 107 sets the coded Doppler phase rotation amount ψ ndm shown in the following equation (7) for the phase rotation amount φ ndm that imparts the n-th Doppler shift amount DOP, and outputs it to the phase rotation unit 108. ndop_code(ndm), ndm (m). [Number]

[0084] Here, the subscript "ndop_code(ndm)" represents the index below the coded Doppler multiplicity N ndm for the phase rotation amount φ ndm that imparts the Doppler shift amount DOP. For example, ndop_code(ndm) = 1, ~, N DOP_CODE (ndm). Also, angle[x] is an operator that outputs the radian phase of the real number x. For example, angle[1] = 0, angle[-1] = π, and angle[j] = π / 2. j is the imaginary unit. DOP_CODE

[0085] For example, as shown in equation (7), the coded Doppler phase rotation amount ψ ndop_code(ndm), ndm (m) makes the phase rotation amount that imparts the Doppler shift amount DOP constant (for example, the first term in equation (7)) during the period of the transmission period corresponding to the code length Loc used for coding, and imparts the phase rotation amount corresponding to each of the Loc code elements OC ndm of the code Code ndop_code(ndm) used for coding (the second term in equation (7)). ndop_code(ndm) (1), ~, OC ndop_code(ndm) (Loc).

[0086] Also, the symbolization unit 107 outputs the orthogonal code element index OC_INDEX to the radar receiving unit 200 (output switching unit 209 described later) for each transmission period (Tr). OC_INDEX is an orthogonal code element index that indicates an element of the orthogonal code sequence Code ndop_code(ndm) , and varies cyclically within the range from 1 to Loc as shown in the following equation (8) for each transmission period (Tr). ​

number

[0087] Here, mod(x, y) is the modulo operator, a function that outputs the remainder after x is divided by y. Also, m = 1 to Nc. Nc is the number of transmission cycles used for radar positioning (hereinafter referred to as the "number of radar transmission signals"). Furthermore, the number of radar transmission signals Nc is set to be an integer multiple (Ncode multiple) of Loc. For example, Nc = Loc × Ncode.

[0088] Next, in the encoding unit 107, the encoding Doppler multiplexing number N for the Doppler multiplexed signal DOP_CODE This section describes one example of how to set (ndm) to be non-uniform.

[0089] For example, the encoding unit 107 has an orthogonal code sequence number (e.g., code multiplexing or code number) N that satisfies the following conditions. CM Set the number of orthogonal code sequences, for example, N. CM and Doppler multiplexing number N DM The following relationship is satisfied for the number of transmitting antennas Nt used in multiplex transmission. (Number of orthogonal code sequences N) CM ) × (Doppler multiplexing number N) DM )> Number of transmitting antennas Nt used for multiplex transmission

[0090] Next, the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm This section explains an example of the (m) setting.

[0091] For example, in the encoding unit 107, the number of transmitting antennas used for multiplex transmission is Nt=3, and the number of Doppler multiplexers is N. DM =2, code multiplex number N CM Let's consider the case where we set =2 and use orthogonal code sequences Code1={1,1} and Code2={1,-1} with code length Loc=2. In this case, for example, as shown in Figure 7, the number of Doppler multiplexing codes is N. DOP_CODE (1) = 1, N DOP_CODE If (2)=2, the encoding unit 107 will have an encoded Doppler phase rotation amount ψ1, 1 (m), ψ 1, 2 (m), ψ 2, 2 Set (m) and output it to the phase rotation unit 108. For example, the encoded Doppler phase rotation amount ψ 1, 1 When (m) is set, the encoding unit 107 makes the following setting (9). In Figure 7, "○" represents the Doppler shift amount and orthogonal code to be used, and "×" represents the Doppler shift amount and orthogonal code to be not used.

number

[0092] Here, as an example, the Doppler shift amount DOP ndm The phase rotation amount that imparts this is φ in equation (5). ndm =2π(ndm-1) / N DM Using a phase rotation amount φ1=0 that imparts a Doppler shift amount DOP1, and a phase rotation amount φ2=π that imparts a Doppler shift amount DOP2, the encoding unit 107 encodes the Doppler phase rotation amount ψ 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 Set (m) and output it to the phase rotation unit 108. Note that the amount of phase rotation may be expressed in the range of radians between 0 and 2π, after performing modulo calculation by 2π.

[0093] For example, regardless of the value of the number of transmitting antennas Nt, the number of phases used for the phase rotation amount may be set to be less than the number of transmitting antennas Nt used for multiplex transmission. Also, the number of phases used for the phase rotation amount that imparts the Doppler shift amount may be set to the number of Doppler shift amounts N used for multiplex transmission. DM It may be made equal to.

[0094] Furthermore, although the above example used the phase rotation amount setting shown for the maximum equally spaced Doppler shift amount setting, the phase rotation amount setting is not limited to this. For example, the phase rotation amount setting shown for the equally spaced Doppler shift amount setting, for example, equation (6), may also be used.

[0095] The above describes how to set the phase rotation amount in the phase rotation amount setting unit 105.

[0096] In Figure 1, the phase rotation unit 108 controls the encoded Doppler phase rotation amount ψ set in the phase rotation amount setting unit 105. ndop_code(ndm), ndm Based on (m), a phase rotation amount is applied to the chirp signal input from the radar transmission signal generation unit 101 for each transmission period Tr. Here, ndm = 1~N DM Therefore, ndop_code(ndm)=1~N DOP_CODE (ndm)

[0097] The outputs from the Nt phase rotation units 108 (for example, called coded Doppler multiplexed signals) are amplified to a specified transmission power and then radiated into space from the Nt transmitting antennas of the transmitting antenna unit 109.

[0098] Note that the following refers to the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm The phase rotation unit 108 that assigns (m) is denoted as "phase rotation unit PROT#[ndop_code(ndm), ndm]". Similarly, the transmitting antenna that radiates the output of the phase rotation unit PROT#[ndop_code(ndm), ndm] into space is also denoted as "transmitting antenna Tx#[ndop_code(ndm), ndm]". Here, ndm = 1 to N DM Therefore, ndop_code(ndm)=1~N DOP_CODE (ndm). Alternatively, the Nt transmitting antennas can also be denoted as Tx#1, Tx#2, ~, Tx#Nt. The coded Doppler phase rotation amount applied to the radar transmission signal transmitted from transmitting antennas Tx#1, Tx#2, ~, Tx#Nt can be related using a pre-known table or similar method. For example, coded Doppler phase rotation amount ψ ndop_code(ndm), ndm The determination (or detection) of (m) makes it possible to determine (or detect) the transmitting antenna.

[0099] For example, in the case shown in Figure 7, the encoding unit 107 controls the encoding Doppler phase rotation amount ψ to the phase rotation unit 108. 1, 1 (m), ψ1, 2 (m), ψ 2, 2 (m) is input for each transmission cycle.

[0100] For example, the phase rotation unit PROT#[1, 1] rotates the chirp signal cp(t) generated by the radar transmission signal generation unit 101 for each transmission period by a phase rotation amount ψ in the mth transmission period. 1, 1 The signal with (m) added exp[jψ 1, 1 (m)]cp(t) is output. Also, the output of the phase rotation unit PROT#[1, 1] is output from the transmitting antenna Tx#[1, 1]. Here, cp(t) represents the chirp signal for each transmission period. Similarly, the output of the phase rotation unit PROT#[1, 2] is output from the transmitting antenna Tx#[1, 2], and the output of the phase rotation unit PROT#[2, 2] is output from the transmitting antenna Tx#[2, 2].

[0101] The above describes the encoded Doppler phase rotation amount ψ. ndop_code(ndm), ndm An example of setting (m) was explained.

[0102] Furthermore, in this embodiment, the encoding Doppler multiplexing number N for Doppler multiplexed signals DOP_CODE When setting (ndm) to non-uniform, the Doppler shift amount DOP ndm and orthogonal code sequence Code ncm In combination with the above, each Doppler shift amount DOP ndm Corresponding orthogonal code sequence Code ncm The number of multiplexings (for example, the coded Doppler multiplexing number N) DOP_CODE (ndm)) can be different.

[0103] Furthermore, in this embodiment, the encoding Doppler multiplexing number N for Doppler multiplexed signals DOP_CODE When setting (ndm) uniformly, the Doppler shift amount DOP ndm and orthogonal code sequence Code ncm In combination with the above, the Doppler shift amount DOP ndm The corresponding orthogonal code sequence Code ncm The number of multiplexings (for example, the coded Doppler multiplexing number N) DOP_CODE(ndm)) can be the same. In this case, the Doppler shift amount DOP ndm The number of combinations of the orthogonal code sequence and the number of transmitting antennas Nt may be equal (for example, N DM ×N CM (You can also use =Nt)

[0104] Furthermore, in this embodiment, the transmitting antennas Tx#1 to Tx#Nt may constitute a multi-beam transmitting radar that includes transmitting antennas for at least two different main beam directions (or beam directions). The transmitting antennas Tx#1 to Tx#Nt may include multiple transmitting antennas corresponding to different beam directions. Also, the transmitting antennas Tx#1 to Tx#Nt may include multiple transmitting antennas corresponding to the same beam direction.

[0105] For example, the phase rotation amount setting unit 105 considers the configuration of transmitting antennas Tx#1 to Tx#Nt with different beam directions and sets a different coded Doppler phase rotation amount ψ for each transmitting antenna from which the chirp signal is transmitted. ndop_code(ndm), ndm (m) may be added to the chirp signal and output. This allows the radar device 10 to separate coded Doppler multiplexed signals even when the received power levels of reflected waves differ significantly between the received signals corresponding to chirp signals transmitted from transmitting antennas with different beam directions, thereby improving the positioning performance and radar detection performance of the radar device 10.

[0106] The following describes an example of the operation of the phase rotation amount setting unit 105 in the radar transmission unit 100 when configuring a multi-beam transmitting radar that includes transmitting antennas with at least two different beam directions.

[0107] In the following explanation, among the multiple beam directions (or beams) used in a multi-beam transmitting MIMO radar, the first beam direction (or beam) will be referred to as "B1," the second beam direction (or beam) as "B2," and so on. Furthermore, for example, the number of multi-beams with different beam directions will be referred to as "NB," and the q-th beam direction (or beam) will be referred to as "Bq." q is an integer value within the number of different beam directions (e.g., the number of multi-beams NB). For example, if the number of multi-beams NB = 2, then q = 1 or 2.

[0108] Also, for example, if the number of transmitting antennas Nt ≥ 3 and the number of Doppler multiplexers N DM ≧2, code multiplex number N CM Let Nt be ≥ 2. <N DM ×N CM That is the case.

[0109] Furthermore, in the transmitting antenna section 109, the number of transmitting antennas corresponding to the beam direction B1 is set to N. B1 Let N be the number of transmitting antennas corresponding to beam direction B2. B2 Let's assume that N B1 +N B2 = Nt. Also, the number of transmitting antennas corresponding to the beam direction Bq is N. Bq Let's assume that N Bq The condition is ≥ 1, and the total number of transmitting antennas in each beam direction Bq is Nt.

[0110] Furthermore, the number of Doppler multiplexers assigned to the transmitting antenna in beam direction B1 is N. DM_B1 This is expressed as follows, and the number of Doppler multiplexers assigned to the transmitting antenna in beam direction B2 is N. DM_B2 This is how it is written. Here, N DM_B1 , N DM_B2 ≤N DM That is the case.

[0111] The phase rotation amount setting unit 105 sets, for example, the encoding Doppler multiplexing number N for a Doppler multiplexed signal. DOP_CODE Set (ndm) to be non-uniform, and encode the Doppler phase rotation amount ψ such that it satisfies the following <Condition 1>. ndop_code(ndm), ndm Set (m). Here, ndm = 1~NDM Therefore, ndop_code(ndm)=1~N DOP_CODE (ndm)

[0112] <Condition 1> For example, the Doppler shift amount and code sequence pattern (e.g., coded Doppler multiplexing pattern) assigned to the transmitting antenna in beam direction B1 are made different from the coded Doppler multiplexing pattern assigned to the transmitting antenna in beam direction B2. For example, the phase rotation amount setting unit 105 sets a coded Doppler phase rotation amount ψ that satisfies the conditions for different Doppler multiplexing patterns (e.g., Doppler shift amount assignment patterns), different code multiplexing patterns (e.g., different code multiplexing numbers between Doppler multiplexed signals), or different patterns of Doppler multiplexing and code multiplexing for each of the transmitting antennas in beam direction B1 and B2. ndop_code(ndm), ndm Set (m).

[0113] For example, the different Doppler multiple pattern conditions may be any one of the following conditions (for example, also called "condition 1A"). (A-1) The Doppler multiplexing numbers corresponding to each beam direction (for example, the Doppler multiplexing numbers of the transmitted signals transmitted from the transmitting antennas in each beam direction) are the same (for example, N DM_B1 =N DM_B2 However, N DM_B1 =N DM_B2 If ≥ 2, it includes different Doppler shift intervals in each beam direction (for example, the interval of the Doppler shift amounts associated with the transmitting antenna in each beam direction). (A-2) The number of Doppler multiplexers differs for each beam direction (N DM_B1 ≠N DM_B2 ). (A-3)N DM_B1 ≥3, N DM_B2 When the value is ≥3, if the Doppler shift intervals for each beam direction include the same Doppler shift interval, the order of the Doppler shift intervals is different (cyclic mismatch).

[0114] Furthermore, for example, the different code multiplexing pattern conditions may be any one of the following conditions (for example, also called "condition 1B"). (B-1) The code interval (e.g., code index interval) assigned to each Doppler multiplexed signal is different (cyclic mismatch). (B-2) The code multiplexing number assigned to each Doppler multiplexed signal is different (cyclic mismatch).

[0115] Furthermore, the phase rotation amount setting unit 105 further sets the encoded Doppler phase rotation amount ψ such that it satisfies the following condition 2. ndop_code(ndm), ndm You may also set (m).

[0116] <Condition 2> Signals transmitted from transmitting antennas in the same beam direction are multiplexed using a code multiplexing number that is non-uniform among the Doppler multiplexed signals, and the code multiplexing number is 1 or greater and N CM This includes any value in the range of -1 or less. For example, in multiple combinations of Doppler shift amounts and code sequences, with respect to at least one transmitting antenna in beam direction B1 and beam direction B2, the code multiplexing number for the code sequence associated with at least one Doppler shift amount is different from the code multiplexing number for the code sequences associated with other Doppler shift amounts.

[0117] For example, in condition 1, A-3, if the values ​​of each of the multiple intervals of the Doppler shift amount assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 are the same (for example, combinations of Doppler shift intervals), then the order on the Doppler frequency axis of the multiple Doppler shift intervals corresponding to the transmitting antenna in beam direction B1 may be different from the order on the Doppler frequency axis of the multiple Doppler shift intervals corresponding to the transmitting antenna in beam direction B2. For example, the combination of intervals included in the array in which the intervals of the Doppler shift amount assigned to the transmitting antenna in beam direction B1 are arranged in ascending order on the Doppler frequency axis is the same as the combination of intervals included in the array in which the intervals of the Doppler shift amount assigned to the transmitting antenna in beam direction B2 are arranged in ascending order on the Doppler frequency axis, and the first array and the second array are different in circular permutations. If condition 1, A-3 is met, the Doppler shift interval of the transmitting antenna in beam direction B1 and the Doppler shift interval of the transmitting antenna in beam direction B2 will not coincide (cyclic mismatch) even if either one is cyclically shifted in the Doppler frequency domain.

[0118] Furthermore, for example, in condition 1, B-1, the order of the code sequences on the Doppler frequency axis corresponding to the transmitting antenna in beam direction B1 may be different from the order of the code sequences on the Doppler frequency axis corresponding to the transmitting antenna in beam direction B2. For example, the array obtained by arranging the indices of the code sequences corresponding to the Doppler shift amounts assigned to the transmitting antenna in beam direction B1 in ascending order on the Doppler frequency axis is different from the array obtained by arranging the indices of the code sequences corresponding to the Doppler shift amounts assigned to the transmitting antenna in beam direction B2 in ascending order on the Doppler frequency axis, in terms of circular permutations. When condition 1, B-1 is satisfied, the indices of the code sequences corresponding to each Doppler shift amount of the transmitting antenna in beam direction B1 and the indices of the code sequences corresponding to each Doppler shift amount of the transmitting antenna in beam direction B2 will not coincide even if either one is cyclically shifted in the Doppler frequency domain (cyclic mismatch occurs).

[0119] Furthermore, for example, in condition 1, B-2, the order of the code multiplex numbers on the Doppler frequency axis based on the code sequence associated with the transmitting antenna in beam direction B1 may be different from the order of the code multiplex numbers on the Doppler frequency axis based on the code sequence associated with the transmitting antenna in beam direction B2. For example, the arrangement of the code multiplex numbers corresponding to the Doppler shift amounts assigned to the transmitting antenna in beam direction B1, arranged in ascending order on the Doppler frequency axis, and the arrangement of the code multiplex numbers corresponding to the Doppler shift amounts assigned to the transmitting antenna in beam direction B2, arranged in ascending order on the Doppler frequency axis, are different in circular permutations. When condition 1, B-2 is satisfied, the code multiplex numbers corresponding to each Doppler shift amount of the transmitting antenna in beam direction B1 and the code multiplex numbers corresponding to each Doppler shift amount of the transmitting antenna in beam direction B2 will not coincide (a cyclic mismatch will occur) even if either one is cyclically shifted in the Doppler frequency domain.

[0120] By setting the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105 to satisfy condition 1, the radar device 10 can separate Doppler multiplexed signals even when the received power levels of reflected waves differ significantly between received signals from transmitting antennas with different beam directions, thereby suppressing degradation of positioning performance and radar detection performance (examples will be described later).

[0121] Furthermore, by satisfying condition 2 when the coding Doppler phase rotation amount is set by the phase rotation amount setting unit 105, the detectable Doppler frequency range in the radar device 10 becomes -1 / (2Tr) ≤ fd < 1 / (2Tr), which can be expanded to a range equivalent to the Doppler detection range in the case of a single transmitting antenna (an example will be described later).

[0122] For example, in coded Doppler multiplexing by radar device 10, both conditions 1 and 2 may be satisfied, or condition 1 may be satisfied but condition 2 may not be satisfied. For example, the following three cases can be given in which condition 1 is satisfied but condition 2 is not.

[0123] (Case 1) Case 1 is the case where neither beam direction B1 nor beam direction B2 satisfies condition 2. In Case 1, the detectable Doppler frequency range fd depends on the target direction and is in the range of -1 / (2Tr)≦fd <1 / (2Tr), -1 / (2Loc N DM_B1 Tr)≦fd < 1 / (2Loc N DM_B1 The range of Tr), or -1 / (2Loc N) DM_B2 Tr)≦fd < 1 / (2Loc N DM_B2 The range is Tr). Here, if the Doppler multiplexed signal assigned between transmitting antennas in beam direction B1 does not include unused codes, then N DM_B1 =N B1 / Loc, and the detectable Doppler frequency range fd is -1 / (2 N B1 Tr)≦fd < 1 / (2 N B1 The range is Tr). Similarly, the Doppler multiplexed signal assigned between transmitting antennas in beam direction B2 will not contain any unused codes, N DM_B2 =N B2 / Loc, and the detectable Doppler frequency range fd is -1 / (2 N B2 Tr)≦fd <1 / (2 N B2 This falls within the range of Tr).

[0124] (Case 2) Case 2 is the case where the beam direction B2 does not satisfy condition 2. In Case 2, the detectable Doppler frequency range fd depends on the target direction and is in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr), or -1 / (2Loc N DM_B2 Tr)≦fd < 1 / (2Loc N DM_B2 The range is Tr). For example, if the Doppler multiplexed signal assigned between transmitting antennas in beam direction B2 does not include unused codes, then N DM_B2 =N B2 / Loc, and the detectable Doppler frequency range fd is -1 / (2 N B2 Tr)≦fd < 1 / (2 N B2 This falls within the range of Tr).

[0125] (Case 3) Case 3 is the case where the beam direction B1 does not satisfy condition 2. In Case 3, the detectable Doppler frequency range fd depends on the target direction and is in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr), or -1 / (2Loc N DM_B1 Tr)≦fd < 1 / (2Loc N DM_B1 The range is Tr). For example, if the Doppler multiplexed signal assigned between transmitting antennas in beam direction B1 does not include unused codes, then N DM_B1 =N B1 / Loc, and the detectable Doppler frequency range fd is -1 / (2 N B1 Tr)≦fd < 1 / (2 N B1 This falls within the range of Tr).

[0126] In any of cases 1 to 3, the detectable Doppler frequency range is the Doppler detection range in the case of equally spaced Doppler multiplexing - 1 / (2 N t Tr)≦fd < 1 / (2 N t It can be magnified more than Tr).

[0127] The following describes an example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105. In the following, the interval between the Doppler shift amounts applied to Tx#n1 and Tx#n2 will be denoted as the Doppler shift interval "Δfd(n1, n2)". Here, Δfd(n1, n2) is the Doppler shift amount DOP applied to Tx#n1. n1 The Doppler shift amount DOP assigned to Tx#n2 based on n2 interval (DOP n2 -DOP n1 This represents the case where the Doppler shift interval Δfd(n1, n2) is negative (for example, (DOP n2 -DOP n1 If () < 0, the Doppler shift interval Δfd(n1, n2) is calculated using Δfd(n1, n2) = 1 / (Loc Tr) - Δfd(n1, n2), considering the folding in the range of -1 / (2 Loc Tr) and less than 1 / (2 Loc Tr), which is the observation range of the Doppler analysis unit, and is expressed as a positive value.

[0128] <Configuration Example 1> Example setting 1 shows examples of setting the coding Doppler phase rotation amount when condition 1 (when different code multiplexing pattern conditions are met) and when condition 2 is met.

[0129] Figure 8 shows the number of transmitting antennas Nt=4, N B1 =2, N B2 An example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 when = 2 is shown.

[0130] In Figure 8, Tx#1 and Tx#2 are transmitting antennas in beam direction B1, and Tx#3 and Tx#4 are transmitting antennas in beam direction B2. In Figure 8, the shaded circles indicate the assignment of coded Doppler multiplexed signals to the transmitting antennas in beam direction B1 (Tx#1 and Tx#2), and the white circles indicate the assignment of coded Doppler multiplexed signals to the transmitting antennas in beam direction B2 (Tx#3 and Tx#4).

[0131] Furthermore, in Figure 8, the Doppler multiplexing number N DM =3, and the Doppler shift setting unit 106 may set the three Doppler shift amounts DOP1, DOP2, and DOP3 using, for example, the maximum equally spaced Doppler shift amount setting shown in equation (5). In Figure 8, the phase rotation amount φ1=0 that assigns a Doppler shift amount DOP1=0, the phase rotation amount φ2=2π / 3 that assigns a Doppler shift amount DOP2=Δfd, and the phase rotation amount φ3=4π / 3 (φ3=-2π / 3) that assigns a Doppler shift amount DOP3=-Δfd. As shown in Figure 8, the intervals between Doppler multiplexed signals (also called Doppler multiplexing intervals, Doppler shift intervals, or Doppler intervals) Δfd are equally spaced, and Δfd=1 / (6Tr).

[0132] Furthermore, in Figure 8, the code multiplexing number N CM =2, and the encoding unit 107 uses, for example, an orthogonal code sequence with code length Loc=2 of Walsh-Hadamard coding, such as Code1={1,1} and Code2={1,-1}. Note that the following setting examples 2 to 5 also use code multiplexing N. CM= 2, and we use the same sign.

[0133] In Figure 8, the number of transmitting antennas Nt = 4, and the number of Doppler multiplexers N DM =3, code multiplex number N CM = 2, Nt <N DM ×N CM Therefore, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (ndm) can be set non-uniformly (where ndm = 1 to N) DM ).

[0134] As shown in Figure 8, in the encoding unit 107, the setting of the number of encoded Doppler multiplexings for a Doppler multiplexed signal using the three Doppler shift amounts DOP1, DOP2, and DOP3 input from the Doppler shift setting unit 106 is, respectively, N DOP_CODE (1) = 1, N DOP_CODE (2) = 1, N DOP_CODE (3) = 2. Thus, the phase rotation amount setting unit 105 sets the number of encoded Doppler multiplexings for the Doppler multiplexed signal to N DOP_CODE (1) = N DOP_CODE (2) ≠ N DOP_CODE (3) Set to non-uniform.

[0135] Furthermore, in Figure 8, the Doppler shift setting unit 106 sets the Doppler multiplexing number N for the transmitting antennas Tx#1 and Tx#2 in beam direction B1. DM Among the Doppler multiplexed signals with =3, for example, assign a Doppler multiplexed signal using Doppler shift amounts DOP1 and DOP3 (N DM_B1 =2). The encoding unit 107 also assigns Code2 and Code1 to the Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP3 assigned to the transmitting antennas Tx#1 and Tx#2 in beam direction B1. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#1 and Tx#2 in beam direction B1. 2, 1 (m), ψ 1, 3 Set (m).

[0136] Furthermore, in Figure 8, the Doppler shift setting unit 106 sets the Doppler multiplexing number N for the transmitting antennas Tx#3 and Tx#4 in beam direction B2. DM Among the Doppler multiplexed signals with =3, for example, assign Doppler multiplexed signals using Doppler shift amounts DOP2 and DOP3 (N DM_B2 =2). The encoding unit 107 also assigns Code2 and Code2 respectively to the Doppler multiplexed signals using the Doppler shift amounts DOP2 and DOP3 assigned to the transmitting antennas Tx#3 and Tx#4 in beam direction B2. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#3 and Tx#4 in beam direction B2. 2, 2 (m), ψ 2, 3 Set (m).

[0137] In Figure 8, the Doppler multiplexing number assigned by the Doppler shift setting unit 106 to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 is N DM_B1 =N DM_B2 = 2, and they are identical. Also, the Doppler intervals of the Doppler multiplexed signals assigned to transmitting antennas Tx#1 and Tx#2 in beam direction B1 are Δfd(1,2)=2Δfd and Δfd(2,1)=Δfd, and the Doppler intervals of the Doppler multiplexed signals assigned to transmitting antennas Tx#3 and Tx#4 in beam direction B2 are Δfd(3,4)=Δfd and Δfd(4,3)=2Δfd, and they are identical.

[0138] Therefore, the setting of the encoded Doppler phase rotation amount shown in Figure 8 does not match any of the different Doppler multiplexing pattern conditions of condition 1A.

[0139] Furthermore, in Figure 8, the codes assigned to the transmitting antenna in beam direction B1 for each of the Doppler multiplexed signals using Doppler shift amounts DOP1, DOP2, and DOP3 are [Code2, No assignment, Code1], and the code multiplexing number assigned to each Doppler multiplexed signal is 0 or 1.

[0140] Hereafter, the code index assigned to a transmitting antenna with beam direction B1 for each Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP3 will be written as "CodeIndex_B1=(2,*,1)". In CodeIndex_B1, "*" indicates that no code is assigned. If multiple codes are assigned to a single Doppler multiplexed signal, this is represented using "&". For example, if Code1 and Code2 are assigned to a single Doppler multiplexed signal, it will be written as "1&2". The code index is also called the "code interval".

[0141] Furthermore, from now on, the code multiplexing number assigned to the transmitting antenna in beam direction B1 for each Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP3 will be described as "N_Code_B1=(1,0,1)" (in the case of Figure 8).

[0142] In Figure 8, the code assigned to the transmitting antenna in beam direction B2 for each Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP3 is [No assignment, Code2, Code2], and the code multiplexing number assigned to each Doppler multiplexed signal is 0 or 1. Similar to beam direction B1, the code index assigned to the transmitting antenna in beam direction B2 for each Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP3 is denoted as "CodeIndex_B2=(*,2,2)". Furthermore, the code multiplexing number assigned to the transmitting antenna in beam direction B2 for each Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP3 is denoted as "N_Code_B2=(0,1,1)".

[0143] Thus, for the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2, the code multiplexing numbers assigned to each Doppler multiplexed signal are N_Code_B1=(1,0,1) and N_Code_B2=(0,1,1), which result in cyclic matching and therefore do not satisfy condition B-2 of condition 1.

[0144] On the other hand, the code indices assigned to each Doppler multiplexed signal for the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 are CodeIndex_B1=(2,*,1) and CodeIndex_B2=(*,2,2), which are different (or result in a cyclic mismatch; hereafter, this will also be expressed as having different code index intervals).

[0145] Furthermore, when the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210, described later, observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1_alias=(1,*,2) and CodeIndex_B2_alias=(*,1,1), which are different (a cyclic mismatch). Therefore, in the example of Figure 8, in the range where the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), the code indices are cyclic mismatched and the code intervals are different. Consequently, since the code intervals assigned to each Doppler multiplexed signal are different across the multibeams, condition B-1 of condition 1 is satisfied, and the different code multiplexing pattern conditions are met.

[0146] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 8 is an example of a setting that satisfies condition 1.

[0147] Furthermore, in Figure 8, the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B1 is N_Code_B1=(1,0,1), and the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B2 is N_Code_B2=(0,1,1). In both cases, the Doppler multiplexed signals are multiplexed with a code multiplexing number that is non-uniform between the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less.

[0148] Therefore, in the example in Figure 8, signals transmitted from transmitting antennas in the same beam direction (for example, beam directions B1 and B2) are multiplexed with a code multiplexing number that is non-uniform between the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less. Therefore, the coding Doppler phase rotation setting shown in Figure 8 is an example setting that satisfies condition 2 in both beam direction B1 and beam direction B2.

[0149] The following describes an example of a received signal at the output of the Doppler analysis unit 210 when the transmitting antenna unit 109 includes transmitting antennas with beam directions B1 and B2 based on the setting of the encoded Doppler phase rotation amount shown in Figure 8, and the receiving antenna unit 202 is an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both transmitting antennas with beam directions B1 and B2).

[0150] Figure 9 shows an example of the output of the Doppler analysis unit 210 of a target reflected wave at a certain distance index. For example, the target reflected wave has fd target The Doppler frequency of the target is included. Therefore, the radar device 10 uses the Doppler shift amount set in the radar transmitter 100 to determine fd target The signal is received after undergoing a Doppler shift of 1 minute. In Figure 9, as an example, the Doppler frequency fd of the target reflection wave is shown. target If =0, and fd target Let's show the case where =1 / (2Tr).

[0151] Figure 10 also shows an example of a multi-beam transmitting MIMO radar (e.g., radar device 10) that forms transmitting beams in beam direction B1 (Tx Beam #1) and beam direction B2 (Tx Beam #2).

[0152] For example, when the target direction is target direction (1) as shown in Figure 10 (for example, when a target exists around beam direction B1), the radiation direction of the radar transmitted waves sent from Tx#1 and Tx#2 in beam direction B1 coincides with the target direction. Therefore, as shown in Figure 9(a), the reception level of the received signals of reflected waves from targets corresponding to Tx#1 and Tx#2 in the radar device 10 is relatively high. On the other hand, when the target direction is target direction (1) as shown in Figure 10, the radiation direction of the radar transmitted waves sent from Tx#3 and Tx#4 in beam direction B2 does not coincide with the target direction, and the target direction corresponds to the null direction of the transmitting beam B2. Therefore, as shown in Figure 9(a), the reception level of the received signals of reflected waves from targets corresponding to Tx#3 and Tx#4 in the radar device 10 is lower than the reception level of the received signals corresponding to each transmitting antenna (e.g., Tx#1, Tx#2) in beam direction B1. For example, as shown in Figure 9(a), the received levels of the received signals corresponding to Tx#3 and Tx#4 differ significantly from those of the received signals corresponding to Tx#1 and Tx#2, and can be 10 dB or more lower, depending on the null-direction beam directivity characteristics of Tx#3 and Tx#4. In Figure 9, the size of the shaded or white circles represents the received power. Smaller circles indicate lower received power compared to larger circles (for example, received power as low as the noise level).

[0153] Furthermore, for example, if the target direction is an intermediate direction between beam direction B1 and beam direction B2, and the target direction is an area direction where the beam widths of both beams overlap by approximately 3 dB or 6 dB (for example, target direction (2) shown in Figure 10), then, as shown in Figure 9(b), the received levels of the received signals (reflected waves of the radar transmission) corresponding to Tx#1 and Tx#2 in beam direction B1 and the received levels of the received signals (reflected waves of the radar transmission) corresponding to Tx#3 and Tx#4 in beam direction B2 are approximately the same.

[0154] Furthermore, for example, if the target direction is target direction (3) as shown in Figure 10 (for example, if a target exists around beam direction B2), the radiation direction of the radar transmitted waves sent from Tx#3 and Tx#4 in beam direction B2 coincides with the target direction. Therefore, as shown in Figure 9(c), the reception level of the received signals of reflected waves from targets corresponding to Tx#3 and Tx#4 in the radar device 10 is relatively high. On the other hand, if the target direction is target direction (3) as shown in Figure 10, the radiation direction of the radar transmitted waves sent from Tx#1 and Tx#2 in beam direction B1 does not coincide with the target direction, and the target direction corresponds to the null direction of the transmitting beam B1. Therefore, as shown in Figure 9(c), the reception level of the received signals of reflected waves from targets corresponding to Tx#1 and Tx#2 in the radar device 10 is lower than the reception level of the received signals corresponding to each transmitting antenna (e.g., Tx#3, Tx#4) in beam direction B2. For example, as shown in Figure 9(c), the received signal levels corresponding to Tx#1 and Tx#2 differ significantly from those corresponding to Tx#3 and Tx#4, and can be 10 dB or more lower depending on the null beam directivity characteristics of Tx#1 and Tx#2.

[0155] For example, as shown in Figure 9(b), when the target direction is an intermediate direction between beam direction B1 and beam direction B2 (target direction (2) shown in Figure 10), the radar device 10 receives the received signals corresponding to the transmitting antennas in each beam direction at approximately the same reception level. Therefore, the signals transmitted from Nt transmitting antennas, including the transmitting antennas in beam direction B1 and beam direction B2, are transmitted using known encoded Doppler multiplexing signal settings. Thus, the radar device 10 can separate the encoded Doppler multiplexed signals based on existing encoded Doppler multiplexing signal separation operations. Existing encoded Doppler multiplexing signal separation operations are disclosed, for example, in Patent Documents 5 and 6. The same applies to the following embodiments.

[0156] Furthermore, as shown in Figure 9(a), when the target direction is beam direction B1 (target direction (1) shown in Figure 10), and as shown in Figure 9(c), when the target direction is beam direction B2 (target direction (3) shown in Figure 10), the radar device 10 receives two Doppler multiplexed signals with similar Doppler intervals. For this reason, it is difficult for the radar device 10 to distinguish between Doppler multiplexed signals based on the amount of Doppler shift. On the other hand, as shown in Figures 9(a) and (c), the coded multiplexed signals for the Doppler multiplexed signals are different (for example, the code intervals are different and condition B-1 of 1 is satisfied), so the radar device 10 receives different coded Doppler multiplexed signals in Figures 9(a) and (c).

[0157] As a result, when the target direction is beam direction B1 or B2, the radar device 10 can distinguish in the coded Doppler multiplexing / decoupling unit 212 (described later) whether the received level of the received signal corresponding to the transmitting antenna in beam direction B1 decreases or whether the received level of the received signal corresponding to the transmitting antenna in beam direction B2 decreases.

[0158] Furthermore, if this determination result indicates that the signal is a received signal from the transmitting antenna (Tx#1, Tx#2) in beam direction B1, the settings for the encoded Doppler multiplexed signals for Tx#1 and Tx#2 in beam direction B1 are known, so the radar device 10 can separate the multiplexed signals by, for example, the operation disclosed in Patent Documents 5 and 6. Similarly, if the signal is a received signal from the transmitting antenna (Tx#3, Tx#4) in beam direction B2, the settings for the encoded Doppler multiplexed signals for Tx#3 and Tx#4 in beam direction B2 are known, so the radar device 10 can similarly separate the multiplexed signals.

[0159] Furthermore, by setting the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105, and satisfying condition 2 in addition to condition 1, the Doppler detection range can be expanded to the same range as when using one transmitting antenna (a range of ±1 / (2Tr)) (an example will be described later).

[0160] Through the operation of the coded Doppler multiplexing / decompression unit 212, the radar device 10 can determine the Doppler frequency fd of the target within the range of -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each coded Doppler multiplexed signal.

[0161] <Setting Example 2> Example 2 of the settings is an example of setting the coding Doppler phase rotation amount when condition 1 (when different code multiplexing pattern conditions are met) and when condition 2 is met.

[0162] Figure 11 shows the number of transmitting antennas Nt=6, N B1 =3, N B2 An example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 when =3 is shown.

[0163] In Figure 11, Tx#1 to #3 are transmitting antennas in beam direction B1, and Tx#4 to #6 are transmitting antennas in beam direction B2. In Figure 11, the shaded circles indicate the assignment of coded Doppler multiplexed signals for the transmitting antennas in beam direction B1 (Tx#1 to #3), and the white circles indicate the assignment of coded Doppler multiplexed signals for the transmitting antennas in beam direction B2 (Tx#4 to #6).

[0164] Furthermore, in Figure 11, the Doppler multiplexing number N DM = 4, and the Doppler shift setting unit 106 may set the four Doppler shift amounts DOP1=0, DOP2=Δfd, DOP3=-2Δfd, and DOP4=-Δfd using, for example, the maximum equally spaced Doppler shift amount setting shown in equation (5). In Figure 11, the phase rotation amounts that impart the Doppler shift amounts DOP1 to DOP4 are φ1=0, φ2=π / 4, φ3=π / 2, and φ2=3π / 4, respectively. As shown in Figure 11, the Doppler multiple spacing Δfd is equally spaced, and Δfd=1 / (8Tr).

[0165] In Figure 11, the number of transmitting antennas Nt = 6, and the number of Doppler multiplexers N DM =4, code multiplex number N CM = 2, N t <NDM ×N CM Therefore, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (ndm) can be set non-uniformly (where ndm = 1 to N) DM ).

[0166] As shown in Figure 11, in the encoding unit 107, the setting of the number of encoded Doppler multiplexings for a Doppler multiplexed signal using the four Doppler shift amounts DOP1 to DOP4 input from the Doppler shift setting unit 106 is, for each case, N DOP_CODE (1) = 2, N DOP_CODE (2) = 1, N DOP_CODE (3) = 2, N DOP_CODE (4) = 1. Thus, the phase rotation amount setting unit 105 sets the number of encoded Doppler multiplexings for the Doppler multiplexed signal to N DOP_CODE (1) ≠ N DOP_CODE (2), or N DOP_CODE (3) ≠ N DOP_CODE (4) Set it to be non-uniform.

[0167] Furthermore, in Figure 11, for the transmitting antennas Tx#1~#3 in the beam direction B1, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DM Among the Doppler multiplexed signals with =4, for example, assign a Doppler multiplexed signal using Doppler shift amounts DOP1, DOP3, and DOP4 (N DM_B1 =3). The encoding unit 107 also assigns Code1, Code1, and Code2 respectively to Doppler multiplexed signals using Doppler shift amounts DOP1, DOP3, and DOP4. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#1 to #3 in beam direction B1. 1, 1 (m), ψ 1,3 (m), ψ 2, 4 Set (m).

[0168] Furthermore, in Figure 11, for transmitting antennas Tx#4~#6 in beam direction B2, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DMAmong the Doppler multiplexed signals with =4, for example, assign a Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP3 (N DM_B2 =3). The encoding unit 107 also assigns Code2, Code2, and Code2 respectively to Doppler multiplexed signals using Doppler shift amounts DOP1, DOP2, and DOP3. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#4 to #6 in beam direction B2. 2, 1 (m), ψ 2, 2 (m), ψ 2, 3 Set (m).

[0169] In Figure 11, the Doppler multiplexing number assigned by the Doppler shift setting unit 106 to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 is N DM_B1 =N DM_B2 = 3, which is the same. Also, the Doppler intervals of the Doppler multiplexed signals assigned to the transmitting antennas Tx#1~#3 in beam direction B1 are Δfd(1,3)=2Δfd, Δfd(3,4)=Δfd, and Δfd(4,1)=Δfd, and the Doppler intervals of the Doppler multiplexed signals assigned to the transmitting antennas Tx#4~#6 in beam direction B2 are Δfd(1,2)=Δfd, Δfd(2,3)=Δfd, and Δfd(3,1)=2Δfd, which are the same (cyclic coincidence).

[0170] Therefore, the encoding Doppler phase rotation amount setting shown in Figure 11 does not match any of the different Doppler multiplexing pattern conditions of condition 1A.

[0171] Furthermore, in Figure 11, the code indices assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1 to DOP4 are CodeIndex_B1=(1,*,1,2) and CodeIndex_B2=(2,2,2,*), respectively. This results in a cyclic mismatch, and since the code index intervals are different, condition B-1 of condition 1 is satisfied.

[0172] Furthermore, in Figure 11, the code multiplexing numbers assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1 to DOP4 are N_Code_B1=(1,0,1,1) and N_Code_B2=(1,1,0,1). This results in cyclic agreement, and since the code multiplexing numbers are the same, condition B-2 of condition 1 is not satisfied.

[0173] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210, described later, observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1_alias=(2,*,2,1) and CodeIndex_B2_alias=(1,1,1,*), which are different (a cyclic mismatch). Therefore, in the example in Figure 11, within the range of the target's Doppler frequency being -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), the code indices are cyclic mismatched and the code intervals are different. Thus, condition B-1 of condition 1 is satisfied, and the different code multiplexing pattern conditions are met.

[0174] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 11 is an example of a setting that satisfies condition 1.

[0175] Furthermore, in Figure 11, the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B1 is N_Code_B1=(1,0,1,1), and the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B2 is N_Code_B2=(1,1,0,1). In both cases, the Doppler multiplexed signals are multiplexed with a code multiplexing number that is non-uniform between the signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less.

[0176] Therefore, in the example in Figure 11, signals transmitted from transmitting antennas in the same beam direction (for example, beam directions B1 and B2) are multiplexed with a code multiplexing number that is non-uniform between the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less. Therefore, the coding Doppler phase rotation setting shown in Figure 11 is an example setting that satisfies condition 2 in both beam direction B1 and beam direction B2.

[0177] The following describes an example of a received signal at the output of the Doppler analysis unit 210 when the transmitting antenna unit 109 includes transmitting antennas with different beam directions B1 and B2 based on the Doppler shift amount setting shown in Figure 11, and the receiving antenna unit 202 is an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both transmitting antennas in beam direction B1 and beam direction B2).

[0178] For example, when the target direction is target direction (1) shown in Figure 10 (for example, when a target exists around beam direction B1), or when the target direction is target direction (3) shown in Figure 10 (for example, when a target exists around beam direction B2), the number of Doppler multiplexed signals, the code interval, and the code multiplexing number differ between the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B1. Therefore, the radar device 10 can distinguish between a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B1 and a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B2 using the coded Doppler multiplexing / decompression unit 212, which will be described later.

[0179] Furthermore, if this determination result determines that the signal is a received signal from the transmitting antenna (Tx#1~#3) in beam direction B1, the settings for the encoded Doppler multiplexed signals for Tx#1~#3 in beam direction B1 are known, so the radar device 10 can separate the multiplexed signals by, for example, the operation disclosed in Patent Documents 5, 6, etc. Similarly, if the signal is a received signal from the transmitting antenna (Tx#4~#6) in beam direction B2, the settings for the encoded Doppler multiplexed signals for Tx#4~#6 in beam direction B2 are known, so the radar device 10 can similarly separate the multiplexed signals.

[0180] Furthermore, by setting the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105, and satisfying condition 2 in addition to condition 1, the Doppler detection range can be expanded to the same range as when using one transmitting antenna (a range of ±1 / (2Tr)) (an example will be described later).

[0181] Through the operation of the coded Doppler multiplexing / decompression unit 212, the radar device 10 can determine the Doppler frequency fd of the target within the range of -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each coded Doppler multiplexed signal.

[0182] <Setting Example 3> Example 3 of the settings is an example of setting the encoded Doppler phase rotation amount when condition 1 (when different code multiplexing pattern conditions and Doppler multiplexing pattern conditions are met) and when condition 2 is met.

[0183] Figure 12 shows the number of transmitting antennas Nt=6, N B1 =3, N B2 An example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 when =3 is shown.

[0184] In Figure 12, Tx#1 to #3 are transmitting antennas in beam direction B1, and Tx#4 to #6 are transmitting antennas in beam direction B2. In Figure 12, the shaded circles indicate the assignment of coded Doppler multiplexed signals to the transmitting antennas in beam direction B1 (Tx#1 to #3), and the white circles indicate the assignment of coded Doppler multiplexed signals to the transmitting antennas in beam direction B2 (Tx#4 to #6).

[0185] Furthermore, in Figure 12, the Doppler multiplexing number N DM = 4, and the Doppler shift setting unit 106 may set the four Doppler shift amounts DOP1 to DOP4 using, for example, the maximum equally spaced Doppler shift amount setting shown in equation (5). In Figure 12, the phase rotation amounts that impart Doppler shift amounts DOP1=0, DOP2=Δfd, DOP3=-2Δfd, and DOP4=-Δfd are φ1=0, φ2=π / 4, φ3=π / 2, and φ2=3π / 4, respectively. As shown in Figure 12, the Doppler multiple spacing Δfd is equally spaced, and Δfd=1 / (8Tr).

[0186] In Figure 12, the number of transmitting antennas Nt = 6, and the number of Doppler multiplexers N DM =4, code multiplex number N CM = 2, N t <N DM ×N CM Therefore, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (ndm) can be set non-uniformly (where ndm = 1 to N) DM ).

[0187] As shown in Figure 12, in the encoding unit 107, the setting of the number of encoded Doppler multiplexings for a Doppler multiplexed signal using the four Doppler shift amounts DOP1 to DOP4 input from the Doppler shift setting unit 106 is, respectively, N DOP_CODE (1) = 2, N DOP_CODE (2) = 1, N DOP_CODE (3) = 2, N DOP_CODE (4) = 1. Thus, the phase rotation amount setting unit 105 sets the number of encoded Doppler multiplexings for the Doppler multiplexed signal to N DOP_CODE (1) ≠ NDOP_CODE (2), or N DOP_CODE (3) ≠ N DOP_CODE (4) Set it to be non-uniform.

[0188] Furthermore, in Figure 12, for the transmitting antennas Tx#1~#3 in beam direction B1, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DM Among the Doppler multiplexed signals with =4, for example, assign a Doppler multiplexed signal using Doppler shift amounts DOP1 and DOP3 (N DM_B1 =2). The encoding unit 107 also assigns Code1, Code1, and Code2 respectively to Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP3 (for example, using two codes). For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#1 to #3 in beam direction B1. 1, 1 (m), ψ 1,3 (m), ψ 2, 3 Set (m).

[0189] Furthermore, in Figure 12, for the transmitting antennas Tx#4~#6 in beam direction B2, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DM Among the Doppler multiplexed signals with =4, for example, assign a Doppler multiplexed signal using Doppler shift amounts DOP1, DOP2, and DOP4 (N DM_B2 =3). The encoding unit 107 also assigns Code2, Code2, and Code2 respectively to Doppler multiplexed signals using Doppler shift amounts DOP1, DOP2, and DOP4 (for example, using one code). For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#4 to #6 in beam direction B2. 2, 1 (m), ψ 2, 2 (m), ψ 2, 4 Set (m).

[0190] In Figure 12, the Doppler multiplexing number assigned by the Doppler shift setting unit 106 to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 is N DM_B1 =2, N DM_B2Since these are different Doppler multiple numbers equal to 3, condition A-2 of condition 1 is satisfied.

[0191] Furthermore, in Figure 12, the code indices assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1 to DOP4 are CodeIndex_B1=(1,*,1&2,*) and CodeIndex_B2=(2,2,*,2), which are cyclic mismatches and have different code index intervals, thus satisfying condition B-1 of condition 1.

[0192] Furthermore, in Figure 12, the code multiplexing numbers assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1 to DOP4 are N_Code_B1=(1,0,2,0) and N_Code_B2=(1,1,0,1). Since the code multiplexing numbers are different, condition B-2 of condition 1 is satisfied.

[0193] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210, described later, observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1_alias=(2,*,1&2,*) and CodeIndex_B2_alias=(1,1,*,1), which are different (a cyclic mismatch). Therefore, in the example in Figure 12, within the range of the target's Doppler frequency -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), the code indices are cyclic mismatched and the code intervals are different. Thus, condition B-1 of condition 1 is satisfied, and the different code multiplexing pattern conditions are met.

[0194] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 12 is an example of a setting that satisfies condition 1.

[0195] Furthermore, in Figure 12, the code multiplexing numbers assigned to each Doppler multiplexed signal at the respective transmitting antennas in beam direction B1 and beam direction B2 are N_Code_B1=(1,0,2,0) and N_Code_B2=(1,1,0,1). Therefore, in the example in Figure 12, signals transmitted from transmitting antennas in the same beam direction are multiplexed with a code multiplexing number that is non-uniform among the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less. Therefore, the coding Doppler phase rotation setting shown in Figure 12 is an example setting that satisfies condition 2 in both beam direction B1 and beam direction B2.

[0196] The following describes an example of a received signal at the output of the Doppler analysis unit 210 when the transmitting antenna unit 109 includes transmitting antennas with different beam directions B1 and B2 based on the Doppler shift amount setting shown in Figure 12, and the receiving antenna unit 202 is an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both transmitting antennas in beam direction B1 and beam direction B2).

[0197] For example, when the target direction is target direction (1) shown in Figure 10 (for example, when a target exists around beam direction B1), or when the target direction is target direction (3) shown in Figure 10 (for example, when a target exists around beam direction B2), the number of Doppler multiplexed signals, the code interval, and the code multiplexing number differ between the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B1. Therefore, the radar device 10 can distinguish between a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B1 and a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B2 using the coded Doppler multiplexing / decompression unit 212, which will be described later.

[0198] Furthermore, if this determination result determines that the signal is a received signal from the transmitting antenna (Tx#1~#3) in beam direction B1, the settings for the encoded Doppler multiplexed signals for Tx#1~#3 in beam direction B1 are known, so the radar device 10 can separate the multiplexed signals by, for example, the operation disclosed in Patent Documents 5, 6, etc. Similarly, if the signal is a received signal from the transmitting antenna (Tx#4~#6) in beam direction B2, the settings for the encoded Doppler multiplexed signals for Tx#4~#6 in beam direction B2 are known, so the radar device 10 can similarly separate the multiplexed signals.

[0199] Furthermore, by setting the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105, and satisfying condition 2 in addition to condition 1, the Doppler detection range can be expanded to the same range as when using one transmitting antenna (a range of ±1 / (2Tr)) (an example will be described later).

[0200] Through the operation of the coded Doppler multiplexing / decompression unit 212, the radar device 10 can determine the Doppler frequency fd of the target within the range of -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each coded Doppler multiplexed signal.

[0201] <Setting Example 4> Example setting 4 is an example of setting the coding Doppler phase rotation amount when condition 1 (different code multiplexing pattern condition) is met but condition 2 is not met.

[0202] Figure 13 shows the number of transmitting antennas Nt=3, N B1 =2, N B2 An example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 when = 1 is shown.

[0203] In Figure 13, Tx#1 and Tx#2 are transmitting antennas in beam direction B1, and Tx#3 is a transmitting antenna in beam direction B2. In Figure 13, the shaded circles indicate the coding Doppler multiplexed signal assignments for the transmitting antennas in beam direction B1 (Tx#1 and Tx#2), and the white circles indicate the coding Doppler multiplexed signal assignments for the transmitting antenna in beam direction B2 (Tx#3).

[0204] Furthermore, in Figure 13, the Doppler multiplexing number N DM = 2, and the Doppler shift setting unit 106 may set the two Doppler shift amounts DOP1 and DOP2 using, for example, the maximum equally spaced Doppler shift amount setting shown in equation (5). In Figure 13, the phase rotation amount φ1 = 0 that assigns a Doppler shift amount DOP1 = 0, and the phase rotation amount φ2 = π that assigns a Doppler shift amount DOP2 = -Δfd. As shown in Figure 13, the Doppler multiple spacing Δfd is equally spaced, and Δfd = 1 / (4Tr).

[0205] In Figure 13, the number of transmitting antennas Nt = 3, and the number of Doppler multiplexers N DM =2, code multiplex number N CM = 2, N t <N DM ×N CM Therefore, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (ndm) can be set non-uniformly (where ndm = 1 to N) DM ).

[0206] As shown in Figure 13, in the encoding unit 107, the number of encoded Doppler multiplexings for a Doppler multiplexed signal using two Doppler shift amounts DOP1 and DOP2 input from the Doppler shift setting unit 106 is N, respectively. DOP_CODE (1) = 1, N DOP_CODE (2)=2. Thus, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (1) ≠ N DOP_CODE (2) Set to non-uniform.

[0207] Furthermore, in Figure 13, for the transmitting antennas Tx#1 and Tx#2 in beam direction B1, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DM Among the Doppler multiplexed signals with =2, for example, assign Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP2 (N DM_B1 =2). The encoding unit 107 also assigns Code1 and Code1 to the Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP2 assigned to the transmitting antennas Tx#1 and Tx#2 in beam direction B1, respectively. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#1 and Tx#2 in beam direction B1. 1, 1 (m), ψ 1, 2 Set (m).

[0208] Furthermore, in Figure 13, for the transmitting antenna Tx#3 in beam direction B2, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DM Among the Doppler multiplexed signals with =2, for example, assign a Doppler multiplexed signal using a Doppler shift amount DOP2 (N DM_B2 =1). The encoding unit 107 also assigns Code2 to the Doppler multiplexed signal using the Doppler shift amount DOP2 assigned to the transmitting antenna Tx#3 in beam direction B2. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for the transmitting antenna Tx#3 in beam direction B2. 2, 2 Set (m).

[0209] In Figure 13, the Doppler multiplexing number assigned by the Doppler shift setting unit 106 to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 is N DM_B1 =2, N DM_B2 Since they are different Doppler multiplex numbers equal to 1, condition A-2 of condition 1 is satisfied.

[0210] Furthermore, in Figure 13, the code indices assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1 and DOP2 are CodeIndex_B1=(1,1) and CodeIndex_B2=(*,2), respectively. This results in a cyclic mismatch, and since the code index intervals are different, condition B-1 of condition 1 is satisfied.

[0211] Furthermore, in Figure 13, the code multiplexing numbers assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1 and DOP2 are N_Code_B1=(1,1) and N_Code_B2=(0,1). Since the code multiplexing numbers are different, condition B-2 of condition 1 is satisfied.

[0212] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210, described later, observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1_alias=(2,2) and CodeIndex_B2_alias=(*,1), which are different (a cyclic mismatch). Therefore, in the example in Figure 13, in the range where the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), the code indices are cyclic mismatched and the code intervals are different. Thus, conditions B-1 and B-2 of condition 1 are satisfied, and the different code multiplexing pattern conditions are met.

[0213] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 13 is an example of a setting that satisfies condition 1.

[0214] Furthermore, in Figure 13, the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B1 is N_Code_B1=(1,1), and since the signals are multiplexed with a uniform code multiplexing number among the Doppler multiplexed signals, condition 2 is not satisfied.

[0215] On the other hand, in Figure 13, the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B2 is N_Code_B2=(0,1), and multiplexed transmission is performed with a code multiplexing number that is non-uniform among the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less. Therefore, the setting of the encoded Doppler phase rotation amount shown in Figure 12 is an example of a setting that satisfies condition 2.

[0216] Based on the above, the coding Doppler phase rotation setting shown in Figure 13 is an example of a setting that does not satisfy condition 2 for the transmitting antenna in beam direction B1, but satisfies condition 2 for the transmitting antenna in beam direction B2.

[0217] The following describes an example of a received signal at the output of the Doppler analysis unit 210 when the transmitting antenna unit 109 includes transmitting antennas with different beam directions B1 and B2 based on the Doppler shift amount setting shown in Figure 13, and the receiving antenna unit 202 is an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both transmitting antennas in beam direction B1 and beam direction B2).

[0218] For example, if the target direction is target direction (1) shown in Figure 10 (for example, if the target is located around beam direction B1), or if the target direction is target direction (3) shown in Figure 10 (for example, if the target is located around beam direction B2), the code multiplexing number differs between the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B1. Therefore, the radar device 10 can distinguish between a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B1 and a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B2 using the coded Doppler multiplexing / decompression unit 212, which will be described later.

[0219] Furthermore, if this determination result indicates that the signal is a received signal from the transmitting antenna (Tx#1, Tx#2) in beam direction B1, the settings for the encoded Doppler multiplexed signals for Tx#1 and Tx#2 in beam direction B1 are known, so the radar device 10 can separate the multiplexed signals by, for example, the operation disclosed in Patent Documents 5, 6, etc. Similarly, if the signal is a received signal from the transmitting antenna (Tx#3) in beam direction B2, the settings for the encoded Doppler multiplexed signals for Tx#3 in beam direction B2 are known, so the radar device 10 can similarly separate the multiplexed signals.

[0220] Furthermore, in setting example 4, the setting of the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105 does not satisfy condition 2 with respect to the beam direction B1. In this case, the detectable Doppler frequency range fd depends on the target direction and is in the range of -1 / (2Tr)≦fd < 1 / (2Tr), or -1 / (2Loc N DM_B1 Tr)≦fd < 1 / (2 Loc N DM_B1 This is within the range of Tr), and compared to the Doppler detection range of an equally spaced DDM -1 / (6 Tr) ≤ fd < 1 / (6 Tr), an effect is obtained in which the Doppler detection range can be expanded depending on the target direction.

[0221] <Example Configuration 5> Example setting 5 is an example of setting the encoded Doppler phase rotation amount when condition 1 (different Doppler multiplexing pattern condition and code multiplexing pattern condition) is met but condition 2 is not met.

[0222] Figure 14 shows the number of transmitting antennas Nt=4, N B1 =2, N B2 An example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 when = 2 is shown.

[0223] In Figure 14, Tx#1 and Tx#2 are transmitting antennas in beam direction B1, and Tx#3 and Tx#4 are transmitting antennas in beam direction B2. In Figure 14, the shaded circles indicate the assignment of coded Doppler multiplexed signals to the transmitting antennas in beam direction B1 (Tx#1 and Tx#2), and the white circles indicate the assignment of coded Doppler multiplexed signals to the transmitting antennas in beam direction B2 (Tx#3 and Tx#4).

[0224] Furthermore, in Figure 14, the Doppler multiplexing number N DM =3, and the Doppler shift setting unit 106 may set the three Doppler shift amounts DOP1, DOP2, and DOP3 using, for example, the maximum equally spaced Doppler shift amount setting shown in equation (5). In Figure 14, the phase rotation amounts that impart Doppler shift amounts DOP1=0, DOP2=Δfd, and DOP3=-Δfd are φ1=0, φ2=2π / 3, and φ3=4π / 3 (or φ3=-2π / 3), respectively. As shown in Figure 14, the Doppler multiple spacing Δfd is equally spaced, and Δfd=1 / (6Tr).

[0225] In Figure 14, the number of transmitting antennas Nt = 4, and the number of Doppler multiplexers N DM =3, code multiplex number N CM = 2, N t <N DM ×N CM Therefore, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (ndm) can be set non-uniformly (where ndm = 1 to N) DM ).

[0226] As shown in Figure 14, in the encoding unit 107, the number of encoded Doppler multiplexings for a Doppler multiplexed signal using the three Doppler shift amounts DOP1, DOP2, and DOP3 input from the Doppler shift setting unit 106 is, each, N DOP_CODE (1) = 1, N DOP_CODE (2) = 1, N DOP_CODE (3)=2. Thus, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (1) = N DOP_CODE(2) ≠ N DOP_CODE (3) Set to non-uniform.

[0227] Furthermore, in Figure 14, for the transmitting antennas Tx#1 and Tx#2 in the beam direction B1, the Doppler shift setting unit 106 sets the Doppler multiplexing number N. DM Among the Doppler multiplexed signals with =3, for example, assign Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP2 (N DM_B1 =2). Furthermore, the encoding unit 107 assigns Code2 and Code2 to the Doppler multiplexed signals using the Doppler shift amounts DOP1 and DOP2 assigned to the transmitting antennas Tx#1 and Tx#2 in beam direction B1, respectively. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#1 and Tx#2 in beam direction B1. 2, 1 (m), ψ 2, 2 Set (m).

[0228] Furthermore, in Figure 14, the Doppler multiplexing number N is set for transmitting antennas Tx#3 and Tx#4 in beam direction B2. DM Among the Doppler multiplexed signals with =3, for example, assign a Doppler multiplexed signal using Doppler shift amount DOP3 (N DM_B2 =1). Furthermore, the coding unit 107 assigns two codes, Code1 and Code2, to the Doppler multiplexed signal using the Doppler shift amount DOP3 assigned to the transmitting antennas Tx#3 and Tx#4 in beam direction B2. For example, the phase rotation amount setting unit 105 sets the coded Doppler phase rotation amount ψ for the transmitting antennas Tx#3 and Tx#4 in beam direction B2. 1, 3 (m), ψ 2, 3 Set (m).

[0229] In Figure 14, the Doppler multiplexing number assigned by the Doppler shift setting unit 106 to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 is N DM_B1 =2, N DM_B2 Since they are different Doppler multiplex numbers equal to 1, condition A-2 of condition 1 is satisfied.

[0230] Furthermore, in Figure 14, the code indices assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1, DOP2, and DOP3 are CodeIndex_B1=(1,1,*) and CodeIndex_B2=(*,*,1&2), respectively. This results in a cyclic mismatch, and since the code index intervals are different, condition B-1 of condition 1 is satisfied.

[0231] Furthermore, in Figure 14, the code multiplexing numbers assigned to the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B2 for each of the Doppler multiplexed signals DOP1, DOP2, and DOP3 are N_Code_B1=(1,1,0) and N_Code_B2=(0,0,2), respectively. Since the code multiplexing numbers are different, condition B-2 of condition 1 is satisfied.

[0232] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210, described later, observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1_alias=(2,2,*) and CodeIndex_B2_alias=(*,*,1&2), which are different (a cyclic mismatch). Therefore, in the example of Figure 14, within the range of the target's Doppler frequency being -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), the code indices are cyclic mismatched and the code intervals are different. Thus, conditions B-1 and B-2 of Condition 1 are satisfied, and the different code multiplexing pattern conditions are met.

[0233] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 14 is an example of a setting that satisfies condition 1.

[0234] Furthermore, in Figure 14, the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B1 is N_Code_B1=(1,1,0), and the Doppler multiplexed signals are transmitted with a code multiplexing number that is non-uniform among the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N.CM Since it falls within the range of -1 or less, condition 2 is satisfied.

[0235] On the other hand, in Figure 14, the code multiplexing number assigned to each Doppler multiplexed signal in the transmitting antenna in beam direction B2 is N_Code_B2=(0,0,2), and multiplexed transmission is performed with a code multiplexing number that is non-uniform among the Doppler multiplexed signals, but the code multiplexing number ranges from 1 to N. CM Since it does not fall within the range of -1 or less, condition 2 is not met.

[0236] Based on the above, the coding Doppler phase rotation setting shown in Figure 14 is an example of a setting that satisfies condition 2 for the transmitting antenna in beam direction B1, but does not satisfy condition 2 for the transmitting antenna in beam direction B2.

[0237] The following describes an example of a received signal at the output of the Doppler analysis unit 210 when the transmitting antenna unit 109 includes transmitting antennas with different beam directions B1 and B2 based on the Doppler shift amount setting shown in Figure 14, and the receiving antenna unit 202 is an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both transmitting antennas in beam direction B1 and beam direction B2).

[0238] For example, if the target direction is target direction (1) shown in Figure 10 (for example, if the target is located around beam direction B1), or if the target direction is target direction (3) shown in Figure 10 (for example, if the target is located around beam direction B2), the code multiplexing number differs between the transmitting antenna in beam direction B1 and the transmitting antenna in beam direction B1. Therefore, the radar device 10 can distinguish between a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B1 and a decrease in the reception level of the received signal corresponding to the transmitting antenna in beam direction B2 using the coded Doppler multiplexing / decompression unit 212, which will be described later.

[0239] Furthermore, if this determination result determines that the signal is a received signal from the transmitting antenna (Tx#1, Tx#2) in beam direction B1, the settings for the encoded Doppler multiplexed signals for Tx#1 and Tx#2 in beam direction B1 are known, so the radar device 10 can separate the multiplexed signals by, for example, the operation disclosed in Patent Documents 5, 6, etc. Similarly, if the signal is a received signal from the transmitting antenna (Tx#3, Tx#4) in beam direction B2, the settings for the encoded Doppler multiplexed signals for Tx#3 and Tx#4 in beam direction B2 are known, so the radar device 10 can similarly separate the multiplexed signals.

[0240] Furthermore, in setting example 5, the setting of the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105 does not satisfy condition 2 with respect to the beam direction B2. In this case, the detectable Doppler frequency range fd depends on the target direction and is in the range of -1 / (2Tr)≦fd < 1 / (2Tr), or -1 / (2Loc N DM_B2 Tr)≦fd < 1 / (2 Loc N DM_B2 This is within the range of Tr), and compared to the Doppler detection range of an equally spaced DDM -1 / (6 Tr) ≤ fd < 1 / (6 Tr), an effect is obtained in which the Doppler detection range can be expanded depending on the target direction.

[0241] The above describes an example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105.

[0242] Note that the setting of the encoded Doppler phase rotation amount is not limited to the setting examples 1 to 5 described above. For example, the number of transmitting antennas Nt and the number of transmitting antennas in beam direction B1 N B1 Number of transmitting antennas in beam direction B2: N B2 , Doppler multiplexing number (N DM , N DM_B1 , N DM_B2 ), code multiplexing number (N CM , N CM_B1 , N CM_B2 At least one of the multi-beam number NB, code interval, or Doppler shift interval may be other values. Note that the above setting examples 1 to 5 use code multiplexing N. CMAn example setting using the sign =2 was shown, but it is not limited to this, for example, the number of sign multiples N CM Setting it to ≥3 also allows for the same setting of the encoded Doppler phase rotation amount.

[0243] [Configuration of radar receiver 200] In Figure 5, the radar receiver 200 includes a receiving antenna section 202 containing Na receiving antennas Rx#1 to Rx#Na. The radar receiver 200 also includes Na antenna system processing sections 201-1 to 201-Na, a CFAR (Constant False Alarm Rate) section 211, an encoded Doppler multiplexing / decoupling section 212, and a direction estimation section 213. The Na antenna system processing sections 201-1 to 201-Na, the CFAR section 211, the encoded Doppler multiplexing / decoupling section 212, and the direction estimation section 213 may be collectively referred to as the receiving circuit. The receiving circuit uses the reflected wave signal obtained by reflecting the transmitted signal off the target to estimate the direction of the target.

[0244] The receiving antennas Rx#1 to Rx#Na of the receiving antenna unit 202 receive reflected wave signals, which are radar transmission signals reflected by a target, and output the received reflected wave signals as received signals to the corresponding antenna system processing unit 201.

[0245] Each antenna system processing unit 201 includes a receiving radio unit 203 and a signal processing unit 206.

[0246] Each signal received by the Na receiving antennas Rx#1 to Rx#Na is output to Na receiving radio units 203. The output signals from the Na receiving radio units 203 are then output to Na signal processing units 206.

[0247] The receiving radio unit 203 includes a mixer unit 204 and an LPF (low-pass filter) 205. The mixer unit 204 mixes the received reflected wave signal with the chirp signal, which is the transmission signal, input from the radar transmission signal generation unit 101. The receiving radio unit 203 passes the output of the mixer unit 204 through the LPF 205, for example. This outputs a beat signal with a frequency corresponding to the delay time of the reflected wave signal. For example, the difference frequency between the frequency of the transmitted chirp signal (transmitted frequency modulated wave), which is the transmission signal (radar transmission wave), and the frequency of the received chirp signal (received frequency modulated wave), which is the received signal (radar reflected wave), is obtained as the beat frequency.

[0248] Each antenna system processing unit 201-z (where z=1 to Na) has a signal processing unit 206 comprising an AD conversion unit 207, a beat frequency analysis unit 208, an output switching unit 209, and a Doppler analysis unit 210.

[0249] The signal output from the LPF205 (for example, a beat signal) is converted into discrete sample data by the AD conversion unit 207 in the signal processing unit 206.

[0250] The beat frequency analysis unit 208 analyzes the N obtained within a defined time range (range gate) for each transmission period Tr. data The discrete sample data is subjected to frequency analysis (e.g., FFT). As a result, the signal processing unit 206 outputs a frequency spectrum in which a peak appears at the beat frequency corresponding to the delay time of the reflected wave signal (radar reflected wave).

[0251] Here, the beat frequency response output from the beat frequency analysis unit 208 in the z-th signal processing unit 206 obtained by transmitting the m-th chirp pulse is called "RFT". z (f b It is expressed as ", m)". Here, f b This represents the beat frequency index and corresponds to the index (bin number) of the FFT. For example, f b =0,~,( N data / 2)-1, z=1~Na, and m=1~N C This is the beat frequency index f. b The smaller the value, the smaller the delay time of the reflected wave signal (for example, the closer the distance to the target), indicating a beat frequency.

[0252] Also, the beat frequency index f b The distance information R(f) is calculated using the following equation (10). b It can be converted to ). Therefore, below, the beat frequency index f b to "distance index f b They call it that.

number

[0253] Here, B w represents the frequency modulation bandwidth within the range gate in the chirp signal, and C0 represents the speed of light. Also, in equation (10), C0 / (2B w ) represents the distance resolution.

[0254] The output switching unit 209 selectively switches the output of the beat frequency analysis unit 208 for each transmission period to the OC_INDEX-th Doppler analysis unit 210 out of Loc Doppler analysis units 210, based on the orthogonal code element index OC_INDEX input from the encoding unit 107 of the phase rotation amount setting unit 105. For example, in the m-th transmission period Tr, the output switching unit 209 selects the OC_INDEX-th Doppler analysis unit 210 obtained by equation (8).

[0255] The signal processing unit 206 has Loc Doppler analysis units 210-1 to 210-Loc. For example, the noc-th Doppler analysis unit 210 receives data every Loc transmission cycles (Loc × Tr) via the output switching unit 209. Therefore, the noc-th Doppler analysis unit 210 receives data from Ncode transmission cycles out of Nc transmission cycles (for example, the beat frequency response RFT input from the beat frequency analysis unit 208). z (f bUsing , m)), distance index f b Doppler analysis is performed for each step. Here, noc is the index of the sign element, and noc = 1 to Loc.

[0256] For example, if Ncode is a power of 2, FFT processing can be applied to Doppler analysis. In this case, the FFT size is Ncode, and the maximum Doppler frequency at which no aliasing occurs, derived from the sampling theorem, is ±1 / (2Loc×Tr). Also, the Doppler frequency index f s The Doppler frequency interval is 1 / (Ncode × Loc × Tr), and the Doppler frequency index f s The range is f s = -Ncode / 2,~, 0,~,Ncode / 2-1.

[0257] The following example explains the case where Ncode is a power of 2. Note that if Ncode is not a power of 2, FFT processing is possible with a data size (FFT size) that is a power of 2, for example, by including zero-padding data.

[0258] For example, the output VFT of the Doppler analysis unit 210 of the z-th signal processing unit 206. z noc (f b , f s The expression is given by equation (11). Note that j is the imaginary unit, and z = 1 to Na.

number

[0259] The processing in each component of the signal processing unit 206 has been described above.

[0260] [Example of operation of CFAR unit 211] In Figure 5, the CFAR unit 211 uses the outputs of Loc Doppler analysis units 210 of each of the 1st to Nath signal processing units 206 to perform CFAR processing (e.g., adaptive threshold determination) and obtains a distance index f that gives a peak signal. b_cfar and Doppler frequency index f s_cfar Extract it.

[0261] The CFAR unit 211, for example, as shown in equation (12) below, outputs the VFT of the Doppler analysis unit 210 of the 1st to Nath signal processing unit 206. z noc (f b , f s The power is added to perform a CFAR process that is either a two-dimensional CFAR process consisting of a distance axis and a Doppler frequency axis (corresponding to relative velocity), or a CFAR process that combines a one-dimensional CFAR process (for example, the process disclosed in Non-Patent Document 2 may be applied).

number

[0262] The CFAR unit 211 adaptively sets a threshold and determines the distance index f that results in a received power greater than the threshold. b_cfar , Doppler frequency index f s_cfar , and received power information PowerFT(f b_cfar , f s_cfar The encoded Doppler multiplexing unit 212 outputs the result to the Doppler multiplexing / decoupling unit 212.

[0263] Note that the Doppler shift amount is DOP. ndm Phase rotation amount φ to impart ndm For example, when using equation (5), the intervals of the Doppler shift amounts in the Doppler frequency domain at the output of the Doppler analysis unit 210 are equal, and if the interval ΔFD of the Doppler shift amount is expressed in terms of the interval of the Doppler frequency index, then ΔFD = Ncode / N DM Therefore, in the output of the Doppler analysis unit 210, in the Doppler frequency domain, peaks are detected for each Doppler-shifted multiplexed signal at intervals of ΔFD.

[0264] Figure 15(a) shows N DM An example of the output of the Doppler analysis unit 210 at the distance where the reflected waves of the three targets exist when = 2 is shown. For example, as shown in Figure 15(a), when the reflected waves of the three targets are observed at Doppler frequency indices f1, f2, and f3, these reflected waves are also observed at Doppler frequency indices at intervals of ΔFD for each of f1, f2, and f3 (e.g., f1-ΔFD, f2-ΔFD, f3-ΔFD+Ncode).

[0265] Therefore, the CFAR unit 211 may divide each output of the Doppler analysis unit 210 into intervals ΔFD of Doppler shift amounts, and for each divided range, perform CFAR processing (for example, called "Doppler region compression") after adding the power of each Doppler multiplexed signal peak position as shown in equation (13) below. Here, f s_comp = -ΔFD / 2, ..., -ΔFD / 2-1. For example, ΔFD = Ncode / N DM In the case of f s_comp =Ncode / (2N DM ),…,Ncode / (2N DM )-1.

number

[0266] However, in equation (13),

number

[0267] Similarly, in equation (13),

number

[0268] Figure 15(b) shows an example of the output after applying the Doppler region compression process shown in equation (13) to the output of the Doppler analysis unit 210 shown in Figure 15(a). As shown in Figure 15(b), N DM When = 2, the CFAR unit 211 outputs the sum of the power component of Doppler frequency index f1 and the power component of f1-ΔFD by Doppler region compression processing. Similarly, as shown in Figure 15(b), the CFAR unit 211 outputs the sum of the power component of Doppler frequency index f2 and the power component of f2-ΔFD. Also, for the power component of Doppler frequency index f3, since f3-ΔFD is smaller than -Ncode / 2, the CFAR unit 211 outputs the sum of the power component of Doppler frequency index f3 and f3-ΔFD+Ncode (for example, N DM If = 2, the power component of f3 + ΔFD) is added and output.

[0269] As a result of Doppler region compression, the range of the Doppler frequency index fs_comp in the Doppler frequency domain is -ΔFD / 2 or greater, ~, ΔFD / 2-1 or less (ΔFD = Ncode / N). DM In this case, -Ncode / (2N DM ) or more,…,Ncode / (2N DM It is reduced to )-1 or less.

[0270] The CFAR unit 211, which uses Doppler region compression CFAR processing, for example, adaptively sets a threshold and determines the distance index f that results in a received power greater than the threshold. b_cfar , Doppler frequency index f s_comp_cfar , and, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power information PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM / 2)-1)×ΔFD), nfd=1,…,N DM The result is output to the encoded Doppler multiplexing / decoupling unit 212.

[0271] [Example of operation of the Doppler encoding / multiplexing / decoupling unit 212] Next, we will describe an example of the operation of the encoding Doppler multiplexing / decoupling unit 212 shown in Figure 5.

[0272] In the following, an example of the processing of the encoded Doppler multiplexing / decoupling unit 212 when Doppler region compression CFAR processing is used in the CFAR unit 211 will be described. Furthermore, the operation of the encoded Doppler multiplexing / decoupling unit 212 when omnidirectional antennas (or antennas with nearly uniform directional characteristics across the entire field of view covered by multiple transmitting antennas with different beam directions) are used as multiple receiving antennas will be described.

[0273] Figure 16 is a flowchart showing an example of the separation operation in the encoded Doppler multiplexing / separation unit 212.

[0274] <Step A-1> The encoded Doppler multiplexing / decoupling unit 212 performs encoded Doppler multiplexing / decoupling processing on Nt encoded Doppler multiplexed signals.

[0275] For example, the encoding Doppler multiplexing / decoupling unit 212 receives the distance index f from the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar , and, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power information (PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM / 2)-1)×ΔFD), nfd=1~N DM Based on this, the output of the Doppler analysis unit 210 is used to separate Nt encoded Doppler multiplexed transmitted signals, and the transmitting antenna is identified (e.g., determined or identified), and the Doppler frequency (e.g., Doppler velocity or relative velocity) is determined.

[0276] As described above, when the encoding unit 107 of the phase rotation amount setting unit 105 uses the setting of the equal interval Doppler shift amount, which includes the setting of the maximum equal interval Doppler shift amount, for example, N DM The number of Doppler multiplexers for each encoding is N. DOP_CODE (1), N DOP_CODE (2), ..., N DOP_CODE (N DM All of ) N CM Instead of setting the number of encodings individually, set the encoding Doppler multiplexing number to N to at least one. CM This method utilizes setting the value to be smaller than one (setting it unevenly).

[0277] For example, the coded Doppler multiplexing unit 212 (1) performs code separation processing and the coded Doppler multiplexing number N CM The coded Doppler multiplexed signals set to a number smaller than (for example, unused coded Doppler multiplexed signals not used for multiplexed transmission) are detected, and aliasing is determined. Subsequently, the coded Doppler multiplexing / decoupling unit 212 performs Doppler code decoupling processing on the coded Doppler multiplexed signals used for multiplexed transmission based on the aliasing determination result.

[0278] The operation of this coded Doppler multiplexing / decoupling unit 212 is similar to that of the coded Doppler multiplexing / decoupling unit in existing MIMO radars using coded Doppler multiplexing transmission, and is described, for example, in Patent Documents 5 and 6, so a detailed explanation of its operation will be omitted.

[0279] For example, N is a setting for the equal interval Doppler shift amount, which includes the setting for the maximum equal interval Doppler shift amount. DM The number of Doppler multiplexers for each encoding is N. DOP_CODE (1), N DOP_CODE (2), ~, N DOP_CODE (N DM All of ) N CM Instead of setting the number of encodings individually, set the encoding Doppler multiplexing number to N to at least one. CM When set to a value smaller than 1, the Doppler frequency of the estimated target can be detected in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr) by the operation of the coded Doppler multiplexing unit 212 described above (for example, Patent Documents 5 and 6).

[0280] <Step A-2> The encoded Doppler multiplexing / decompression unit 212 determines whether Nt encoded Doppler multiplexed signals have been successfully detected. If Nt encoded Doppler multiplexed signals are successfully detected, the encoded Doppler multiplexing / decompression unit 212 performs the process in step A-3; otherwise, it performs the process in step B-1.

[0281] For example, in the processing of step A-1, depending on the agreement between the main beam direction of the multibeam and the target direction, Nt coded Doppler multiplexed signals may not be detected correctly.

[0282] For example, a multi-beam MIMO radar is configured using two transmitting antennas with beam directions B1 and B2, and the setting of the phase rotation amount setting unit 105 is N DM >N DM_B1 , or, N DM >N DM_B2 Let's assume (where N DM_B1 , N DM_B2 <N DM ). In this case, if the main beam direction of the multibeam does not coincide with the target direction, and the target is in the null direction, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM Between / 2)-1)×ΔFD), the received power will differ by more than a predetermined value, or a component with a received power as low as the noise level will be included. In such a case, the coded Doppler multiplexing / decoupling unit 212 will N DM Since fewer than one encoded Doppler multiplexed signal is detected, it is determined that the detection is not normal, and the process in step B-1 is performed.

[0283] Furthermore, for example, for a transmitting antenna with beam direction B1, the setting of the phase rotation amount setting unit 105 is N DM =N DM_B1Therefore, if the main beam direction B2 of the multibeam does not coincide with the target direction, and the target direction is in the null direction, or if the setting of the phase rotation amount setting unit 105 is N for the transmitting antenna with beam direction B2 DM = DM_B2 Therefore, if the main beam direction B2 of the multibeam does not coincide with the target direction, and the target direction is in the null direction, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM Between (2)-1)×ΔFD), the received power will be within a predetermined range. In this case, during the code separation process, unused coded Doppler multiplexed signals that are not used for multiplex transmission will be assumed to be (N DM Since the number of encoded Doppler multiplexed signals is greater than (Nt), the encoded Doppler multiplexing and decoupling unit 212 fails to determine aliasing, making it difficult to properly detect Nt encoded Doppler multiplexed signals. Therefore, the encoded Doppler multiplexing and decoupling unit 212 finds that the unused encoded Doppler multiplexed signals not used for multiplex transmission are greater than the assumed (Nt). DM Since more than -Nt) items are detected, it is determined that the detection is not normal, and the process in step B-1 is performed.

[0284] <Step A-3> The encoded Doppler multiplexing and decoupling unit 212 performs encoded Doppler multiplexing and decoupling processing on the encoded Doppler multiplexed signal used for multiplex transmission based on the aliasing determination result, and then processes the received signal Y z (f b_cfar ,f s_comp_cfar (, ncm, ndm) is used as the distance index f b_cfar and Doppler frequency index f s_comp_cfar It also outputs to the direction estimation unit 213.

[0285] Here, Y z (f b_cfar ,f s_comp_cfar,ndop_code(ndm),ndm) is the distance index f of the Doppler analysis unit 210 in the z-th antenna system processing unit 201. b_cfar and Doppler frequency index f s_comp_cfar , in, Doppler shift amount DOP ndm and orthogonal code ndop_code(ndm) This is the separated output of an encoded Doppler multiplexed signal (e.g., the encoded Doppler multiplexed separation result) using [a specific method]. For example, Y z (f b_cfar ,f s_comp_cfar ,ndop_code(ndm),ndm) represents the received signal transmitted from the transmitting antenna Tx#[ndop_code(ndm), ndm], reflected by the target, and received by the z-th antenna system processing unit 201. Note that z = 1 to Na, and ncm = 1 to N CM Therefore, ndm = 1 to N DM Therefore, ndop_code(ndm)=1~N DOP_CODE (ndm)

[0286] Furthermore, the encoded Doppler multiplexing / decoupling unit 212 may, for example, output information regarding the Doppler frequency of the detected target to the direction estimation unit 213.

[0287] Furthermore, if condition 2 is met, the coded Doppler multiplexing / decoupling unit 212 can detect the estimated Doppler frequency of the target in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr) by using the aliasing determination result.

[0288] <Step B-1> The coding Doppler multiplexing / decoupling unit 212 assumes that the target direction is the beam direction B1, and N B1 Encoded Doppler multiplexing is performed on the encoded Doppler multiplexed signals.

[0289] For example, the encoding Doppler multiplexing / decoupling unit 212 receives the distance index f from the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar , and, N DMThe Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power information (PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM / 2)-1)×ΔFD), nfd=1~N DM Based on this, the output of the Doppler analysis unit 210 is used to determine N B1 The system separates the encoded Doppler multiplexed signals, identifies the transmitting antenna (e.g., determination or identification), and determines the Doppler frequency (e.g., Doppler velocity or relative velocity).

[0290] Here, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM If the received power differs by more than a predetermined value between (2)-1)×ΔFD), or if there is a component with a received power as small as the noise level, then (N DM -N DM_B1 ) may be included. Note that the setting of the phase rotation amount setting unit 105 is N DM =N DM_B1 If that is the case, (N DM -N DM_B1 )=0, and it does not contain components with received power as low as the noise level. These Doppler multiplexed signals are unused Doppler multiplexed signals that are not used for multiplexed transmission.

[0291] Therefore, the encoding Doppler multiplexing / decoupling unit 212 is, for example, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DMBetween (2)-1)×ΔFD), the higher power N DM_B1 Extract individual Doppler multiplexed signals.

[0292] For example, the top N power levels extracted DM_B1 If the Doppler multiplexing interval of the individual Doppler multiplexed signals matches the Doppler multiplexing interval assigned to the transmitting antenna in beam direction B1, the coded Doppler multiplexing / decompression unit 212 (1) performs code separation processing and extracts the number of coded Doppler multiplexed signals from the coded Doppler multiplexed signals assigned to the transmitting antenna in beam direction B1, N CM The coded Doppler multiplexed signals set to a number smaller than (for example, unused coded Doppler multiplexed signals not used for multiplexed transmission) are detected, and aliasing is determined. Subsequently, the coded Doppler multiplexing / decoupling unit 212 performs Doppler code decoupling processing on the coded Doppler multiplexed signals used for multiplexed transmission based on the aliasing determination result.

[0293] The operation of this coded Doppler multiplexing / decoupling unit 212 is similar to that of the coded Doppler multiplexing / decoupling unit in existing MIMO radars using coded Doppler multiplexing transmission, and is described, for example, in Patent Documents 5 and 6, so a detailed explanation of its operation will be omitted.

[0294] Furthermore, by setting the encoded Doppler phase rotation amount to satisfy condition 2, for example, the operation of the encoded Doppler multiplexing / decoupling unit 212 described above makes it possible to detect the estimated Doppler frequency of the target in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr) (for example, Patent Documents 5, 6).

[0295] <Step B-2> The coding Doppler multiplexing / decoupling unit 212 is N included in the beam direction B1. B1 N is assigned to each transmitting antenna B1 The coding Doppler multiplexing unit 212 determines whether the number of coded Doppler multiplexed signals are detected correctly. B1 If the encoded Doppler multiplexed signal is successfully detected, the process in step B-3 is performed; otherwise, the process in step C-1 is performed.

[0296] For example, in the processing of step B-1, depending on the agreement between the main beam direction of the multibeam and the target direction, N B1 In some cases, individual encoded Doppler multiplexed signals may not be detected correctly.

[0297] The coding Doppler multiplexing unit 212, for example, extracts the higher N power values. DM_B1 Individual Doppler multiplexed signals and other lower power (N DM -N DM_B1 If the power difference (or power ratio) between the ) Doppler multiplexed signals does not exceed a predetermined level, it is determined that the target direction is not the beam direction B1, and the process in step C-1 is performed.

[0298] Also, the top N power levels extracted DM_B1 If the Doppler multiplexing interval of the individual Doppler multiplexed signals does not match the Doppler multiplexing interval assigned to the transmitting antenna in beam direction B1, the encoded Doppler multiplexing / decompression unit 212 determines that the target direction is not beam direction B1 and performs the process in step C-1.

[0299] Furthermore, for example, the setting of the phase rotation amount setting unit 105 with respect to the beam direction B1 is N DM_B1 =N DM_B2 In this case, if the main beam direction B2 of the multibeam does not coincide with the target direction, and the target is in the null direction, then N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM Between / 2)-1)×ΔFD), the received power will be within a predetermined range. In such a case, during the code separation process, the unused coded Doppler multiplexed signals that are not used for multiplex transmission will be the assumed N B1 The code interval of the encoded Doppler multiplexed signals is different. Therefore, the encoded Doppler multiplexing / decompression unit 212 fails to determine aliasing, and N B1It becomes difficult to properly detect the individual encoded Doppler multiplexed signals. In such cases, the encoded Doppler multiplexing separation unit 212 performs N B1 It is determined that this is not a normal detection of the encoded Doppler multiplexed signal, and the process in step C-1 is performed.

[0300] <Step B-3> The coding Doppler multiplexing / decompression unit 212 determines the N of the beam direction B1 based on the processing result of step B-2. B1 The received signal YB1 is the result of decoding the encoded Doppler multiplexed signal used for multiplexed transmission by this transmitting antenna. z (f b_cfar ,f s_comp_cfar (, ncm, ndm) is used as the distance index f b_cfar and Doppler frequency index f s_comp_cfar It also outputs to the direction estimation unit 213.

[0301] Here, YB1 z (f b_cfar ,f s_comp_cfar ,ndop_code(ndm),ndm) is the distance index f of the Doppler analysis unit 210 in the z-th antenna system processing unit 201. b_cfar and Doppler frequency index f s_comp_cfar , in, Doppler shift amount DOP ndm and orthogonal code ndop_code(ndm) This is the separated output of an encoded Doppler multiplexed signal (e.g., the encoded Doppler multiplexing separation result) using [a specific method]. For example, YB1 z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm) is the N of the beam direction B1. B1 This represents the received signal transmitted from each transmitting antenna Tx#[ndop_code(ndm), ndm], reflected by a target, and received by the z-th antenna system processing unit 201. Note that z = 1 to Na, and ndm = 1 to N. DM Therefore, ndop_code(ndm)=1~N DOP_CODE (ndm) and N is the beam direction B1. B1Signals other than those assigned to each transmitting antenna are output as zero.

[0302] The encoded Doppler multiplexing / decoupling unit 212 may also output the Doppler frequency of the detected target to the direction estimation unit 213.

[0303] Furthermore, if condition 2 is met, the coded Doppler multiplexing / decoupling unit 212 can detect the estimated Doppler frequency of the target in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr) by using the aliasing determination result.

[0304] <Step C-1> The coding Doppler multiplexing / decoupling unit 212 assumes that the target direction is the beam direction B2, and N B2 Encoded Doppler multiplexing is performed on the encoded Doppler multiplexed signals.

[0305] For example, the encoding Doppler multiplexing / decoupling unit 212 uses the distance index f, which is the output of the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar , and, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power information (PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM / 2)-1)×ΔFD), nfd=1~N DM Based on this, the output of the Doppler analysis unit 210 is used to determine N B2 The system separates the encoded Doppler multiplexed signals, performs transmitting antenna identification (e.g., determination or identification), and determines the Doppler frequency (e.g., Doppler velocity or relative velocity).

[0306] Here, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD)b_cfar , f s_comp_cfar +(nfd-ceil(N DM If the received power differs by more than a predetermined value between (2)-1)×ΔFD), or if a component with a received power as small as the noise level is (N DM -N DM_B2 ) may be included. Note that the setting of the phase rotation amount setting unit 105 is N DM =N DM_B2 If this is the case, then (N DM -N DM_B2 )=0, and it does not contain components with received power as low as the noise level. These Doppler multiplexed signals are unused Doppler multiplexed signals that are not used for multiplexed transmission.

[0307] Therefore, the encoding Doppler multiplexing / decoupling unit 212 is, for example, N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM Between (2)-1)×ΔFD), the higher power N DM_B2 Extract individual Doppler multiplexed signals.

[0308] For example, the top N power levels extracted DM_B2 If the Doppler multiplexing interval of the individual Doppler multiplexed signals matches the Doppler multiplexing interval assigned to the transmitting antenna in beam direction B2, the coded Doppler multiplexing / decompression unit 212 (1) performs code separation processing and extracts the number of coded Doppler multiplexed signals from the coded Doppler multiplexed signals assigned to the transmitting antenna in beam direction B2, N CM The coded Doppler multiplexed signals set to a number smaller than (for example, unused coded Doppler multiplexed signals not used for multiplexed transmission) are detected, and aliasing is determined. Subsequently, the coded Doppler multiplexing / decoupling unit 212 performs Doppler code decoupling processing on the coded Doppler multiplexed signals used for multiplexed transmission based on the aliasing determination result.

[0309] The operation of this coded Doppler multiplexing / decoupling unit 212 is similar to that of the coded Doppler multiplexing / decoupling unit in existing MIMO radars using coded Doppler multiplexing transmission, and is described, for example, in Patent Documents 5 and 6, so a detailed explanation of its operation will be omitted.

[0310] Furthermore, by setting the encoded Doppler phase rotation amount to satisfy condition 2, for example, the operation of the encoded Doppler multiplexing / decoupling unit 212 described above makes it possible to detect the estimated Doppler frequency of the target in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr) (for example, Patent Documents 5, 6).

[0311] <Step C-2> The coding Doppler multiplexing / decoupling unit 212 is N included in the beam direction B2. B2 N is assigned to each transmitting antenna B2 The coding Doppler multiplexing unit 212 determines whether the number of coded Doppler multiplexed signals are detected correctly. B2 If the encoded Doppler multiplexed signal is successfully detected, the process in step C-3 is performed; otherwise, the process in step D is performed.

[0312] For example, in the processing of step C-1, depending on the agreement between the main beam direction of the multibeam and the target direction, N B2 In some cases, individual encoded Doppler multiplexed signals may not be detected correctly.

[0313] The coding Doppler multiplexing unit 212, for example, extracts the higher N power values. DM_B2 Individual Doppler multiplexed signals and other lower power (N DM -N DM_B2 If the power difference (or power ratio) between the ) Doppler multiplexed signals does not exceed a predetermined level, it is determined that the target direction is not the beam direction B2, and the process in step D is performed.

[0314] Also, the top N power levels extracted DM_B2If the Doppler multiplexing interval of the individual Doppler multiplexed signals does not match the Doppler multiplexing interval assigned to the transmitting antenna in beam direction B2, the encoded Doppler multiplexing / decompression unit 212 determines that the target direction is not beam direction B2 and performs the process in step D.

[0315] Furthermore, for example, the setting of the phase rotation amount setting unit 105 with respect to the beam direction B2 is N DM_B1 =N DM_B2 In this case, if the main beam direction B2 of the multibeam does not coincide with the target direction, and the target is in the null direction, then N DM The Doppler frequency index (f) of each Doppler multiplexed signal. s_comp_cfar +(nfd-ceil(N DM Received power PowerFT(f) in / 2)-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-ceil(N DM Between / 2)-1)×ΔFD), the received power will be within a predetermined range. In such a case, during the code separation process, the unused coded Doppler multiplexed signals that are not used for multiplex transmission will be the assumed N B2 The code interval of the encoded Doppler multiplexed signals is different. Therefore, the encoded Doppler multiplexing / decompression unit 212 fails to determine aliasing, and N B2 It becomes difficult to properly detect the individual encoded Doppler multiplexed signals. In such cases, the encoded Doppler multiplexing separation unit 212 performs N B2 It is determined that this is not a normal detection of the encoded Doppler multiplexed signal, and the process in step D is performed.

[0316] <Step C-3> The coding Doppler multiplexing / decompression unit 212 determines the N of the beam direction B2 based on the processing result of step C-2. B2 The received signal YB2 is the result of decoding the encoded Doppler multiplexed signal used for multiplexed transmission by this transmitting antenna. z (f b_cfar ,f s_comp_cfar (, ncm, ndm) is used as the distance index f b_cfar and Doppler frequency index f s_comp_cfarIt also outputs to the direction estimation unit 213.

[0317] Here, YB2 z (f b_cfar ,f s_comp_cfar ,ndop_code(ndm),ndm) is the distance index f of the Doppler analysis unit 210 in the z-th antenna system processing unit 201. b_cfar and Doppler frequency index f s_comp_cfar , in, Doppler shift amount DOP ndm and orthogonal code ndop_code(ndm) This is the separated output of an encoded Doppler multiplexed signal (e.g., the encoded Doppler multiplexing separation result) using [a specific method]. For example, YB2 z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm) is the N of the beam direction B2. B2 This represents the received signal transmitted from each transmitting antenna Tx#[ndop_code(ndm), ndm], reflected by a target, and received by the z-th antenna system processing unit 201. Note that z = 1 to Na, and ndm = 1 to N. DM Therefore, ndop_code(ndm)=1~N DOP_CODE (ndm) and N is the beam direction B2. B1 Signals other than those assigned to each transmitting antenna are output as zero.

[0318] The encoded Doppler multiplexing / decoupling unit 212 may also output the Doppler frequency of the detected target to the direction estimation unit 213.

[0319] Furthermore, if condition 2 is met, the coded Doppler multiplexing / decoupling unit 212 can detect the estimated Doppler frequency of the target in the range of -1 / (2Tr) ≤ fd < 1 / (2Tr) by using the aliasing determination result.

[0320] <Step D> If the conditions of step C-2 are not met, the encoded Doppler multiplexing / decoupling unit 212 may determine that the received signal is a noise component or an interference component and may not output to the direction estimation unit 213.

[0321] In the above-described example of the operation of the coded Doppler multiplexing / decoupling unit 212, the case where the number of multi-beams NB = 2 was explained, but the number of multi-beams NB is not limited to this, and for example, NB may be 3 or more. For example, when the number of multi-beams NB = 3, the coded Doppler multiplexing / decoupling unit 212 may, in step D (or between step C-2 and step D), continue to perform Doppler multiplexing / decoupling processing for beam directions different from beam directions B1 and B2 (or overlapping beam ranges or different beams; for example, beam direction B3). This makes it possible to perform similar Doppler multiplexing / decoupling operations even when the number of multi-beams increases further.

[0322] The above describes an example of the operation of the encoding Doppler multiplexing / decoupling unit 212.

[0323] The distance index f input from the CFAR unit 211 b_cfar , Doppler frequency index f sddm_cfar , and received power information (PowerFT(f b_cfar , f sddm_cfar +(ndm-1)×N Δfd If there are multiple )) units, the coded Doppler multiplexing / decoupling unit 212 may perform the above-described coded Doppler multiplexing / decoupling operation multiple times for each of the distance index, Doppler frequency index, and received power information, for example.

[0324] [Example of operation of the direction estimation unit 213] Next, we will explain an example of the operation of the direction estimation unit 213 shown in Figure 5.

[0325] In the following description, we will explain an example of the operation of the direction estimation unit 213 when the multiple receiving antennas of the receiving antenna unit 202 are identical omnidirectional antennas or antennas with substantially uniform directional characteristics within the field of view of multiple transmitting antennas with different beam directions.

[0326] The direction estimation unit 213 receives, for example, a signal (for example, distance index f) from the encoded Doppler multiplexing / decoupling unit 212.b_cfar , the received signal Y after encoding Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm) or YBq z (f b_cfar ,f s_comp_cfar The target direction estimation process is performed based on ndop_code(ndm),ndm). Here, q = 1 to NB. When the number of multibeams is 2 (NB = 2), q = 1 or 2.

[0327] Note that the received signal Y undergoes encoded Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar ,ndop_code(ndm),ndm) is the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm Since this is a received signal from a transmitting antenna using (m), it can be associated with transmitting antennas Tx#1, Tx#2, ~, and Tx#Nt.

[0328] Therefore, in the following, the received signal Y z (f b_cfar ,f s_comp_cfar Encoded Doppler phase rotation ψ in ndop_code(ndm),ndm) ndop_code(ndm), ndm (m) is a notation that corresponds to one of the transmitting antennas Tx#1 to Tx#Nt. z (f b_cfar ,f s_comp_cfar Use ,nt). Here, nt = 1 to Nt.

[0329] Similarly, the received signal YBq z (f b_cfar ,f s_comp_cfar Encoded Doppler phase rotation ψ in ndop_code(ndm),ndm) ndop_code(ndm), ndm (m) is a notation corresponding to one of the transmitting antennas Tx#1 to Tx#Nt: YBT z (f b_cfar ,f s_comp_cfar Use ,nt). Here, nt = 1 to Nt and q = 1 to NB. When the number of multi-beams is 2 (when NB = 2), q = 1 or 2.

[0330] The following describes examples 1 and 2 of the operation of the direction estimation unit 213.

[0331] <Example of operation of direction estimation unit 213 1> In example operation 1, for instance, the direction estimation unit 213 uses the distance index f b_cfar and the received signal Y after encoding Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar Based on ndop_code(ndm),ndm), the virtual receive array correlation vector h(f) of the direction estimation unit 213 is given by equation (14) below. b_cfar ,f s_comp_cfar It generates a ) and performs direction estimation processing.

[0332] Here, the information input from the encoded Doppler multiplexing / decoupling unit 212 is the received signal Y that has undergone encoded Doppler multiplexing / decoupling processing. z (f b_cfar ,f s_comp_cfar If it includes ndop_code(ndm),ndm), it includes coded Doppler multiplexed and separated received signals for Nt transmitting antennas. Therefore, the virtual received array correlation vector h(f b_cfar ,f s_comp_cfar The virtual receive array correlation vector h(f) includes Nt × Na elements, which is the product of the number of transmitting antennas Nt and the number of receiving antennas Na, as shown in equation (14). The direction estimation unit 213 calculates the virtual receive array correlation vector h(f b_cfar ,f s_comp_cfar Using this method, direction estimation is performed on the reflected wave signal from the target based on the phase difference between each transmitting and receiving antenna.

number

[0333] In equation (14), h cal[b] This is an array correction value that corrects the phase deviation and amplitude deviation between transmitting and receiving antennas. b is an integer between 1 and (Nt × Na).

[0334] The direction estimation unit 213, for example, calculates the virtual received array correlation vector h(f b_cfar , f s_comp_cfar Using the direction estimation evaluation function P H (θ u , f b_cfar , f s_comp_cfar ) in the direction θ u The spatial profile is calculated by varying the angle within a predetermined range.

[0335] The direction estimation unit 213 may extract a predetermined number of maximum peaks from the calculated spatial profile in descending order, and output the azimuth direction of the maximum peaks as an estimated direction of arrival (for example, a positioning output).

[0336] Note that the direction estimation evaluation function value P H (θ u , f b_cfar , f s_comp_cfar There are various methods for estimating the direction of arrival, depending on the direction of arrival algorithm. For example, the estimation method using an array antenna disclosed in Non-Patent Document 3 may be used.

[0337] Furthermore, while the above example described an example in which the direction estimation unit 213 calculates the azimuth direction as the estimated direction of arrival, it is not limited to this, and it is also possible to estimate the direction of arrival in the elevation direction, or in both the azimuth and elevation directions by using MIMO antennas arranged in a rectangular grid. For example, the direction estimation unit 213 may calculate the azimuth and elevation directions as estimated directions of arrival for each transmitting antenna with a different beam direction and use them as positioning output. The same application is possible in the operation example 2 of the direction estimation unit 213 described later.

[0338] Through the above operations, the direction estimation unit of the radar device 10 outputs, for example, the distance index f as a positioning output. b_cfar and the received signal Y after encoding Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar Based on ndop_code(ndm),ndm), an estimated direction of arrival value may be output. Furthermore, the direction estimation unit 213 may output distance index f as a positioning output.b_cfar The system may also output an estimated Doppler frequency of the target.

[0339] Also, distance index f b_cfar This may be converted into distance information using equation (10) and output. The same can be applied in the operation example 2 of the direction estimation unit 213 described later.

[0340] Furthermore, information input from the coding Doppler multiplexing / decoupling unit 212 (for example, distance index f b_cfar , and the received signal Y after encoding Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar If there are multiple ndop_code(ndm),ndm)), the direction estimation unit 213 may calculate estimated directions of arrival for them in the same manner as described above and output the positioning result.

[0341] <Example of operation of direction estimation unit 213 2> In example 2, for instance, the direction estimation unit 213 uses the distance index f b_cfar and the received signal YBq after encoding Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar Based on ndop_code(ndm),ndm), the virtual receive array correlation vector hq(f) of the direction estimation unit 213 shown in equation (15) is obtained. b_cfar ,f s_comp_cfar It generates ndop_code(ndm),ndm) and performs direction estimation based on the received signal from the transmitting antenna in beam direction Bq.

[0342] Here, q = 1 to NB. For example, if the number of multi-beams NB = 2, then q = 1 or 2. Below, we will explain the operation when NB = 2 as an example, but the value of NB is not limited to this.

[0343] The direction estimation unit 213 processes the received signal YBq using coded Doppler multiplexing and separation. z (f b_cfar ,f s_comp_cfarThe beam direction Bq corresponding to q that matches ndop_code(ndm),ndm) is estimated.

[0344] Here, the information input from the encoded Doppler multiplexing / decoupling unit 212 is the received signal YBq after encoded Doppler multiplexing / decoupling processing. z (f b_cfar ,f s_comp_cfar If it includes ndop_code(ndm),ndm), it includes coded Doppler multiplexed and decoupled received signals for Nt transmitting antennas, but N Bq Since no received signal is obtained other than the encoded Doppler multiplexed signal for each transmitting antenna, it includes zero-value signals. Therefore, the virtual received array correlation vector hq(f) of the direction estimation unit 213. b_cfar ,f s_comp_cfar The virtual receive array correlation vector hq(f b_cfar ,f s_comp_cfar Using this method, direction estimation is performed on the reflected wave signal from the target based on the phase difference between each transmitting and receiving antenna.

number

[0345] For example, the transmitting antennas in beam direction B1 are Tx#1 and Tx#3, and the transmitting antennas in beam direction B2 are Tx#2 and Tx#4, N B1 =2, N B2 =2, N t When = 4 and the number of receiving antennas Na = 4, the B1 beam antenna extraction vector SP extracts the received signal corresponding to the transmitting antenna in beam direction B1. B1 , and a B2 beam antenna extraction vector SP that extracts the received signal corresponding to the transmitting antenna in beam direction B2. B2 This is 16(=N) as shown in equations (16) and (17) below. t ×Na) It may be expressed as the following column vector, where the superscript T represents the vector transpose.

number

number

[0346] The direction estimation unit 213, for example, extracts the B1 beam antenna vector SP. B1 Using the element index where an element is 1, the virtual receive array correlation vector h1(f b_cfar , f s_comp_cfar The element components of the element index are extracted from ), and the column vector obtained by arranging the element index in ascending order is used as the virtual received array correlation vector h by the B1 beam antenna. B1 (f b_cfar , f s_comp_cfar ) is generated as follows. For example, the B1 beam antenna extraction vector SP shown in equation (16) B1 In this case, the elements in the 1st to 4th and 9th to 12th element indices are 1. In this case, the direction estimation unit 213 calculates the virtual received array correlation vector h1(f b_cfar , f s_comp_cfar From ), element components are extracted in the order of the 1st to 4th and 9th to 12th element indices, and the B1 beam antenna virtual receive array correlation vector h B1 (f b_cfar , f s_comp_cfar ) generates.

[0347] Similarly, the direction estimation unit 213 extracts, for example, the B2 beam antenna vector SP B2 Using the element index where an element is 1, the virtual receive array correlation vector h2(f b_cfar , f s_comp_cfar The element components of the element index are extracted from ), and the column vector obtained by arranging the element index in ascending order is used as the virtual received array correlation vector h by the B2 beam antenna. B2 (f b_cfar , f s_comp_cfar It is generated as follows: For example, the B2 beam antenna extraction vector SP shown in equation (17). B2In this case, the elements at the 5th to 8th and 13th to 16th element indices are 1. In this case, the direction estimation unit 213 calculates the virtual received array correlation vector h2(f b_cfar , f s_comp_cfar From ), element components are extracted in the order of the 5th to 8th and 13th to 16th element indices, and the B2 beam antenna virtual receive array correlation vector h B2 (f b_cfar , f s_comp_cfar ) generates.

[0348] The direction estimation unit 213, for example, the Bq beam antenna virtual receiving array correlation vector h Bq (f b_cfar , f s_comp_cfar Using the direction estimation evaluation function P H-Bq (θ u , f b_cfar , f s_comp_cfar ) in the direction θ u The angle is varied within a predetermined range, and the spatial profile for each Bq beam is calculated. Here, q = 1 or 2.

[0349] The direction estimation unit 213 may extract a predetermined number of maximum peaks in descending order of magnitude from the spatial profile based on the received signal corresponding to the transmitting antenna of the calculated beam direction Bq, and output the azimuth direction of the maximum peak as an estimated arrival direction value by the Bq beam (for example, a positioning output).

[0350] Note that the direction estimation evaluation function value P H-Bq (θ u , f b_cfar , f s_comp_cfar There are various methods for estimating the direction of arrival, depending on the direction of arrival algorithm. For example, the estimation method using an array antenna disclosed in Non-Patent Document 3 may be used.

[0351] Through the above operations, the direction estimation unit 213 of the radar device 10 outputs, for example, the distance index f b_cfar The received signal YB is the received signal from the transmitting antenna with beam direction Bq, which has undergone coded Doppler multiplexing and separation. z (f b_cfar ,fs_comp_cfar Based on ndop_code(ndm),ndm), the estimated direction of arrival by the Bq beam may be output. Furthermore, the direction estimation unit 213 may output the distance index f as a positioning output. b_cfar The system may also output an estimated Doppler frequency of the target.

[0352] Furthermore, information input from the coding Doppler multiplexing / decoupling unit 212 (for example, distance index f b_cfar , and the received signal YBq after encoding Doppler multiplexing and decoupling. z (f b_cfar ,f s_comp_cfar If there are multiple ndop_code(ndm),ndm)), the direction estimation unit 213 may calculate estimated directions of arrival for them in the same manner as described above and output the positioning result.

[0353] The above describes the operation examples 1 and 2 of the direction estimation unit 213.

[0354] Next, we will describe examples of MIMO antenna configurations and examples of the operation of the direction estimation unit 213 when using these MIMO antenna configurations. In the following, the transmitting antenna and receiving antenna in a MIMO radar will be collectively referred to as MIMO antennas.

[0355] In the following description, each transmitting antenna included in the transmitting antenna section 109 may be a sub-array configuration in which multiple planar patch antennas are arranged vertically and horizontally, as shown in Figure 17. In the example in Figure 17, the transmitting antenna consists of eight planar patch antennas in the vertical direction and four in the horizontal direction. For example, by changing the feeding phase for each patch antenna included in one transmitting antenna, it is possible to form a beam pattern (element pattern of the transmitting antenna) that directs a directional beam in a desired direction. Also, for example, the more horizontal (or vertical) planar patch antennas that make up one transmitting antenna, the sharper the horizontal (or vertical) directional beam can be formed. One transmitting antenna may consist of, for example, a number of planar patches that satisfies the desired beam width.

[0356] Note that the configuration of a single transmitting antenna is not limited to the example shown in Figure 17, and the number of patch antennas constituting a single transmitting antenna (for example, at least one of the total number, the number in the horizontal direction, and the number in the vertical direction) is not limited to the number shown in Figure 17. Also, a single transmitting antenna is not limited to a planar patch antenna configuration, but may be a configuration in which patch antennas are arranged in either the vertical or horizontal direction. Furthermore, for example, the configuration of each patch antenna of multiple transmitting antennas may be different.

[0357] The following describes an example of a MIMO antenna configuration where two transmitting antennas correspond to each transmitting beam. Each transmitting beam may be formed, for example, by two transmitting antennas.

[0358] Below, as an example, we will describe the antenna configuration of a MIMO radar with four transmitting antennas (e.g., Tx#1 to Tx#4) and three receiving antennas (e.g., Rx#1 to Rx#3).

[0359] For example, as shown in Figure 18 or Figure 19, transmitting antennas Tx#1 to Tx#4 have different directional patterns for the transmitting beam direction (or directional beam direction). In Figures 18 and 19, Tx#1 and Tx#2 have directional patterns for beam direction B1 (beam B1), and Tx#3 and Tx#4 have directional patterns for beam direction B2 (beam B2). As shown in Figures 18 and 19, there are 2 transmitting antennas each with directional patterns for beam direction B1 and beam direction B2, and N B1 =2, N B2 = 2

[0360] Furthermore, in the following, the directivity of the receiving antenna (e.g., Rx#1 to Rx#3) may be omnidirectional, or it may be a nearly uniform directivity characteristic within the field of view of the transmitting antennas (e.g., Tx#1 to Tx#4) in multiple beam directions.

[0361] For example, when the number of transmitting antennas Nt = 4 used for multiplex transmission, the radar device 10 sets the coded Doppler phase rotation amount in the phase rotation amount setting unit 105 to either a code using setting example 1 or a Doppler multiplex signal (Doppler multiplexing number N). DM =3, code multiplex number N CM The radar transmission signal is transmitted using =2). In this case, for example, in setting the Doppler shift amount as described above, N B1 =2, N B2 The Doppler multiplexing signal assignment of =2 can be applied.

[0362] Furthermore, for example, the arrangement of the transmitting antennas Tx#1 to Tx#4 and the receiving antennas Rx#1 to Rx#3 constitutes the arrangement of virtual receiving antennas (or MIMO virtual antennas) VA#1 to VA#12.

[0363] Here, the arrangement of the virtual receiving antenna (virtual receiving array) may be expressed as shown in equation (18) below, based on, for example, the position of the transmitting antenna constituting the transmitting antenna section 109 (e.g., the position of the feed point) and the position of the receiving antenna constituting the receiving antenna section 202 (e.g., the position of the feed point).

number

[0364] Here, the position coordinates of the transmitting antenna (e.g., Tx#n) that constitutes the transmitting antenna section 109 are (X T_#n ,Y T_#n (For example, n=1 to Nt) is expressed as (X R_#z ,Y R_#z (For example, z=1~Na) is expressed as (X V_#b ,Y V_#b (For example, b = 1 ~ Nt × Na)

[0365] In equation (18), for example, VA#1 is represented as the position reference (0,0) of the virtual receive array.

[0366] The following describes examples of MIMO antenna configurations. Note that X T_#n represents the horizontal position coordinate, Y T_#n This is explained as representing vertical position coordinates, but it is not limited to this.

[0367] Figures 18 and 19 show examples of transmitting and receiving antenna configurations (MIMO antenna configurations) used in MIMO radar. Hereafter, the MIMO antenna configuration shown in Figure 18 will be referred to as "Configuration Example A," and the MIMO antenna configuration shown in Figure 19 will be referred to as "Configuration Example B." Figures 18 and 19(a) show an example of MIMO antenna configuration (Tx#1~Tx#4, Rx#1~Rx#3), and Figures 18 and 19(b) show an example of virtual receiving antenna configuration (VA#1~VA#12) formed by the MIMO antenna configuration in Figures 18 and 19(a).

[0368] As shown in Figures 18 and 19(a), in arrangement example A and arrangement example B, the receiving antennas Rx#1 to Rx#3 are arranged horizontally (horizontal direction in Figures 18 and 19) at intervals of Dr. Also in arrangement example A and arrangement example B, the transmitting antennas Tx#1 and Tx#2 corresponding to beam direction B1 are arranged horizontally at intervals of Dr (Dt=Dr) and vertically (vertical direction in Figures 18 and 19) at different positions (for example, at intervals of Dv). Also in arrangement example A and arrangement example B, the transmitting antennas Tx#3 and Tx#4 corresponding to beam direction B2 are arranged horizontally at intervals of Dt and vertically at different positions (for example, at intervals of Dv). Furthermore, as shown in Figures 18 and 19(a), the transmitting antennas Tx#1 and Tx#3 (or Tx#2 and Tx#4) are positioned at the same location vertically and spaced horizontally apart by a distance greater than the aperture (2Dr) of the receiving antennas Rx#1 to Rx#3 (for example, a distance of 3Dr).

[0369] For example, the arrangement of transmitting antennas Tx#1 to Tx#4 shown in Figures 18 and 19(a) (X T_#1 ,Y T_#1 )=(0,0),(X T_#2 ,Y T_#2)=(D r , D V ), (X T_#3 ,Y T_#3 )=(3D r , 0), (X T_#4 ,Y T_#4 )=(D t +3D r , D V ), and the arrangement of receiving antennas Rx#1~Rx#3 (X R_#1 ,Y R_#1 )=(ax,ay),(X R_#2 ,Y R_#2 ) = (ax + D r ,ay),(X R_#3 ,Y R_#3 )=(ax+2D r In the case of ,ay), the position coordinates of the virtual antennas VA#1 to VA#12 that constitute the virtual receiving antenna are calculated from equation (18). Here, ax and ay are arbitrary constants.

[0370] For example, the position coordinates of virtual antennas VA#1 to VA#12 are, as shown in Figures 18 and 19(b), independent of ax and ay, (X V_#1 ,Y V_#1 )=(0,0), (X V_#2 ,Y V_#2 )=(D r , 0), (X V_#3 ,Y V_#3 )=(2D r , 0), (X V_#4 ,Y V_#4 )=(D t ,D V ), (X V_#5 ,Y V_#5 )=(D t +D r , D V ), (X V_#6 ,Y V_#6 )=(D t +2D r , D V ) , (X V_#7 ,Y V_#7 )=(3D r , 0), (X V_#8 ,Y V_#8 )=(4D r , 0), (X V_#9 ,YV_#9 )=(5D r , 0), (X V_#10 ,Y V_#10 )=(D t +3D r ,D V ), (X V_#11 ,Y V_#11 )=(D t +4D r , D V ), (X V_#12 ,Y V_#12 )=(D t +5D r , D V )

[0371] Here, arrangement example A (Figure 18) shows an arrangement example using Dt = Dr. Arrangement example B (Figure 19) shows an arrangement example using Dr and Dt such that the absolute value of the difference between Dt and Dr is approximately 0.5 wavelengths (|Dt-Dr| ≈ 0.5). For example, Figure 19 shows an arrangement example where Dt = 1.5 Dr, and an example where Dt - Dr = Dr / 2. This is an arrangement where, for example, assuming Dt = 1.5 wavelengths and Dr = 1 wavelength, Dt - Dr = Dr / 2 = 0.5 wavelengths.

[0372] For example, in the operation example 1 of the direction estimation unit 213 described above, the direction estimation unit 213 processes the information input from the encoded Doppler multiplexing / decompression unit 212 into the received signal Y after encoding Doppler multiplexing / decompression processing. z (f b_cfar ,f s_comp_cfar If it includes ndop_code(ndm),ndm), the virtual receive array correlation vector h(f) shown in equation (14) b_cfar ,f s_comp_cfar It generates a ) and performs direction estimation processing.

[0373] Here, the signal received by the b-th virtual antenna VA#b is the virtual received array correlation vector h(f b_cfar ,f s_comp_cfar It is represented by the b-th element of ). b = an integer between 1 and (Nt × Na).

[0374] Furthermore, the received signal Y, which has undergone coded Doppler multiplexing and separation processing, is input from the coded Doppler multiplexing and separation unit 212. z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm) contains coded Doppler separation signals for Nt transmitting antennas. This is the case when the target direction is, for example, the target direction (2) shown in Figure 10, and corresponds to the region where the beam directions of transmitting antennas Tx#1 to Tx#4 overlap. In this case, the radar transmission signals from transmitting antennas Tx#1 to Tx#4 are reflected by the target and received by receiving antennas Rx#1 to Rx#3. Therefore, in this case, the direction estimation unit 213 can perform direction estimation using the received signals of virtual antennas VA#1 to VA#12 corresponding to Tx#1 to Tx#4.

[0375] In the MIMO antenna configuration shown in Figures 18 and 19(a), Tx#1 and Tx#2 have directional characteristics in beam direction B1, and Tx#3 and Tx#4 have directional characteristics in beam direction B2, corresponding to different beam directions. Also, as shown in Figure 10, beam direction B1 and beam direction B2 overlap in an angular region approximately equal to the beam width. Here, as shown in Figures 18 and 19(a), the configurations of Tx#1 and Tx#2, and Tx#3 and Tx#4, are offset vertically (for example, by an offset value Dv), so that the direction estimation unit 213 can measure angles in the vertical direction in addition to the horizontal direction. Furthermore, the arrangements of Tx#1 and Tx#2, and Tx#3 and Tx#4, respectively, allow the aperture length of the virtual receiving antenna to be expanded horizontally when a target exists in the overlapping region of beam direction B1 and beam direction B2 (for example, target direction (2) shown in Figure 10), thereby improving the horizontal estimation accuracy and angular resolution in the angle measurement processing of the direction estimation unit 213.

[0376] Furthermore, in arrangement example A, as shown in the arrangement of Tx#1 and Tx#2 (or the arrangement of Tx#3 and Tx#4) in Figure 18(a), the horizontal offset Dt is Dt = Dr. Thus, Tx#1 and Tx#2 (or Tx#3 and Tx#4) are arranged with an offset in the horizontal direction equal to the element spacing Dr of the receiving antennas Rx#1 to Rx#3. For this reason, as shown in Figure 18(b), the virtual receiving antenna arrangement includes arrangements in which the horizontal positions of multiple virtual antennas (e.g., VA#2 and VA#4, or VA#3 and VA#5) coincide, but their vertical positions differ by Dv. With such a virtual receiving antenna arrangement, the direction estimation unit 213 can easily measure the vertical angle based, for example, on the received phase difference between two virtual antennas (e.g., VA#2 and VA#4, or VA#3 and VA#5) whose horizontal positions coincide.

[0377] Furthermore, arrangement example B is an arrangement using Dr and Dt such that the absolute value of the difference between Dt and Dr is approximately 0.5 wavelengths (|Dt-Dr|≈0.5), as shown in the arrangement of Tx#1 and Tx#2 (or the arrangement of Tx#3 and Tx#4) in Figure 19(a). With this arrangement, for example, as shown in Figure 19(b), the spacing between virtual antennas VA#2 and VA#4 (or the spacing between VA#3 and VA#5, VA#7 and VA#6, VA#8 and VA#10, and VA#9 and VA#11) is Dt-Dr if Dt>Dr, and Dr-Dt if Dr>Dt. For example, when the absolute value of the difference between the transmitting antenna spacing Dt and the receiving antenna spacing Dr, |Dt-Dr|, is set to half a wavelength, the radar device 10 can suppress grating lobes within a field of view of ±90°. For example, if Dt = 1.5λ and Dr = 1λ, then |Dt - Dr| = 0.5λ.

[0378] Although the explanation described the case where the difference between Dt and Dr, |Dt-Dr| (default value), is set to half a wavelength (0.5λ), it is not limited to this. For example, |Dt-Dr| may be set to any value in the range of approximately 0.45λ to 0.8λ (for example, any value in the range of 0.5 to 0.8 times the wavelength of the radar transmission signal).

[0379] For example, |Dt-Dr| may be set according to the horizontal field of view of the radar device 10, and grating lobes within the field of view can be suppressed. For example, if the horizontal field of view is wide, in the range of ±70 degrees to ±90 degrees, |Dt-Dr| may be set to about 0.5λ. Alternatively, if the horizontal field of view is narrow, in the range of ±20 degrees to ±40 degrees, |Dt-Dr| may be set to a wider interval, for example, about 0.7λ.

[0380] Furthermore, in the above-described example of the operation of the direction estimation unit 213, the direction estimation unit 213 processes the received signal YB1 that has undergone encoded Doppler multiplexing and separation processing, which is input from the encoded Doppler multiplexing and separation unit 212. z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm), or YB2 z (f b_cfar ,f s_comp_cfar Based on ndop_code(ndm),ndm), the virtual receive array correlation vector h B1 (f b_cfar , f s_comp_cfar ), or h B2 (f b_cfar , f s_comp_cfar It generates a ) and performs direction estimation processing.

[0381] Here, the signal received by the b-th virtual antenna VA#b is the virtual received array correlation vector hq(f b_cfar , f s_comp_cfar It is represented by the b-th element of ), where q = 1 or 2.

[0382] Furthermore, the received signal YBq, which has undergone coded Doppler multiplexing and separation processing, is input from the coded Doppler multiplexing and separation unit 212. z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm) is N BqThis includes the received signal for the transmitting antenna in beam direction Bq. This is the case where the target direction is, for example, target direction (1) (e.g., beam direction B1) or target direction (3) (e.g., beam direction B2) as shown in Figure 10, and corresponds to the region of beam direction Bq. In this case, the radar transmitted signal from the transmitting antenna in beam direction Bq is reflected by the target and received by receiving antennas Rx#1 to Rx#3.

[0383] Therefore, in this case, for example, when q=1 (when the target direction is the target direction (1) shown in Figure 10), the direction estimation unit 213 performs direction estimation using the received signals of virtual antennas VA#1 to VA#6 corresponding to transmitting antennas Tx#1 and Tx#2 included in beam direction B1. Also, for example, when q=2 (when the target direction is the target direction (3) shown in Figure 10), the direction estimation unit 213 performs direction estimation using the received signals of virtual antennas VA#7 to VA#12 corresponding to transmitting antennas Tx#3 and Tx#4 included in beam direction B2.

[0384] In example configuration A, in Figure 18(a), Dt and Dr may be set to, for example, one wavelength or more. In this case, as a result of the direction estimation processing in the direction estimation unit 213, grating lobes may occur, and ambiguity may arise in the horizontal direction estimation. On the other hand, the direction estimation unit 213 processes the received signal Y that has undergone encoded Doppler multiplexing processing input from the encoded Doppler multiplexing / decomposition unit 212. z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm),YB1 z (f b_cfar ,f s_comp_cfar ndop_code(ndm),ndm), or YB2 z (f b_cfar ,f s_comp_cfar Direction estimation processing is performed based on ndop_code(ndm),ndm). As a result, the direction estimation unit 213 can identify that the target is in one of the directions of beam direction B1, beam direction B2, or the overlapping region between beam directions B1 and B2, so that the true direction can be detected even if a grating lobe occurs.

[0385] Furthermore, in arrangement examples A and B, Dv may be set to a value of approximately 0.45λ to 0.8λ, respectively (for example, any value in the range of 0.5 to 0.8 times the wavelength of the radar transmission signal). Dv may be set, for example, according to the vertical field of view of the radar device 10. For example, if the vertical field of view is wide, in the range of ±70 degrees to ±90 degrees, Dv may be set to approximately 0.5λ. Alternatively, if the vertical field of view is narrow, in the range of ±20 degrees to ±40 degrees, Dv may be set to a wider interval, for example, approximately 0.7λ.

[0386] Here, λ represents the wavelength of the carrier frequency of the radar transmission signal. For example, when a chirp signal is used as the radar transmission signal, λ is the wavelength of the center frequency in the frequency sweep bandwidth of the chirp signal.

[0387] In arrangement examples A and B, the arrangement of the receiving antennas (Rx#1 to Rx#3) was described as being in the same position vertically and offset horizontally at equal intervals of Dr. However, the arrangement of the receiving antennas is not limited to this. For example, in the horizontal arrangement of the receiving antennas, the spacing between the receiving antennas may be unequal.

[0388] Furthermore, the MIMO antenna configurations described in Configuration Example A and Configuration Example B are merely examples and are not limiting. For example, a configuration in which other antennas (at least one of a transmitting antenna and a receiving antenna) are further arranged in addition to the MIMO antenna configuration described in Configuration Example A and Configuration Example B is also possible, with the horizontal and vertical directions reversed. Additionally, the spacing between transmitting antennas described in Configuration Example A and Configuration Example B may be applied to the spacing between receiving antennas, and the spacing between receiving antennas described in Configuration Example A and Configuration Example B may be applied to the spacing between transmitting antennas.

[0389] Through the operations described above, the direction estimation unit 213 can perform direction estimation processing in response to the fact that the separation operation of the coded Doppler multiplexing / separation unit 212 differs depending on the target direction in multibeam transmission.

[0390] For example, the direction estimation unit 213 can improve angle measurement accuracy and angle measurement resolution by performing direction estimation using the received signals of Nt × Na virtual receiving antennas when the coded Doppler multiplexing separation unit 212 can separate Doppler multiplexed signals from all transmitting antennas (for example, in the case of target direction (2)).

[0391] Furthermore, for example, the direction estimation unit 213 determines if the coded Doppler multiplexing / decoupling unit 212 can separate the Doppler multiplexed signal from the transmitting antenna in beam direction Bq (for example, in the case of target direction (1) or (3)), N Bq By performing direction estimation using the received signals from ×Na virtual receiving antennas, the angle measurement accuracy and angle measurement resolution can be improved.

[0392] The above describes an example of the operation of the direction estimation unit 213.

[0393] As described above, in this embodiment, the radar device 10, in a multi-beam transmitting MIMO radar using coded Doppler multiplexing, assigns different coded Doppler multiplexed signals (for example, signals in which at least one of the Doppler multiplexing patterns and coded multiplexing patterns is different) between multi-beams that satisfy at least condition 1 in the phase rotation amount setting unit 105. As a result, even when the received levels between reflected waves corresponding to transmitting antennas having different directional characteristics differ significantly, the radar device 10 can distinguish the transmitting antenna in the coded Doppler multiplexing separation unit 212, enabling coded Doppler multiplexing separation. Therefore, according to this embodiment, deterioration of target detection performance, or misestimation of Doppler frequency or deterioration of angle measurement performance can be suppressed.

[0394] Furthermore, for example, when assigning coded Doppler multiplexed signals in the phase rotation amount setting unit 105, if conditions 1 and 2 described above are met, the radar device 10 can expand the detectable Doppler frequency range fd to the range -1 / (2Tr) ≤ fd < 1 / (2Tr) even when the received levels between reflected waves corresponding to transmitting antennas with different directional characteristics differ significantly, thereby expanding the Doppler frequency range to the same extent as when using one transmitting antenna.

[0395] Furthermore, in the radar device 10 of this embodiment, as a multi-beam transceiver MIMO radar configuration, Doppler multiplexing and separation is possible without using beam direction determination processing using a directional receiving antenna (or directional receiving processing using a receiving array antenna), thus reducing the amount of computation required for receiving processing.

[0396] Furthermore, for example, in a multi-beam transceiver MIMO radar configuration, if receiving antennas with different beam directions are used, the number of receiving antennas available during angle measurement may decrease depending on the target direction, which can lead to a decrease in the angle measurement accuracy or angle measurement resolution of the radar device 10. In this embodiment, for example, Doppler multiplexing and separation can be performed regardless of the target direction without using directional receiving antennas, thus suppressing a decrease in angle measurement accuracy and angle measurement resolution.

[0397] Therefore, according to this embodiment, the detection performance of a multi-beam MIMO radar using coded Doppler multiplexing can be improved.

[0398] (Variation 1) In the above embodiment, the case where the number of multi-beams NB = 2 was described, but the number of multi-beams NB may be 3 or more. Modification 1 describes the case where the number of multi-beams NB ≥ 3.

[0399] When the number of multi-beams NB ≥ 3, the setting of the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105 applies the following condition 1-a and condition 1-b instead of the above-mentioned condition 1. Similar to the above embodiment, even when there is a large difference in the received power level of the reflected wave between the received signals from the transmission antennas in different beam directions, it is possible to separate the Doppler multiplexed signals and obtain the effect of suppressing the deterioration of the positioning performance and the radar detection performance.

[0400] Hereinafter, an example of the setting condition of the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105 when the number of multi-beams NB ≥ 3 will be described.

[0401] For example, in the transmission antenna unit 109, the transmission antennas in Q different beam directions Bq each include (N B1 , N B2 , ~, N BQ ). For example, the phase rotation amount setting unit 105 of the radar transmission unit 100 in a MIMO radar (for example, the radar device 10) that transmits multi-beams sets the encoded Doppler multiplex number N DOP_CODE (ndm) for the Doppler multiplexed signal unevenly, and sets the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm (m) so as to satisfy the following <Condition 1-a> and <Condition 1-b>. Here, ndm = 1 to N DM , and ndop_code(ndm) = 1 to N DOP_CODE (ndm).

[0402] <Condition 1-a> The phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm (m) that satisfies different conditions of Doppler multiplex patterns, different conditions of code multiplex patterns, or different patterns of Doppler multiplex and code multiplex for each transmission antenna in each beam direction Bq. Here, q = 1 to Q.

[0403] <Condition 1-b> When the phase rotation amount setting unit 105 includes a field angle region that overlaps between each beam direction Bq, it includes a set of a plurality of transmission antennas included in the overlapping region (hereinafter referred to as the "transmission antenna set"), and satisfies the conditions of different code multiplexing patterns, or the conditions of different patterns of Doppler multiplexing and code multiplexing, and sets the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm (m). Here, q = 1 to Q.

[0404] The codes and Doppler multiplex signals assigned to the transmission antennas of each beam Bq and the transmission antenna set included in the overlapping region satisfy at least one of the following conditions.

[0405] For example, the different Doppler multiplexing pattern conditions may be any one of the following conditions (for example, also referred to as condition 1A-a). (A-1) The Doppler multiplex numbers corresponding to each beam direction are the same, and different Doppler intervals are included in each beam direction (however, N DM_Bq ≧2). (A-2) The Doppler multiplex numbers for each beam direction are different. (A-3) When the Doppler multiplex number is 3 or more, if the same Doppler interval is included in the Doppler shift interval for each beam direction, the order of the Doppler intervals is different (circular mismatch).

[0406] Also, the different code multiplexing pattern conditions may be any one of the following conditions (for example, also referred to as condition 1B-a). (B-1) The code intervals (code INDEX intervals) assigned to each Doppler multiplex signal are different (circular mismatch). (B-2) The code multiplex numbers assigned to each Doppler multiplex signal are different (circular mismatch).

[0407] Here, when the multi-beam number NB≧3, the number of transmission antennas Nt≧4, the Doppler multiplex number N DM ≧2, the maximum code multiplex number N CM ≧2, and Nt < N DM ×N CM And the number of transmission antennas N in the beam direction BqBq This is how it is written. N Bq ≥ 1, and the sum of transmitting antennas in each beam direction Bq is Nt (N B1 + N B2 + ~ + N BQ =Nt ) is also the Doppler multiplexing number N assigned to the transmitting antenna in beam direction Bq. DM_Bq This is how it is written. N DM_Bq <N DM That is the case.

[0408] Furthermore, Q different transmitting antennas with beam directions Bq are each (N B1 ,N B2 ,~,N BQ In a MIMO radar (for example, radar device 10) that transmits multiple beams using ) units, the phase rotation amount setting unit 105 of the radar transmission unit 100 further satisfies the following conditions 2-a and 2-b, by encoding the Doppler phase rotation amount ψ ndop_code(ndm), ndm You may also set (m).

[0409] <Condition 2-a> The signals transmitted from each beam Bq's transmitting antenna are multiplexed using a code multiplexing number that is non-uniform among the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It is one of the values ​​in the range less than or equal to -1. Here, q = 1 to Q.

[0410] <Condition 2-b> When overlapping beam regions are included between each beam Bq, signals transmitted from the transmitting antenna set included in the overlapping beam region are multiplexed using a code multiplexing number that is non-uniform among the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It is one of the values ​​in the range of -1 or less.

[0411] By setting the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105, satisfying conditions 1-a and 1-b, as well as conditions 2-a and 2-b, the Doppler detection range detectable by the radar device 10 can be expanded to a range equivalent to that with one transmitting antenna (for example, a range of ±1 / (2Tr)), similar to the embodiment described above. Furthermore, even if conditions 1-a and 1-b are satisfied, but conditions 2-a and 2-b are not, the Doppler detection range for equally spaced DDMs (for example, -1 / (2 N) can be expanded, similar to the embodiment described above. t Tr)≦fd < 1 / (2 N t This allows for a wider Doppler detection range than Tr)).

[0412] The following describes an example of the operation of the radar device 10.

[0413] <Example of operation 1> In Operation Example 1, the number of multi-beams NB = 3, and there are no overlapping beam regions between each beam direction Bq.

[0414] For example, Figure 20 shows example beam patterns of transmitting antennas in beam directions B1, B2, and B3 when the number of multi-beams NB = 3. As shown in Figure 20, if there is no (or little) overlap in the beam patterns of the transmitting antennas in each beam direction, conditions 1-a and 2-a may be applied.

[0415] For example, in Figure 20, if the target direction is one of beam direction B1, beam direction B2, or beam direction B3, the Doppler shift setting unit 106 may assign Doppler multiplexed signals to satisfy condition 1-a. This allows the radar device 10 to distinguish in the coded Doppler multiplexing / deselection unit 212 whether the received level of the received signal corresponding to the transmitting antenna in beam direction B1 decreases, whether the received level of the received signal corresponding to the transmitting antenna in beam direction B2 decreases, or whether the received level of the received signal corresponding to the transmitting antenna in beam direction B3 decreases.

[0416] Furthermore, if this determination result determines that the signal is a received signal from the transmitting antenna in beam direction B1 (or B2, B3), the assignment of the coded Doppler phase rotation amount in the phase rotation amount setting unit 105 satisfies condition 2-a, and the coded Doppler multiplexed signal for the transmitting antenna in beam direction B1 (or B2, B3) can be separated using the operation of the existing coded Doppler multiplexed signal separation unit. Through this operation of the coded Doppler multiplexed signal separation unit 212, the radar device 10 can determine the Doppler frequency fd of the target in the range -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each coded Doppler multiplexed signal.

[0417] <Example of operation 2> In Operation Example 2, the number of multi-beams NB = 3, and overlapping beam regions are included between each beam direction Bq.

[0418] For example, Figure 21 shows example beam patterns of transmitting antennas in beam directions B1, B2, and B3 when the number of multi-beams NB = 3. As shown in Figure 21, if the beam patterns of the transmitting antennas in each beam direction include overlapping portions (overlapping beam regions), conditions 1-a, 1-b, 2-a, and 2-b may be applied.

[0419] For example, in Figure 21, if the target direction is one of the transmission beam directions B1, B2, or B3 outside the overlapping beam range (in Figure 21, target directions (1), (3), or (5)), the assignment of the coded Doppler phase rotation amount by the phase rotation amount setting unit 105 may satisfy condition 1-a. This allows the radar device 10 to determine in the coded Doppler multiplexing / decompression unit 212 which of the transmission antennas in beam directions B1, B2, or B3 the received signal corresponds to.

[0420] Furthermore, for example, in Figure 21, if the target direction is within the overlapping beam range (in Figure 21, target direction (2) or (4)), the assignment of the coded Doppler phase rotation amount by the phase rotation amount setting unit 105 may satisfy conditions 1-a and 1-b. This allows the radar device 10 to determine which of the transmitting antennas in beam directions B1, B2, and B3 the received signal corresponds to, as well as to determine in the coded Doppler multiplexing / decoupling unit 212 whether the received signal is from the overlapping beam region of the transmitting antennas in beam directions B1 and B2, or from the overlapping beam region of the transmitting antennas in beam directions B2 and B3.

[0421] Furthermore, if this determination result determines that the received signal corresponds to the transmitting antenna in beam direction B1 (or B2, B3), the assignment of the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 satisfies condition 2-a, and the encoded Doppler multiplexed signal for the transmitting antenna in beam direction B1 (or B2, B3) can be separated using the operation of the existing encoded Doppler multiplexed signal separation unit. Through this operation of the encoded Doppler multiplexed signal separation unit 212, the radar device 10 can determine the Doppler frequency fd of the target in the range -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each encoded Doppler multiplexed signal.

[0422] Furthermore, if it is determined that the received signal is from the overlapping beam region of the transmitting antennas in beam directions B1 and B2 (or beam directions B2 and B3), the assignment of coded Doppler multiplexed signals in the phase rotation amount setting unit 105 satisfies condition 2-b, so that coded Doppler multiplexed signals for the transmitting antennas included in the overlapping beam region of the transmitting antennas in beam directions B1 and B2 (or beam directions B2 and B3) can be separated using the operation of the existing coded Doppler multiplexed signal separation unit. Through this operation of the coded Doppler multiplexed signal separation unit 212, the radar device 10 can determine the Doppler frequency fd of the target in the range -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each coded Doppler multiplexed signal.

[0423] The above describes an example of the operation of the radar device 10.

[0424] Next, we will describe an example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105.

[0425] The following describes an example of setting the encoded Doppler phase rotation amount (when NB=3) when condition 1 (e.g., condition 1-a, condition 1-b) and condition 2 (e.g., condition 2-a, condition 2-b) are satisfied.

[0426] Figure 22 shows the number of transmitting antennas Nt=6, N B1 =2, N B2 =2, N B2 An example of setting the encoded Doppler phase rotation amount in the phase rotation amount setting unit 105 when =3 is shown.

[0427] In Figure 22, Tx#1 and Tx#2 are transmitting antennas in beam direction B1, Tx#3 and Tx#4 are transmitting antennas in beam direction B2, and Tx#5 and Tx#6 are transmitting antennas in beam direction B3.

[0428] Furthermore, in Figure 22, the Doppler multiplexing number N DM = 5, and the Doppler shift setting unit 106 may set the five Doppler shift amounts DOP1 to DOP5 using, for example, the maximum equally spaced Doppler shift amount setting shown in equation (5). In Figure 22, the phase rotation amounts that impart Doppler shift amounts DOP1=0, DOP2=Δfd, DOP3=2Δfd, DOP4=-2Δfd, and DOP5=-Δfd are φ1=0, φ2=2π / 5, φ3=4π / 5, φ4=6π / 5 (or φ4=-4π / 5), and φ5=8π / 5 (or φ5=-2π / 5), respectively. As shown in Figure 22, the Doppler multiple spacing Δfd is equally spaced, and Δfd=1 / (10Tr).

[0429] Furthermore, in Figure 22, the code multiplexing number N CM=2, and the coding unit 107 uses, for example, an orthogonal code sequence of Walsh-Hadamard code with code length Loc=2, namely Code1={1,1} and Code2={1,-1}.

[0430] In Figure 22, the number of transmitting antennas Nt = 6, and the number of Doppler multiplexers N DM =5, code multiplex number N CM = 2, Nt <N DM ×N CM Therefore, the phase rotation amount setting unit 105 sets the encoding Doppler multiplexing number N for the Doppler multiplexed signal. DOP_CODE (ndm) can be set non-uniformly (where ndm = 1 to N) DM ).

[0431] As shown in Figure 22, in the encoding unit 107, the number of encoded Doppler multiplexings for a Doppler multiplexed signal using the five Doppler shift amounts DOP1 to DOP5 input from the Doppler shift setting unit 106 is N DOP_CODE (1) = 2, N DOP_CODE (2) = 1, N DOP_CODE (3) = 1, N DOP_CODE (4) = 1, N DOP_CODE (5)=1. In this way, the phase rotation amount setting unit 105 sets the number of encoded Doppler multiplexings for the Doppler multiplexed signal to be non-uniform.

[0432] Furthermore, in Figure 22, the Doppler shift setting unit 106 sets the Doppler multiplexing number N for the transmitting antennas Tx#1 and Tx#2 in beam direction B1. DM Among the Doppler multiplexed signals with =5, for example, assign Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP2 (N DM_B1 =2). The encoding unit 107 also assigns Code2 and Code1 to the Doppler multiplexed signals using the Doppler shift amounts DOP1 and DOP2 assigned to the transmitting antennas Tx#1 and Tx#2 in beam direction B1. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#1 and Tx#2 in beam direction B1. 2, 1 (m), ψ 1, 2 Set (m).

[0433] Furthermore, in Figure 22, the Doppler shift setting unit 106 sets the Doppler multiplexing number N for the transmitting antennas Tx#3 and Tx#4 in beam direction B2. DM Among the Doppler multiplexed signals with =5, for example, assign Doppler multiplexed signals using Doppler shift amounts DOP4 and DOP5 (N DM_B2 =2). Furthermore, the encoding unit 107 assigns Code1 and Code1 to the Doppler multiplexed signals using Doppler shift amounts DOP4 and DOP5 assigned to the transmitting antennas Tx#3 and Tx#4 in beam direction B2, respectively. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#3 and Tx#4 in beam direction B2. 1, 4 (m), ψ 1, 5 Set (m).

[0434] Furthermore, in Figure 22, the Doppler shift setting unit 106 sets the Doppler multiplexing number N for the transmitting antennas Tx#5 and Tx#6 in beam direction B3. DM Among the Doppler multiplexed signals with =5, for example, assign a Doppler multiplexed signal using Doppler shift amounts DOP1 and DOP3 (N DM_B3 =2). The encoding unit 107 also assigns Code1 and Code2 to the Doppler multiplexed signals using Doppler shift amounts DOP1 and DOP3 assigned to the transmitting antennas Tx#5 and Tx#6 in beam direction B2. For example, the phase rotation amount setting unit 105 sets the encoded Doppler phase rotation amount ψ for each of the transmitting antennas Tx#5 and Tx#6 in beam direction B3. 1, 1 (5), ψ 2, 3 Set (m).

[0435] In Figure 22, the Doppler multiplexing numbers assigned by the Doppler shift setting unit 106 to each transmitting antenna in beam directions B1, B2, and B3 are N DM_B1 =N DM_B2 =N DM_B3 = 2, which is the same. Therefore, the setting of the encoded Doppler phase rotation amount shown in Figure 22 does not match the different Doppler multiplexing pattern conditions of condition 1A-a.

[0436] On the other hand, in Figure 22, the code indices assigned to the respective transmitting antennas in beam directions B1, B2, and B3 for each of the Doppler multiplexed signals DOP1 to DOP5 are CodeIndex_B1=(2,1,*,*,*), CodeIndex_B2=(*,*,*,1,1), and CodeIndex_B3=(1,*,2,*,*). This results in a cyclic mismatch, and the code index intervals are different, thus satisfying condition 1B-a(B-1).

[0437] Furthermore, in Figure 22, the code multiplexing numbers assigned to each transmitting antenna in beam directions B1, B2, and B3 for each of the Doppler multiplexed signals DOP1 to DOP5 are N_Code_B1=(1,1,0,0,0), N_Code_B2=(0,0,0,1,1), and N_Code_B3=(1,0,1,0,0). These include code multiplexing numbers that result in cyclic matching, and since the code multiplexing numbers are the same, condition 1B-a(B-2) is not satisfied.

[0438] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210 observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1_alias=(1,2,*,*,*), CodeIndex_B2_alias=(*,*,*,2,2), and CodeIndex_B3_alias=(2,*,1,*,*), which are different (a cyclic mismatch). Therefore, in the example in Figure 22, for the target's Doppler frequency in the range of -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), the code indices are cyclic mismatched and the code intervals are different. Thus, condition 1-a is satisfied, and the different code multiplexing pattern conditions are met.

[0439] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 22 is an example of a setting that satisfies condition 1-a.

[0440] Furthermore, in Figure 22, the code indices assigned to the overlapping beam regions (transmitting antenna sets) in beam directions B1 and B2, and the overlapping beam regions (transmitting antenna sets) in beam directions B2 and B3, for each of the Doppler multiplexed signals DOP1 to DOP5, are CodeIndex_B1&B2=(2,1,*,1,1) and CodeIndex_B2&B3=(1,*,2,1,1), resulting in a cyclic mismatch. In addition, even if CodeIndex_B1, CodeIndex_B2, and CodeIndex_B3 are included in addition to CodeIndex_B1&B2 and CodeIndex_B2&B3, the code index intervals are different (cyclic mismatch), thus satisfying condition 1-b.

[0441] Furthermore, if the target's Doppler frequency is -1 / (2Tr) ≤ fdtarget < -1 / (4Tr) or 1 / (4Tr) ≤ fdtarget < 1 / (2Tr), the Doppler analysis unit 210 observes the folded Doppler frequency. In this case, the code indices are CodeIndex_B1&B2_alias=(1,2,*,2,2) and CodeIndex_B2&B3_alias=(2,*,1,2,2), which are different (a cyclic mismatch). Therefore, in the example in Figure 22, even including CodeIndex_B1_alias, CodeIndex_B2_alias, and CodeIndex_B3_alias, the code indices are cyclic mismatches within the range of -1 / (2Tr) ≤ fdtarget < -1 / (2Tr), and the code index intervals are different, thus satisfying condition 1-b.

[0442] Based on the above, the setting of the encoded Doppler phase rotation amount shown in Figure 22 is an example of a setting that satisfies condition 1-b.

[0443] Furthermore, in Figure 22, the code multiplexing numbers assigned to each Doppler multiplexed signal at the transmitting antennas in beam directions B1, B2, and B3 are N_Code_B1=(1,1,0,0,0), N_Code_B2=(0,0,0,1,1), and N_Code_B3=(1,0,1,0,0). The signals are multiplexed with code multiplexing numbers that are non-uniform among the Doppler multiplexed signals, and the code multiplexing numbers range from 1 to N. CM It falls within the range of -1 or less. Therefore, the setting of the encoded Doppler phase rotation amount shown in Figure 22 is an example of a setting that satisfies condition 2-a.

[0444] Furthermore, in Figure 22, the code multiplexing numbers assigned to each Doppler multiplexed signal in the overlapping beam regions of beam directions B1 and B2, and the overlapping beam regions of beam directions B2 and B3, are N_Code_B1&B2=(1,1,0,1,1) and N_Code_B2&B3=(1,0,1,1,1). The signals are multiplexed with a code multiplexing number that is non-uniform between the Doppler multiplexed signals, and the code multiplexing number ranges from 1 to N. CM It falls within the range of -1 or less. Therefore, the setting of the encoded Doppler phase rotation amount shown in Figure 22 is an example of a setting that satisfies condition 2-b.

[0445] The following describes an example of a received signal at the output of the Doppler analysis unit 210 when the transmitting antenna unit 109 includes transmitting antennas with different beam directions B1, B2, and B3 based on the Doppler shift amount setting shown in Figure 22, and the receiving antenna unit 202 is an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both transmitting antennas in beam direction B1 and beam direction B2).

[0446] For example, when the target direction is one of the target directions (1), (3), or (5) shown in Figure 21 (for example, when a target exists around beam direction B1, B2, or B3), or when the target direction is one of the target directions (2) or (4) (for example, when a target exists around overlapping beam regions B2&B3 or B2&B3), the code interval differs for each beam direction transmitting antenna and each overlapping beam direction transmitting antenna set. Therefore, the radar device 10 can determine in the coded Doppler multiplexing / decoupling unit 212 a decrease in the received level of the received signal corresponding to a transmitting antenna included in any of the beam directions B1, B2, or B3, or overlapping beam regions B2&B3 or B2&B3.

[0447] If, based on this determination result, it is determined that the signal is a received signal from a transmitting antenna in beam direction Bq or overlapping beam region (e.g., B2&B3 or B2&B3), the settings for the encoded Doppler multiplexed signal for the transmitting antenna in beam direction Bq or overlapping beam region (B2&B3 or B2&B3) are known, so the radar device 10 can separate the multiplexed signal by, for example, the operation disclosed in Patent Documents 5, 6, etc.

[0448] Furthermore, in the example shown in Figure 22, the setting of the encoded Doppler phase rotation amount by the phase rotation amount setting unit 105 satisfies conditions 2-a and 2-b, so the detectable Doppler frequency range fd is in the range of -1 / (2Tr)≦fd < 1 / (2Tr) depending on the target direction, and the Doppler detection range can be expanded compared to the Doppler detection range of equally spaced Doppler multiplexing.

[0449] (Modification 2) In the embodiments and modifications described above, the case in which the beam directions of each beam in a multi-beam system are different from each other was explained, as shown in Figures 10, 20, and 21. However, the settings for the multi-beam system (e.g., beam direction and beam width) are not limited to the examples described above. For example, each beam constituting the multi-beam system may have at least one difference in beam direction and beam width. Also, the number of multi-beams NB may be ≥ 2.

[0450] The following describes an example of a multi-beam configuration.

[0451] <Multibeam configuration example 1> In Example Setting 1, for example, as shown in Figure 23, the beam directions and beam widths may differ in the multi-beam configuration (e.g., beam directions B1, B2, and B3). The beam directions in the horizontal direction (or horizontal plane) may differ in the multi-beam configuration (e.g., beam directions B1, B2, and B3), and the beam widths in the horizontal direction (or horizontal plane) may differ. The beam directions in the vertical direction (or vertical plane) may differ in the vertical direction (or vertical plane), and the beam widths in the vertical direction (or vertical plane) may differ.

[0452] <Multibeam configuration example 2> In the above embodiment, as shown in Figure 10, an example was described in which the beam direction differs in the horizontal direction (or horizontal plane), but the embodiment is not limited to this. In example setting 2, for example, the beam direction may also differ in the vertical direction (or vertical plane).

[0453] For example, as shown in Figure 24(a), in a multi-beam system (e.g., beam directions B1 and B2), the beam directions may be approximately the same in the horizontal direction (or horizontal plane), while they may be different in the vertical direction (or vertical plane).

[0454] Furthermore, as shown in Figure 24(b), for example, in a multi-beam system (e.g., beam directions B1, B2, and B3), the beam directions may differ in both the horizontal (or horizontal plane) and vertical (or vertical surface) directions.

[0455] <Multibeam configuration example 3> In example setting 3, for example, as shown in Figure 25, the beam directions may be approximately the same, but the beam widths may differ in the multi-beam configuration (e.g., beam directions B1 and B2). Furthermore, the beam directions in the horizontal direction (or horizontal plane) may be approximately the same, but the beam widths in the horizontal direction (or horizontal plane) may differ in the multi-beam configuration (e.g., beam directions B1 and B2). Additionally, the beam directions in the vertical direction (or vertical plane) may be approximately the same, but the beam widths in the vertical direction (or vertical plane) may differ in the multi-beam configuration (e.g., beam directions B1 and B2).

[0456] In Example 3, for example, the same configuration can be applied as in the above embodiment by replacing the "transmitting antennas with different beam directions" described in the above embodiment with "transmitting antennas with different beam widths" (hereinafter referred to as "different beams").

[0457] Below, as an example, we will describe the operation of the radar device 10 when the beam direction is the same but the beam width is different, using Example 1 of the coded Doppler phase rotation setting. Note that the coding Doppler phase rotation setting is not limited to Example 1, and the device can operate similarly when using other coding Doppler phase rotation setting examples, and the same effects as in the above embodiment can be obtained.

[0458] For example, if the number of transmitting antennas Nt = 4 (e.g., Tx#1, Tx#2, Tx#3, Tx#4), N B1 =2, N B2When = 2, the above-described example 1 of setting the coded Doppler phase rotation amount in the phase rotation amount setting unit 105 is applied. For example, Tx#1 and Tx#2 are transmitting antennas with beam width B1 (e.g., beam B1) as shown in Figure 25, and Tx#3 and Tx#4 are transmitting antennas with beam width B2 (e.g., beam B2) as shown in Figure 25. In Figure 25, an example is shown where the beam width of beam B1 is wider than the beam width of beam B2. Here, the beam widths of beam B1 and beam B2 may be in the horizontal direction (or horizontal plane), or in the vertical direction (or vertical plane), or both in the horizontal direction (or horizontal plane) and the vertical direction (or vertical plane), and similar effects can be obtained.

[0459] Furthermore, in the radar device 10, the receiving antenna may be an omnidirectional antenna (or an antenna with substantially uniform directional characteristics within the field of view covered by both the transmitting antennas of beam B1 and beam B2).

[0460] For example, if the target position is either target position (1) or target position (3) as shown in Figure 25, the target position is within the beam width and field of view of beam B1, so the received level of the reflected waves corresponding to the radar transmitted waves transmitted from Tx#1 and Tx#2 of beam B1 will be relatively high. On the other hand, target positions (1) and (3) are outside the beam width and field of view of beam B2, so the radiation direction of the radar transmitted waves transmitted from Tx#3 and Tx#4 of beam B2 does not coincide with the direction of target positions (1) and (3), and target positions (1) and (3) are in the null direction of the transmitting antenna Tx#3 of beam B2. For this reason, the received level of the received signals corresponding to Tx#3 and Tx#4 in the radar device 10 will be lower than the received level of the received signals corresponding to Tx#1 and Tx#2. For example, the reception levels of the received signals corresponding to Tx#3 and Tx#4 differ significantly from those of the received signals corresponding to Tx#1 and Tx#2, and depending on the null-direction beam directivity characteristics of Tx#3 and Tx#4, the reception levels can be, for example, 10 dB or more lower. In such cases, the received signal received by the radar device 10 will be the received signal shown in Figure 9(a).

[0461] Furthermore, for example, if the target position is in a region where the field of view angles of both beam B1 and beam B2 overlap, as shown in target position (4) in Figure 25 (for example, if it is at close range), the radar device 10 receives reflected waves corresponding to the radar transmitted waves from Tx#1 and Tx#2 of beam B1, and reflected waves corresponding to the radar transmitted waves from Tx#3 and Tx#4 of beam B2. In this case, the received signal received by the radar device 10 may be, for example, a received signal like that shown in Figure 9(b). Alternatively, for example, if the directional gain of beam B2 is about 10 dB or more higher than that of beam B1, the received signal received by the radar device 10 may be, for example, a received signal like that shown in Figure 9(c).

[0462] Furthermore, for example, if the target position is within the field of view of beam B2 but outside the field of view of beam B1 (for example, at a far distance), as shown in target position (2) in Figure 25, the received level of the reflected waves corresponding to the radar transmitted waves from Tx#3 and Tx#4 of beam B2 will be relatively high. On the other hand, since the directivity gain of beam B1 is smaller than that of beam B2, the received level of the reflected waves corresponding to the radar transmitted waves from Tx#1 and Tx#2 of beam B1 will be lower compared to the received level of the received signals corresponding to Tx#3 and Tx#4. For example, the received level of the received signals corresponding to Tx#1 and Tx#2 will differ significantly from the received level of the received signals corresponding to Tx#3 and Tx#4, and depending on the beam directivity characteristics of Tx#1 and Tx#2, the received level may be, for example, 10 dB or more lower. In such a case, the received signal received by the radar device 10 will be the received signal shown in Figure 9(c).

[0463] For example, as shown in Figure 9(b), when the radar device 10 receives the received signals corresponding to the transmitting antennas of each beam at approximately the same reception level, the signals transmitted from Nt transmitting antennas, including the respective transmitting antennas of beam B1 and beam B2, are transmitted using coded Doppler multiplexing with an unevenly set coding Doppler multiplexing number for the Doppler multiplexed signals. Therefore, the radar device 10 can separate the coded Doppler multiplexed signals based on the existing coding Doppler multiplexing operation.

[0464] Furthermore, as shown in Figures 9(a) and 9(c), when the radar device 10 receives reflected waves from either beam B1 or beam B2 (when the reception levels are significantly different), it receives different coded Doppler multiplexed signals (for example, Doppler multiplexed signals that satisfy condition 1) depending on the target position. Therefore, the coded Doppler multiplexing / deselection unit 212 can determine whether a decrease in the reception level of the received signal corresponding to the transmitting antenna of beam B1 has occurred, or whether a decrease in the reception level of the received signal corresponding to the transmitting antenna of beam B2 has occurred.

[0465] For example, the encoded Doppler multiplexed signal transmitted from the transmitting antenna of beam B1 (or beam B2) is transmitted using encoded Doppler multiplexing with an unevenly set encoding Doppler multiplexing number for the Doppler multiplexed signal. Therefore, for example, if the received signal is determined to be the received signal corresponding to the transmitting antenna of beam B1 (or beam B2) based on the determination result of the encoded Doppler multiplexing separation unit 212, the radar device 10 can separate the encoded Doppler multiplexed signal using the existing encoding Doppler multiplexing signal separation operation.

[0466] Through the operation of the coded Doppler multiplexing / decompression unit 212, the radar device 10 can determine the Doppler frequency fd of the target within the range of -1 / (2Tr) ≤ fd < 1 / (2Tr), and obtain an output that associates the transmitting antenna with each coded Doppler multiplexed signal.

[0467] The embodiments of this disclosure have been described above.

[0468] [Other embodiments] (1) In a radar device according to one embodiment of the present disclosure, the radar transmitter and the radar receiver may be individually arranged in physically separate locations. Also, in a radar receiver according to one embodiment of the present disclosure, the direction estimation unit and the other components may be individually arranged in physically separate locations.

[0469] (2) The number of transmitting antennas Nt, the number of receiving antennas Na, and the number of Doppler multiplexers N used in one embodiment of the present disclosure DM NB is the number of beams in a multibeam system, and N is the number of transmitting antennas in each beam direction. Bq , Doppler shift amount, Doppler shift interval, code multiplexing number N CM The numerical values ​​of parameters such as the code interval (code index) are examples only and are not limited to those values. Furthermore, for example, a portion of the transmitting antennas equipped with the radar system may be used as the number of transmitting antennas Nt, and a portion of the receiving antennas equipped with the radar system may be used as the number of receiving antennas Na.

[0470] (3) The MIMO antenna arrangement examples used in one embodiment of this disclosure (e.g., arrangement example A, arrangement example B) were described as cases where radar transmission signals are transmitted from multiple transmitting antennas using coded Doppler multiplexing, but are not limited to this. For example, the arrangement can also be applied when radar transmission signals are transmitted from multiple transmitting antennas using time division multiplexing or coded multiplexing, and the effects of the disclosed MIMO antenna arrangement can be obtained.

[0471] (4) In the above embodiment, in the multi-beam transmission MIMO radar using coded Doppler multiplex transmission, in order to expand the detectable Doppler frequency range to the range of ±1 / (2Tr) for the transmission antennas including Nt different directivities, it was premised that the code multiplexing number between Doppler multiplex signals was set unevenly and coded Doppler multiplex transmission was performed from a plurality of transmission antennas. In the above embodiment, furthermore, a method for improving the detection performance of the multi-beam transmission MIMO radar by applying coded Doppler multiplex transmission that satisfies Condition 1 and Condition 2 was described. For example, when the assumed moving speed of the target is relatively low, or when the relative speed between the radar device and the target is limited to a narrow range, the above premise may not be applied.

[0472] For example, the coding unit 107 uses an equally spaced Doppler shift amount setting with an interval narrower than the maximum equally spaced Doppler shift amount setting to set the coded Doppler multiplexing number N DOP_CODE (1), N DOP_CODE (2), ~, N DOP_CODE (N DM ) such that all the coded Doppler multiplexing numbers are included in the same number within the range of 1 or more and N CM or less. For example, the coding unit 107 may set the number of codes N CM in all of the coded Doppler multiplexing numbers. Therefore, in a plurality of combinations of the Doppler shift amount DOP ndm and the orthogonal code sequences, the multiplexing number (coded Doppler multiplexing number) N ndm corresponding to each of the Doppler shift amounts DOP DOP_CODE (ndm) may be the same. For example, the coding unit 107 may uniformly set the coded Doppler multiplexing number for the Doppler multiplex signals. With this setting, the Doppler multiplex signals become non-equally spaced Doppler multiplexing, so the radar device 10 can separately receive and separate the signals transmitted by coded Doppler multiplexing from a plurality of transmission antennas over the Doppler range of ±1 / (2×Loc×Tr). By applying such a setting of coded Doppler multiplex transmission and further applying coded Doppler multiplex transmission that satisfies Condition 1, the detection performance of the multi-beam transmission MIMO radar can be improved.

[0473] Alternatively, the encoding unit 107 may, for example, use the maximum equally spaced Doppler shift amount setting to determine the number of encoded Doppler multiplexers N. DOP_CODE (1), N DOP_CODE (2), ~, N DOP_CODE (N DM ) is 1 or more N CM The settings may be configured so that all numbers within a range of up to 1 include the same number of coded Doppler multiplexing numbers. For example, the coding unit 107 may set all coded Doppler multiplexing numbers to include the code number N CM You may set the number of units. In this case, the Doppler shift amount DOP ndm The number of combinations of the orthogonal code sequence and the number of transmitting antennas Nt may be equal (for example, N DM ×N CM (This may be set to =Nt). For example, the encoding unit 107 may uniformly set the number of encoded Doppler multiplexings for Doppler multiplexed signals. In this setting, the aliasing determination process in the reception processing of the radar device 10 is not applied. Also, the radar device 10 may, for example, ±1 / (2Loc×N DM Over the Doppler range of ×Tr), signals transmitted via coded Doppler multiplexing from multiple transmitting antennas can be individually separated and received. By applying such coded Doppler multiplexing settings, and further by applying coded Doppler multiplexing that satisfies condition 1, the detection performance of a multibeam MIMO radar can be improved.

[0474] (5) In one embodiment of the present disclosure, code multiplexing transmission in one embodiment of the present disclosure may be performed using only some of the Nt transmitting antennas provided by the radar device 10, rather than using all of them.

[0475] Furthermore, when applying code multiplexing transmission using only some of the Nt transmitting antennas provided by the radar device 10, the radar device 10 may set (or change) at least one of the combination of transmitting antennas used for code Doppler multiplexing transmission and the number of multiplexed transmissions in time division and transmit. In this case, for example, the radar device 10 may time-division switch the combination of transmitting antennas for each transmission cycle or for each code transmission cycle (for example, a cycle corresponding to the code length of the code sequence). Alternatively, for example, the radar device 10 may switch the combination of transmitting antennas or the number of multiplexed transmitting antennas for each measurement cycle (for every Nc radar transmission signal transmissions). Even if such operation is applied, the effects of the above-described embodiment can be obtained in the same way.

[0476] Furthermore, when applying code multiplexing transmission using only some of the Nt transmitting antennas provided by the radar device 10, the radar device 10 may set (for example, change) the combination of transmitting antennas used for code Doppler multiplexing transmission to time division and transmit using different chirp signals. For example, the radar device 10 may transmit using different chirp signals by changing at least one of the transmission bandwidth, frequency sweep time, and center frequency of the chirp signal, or by combining multiple of these parameters.

[0477] (6) A radar device according to one embodiment of the present disclosure, although not shown in the figures, includes, for example, a CPU (Central Processing Unit), a storage medium such as a ROM (Read Only Memory) storing a control program, and a working memory such as a RAM (Random Access Memory). In this case, the functions of each of the above-mentioned parts are realized by the CPU executing the control program. However, the hardware configuration of the radar device is not limited to this example. For example, each functional part of the radar device may be realized as an integrated circuit (IC). Each functional part may be individually integrated into a single chip, or a part or all of them may be integrated into a single chip.

[0478] Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the disclosure.

[0479] Furthermore, the notation "...part" in the above-described embodiment may be replaced with other notations such as "...circuitry," "...assembly," "...device," "...unit," or "...module."

[0480] In the embodiments described above, the disclosure has been explained using examples configured with hardware, but the disclosure can also be implemented with software in conjunction with hardware.

[0481] Furthermore, each functional block used in the description of the above embodiments is typically implemented as an integrated circuit (LSI). The integrated circuit controls each functional block used in the description of the above embodiments and may have input and output terminals. These may be individually integrated into a single chip, or some or all of them may be integrated into a single chip. Here, we refer to it as an LSI, but depending on the degree of integration, it may also be called an IC, system LSI, super LSI, or ultra LSI.

[0482] Furthermore, the method of integrated circuit implementation is not limited to LSIs; it may also be implemented using dedicated circuits or general-purpose processors. After LSI manufacturing, FPGAs (Field Programmable Gate Arrays) that can be programmed, or reconfigurable processors that allow for the reconfiguration of the connections or settings of circuit cells inside the LSI, may also be used.

[0483] Furthermore, if advances in semiconductor technology or other derived technologies lead to the emergence of integrated circuit technologies that can replace LSIs, then naturally, functional blocks can be integrated using those technologies. The application of biotechnology, for example, is a possibility.

[0484] <Summary of this disclosure> A radar system according to one embodiment of the present disclosure comprises a plurality of transmitting antennas, including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, and a transmitting circuit that multiplexes a transmission signal to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is assigned from the plurality of transmitting antennas, wherein each of the plurality of transmitting antennas is associated with the combination in which at least one of the Doppler shift amount and the code sequence is different, and a first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from a second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna.

[0485] In one embodiment of the present disclosure, the number of the plurality of transmitting antennas is less than the total number of combinations.

[0486] In one embodiment of the present disclosure, the first pattern and the second pattern have the same Doppler multiplexing number for the first transmitting antenna and the same Doppler multiplexing number for the second transmitting antenna with respect to the interval of the Doppler shift amount, and at least one of the intervals of the Doppler shift amount for the first transmitting antenna is different from the interval of the Doppler shift amount for the second transmitting antenna.

[0487] In one embodiment of the present disclosure, the first pattern and the second pattern differ in terms of Doppler multiplexing numbers, with respect to the Doppler multiplexing number of the first transmitting antenna and the Doppler multiplexing number of the second transmitting antenna.

[0488] In one embodiment of the present disclosure, the first pattern and the second pattern are such that, with respect to the order of the intervals of the Doppler shift amounts, a plurality of first Doppler shift intervals by the first transmitting antenna and a plurality of second Doppler shift intervals by the second transmitting antenna are the same, and the order of the plurality of first Doppler shift intervals on the Doppler frequency axis is different from the order of the plurality of second Doppler shift intervals on the Doppler frequency axis.

[0489] In one embodiment of the present disclosure, the first pattern and the second pattern, with respect to the code sequence, differ in a plurality of combinations between the index of the code sequence corresponding to each of the Doppler shift amounts associated with the first transmitting antenna and the index of the code sequence corresponding to each of the Doppler shift amounts associated with the second transmitting antenna.

[0490] In one embodiment of the present disclosure, the first pattern and the second pattern, with respect to the code multiplexing number by the code sequence, are different in a plurality of combinations from the code multiplexing number by the code sequence corresponding to each of the Doppler shift amounts associated with the first transmitting antenna and the code multiplexing number by the code sequence corresponding to each of the Doppler shift amounts associated with the second transmitting antenna.

[0491] In one embodiment of the present disclosure, in a plurality of such combinations, with respect to at least one of the first transmitting antenna and the second transmitting antenna, the code multiplexing number of the code sequence associated with at least one of the Doppler shift amounts is different from the code multiplexing number of the code sequence associated with other Doppler shift amounts.

[0492] One embodiment of the present disclosure further comprises a plurality of receiving antennas that receive reflected wave signals of the transmitted signal reflected by a target, and a receiving circuit that uses the reflected wave signals to estimate the direction of the target.

[0493] In one embodiment of the present disclosure, the present invention further comprises a plurality of receiving antennas arranged at a first interval in a first direction, wherein the first transmitting antenna is arranged at a first interval in the first direction and at different positions in a second direction perpendicular to the first direction, and the second transmitting antenna is arranged at a first interval in the first direction and at different positions in a second direction perpendicular to the first direction, and in the first direction, the first transmitting antenna and the second transmitting antenna are spaced at an interval greater than the aperture length of the plurality of receiving antennas.

[0494] In one embodiment of the present disclosure, the present invention further comprises a plurality of receiving antennas arranged at a first interval in a first direction, wherein the first transmitting antenna is arranged at a second interval in the first direction and at a different position in a second direction perpendicular to the first direction, the second transmitting antenna is arranged at a second interval in the first direction and at a different position in a second direction perpendicular to the first direction, and in the first direction, the first transmitting antenna and the second transmitting antenna are spaced at an interval greater than the aperture length of the plurality of receiving antennas, and the difference between the first interval and the second interval is a specified value based on the wavelength of the transmitted signal.

[0495] In one embodiment of the present disclosure, the specified value is any value in the range of 0.45 to 0.8 times the wavelength.

[0496] In one embodiment of the present disclosure, the first beam and the second beam differ in at least one of their beam direction and beam width.

[0497] In one embodiment of the present disclosure, the combination of transmitting antennas used for multiplex transmission of the transmitted signal among the plurality of transmitting antennas is switched each time the transmission period of the transmitted signal is set, each time the period corresponding to the code length of the code sequence is set, or each time the measurement period of the radar device is set. [Industrial applicability]

[0498] This disclosure is suitable as a radar device for detecting a wide-angle range. [Explanation of Symbols]

[0499] 10 Radar equipment 100 Radar Transmitter 101 Radar transmission signal generation unit 102 Transmission signal generation control unit 103 Modulation signal generation unit 104 VCO 105 Phase rotation amount setting unit 106 Doppler Shift Setting Section 107 Encoding section 108 Phase rotation section 109 Transmitting antenna section 200 Radar Receiver 201 Antenna System Processing Unit 202 Receiving antenna section 203 Receiving Radio Unit 204 Mixer Section 205 LPF 206 Signal Processing Unit 207 AD Conversion Unit 208 Beat Frequency Analysis Unit 209 Output switching section 210 Doppler Analysis Unit 211 CFAR Department 212 Coded Doppler demultiplexer 213 Direction estimation part

Claims

1. A plurality of transmitting antennas, including a first transmitting antenna that forms a first beam, and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern are defined with respect to the interval of the Doppler shift amount. The Doppler multiplexing number of the transmission signal transmitted by the first transmitting antenna and the Doppler multiplexing number of the transmission signal transmitted by the second transmitting antenna are the same. At least one of the intervals of Doppler shift amounts associated with the first transmitting antenna is different from the interval of Doppler shift amounts associated with the second transmitting antenna. Radar device.

2. A plurality of transmitting antennas including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first and second patterns described above relate to the Doppler multiplexing number, The Doppler multiplexing of the transmission signal transmitted by the first transmitting antenna is different from the Doppler multiplexing of the transmission signal transmitted by the second transmitting antenna. Radar device.

3. A plurality of transmitting antennas including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern relate to the order of the intervals of the Doppler shift amounts, The plurality of first Doppler shift intervals between the Doppler shift amounts associated with the first transmitting antenna and the plurality of second Doppler shift intervals between the Doppler shift amounts associated with the second transmitting antenna are the same, The order of the plurality of first Doppler shift intervals on the Doppler frequency axis is different from the order of the plurality of second Doppler shift intervals on the Doppler frequency axis. Radar device.

4. A plurality of transmitting antennas including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern are, with respect to the code sequence, In multiple such combinations, the order of the code sequence associated with the first transmitting antenna on the Doppler frequency axis is different from the order of the code sequence associated with the second transmitting antenna on the Doppler frequency axis. Radar device.

5. A plurality of transmitting antennas including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern are related to the code multiplexing by the code sequence, In multiple such combinations, the order on the Doppler frequency axis of the code multiplexing numbers by the code sequence associated with the first transmitting antenna is different from the order on the Doppler frequency axis of the code multiplexing numbers by the code sequence associated with the second transmitting antenna. Radar device.

6. A plurality of transmitting antennas, including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. In a plurality of such combinations, with respect to at least one of the first transmitting antenna and the second transmitting antenna, the code multiplexing number of the code sequence associated with at least one of the Doppler shift amounts is different from the code multiplexing number of the code sequence associated with other Doppler shift amounts. Radar device.

7. Multiple receiving antennas that receive the reflected wave signal that the transmitted signal has reflected off the target, A receiving circuit that uses the reflected wave signal to estimate the direction of the target, It further possesses, The radar device according to claim 1.

8. A plurality of transmitting antennas, including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The system further comprises a plurality of receiving antennas arranged at first intervals in a first direction, Each antenna included in the first transmitting antenna is arranged at a first interval in the first direction and at different positions in a second direction perpendicular to the first direction. Each antenna included in the second transmitting antenna is arranged at a first interval in the first direction and at different positions in a second direction perpendicular to the first direction. In the first direction, the first transmitting antenna and the second transmitting antenna are arranged at a distance greater than the aperture length of the plurality of receiving antennas. Radar device.

9. A plurality of transmitting antennas including a first transmitting antenna that forms a first beam and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The system further comprises a plurality of receiving antennas arranged at first intervals in a first direction, Each antenna included in the first transmitting antenna is arranged at a second interval in the first direction and at different positions in a second direction perpendicular to the first direction. Each antenna included in the second transmitting antenna is arranged at the second interval in the first direction and at different positions in the second direction perpendicular to the first direction. In the first direction, the first transmitting antenna and the second transmitting antenna are arranged at a distance greater than the aperture length of the plurality of receiving antennas. The difference between the first interval and the second interval is a specified value based on the wavelength of the transmitted signal. Radar device.

10. The specified value is any value within the range of 0.45 to 0.8 times the wavelength. The radar device according to claim 9.

11. A radar device, A plurality of transmitting antennas, including a first transmitting antenna that forms a first beam, and a second transmitting antenna that forms a second beam different from the first beam, A transmitting circuit that multiplexes a transmission signal, to which a phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is applied, from the multiple transmitting antennas, It is equipped with, For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. Of the plurality of transmitting antennas, the combination of transmitting antennas used for multiplex transmission of the transmitted signal is switched according to the transmission period of the transmitted signal, the period corresponding to the code length of the code sequence, or the measurement period in the radar device. Radar device.

12. A phase rotation amount corresponding to the combination of Doppler shift amount and code sequence is added to the radar signal. The radar signal to which the aforementioned phase rotation amount is applied is multiplexed and transmitted from multiple transmitting antennas. A method for transmitting radar signals, The plurality of transmitting antennas include a first transmitting antenna that forms a first beam, and a second transmitting antenna that forms a second beam different from the first beam. For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern are defined with respect to the interval of the Doppler shift amount. The Doppler multiplexing number of the radar signal transmitted by the first transmitting antenna and the Doppler multiplexing number of the radar signal transmitted by the second transmitting antenna are the same. At least one of the intervals of Doppler shift amounts associated with the first transmitting antenna is different from the interval of Doppler shift amounts associated with the second transmitting antenna. Method of transmitting radar signals.

13. A phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is added to the radar signal, The radar signal to which the aforementioned phase rotation amount is applied is multiplexed and transmitted from multiple transmitting antennas. A method for transmitting radar signals, The plurality of transmitting antennas include a first transmitting antenna that forms a first beam, and a second transmitting antenna that forms a second beam different from the first beam. For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first and second patterns described above relate to the Doppler multiplexing number, The Doppler multiplexing number of the radar signal transmitted by the first transmitting antenna is different from the Doppler multiplexing number of the radar signal transmitted by the second transmitting antenna. Method of transmitting radar signals.

14. A phase rotation amount corresponding to a combination of Doppler shift amount and code sequence is added to the radar signal, The radar signal to which the aforementioned phase rotation amount is applied is multiplexed and transmitted from multiple transmitting antennas. A method for transmitting radar signals, The plurality of transmitting antennas include a first transmitting antenna that forms a first beam, and a second transmitting antenna that forms a second beam different from the first beam. For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern relate to the order of the intervals of the Doppler shift amounts, The plurality of first Doppler shift intervals between the Doppler shift amounts associated with the first transmitting antenna and the plurality of second Doppler shift intervals between the Doppler shift amounts associated with the second transmitting antenna are the same, The order of the plurality of first Doppler shift intervals on the Doppler frequency axis is different from the order of the plurality of second Doppler shift intervals on the Doppler frequency axis. Method of transmitting radar signals.

15. The radar signal transmitted by the radar signal transmission method described in claim 12 is reflected by a target, and the reflected wave signal is received by a plurality of receiving antennas. The direction of the target is estimated using the reflected wave signal. Method for receiving radar signals.

16. An application circuit that adds a phase rotation amount corresponding to the combination of Doppler shift amount and code sequence to the radar signal, A transmitting circuit that multiplexes the radar signal to which the aforementioned phase rotation amount has been applied from multiple transmitting antennas, It is equipped with, The plurality of transmitting antennas include a first transmitting antenna that forms a first beam, and a second transmitting antenna that forms a second beam different from the first beam. For each of the plurality of transmitting antennas, a combination is associated with which at least one of the Doppler shift amount and the code sequence is different. The first pattern of Doppler shift amount and code sequence assigned to the first transmitting antenna is different from the second pattern of Doppler shift amount and code sequence assigned to the second transmitting antenna. The first pattern and the second pattern are defined with respect to the interval of the Doppler shift amount. The Doppler multiplexing number of the radar signal transmitted by the first transmitting antenna and the Doppler multiplexing number of the radar signal transmitted by the second transmitting antenna are the same. At least one of the intervals of Doppler shift amounts associated with the first transmitting antenna is different from the interval of Doppler shift amounts associated with the second transmitting antenna. Radar signal processing device.

17. The radar signal transmitted from the radar signal processing device described in claim 16 is reflected by a target, and the reflected wave signal is received by a plurality of receiving antennas. The direction of the target is estimated using the reflected wave signal. Radar signal processing device.

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