Radar device, radar signal generation device, and radar signal generation method

Abstract

To improve the accuracy of target detection in radar systems. [Solution] The radar transmission unit 100 comprises a plurality of transmitting antennas that transmit a transmission signal, and a transmission circuit that multiplexes the transmission signal from the plurality of transmitting antennas by applying a phase rotation amount corresponding to a Doppler shift amount to the transmission signal. The transmission circuit code multiplexes the transmission signal corresponding to a first Doppler shift amount, and time multiplexes the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount using different transmitting antennas.

Description

[Technical Field]

[0001] This disclosure relates to a radar device, a radar signal generation device, and a radar signal generation method. [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 transmitter, in addition to the receiver, 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. 2008-304417 [Patent Document 2] Special Publication No. 2011-526371 [Patent Document 3] Japanese Patent Publication No. 2014-119344 [Patent Document 4] Japanese Patent Publication No. 2020-148754 [Patent Document 5] Japanese Patent Publication No. 2020-204603 [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 device according to one embodiment of the present disclosure comprises a plurality of transmitting antennas that transmit a transmission signal, and a transmitting circuit that multiplexes the transmission signal from the plurality of transmitting antennas by applying a phase rotation amount corresponding to a Doppler shift amount to the transmission signal, wherein the transmitting circuit code multiplexes the transmission signal corresponding to a first Doppler shift amount and time multiplexes the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount.

[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] Block diagram showing an example of radar system configuration. [Figure 2] This figure shows an example of a transmitted signal and a reflected wave signal when using chirp pulses. [Figure 3] A diagram showing an example of Doppler shift amount and orthogonal code assignment. [Figure 4] A diagram showing an example of Doppler shift amount and orthogonal code assignment. [Figure 5] A diagram showing an example of Doppler shift amount and orthogonal code assignment. [Figure 6] A diagram showing an example of Doppler region compression processing. [Figure 7] Figure showing an example of the output from the Doppler analysis unit. [Figure 8] Figure showing an example of the output from the Doppler analysis unit. [Figure 9] Diagram showing an example of antenna placement. [Figure 10] A diagram showing an example of Doppler shift amount and orthogonal code assignment. [Figure 11] Figure showing an example of the output from the Doppler analysis unit. [Figure 12]This figure shows an example of a transmitted signal using chirp pulses. [Figure 13] Figure showing an example of the output from the Doppler analysis unit. [Figure 14] Diagram showing an example of antenna placement. [Figure 15] Diagram showing an example of antenna placement. [Figure 16] Diagram showing an example of antenna placement. [Figure 17] Diagram showing an example of antenna placement. [Modes for carrying out the invention]

[0012] MIMO radar transmits multiplexed signals (radar transmit waves) using, for example, time-division, frequency-division, or code-division multiplexing from multiple transmitting antennas (or transmitting array antennas), and receives the signals reflected from surrounding objects (radar reflect waves) using multiple receiving antennas (or receiving array antennas). From each received signal, the multiplexed transmit signal is separated and received. Through this process, MIMO radar can obtain a propagation path response, which is represented by the product of the number of transmitting antennas and the number of receiving antennas. These received signals are called virtual receiving antennas, and MIMO radar performs angle measurement processing using these virtual receiving antennas.

[0013] Thus, in MIMO radar, by appropriately arranging the element spacing in the transmitting and receiving array antennas, the aperture of the virtual receiving antenna can be enlarged, thereby improving the angle measurement performance (for example, angle estimation accuracy or angular resolution).

[0014] Furthermore, by increasing the number of transmitting or receiving antennas, the aperture of the virtual receiving antenna can be enlarged, thereby improving angle measurement performance.

[0015] The following section explains an example of improving angle measurement performance by increasing the number of transmitting antennas to enlarge the aperture of the virtual receiving antenna. Further research is needed on multiplexing methods for transmitting antennas when increasing the number of transmitting antennas.

[0016] For example, Patent Document 1 discloses a MIMO radar (hereinafter referred to as "time-division multiplexed MIMO radar") that uses time-division multiplexing (also called TDM (Time Division Multiplexing) transmission) as a multiplexing method for MIMO radar, in which signals are transmitted by shifting the transmission time for each transmitting antenna.

[0017] Time-division multiplexed MIMO radar sequentially switches the transmitting antennas that transmit the transmission signal (e.g., transmission pulse or radar transmission wave) at a defined period. Therefore, in time-division multiplexed transmission, the more transmitting antennas there are, the longer it can take to transmit the signal from all transmitting antennas. For this reason, for example, as in Patent Document 2, when transmitting a signal from each transmitting antenna and detecting the Doppler frequency (e.g., relative velocity of the target) from the received phase change of the reflected wave from the target, the time interval for observing the received phase change (e.g., sampling interval) becomes longer when applying Fourier frequency analysis to detect the Doppler frequency. Consequently, the Doppler frequency range (e.g., detectable relative velocity range of the target) in which the Doppler frequency can be detected without ambiguity while satisfying the sampling theorem is reduced.

[0018] Furthermore, if reflected signals from a target exceeding the above-mentioned Doppler frequency range (e.g., relative velocity range) are anticipated, the radar system cannot determine whether the reflected signal is an aliased component or not, resulting in ambiguity (uncertainty) in the Doppler frequency (e.g., relative velocity of the target).

[0019] For example, if a radar system transmits a transmission signal (transmission pulse) by sequentially switching Nt transmitting antennas with a period Tr, the transmission time until all transmitting antennas have finished transmitting is Tr × Nt. When such time-division multiplexing is repeated and Fourier frequency analysis is applied to detect the Doppler frequency, the Doppler frequency range in which the Doppler frequency can be detected without aliasing is ±1 / (2Tr × Nt) according to the sampling theorem. Therefore, the Doppler frequency range in which the Doppler frequency can be detected without aliasing decreases as the number of transmitting antennas Nt increases, and ambiguity of the Doppler frequency is more likely to occur even at lower relative speeds.

[0020] Next, as a method of multiplexing and simultaneously transmitting transmission signals from multiple transmitting antennas, there is a method of transmitting signals so that the receiver can separate multiple transmission signals in the Doppler frequency domain (hereinafter also referred to as Doppler multiplexing transmission or DDM (Doppler Division multiplexing) transmission) (see, for example, Patent Document 3).

[0021] In DDM transmission, the transmitter assigns different Doppler shift amounts to the transmission signals from a reference transmitting antenna and the transmission signals from different transmitting antennas, so that transmission signals are transmitted simultaneously from multiple transmitting antennas. In Doppler multiplex transmission, the receiver takes advantage of the fact that each transmitting antenna has a different Doppler shift amount in the Doppler frequency domain to separate and receive the transmission signals transmitted from each transmitting antenna.

[0022] For example, as disclosed in Patent Document 3, when the Doppler shift amount for each transmitting antenna (for example, the interval of the Doppler shift amount) is made uniform (for example, also called "equally spaced DDM"), the detectable Doppler frequency range is ±1 / (2Tr × Nt). In contrast, as disclosed in Patent Document 4, for example, when the Doppler shift amount for each transmitting antenna is made non-uniform (for example, also called "unequal spaced DDM"), the detectable Doppler frequency range is ±1 / (2Tr).

[0023] In DDM transmission, a phase shift is applied to the transmitted signal using a phase shifter to impart a Doppler shift. For example, as the number of transmitting antennas increases, the phase granularity that can be applied by the phase shifter becomes finer, and the number of phases (hereinafter also called "phase multi-level number") increases. Furthermore, as the number of phase multi-level numbers increases, high-precision control of the phase is expected, which makes the phase shifter more complex, and the adjustment costs and component costs associated with the complexity of the phase shifter may increase. In addition, the number of phase multi-level numbers used in the case of unequal-spacing DDM is greater than the number of phase multi-level numbers used in the case of equal-spacing DDM.

[0024] Furthermore, there are methods that combine multiple multiplexing methods. For example, Patent Document 4 discloses a multiplexing method that combines time-division multiplexing and Doppler multiplexing, enabling multiplexing using more transmitting antennas while suppressing the increase in the number of phase levels in the phase shifter used for Doppler multiplexing. For example, Patent Document 4 states that by simultaneously transmitting a Doppler multiplexed signal that switches the transmitting antennas for Doppler multiplexing in time division and a Doppler multiplexed signal that does not switch the transmitting antennas, it is possible to set the detectable Doppler frequency range to ±1 / (2Tr). Even in such multiplexing methods that combine time-division multiplexing and Doppler multiplexing, when multiplexing is performed by increasing the number of transmitting antennas, there is a limit to the increase in the number of time multiplexing levels, so the number of phase levels in the phase shifter may increase. For example, when time-division multiplexing is performed with two transmission cycles using one of two Doppler multiplexed signals, the maximum number of transmitting antennas is limited. Also, for example, when time-division multiplexing is performed with four transmission cycles using one of two Doppler multiplexed signals, the maximum number of transmitting antennas is limited.

[0025] In one non-limiting embodiment relating to this disclosure, a method for increasing the number of transmitting antennas while reducing the number of Doppler multiplexing signals is described. This makes it possible to increase the virtual array aperture while suppressing the increase in the number of phase levels of the phase shifter, thereby improving angle measurement performance.

[0026] Furthermore, in a non-limiting embodiment relating to this disclosure, for example, a method for expanding the unambiguous Doppler frequency range by using time multiplexing and code multiplexing in combination with Doppler multiplexing transmission will be described. This will improve the accuracy of target detection over a wider Doppler frequency range.

[0027] A Doppler multiplexing method using a code-multiplexed Doppler multiplexed signal is disclosed, for example, in Patent Document 5. A non-limiting embodiment of this disclosure relates to a Doppler multiplexing method that increases the number of transmitting antennas while reducing the number of Doppler multiplexers by using time multiplexing and code multiplexing in combination. For example, by using code multiplexing and time multiplexing in combination, the effect of further reducing the code multiplexing separation processing amount (e.g., the complexity of the code separation processing) can be obtained.

[0028] 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.

[0029] 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).

[0030] 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.

[0031] Furthermore, the radar system performs Doppler multiplexing. In addition, the radar system encodes (for example, CDM (Code Division Multiplexing)) signals with different phase rotations (e.g., phase shifts) corresponding to the number of Doppler multiplexings in the Doppler multiplexing transmission (hereinafter referred to as "Doppler multiplexed transmission signals") and transmits them multiplexed (hereinafter referred to as "Coded Doppler Multiplexing").

[0032] [Radar system configuration] Figure 1 is a block diagram showing an example of the configuration of the radar device 10 according to this embodiment.

[0033] The radar device 10 includes a radar transmitting unit (transmitting branch) 100 and a radar receiving unit (receiving branch) 200.

[0034] The radar transmission unit 100 generates a radar signal (radar transmission signal) and transmits the radar transmission signal at a specified transmission period using a transmission array antenna composed of multiple transmission antennas 110 (for example, Nt antennas).

[0035] The radar receiver 200 receives reflected wave signals, which are radar transmission signals reflected by a target (not shown), using a receiving array antenna that includes multiple receiving antennas 202-1 to 202-Na. The radar receiver 200 processes the reflected wave signals received by each receiving antenna 202 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).

[0036] The 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.

[0037] Furthermore, 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.

[0038] 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.

[0039] [Configuration of radar transmitter 100] The radar transmission unit 100 includes a radar transmission signal generation unit 101, a phase rotation amount setting unit 104, a time multiplexing unit 107, a phase rotation unit 108, a transmission control unit 109, and a transmission antenna 110.

[0040] For example, the phase rotation amount setting unit 104, the time multiplexing unit 107, the phase rotation unit 108, and the transmission control unit 109 may constitute a multiplexing unit (for example, corresponding to a multiplexing circuit) that multiplexes radar transmission signals.

[0041] The radar transmission signal generation unit 101 (corresponding to, for example, a signal generation circuit) generates a radar transmission signal. The radar transmission signal generation unit 101 includes, for example, a modulation signal generation unit 102 and a VCO (Voltage Controlled Oscillator) 103. The components of the radar transmission signal generation unit 101 will be described below.

[0042] The modulation signal generation unit 102 periodically generates, for example, a sawtooth-shaped modulation signal. Here, the radar transmission period (also called the transmission period) is denoted as Tr.

[0043] The VCO 103 generates a radar transmission signal based on the modulated signal output from the modulated signal generation unit 102. For example, as shown in the upper part of Figure 2, the VCO 103 outputs a frequency modulated signal (hereinafter referred to as, for example, a frequency chirp signal or chirp signal) as a radar transmission signal to the phase rotation unit 108 and the radar receiving unit 200 (mixer unit 204, which will be described later).

[0044] The phase rotation amount setting unit 104 sets the phase rotation amount in the phase rotation unit 108 (for example, the phase rotation amount corresponding to encoded Doppler multiplex transmission). The phase rotation amount setting unit 104 includes, for example, a Doppler shift setting unit 105 and an encoding unit 106.

[0045] The Doppler shift setting unit 105 sets, for example, a phase rotation amount corresponding to the amount of Doppler shift to be applied to the radar transmission signal (e.g., a chirp signal).

[0046] The encoding unit 106 sets the phase rotation amount corresponding to the encoding. The encoding unit 106 calculates the phase rotation amount for the phase rotation unit 108 based on the phase rotation amount output from the Doppler shift setting unit 105 and the phase rotation amount corresponding to the encoding, and outputs it to the phase rotation unit 108. The encoding unit 106 also outputs information about 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).

[0047] The time multiplexing unit 107 controls (instructs) the transmission control unit 109 to perform time multiplexing transmission using at least one Doppler multiplexed signal.

[0048] The phase rotation unit 108 applies a phase rotation amount input from the encoding unit 106 to the chirp signal input from the VCO 103, and outputs the phase-rotated signal to the transmitting antenna 110. For example, the phase rotation unit 108 includes a phase shifter and a phase modulator (not shown).

[0049] Based on the control signal from the time multiplexing unit 107, the transmission control unit 109 controls the switching of the transmission antenna 110 for the signals used for time multiplexing (for example, Doppler multiplexed signals) among the signals output from the phase rotation unit 108, and performs the operation of switching the transmission antenna 110.

[0050] The output signal from the transmission control unit 109 is amplified to a specified transmission power and radiated into space from each transmitting antenna 110. For example, the radar transmission signal is transmitted by code multiplexing from multiple transmitting antennas 110 by adding a phase rotation amount corresponding to the Doppler shift amount and the orthogonal code sequence. Alternatively, for example, the radar transmission signal is transmitted by time multiplexing from multiple transmitting antennas 110 in multiple transmission cycles by adding a phase rotation amount corresponding to the Doppler shift amount.

[0051] Next, an example of how to set the phase rotation amount in the phase rotation amount setting unit 104 will be described.

[0052] The Doppler shift setting unit 105 sets the Doppler shift amount DOP ndm Phase rotation amount φ to impart ndm Set the following and output to the encoding unit 106. Here, ndm=1,~, N DM N DM This is the number of different Doppler shift settings, and will be referred to as the "Doppler multiplexing number" below.

[0053] In the radar device 10, encoding by the encoding unit 106 and time multiplexing by the time multiplexing unit 107 are used in combination, so the Doppler multiplexing number N DM This can be set to a value less than the number of transmitting antennas 110 used for multiplex transmission, Nt. DM For example, let's say it's 2 or more.

[0054] Doppler shift amounts DOP1, DOP2, ~, DOP DM For example, the phase rotation range of 0 or more and less than 2π is divided, and different phase rotation amounts are assigned respectively. For example, the phase rotation amount φ ndm for applying the Doppler shift amount DOP ndm is assigned as in the following formula (1). Hereinafter, the angle is shown in radians. [Number]

[0055] In formula (1), for example, when the Doppler multiplicity N DM = 2, the phase rotation amount φ1 for applying the Doppler shift amount DOP1 = 0, and the phase rotation amount φ2 for applying the Doppler shift amount DOP2 = π. Similarly, in formula (1), for example, when the Doppler multiplicity N DM = 4, the phase rotation amount φ1 for applying the Doppler shift amount DOP1 = 0, the phase rotation amount φ2 for applying the Doppler shift amount DOP2 = π / 2, the phase rotation amount φ3 for applying the Doppler shift amount DOP3 = π, and the phase rotation amount φ4 for applying the Doppler shift amount DOP4 = 3π / 2. For example, the phase rotation amount φ ndm for applying each Doppler shift amount DOP ndm is equally spaced.

[0056] Note that the phase rotation amount φ ndm for applying each Doppler shift amount DOPndm may be non-equally spaced. For example, the phase rotation amount φ ndm for applying the Doppler shift amount DOP ndm may be assigned as in formula (2). [Number]

[0057] In formula (2), for example, when the Doppler multiplicity N DMWhen =3, the phase rotation amount φ1 = 0 for Doppler shift amount DOP1, the phase rotation amount φ2 = π / 2 for Doppler shift amount DOP2, and the phase rotation amount φ3 = π for Doppler shift amount DOP3. For example, each Doppler shift amount DOP ndm The phase rotation amount φ that imparts ndm The intervals are not equal (=π / 3), but unequal (the phase interval between phase rotation amounts includes π / 2 or π). Similarly, in equation (2), for example, the Doppler multiplexing number N DM When = 5, the phase rotation amount φ1 = 0 for Doppler shift amount DOP1, the phase rotation amount φ2 = π / 3 for Doppler shift amount DOP2, the phase rotation amount φ3 = 2π / 3 for Doppler shift amount DOP3, the phase rotation amount φ4 = π for Doppler shift amount DOP4, and the phase rotation amount φ5 = 4π / 3 for Doppler shift amount DOP5. For example, each Doppler shift amount DOP ndm The phase rotation amount φ that imparts ndm The phase intervals are not equal (=2π / 5), but unequal (the phase interval between phase rotation amounts includes π / 3 or 2π / 3).

[0058] Also, Doppler shift amounts DOP1, DOP2, ~, DOP DM The assignment of the phase rotation amount to which the is assigned is not limited to this assignment method. For example, the assignment of the phase rotation amount shown in equation (1) or equation (2) may be shifted. For example, φ ndm =2π(ndm) / N DM The phase rotation amount may be assigned as follows. Alternatively, a phase rotation amount assignment table can be used to assign Doppler shift amounts DOP1, DOP2, ~, DOP DM For this, the phase rotation amounts are φ1, φ2, ~, φ DM You may assign them randomly.

[0059] The encoding unit 106 outputs N from the Doppler shift setting unit 105. DM Phase rotation amounts φ1,~,φ that impart individual Doppler shift amounts NDM For each of them, one or N CMThe encoding unit 106 sets a phase rotation amount based on multiple orthogonal code sequences of one or fewer elements. The encoding unit 106 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.

[0060] The following describes an example of the operation of the encoding unit 106.

[0061] For example, the encoding unit 106 has a code length Loc and a code number (e.g., code multiplexing) N CM Use a sequence of orthogonal codes.

[0062] 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 specified location]. Here, noc is the index of the sign element, and noc = 1, ~, Loc.

[0063] The orthogonal code sequence used in the encoding unit 106 is, for example, a set of codes that are orthogonal to each other (uncorrelated). For example, the orthogonal code sequence may be a Walsh-Hadamard code. In this case, the number of codes is N. CM Code length L that generates a sequence of orthogonal codes. OC This can be expressed by the following equation (3).

number

[0064] Here, ceil[x] is the operator (ceiling function) that outputs the smallest integer greater than or equal to a real number x.

[0065] For example, N CMWhen = 2, the code length Loc=2 of the Walsh-Hadamard code is 2, and the orthogonal code sequences are Code1={1,1} and Code2={1,-1}. Note that when the code element constituting the orthogonal code sequence is 1, its phase is 0, since 1=exp(j0). Also, when the code element constituting the orthogonal code sequence is -1, its phase is π, since -1=exp(jπ).

[0066] Also, for example, N CM When Loc = 4, the code length Loc = 4, and the orthogonal code sequences are Code1 = {1, 1, 1, 1}, Code2 = {1, -1, 1, -1}, Code3 = {1, 1, -1, -1}, and Code4 = {1, -1, -1, 1}.

[0067] Note that the code elements constituting an orthogonal code sequence may include not only real numbers but also complex values. For example, an orthogonal code sequence like the one shown in equation (4) Code ncm The following may be used. Here, ncm = 1, ~, N CM In this case, the number of codes is N. CM The code length for generating a sequence of orthogonal codes is Loc = N CM This is the result.

number

[0068] For example, N CM If =3, the code length Loc=3(=N CM The encoding unit 106 generates orthogonal code sequences such that Code1={1,1,1}, Code2={1, exp(j2π / 3) ,exp(j4π / 3)}, and Code3={1, exp(-j2π / 3) ,exp(-j4π / 3)}.

[0069] Also, for example, N CM If =4, the code length Loc=4(=N CMThe encoding unit 106 generates an orthogonal code sequence such that Code1={1,1,1, 1}, Code2={1, j,-1 ,-j}, Code3={1,-1,1,-1}, and Code4={1, -j,-1 , j}, where j is the imaginary unit.

[0070] In the encoding unit 106, the ndm-th Doppler shift amount DOP is output from the Doppler shift setting unit 105. 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_CD This is denoted as "(ndm)". Here, ndm = 1, ~, N DM That is the case.

[0071] The encoding unit 106 uses time multiplexing by the time multiplexing unit 107 in combination, for example, the number of Doppler multiplexed signals when encoding a Doppler multiplexed signal N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM The sum of the Doppler multiplexing numbers N is such that it is less than the number of transmitting antennas 110 used for multiplexing N. DOP_CD Set (ndm). For example, the encoding unit 106 satisfies equation (5) below, with an encoding Doppler multiplexing number N. DOP_CD Set (ndm). For example, the encoding unit 106 sets the encoding Doppler multiplexing number N to satisfy equation (5). DOP_CD Set (ndm).

number

[0072] Furthermore, the encoding Doppler multiplexing number N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM At least one of the values ​​in the given set may be 1. The time-multiplexing unit 107 performs time-multiplexing using, for example, a Doppler multiplexed signal with an encoded Doppler multiplexing number of 1 (an example will be described later).

[0073] If time-multiplexing is performed using a Doppler multiplexed signal with a coding Doppler multiplexing number of 2 or more, the switching of the transmitting antenna 110 due to time-multiplexing may disrupt the orthogonality between the coded multiplexed signals, potentially causing mutual interference between the multiplexed signals. Therefore, it may be difficult for the radar receiving unit 200 to properly separate and receive the transmitted signal from the transmitting antenna 110 that transmits using coded multiplexing and time-multiplexing with the said Doppler multiplexed signal, potentially degrading the angle measurement performance of the direction estimation unit 213 and thus degrading the radar's detection performance.

[0074] In contrast, for example, the Doppler multiplexed signal (e.g., Doppler shift amount) and the Doppler multiplexed signal (e.g., Doppler shift amount) may be different. For example, performing time multiplexing using a Doppler multiplexed signal with an encoded Doppler multiplexing number of 1 is preferable for radar detection performance.

[0075] As a result, the radar device 10 is capable of multiplex transmission in the Doppler domain and the coding domain (hereinafter referred to as coded Doppler multiplex transmission) using Nt transmitting antennas 110, as well as multiplex transmission in the Doppler domain and the time domain (hereinafter also referred to as time Doppler multiplex transmission).

[0076] Here, the encoding unit 106 uses, for example, an encoding Doppler multiplexing number N. DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM Regarding ), excluding Doppler multiplexed signals that undergo time Doppler multiplexing (signals with an encoded Doppler multiplexing number of 1), the values ​​are 1 or greater and N. CM The encoding unit 106 may be configured to include different encoding Doppler multiplexing numbers within a range of up to 1. For example, the encoding unit 106 will have a coding number N for all encoding Doppler multiplexing numbers, except for Doppler multiplexed signals that perform time Doppler multiplexing (encoding Doppler multiplexing number is 1). CM Instead of using a set number of encodings, we have at least one encoding Doppler multiplexing number N. CMThe number of encoded Doppler multiplexing signals is set to a value smaller than 1. For example, the encoding unit 106 sets the number of encoded Doppler multiplexing signals for Doppler multiplexing signals to be uneven, except for Doppler multiplexing signals that undergo time Doppler multiplexing (encoded Doppler multiplexing number is 1). This setting allows the radar device 10 to individually separate and receive signals transmitted via encoded Doppler multiplexing from multiple transmitting antennas 110, for example, through the reception processing described later. In addition, the radar device 10 becomes capable of Doppler aliasing detection, and the detectable Doppler frequency range can be expanded (examples will be described later).

[0077] The encoding unit 106 calculates the ndm-th Doppler shift amount DOP in the m-th transmission period Tr. ndm The phase rotation amount φ that imparts ndm For this, the encoded Doppler phase rotation amount ψ shown in equation (6) is ndop_CD(ndm), ndm Set (m) and output it to the phase rotation unit 108.

number

[0078] Here, the subscript "ndop_CD(ndm)" represents the Doppler shift amount DOP. ndm The phase rotation amount φ that imparts ndm Encoded Doppler multiplexing number N DOP_CD (ndm) represents the index below. For example, ndop_CD(ndm)=1,~, N DOP_CD (ndm). Also, angle[x] is an operator that outputs the radian phase of a real number x, for example, angle[1]=0, angle[-1]=π, angle[j]=π / 2, and angle[-j]=-π / 2. Also, floor[x] is an operator that outputs the largest integer not exceeding the real number x. j is the imaginary unit.

[0079] For example, as shown in equation (6), the encoded Doppler phase rotation amount ψ ndop_CD(ndm), ndm (m) is the Doppler shift amount DOP over the duration of a transmission cycle of code length Loc times used for encoding. ndmSet the phase rotation amount to be imparted to a constant (for example, the first term of Equation (6)), and use the code Code for encoding ndop_CD(ndm) for each of the Loc code elements OC ndop_CD(ndm) (1), ~, OC ndop_CD(ndm) impart the corresponding phase rotation amount (the second term of Equation (6)).

[0080] Also, the encoding unit 106 outputs the orthogonal code element index OC_INDEX to the radar receiving unit 200 (the output switching unit 209 described later) for each transmission period (Tr). OC_INDEX is the orthogonal code element index that indicates the elements of the orthogonal code sequence Code ndop_CD(ndm) and varies cyclically within the range from 1 to Loc as shown in the following Equation (7) for each transmission period (Tr).

Equation

[0081] Here, mod(x, y) is the modulo operator and is a function that outputs the remainder after dividing x by y. Also, m = 1, ~, Nc. Nc is the number of transmission periods used for radar positioning (hereinafter referred to as the "number of radar transmission signal transmissions"). Also, the number of radar transmission signal transmissions Nc is set to be an integer multiple (Ncode times) of Loc. For example, Nc = Loc × Ncode.

[0082] Next, an example of a method for unevenly setting the encoding Doppler multiplicity N DOP_CD (ndm) for the Doppler multiplexed signal in the encoding unit 106 will be described.

[0083] For example, the encoding unit 106 sets the number of orthogonal code sequences (for example, the code multiplicity or the number of codes) N CM that satisfies the following conditions. For example, the number of orthogonal code sequences N CM and the Doppler multiplicity N DM satisfy the following relationship with respect to the number Nt of transmission antennas 110 used for multiple transmissions. (Number of orthogonal code sequences N CM ) × (Doppler multiplicity N DM)≧Number of transmission antennas Nt used for multiple transmissions

[0084] For example, the number of orthogonal code sequences N that satisfy the above conditions CM and the Doppler multiplicity N DM Among them, the combination with a smaller value of the product (N CM ×N DM ) is more suitable both characteristically and in terms of circuit configuration complexity. However, the number of orthogonal code sequences N that satisfy the above conditions CM and the Doppler multiplicity N DM Among them, the combination with a smaller value of the product (N CM ×N DM ) is not limited to the combination with a smaller value, and other combinations are also applicable.

[0085] For example, when Nt = 4, N DM = 2 and N CM = 2 is a suitable combination.

[0086] In this case, the assignment of the Doppler shift amounts DOP1, DOP2 and the orthogonal codes Code1, Code2 is determined according to the settings of N DOP_CD (1) and N DOP_CD (2) as shown in FIG. 3 for example. In FIG. 3, "〇" represents the used Doppler shift amount and orthogonal code, and "×" represents the unused Doppler shift amount and orthogonal code (the same applies in the following description).

[0087] For example, (a) in FIG. 3 shows an example where N DOP_CD (1) = 2 and N DOP_CD (2) = 1, and (b) in FIG. 3 shows an example where N DOP_CD (1) = 1 and N DOP_CD (2) = 2. Here, the time multiplexing unit 107 performs time multiplexing using a Doppler multiplexed signal with a coded Doppler multiplicity of 1 (for example, using N DOP_CD (2) in (a) of FIG. 3 and using N DOP_CD (1) in (b) of FIG. 3).

[0088] Note that in FIG. 3, the coded Doppler multiplicity N DOP_CDCode1 is used for the Doppler shift amount corresponding to (ndm)=1 (for example, DOP2 in Figure 3(a) and DOP1 in Figure 3(b)), but is not limited to this. For example, Code2 may be used instead of Code1.

[0089] Also, for example, if Nt = 4, 5, or 6, N DM =3 and N CM =2 combinations, or N DM =2 and N CM The combination of =3 is preferable. Also, for example, when Nt=4~8, N DM =2 and N CM The combination of =4 is also suitable.

[0090] Figure 4 shows, as an example, N DM =3, N CM The case where = 2 is shown. For example, the assignment of Doppler shift amounts DOP1, DOP2, DOP3, and orthogonal codes Code1 and Code2 is as shown in Figure 4, N DOP_CD (1), N DOP_CD (2) and N DOP_CD (3) Determined according to the settings.

[0091] For example, Figure 4(a) is N DOP_CD (1) = 2, N DOP_CD (2) = 1, N DOP_CD (3) An example of 1 is shown, and Figure 4(b) is N DOP_CD (1) = 1, N DOP_CD (2) = 2, N DOP_CD (3) An example of = 1 is shown, and Figure 4(c) is N DOP_CD (1) = 1, N DOP_CD (2) = 1, N DOP_CD (3) An example of 2 is shown. Here, the time multiplexing unit 107 uses a Doppler multiplexed signal with an encoded Doppler multiplexing number of 1 (for example, in Figure 3(a) N DOP_CD (2) and N DOP_CD (3) Perform time multiplexing using either or both of the above.

[0092] Figure 5 shows another example, N DM =2, N CMThe case where = 4 is shown. For example, the assignment of Doppler shift amounts DOP1, DOP2, and orthogonal codes Code1, Code2, Code3, Code4 is as shown in Figure 5, N DOP_CD (1), N DOP_CD (2) is determined according to the settings.

[0093] For example, Figure 5 shows N DOP_CD (1) = 3, N DOP_CD (2) An example of 1 is shown. Here, the time multiplexing unit 107 uses a Doppler multiplexed signal with an encoded Doppler multiplexing number of 1 (for example, in Figure 5, N DOP_CD (2) Perform time multiplexing.

[0094] Next, the encoded Doppler phase rotation amount ψ ndop_CD(ndm), ndm This section explains an example of the (m) setting.

[0095] <Configuration Example 1> For example, in the encoding unit 106, the number of transmitting antennas used for multiplex transmission is Nt=4, and the number of Doppler multiplexers is N. DM =2, 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 3(b), the number of Doppler multiplexing codes is N. DOP_CD (1) = 1, N DOP_CD If (2)=2, the encoding unit 106 has an encoded Doppler phase rotation amount ψ such that it is given by equations (8)~(10) below. 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 Set (m) and output it to the phase rotation unit 108.

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[0096] The transmission control unit 109 sets the encoding Doppler multiplexing number to N.DOP_CD (1) = 1 encoded Doppler phase rotation ψ 1, 1 For a coded Doppler multiplexed signal with (m) assigned to it, time-division multiplexing (for example, time Doppler multiplexing) is performed by switching between two transmitting antennas 110 at each transmission cycle. The transmission control unit 109 also sets the coded Doppler multiplexing number N. DOP_CD (2) Encoded Doppler phase rotation ψ such that = 2 1, 2 (m), ψ 2, 2 For each encoded Doppler multiplexed signal assigned (m), no control is performed to switch the transmitting antenna 110; instead, each encoded Doppler multiplexed signal is transmitted from a single transmitting antenna 110.

[0097] Here, as an example, the Doppler shift amount DOP ndm The phase rotation amount that imparts this is φ in equation (1). ndm =2π(ndm-1) / N DM When a phase rotation amount φ1=0 is used to impart a Doppler shift amount DOP1, and a phase rotation amount φ2=π is used to impart a Doppler shift amount DOP2, the encoding unit 106 uses the following equations (11)~(13) for the encoded Doppler phase rotation amount ψ 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 (m) is set and output to the phase rotation unit 108. Here, m = 1, ~, Nc. Note that modulo calculation by 2π is performed here, and the value is expressed in the range of radians from 0 to less than 2π (the same applies to the following explanation).

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[0098] As shown in equations (11) to (13), the amount of phase rotation is equal to φ divided equally into 2π. ndm =2π(ndm-1) / N DM When set to the encoded Doppler phase rotation amount ψ1, 1 (m), ψ 1, 2 (m), ψ 2, 2 (m) is N DM ×N CM It changes with a transmission period of 2 × 2 = 4.

[0099] Furthermore, as shown in equations (11) to (13), the number of phases used for the phase rotation amount (for example, the phase rotation amount that imparts the Doppler shift amount) (for example, two phases, 0 and π) is less than the number of transmitting antennas 110 used for multiplex transmission Nt = 4. For example, as shown in equations (11) to (13), the number of phases used for the phase rotation amount that imparts the Doppler shift amount (for example, two phases, 0 and π) is less than the number of Doppler shift amounts used for multiplex transmission (for example, the Doppler multiplexing number) N DM = Equivalent to 2.

[0100] <Setting Example 2> For example, in the encoding unit 106, the number of transmitting antennas used for multiplex transmission is Nt=5, and the number of Doppler multiplexers is N. DM =3, 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 4(c), the number of Doppler multiplexing codes is N. DOP_CD (1) = 1, N DOP_CD (2) = 1, N DOP_CD If (3)=2, the encoding unit 106 has an encoded Doppler phase rotation amount ψ as shown in equations (14)~(17) below. 1, 1 (m), ψ 1, 2 (m), ψ 1, 3 (m), ψ 2, 3 (m) is set and output to the phase rotation unit 108. Here, m = 1, ~, Nc.

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[0101] The transmission control unit 109 sets the encoding Doppler multiplexing number to N. DOP_CD (1) = 1 encoded Doppler phase rotation ψ 1, 1 For an encoded Doppler multiplexed signal with (m) assigned to it, time-division multiplexing is performed, for example, by switching 2 (= Loc) transmitting antennas 110 at each transmission cycle (e.g., time Doppler multiplexing). The transmission control unit 109 also sets the encoding Doppler multiplexing number N. DOP_CD (2) = 1 and N DOP_CD (3) Encoded Doppler phase rotation amount ψ such that = 2 1, 2 (m), ψ 1, 3 (m), ψ 2, 3 For each encoded Doppler multiplexed signal assigned (m), no control is performed to switch the transmitting antenna; instead, each encoded Doppler multiplexed signal is transmitted from a single transmitting antenna.

[0102] Here, as an example, the Doppler shift amount DOP ndm The phase rotation amount that imparts this is φ ndm =2π(ndm-1) / N DM If we use a phase rotation amount φ1=0 to impart Doppler shift amount DOP1, a phase rotation amount φ2=π / 2 to impart Doppler shift amount DOP2, and a phase rotation amount φ3=π to impart Doppler shift amount DOP3, the encoding unit 106 will use the following encoded Doppler phase rotation amount ψ 1, 1 (m), ψ 1, 2 (m), ψ 1, 3 (m), ψ 2, 3 (m) is set and output to the phase rotation unit 108. Here, m = 1, ~, Nc.

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[0103] As shown in equations (18) to (21), the amount of phase rotation is φ obtained by dividing 2π into unequal parts. ndm =2π(ndm-1) / (N DM When set to +1), the encoded Doppler phase rotation amount ψ 1, 1 (m), ψ 1, 2 (m), ψ 1, 3 (m), ψ 2, 3 (m) is (N DM (+1) × N CM It changes with a transmission period of 4 × 2 = 8.

[0104] Furthermore, as shown in equations (18) to (21), the number of phases used for the phase rotation amount (for example, the phase rotation amount that imparts the Doppler shift amount) (e.g., four phases: 0, π / 2, π, and 3π / 2) is less than the number of transmitting antennas 110 used for multiplex transmission Nt=5. For example, as shown in equations (18) to (21), the number of phases used for the phase rotation amount that imparts the Doppler shift amount (e.g., four phases: 0, π / 2, π, and 3π / 2) is less than the number of phase divisions N used for the unequal-interval Doppler shift amount used for multiplex transmission. DM It is equal to +1 (=4).

[0105] For this example, we have Nt = 4 for the number of transmitting antennas 110, and N for the Doppler multiplexing. DM If =2, and the number of transmitting antennas 110 Nt=5, then Doppler multiplexing number N DM We have explained the setting of the phase rotation amount in the case of =3, but the number of transmitting antennas 110 Nt and the Doppler multiplexing number N DM These values ​​are not limited to these values. For example, regardless of the value of the number Nt of the transmitting antenna 110, the number of phases used for the phase rotation amount may be set to be less than the number Nt of the transmitting antenna 110 used for multiplex transmission. Also, the number of phases used for the phase rotation amount that imparts the Doppler shift amount may be less than the number Nt of the Doppler shift amount used for multiplex transmission. DM , or N DM You may make it equal to +1.

[0106] The above describes how to set the phase rotation amount in the phase rotation amount setting unit 104.

[0107] In Figure 1, the phase rotation unit 108 controls the encoded Doppler phase rotation amount ψ set in the phase rotation amount setting unit 104. ndop_CD(ndm), ndm Based on (m), a phase rotation amount is applied to the chirp signal output from the radar transmission signal generation unit 101 for each transmission period Tr. Here, ndm = 1, ~, N DM Good, ndop _CD (ndm) = 1, ~, N DOP_CD (ndm)

[0108] Encoded Doppler multiplexing number N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM The sum of the numbers is set to be less than the number Nt of the transmitting antenna 110, and the encoded Doppler phase rotation amounts are input to each of the Nt or fewer phase rotation units 108.

[0109] Encoded Doppler multiplexing number N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM For the portion where the sum of ) does not satisfy Nt, time-multiplexed transmission (also called time-division Doppler multiplexing) using a predetermined Doppler multiplexed signal may be used in combination, for example, by the operation of the time-multiplexing unit 107 and the transmission control unit 109 as follows. This enables multiplexed transmission by Doppler multiplexing using encoding and time division (also called encoded Doppler multiplexing and time-division Doppler multiplexing).

[0110] The time multiplexing unit 107 is N DM Of the individual Doppler multiplexed signals, the number of encoded Doppler multiplexed signals is N. DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM The transmission control unit 109 is controlled to perform time-multiplexed transmission using at least one Doppler multiplexed signal from a Doppler multiplexed signal where ) is 1.

[0111] In the following, the Doppler multiplexed signal used for time multiplexing will be referred to as "ndm_TDM". Furthermore, if there are multiple Doppler multiplexed signals used for time multiplexing (referred to as "NDOP_TDM") (NDOP_TDM > 1), they will be written as ndm_TDM(1), ndm_TDM(2), ~, ndm_TDM(NDOP_TDM), and so on. Here, ndm_TDM(1), ndm_TDM(2), ~, ndm_TDM(NDOP_TDM) range from 1 to N. DM It is one of the following, and the encoding Doppler multiplexing number is N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM It is selected from Doppler multiplexed signals where ) is 1.

[0112] The transmission control unit 109, based on the control signal from the time multiplexing unit 107, controls the switching of the transmitting antenna 110 in relation to the Doppler multiplexed signal used for time multiplexing, and performs the operation of switching the transmitting antenna 110.

[0113] The transmission control unit 109 can switch the transmitting antenna 110 for each transmission period Loc × Tr, which is the code transmission period. Therefore, it is possible to switch up to Loc transmitting antennas 110. Alternatively, the switching of overlapping transmitting antennas 110 may occur within the transmission period Loc, and time-division multiplexing may be performed using at least two transmitting antennas 110.

[0114] In the following, the number of time-division multiplexing numbers using the Doppler multiplexing signal NDM used for time-division multiplexing is "N DOP_TD This is denoted as "(ndm_TDM)". The time multiplexing unit 107 is N if the Doppler multiplexed signal ndm is not the Doppler multiplexed signal used for time multiplexing (ndm ≠ ndm_TDM). DOP_TD(ndm) may be set to 1, and the transmission control unit 109 may be controlled to transmit using a predetermined single transmission antenna 110. Also, when the Doppler multiplexed signal ndm is a Doppler multiplexed signal used for time multiplexing (ndm = ndm_TDM), the time multiplexing unit 107 sets the number of time multiplexing within the range of 1 < N DOP_TD (ndm) ≦ Loc and controls the transmission control unit 109 to transmit using a predetermined N DOP_TD (ndm) antennas. Here, when N DOP_TD (ndm) < Loc, transmission cycles not connected to the transmission antenna 110 may be included.

[0115] For example, when Loc = 4, if the time multiplexing unit 107 sets N DOP_TD (ndm) = Loc, the transmission control unit 109 may be controlled to sequentially switch four transmission antennas 110 (for example, #1, #2, #3, #4) every transmission cycle Tr. Thus, by the operation of the transmission control unit 109, every Loc transmission cycles Loc×Tr, which is the symbol transmission cycle, the transmission antennas #1, #2, #3, #4 are sequentially switched at cycle Tr, and the radar transmission signal is transmitted.

[0116] Alternatively, overlapping transmission antennas 110 may be switched within the transmission cycle Loc. For example, when Loc = 4, if the time multiplexing unit 107 sets N DOP_TD (ndm) = Loc, the transmission control unit 109 may be controlled to sequentially switch four transmission antennas (for example, #1, #2, #1, #2) every transmission cycle Tr. Thus, by the operation of the transmission control unit 109, every Loc transmission cycles Loc×Tr, which is the symbol transmission cycle, the transmission antennas #1, #2, #1, #2 are sequentially switched at cycle Tr, and the radar transmission signal is transmitted.

[0117] Or, when N DOP_TD (ndm) < Loc is set, transmission cycles not connected to the transmission antenna 110 are included. For example, when Loc = 4, the time multiplexing unit 107 sets N DOP_TDWhen (ndm)=Loc-1=3 is set, the transmission control unit 109 may be controlled to sequentially switch the three transmitting antennas 110 (for example, #1, #2, #3) with each transmission period Tr, and to set a no-transmission section in the next transmission period where the transmitting antennas 110 are not connected. As a result, the operation of the transmission control unit 109 causes the transmission section and no-transmission section of the radar transmission signal from transmitting antennas #1, #2, and #3 to be sequentially switched with each transmission period Loc × Tr, which is the code transmission period.

[0118] Each of the Nt phase rotation units 108 adjusts the input encoded Doppler phase rotation amount ψ for the chirp signal output from the radar transmission signal generation unit 101 for each transmission period Tr. ndop_CD(ndm), ndm (m) is assigned to each. The outputs from the Nt phase rotation units 108 (for example, called coded Doppler multiplexed signals) are processed by the transmission control unit 109 as follows.

[0119] When the Doppler multiplexed signal ndm_TDM used for time multiplexing is input to the transmission control unit 109, it performs switching control of the transmitting antenna 110 in response to the Doppler multiplexed signal used for time multiplexing based on the control signal from the time multiplexing unit 107 described above, and performs the operation of switching the transmitting antenna 110. On the other hand, when the Doppler multiplexed signal ndm_TDM used for time multiplexing is not input to the transmission control unit 109, it performs the operation of outputting the input encoded Doppler multiplexed signal from the corresponding transmitting antenna 100 without switching control of the transmitting antenna 110.

[0120] Furthermore, the output from the transmission control unit 109 is amplified to a specified transmission power and then radiated into space from Nt transmission antennas 110.

[0121] Note that the following refers to the encoded Doppler phase rotation amount ψ ndop_CD(ndm), ndmThe phase rotation unit 108 that assigns (m) is denoted as "Phase Rotation Unit PROT#[ndop_CD(ndm), ndm]". The transmission control unit 109, which receives the signal from the phase rotation unit PROT#[ndop_CD(ndm), ndm], is denoted as "Transmission Control Unit TxSW#[ndop_CD(ndm), ndm]". The transmitting antenna 110, connected to the transmission control unit TxSW#[ndop_CD(ndm), ndm] and radiating the signal into space, is denoted as "Transmitting Antenna Tx#[ndop_TDM(ndm), ndop_CD(ndm), ndm]". Here, ndm = 1, ~, N DM And ndop_CD(ndm)=1,~, N DOP_CD (ndm) is the case. Also, if the Doppler multiplexed signal ndm ≠ ndm_TDM, then ndop_TDM(ndm) = 1, and the Doppler multiplexed signal is output from one transmitting antenna 100. On the other hand, if the Doppler multiplexed signal ndm = ndm_TDM, then ndop_TDM(ndm_TDM) = 1, ~, N DOP_TD (ndm_TDM) is used, and the Doppler multiplexed signal is output in time division from multiple transmitting antennas 100.

[0122] For example, when the number of transmitting antennas Nt = 4 used for multiplexing, the Doppler multiplexing number N DM =2, N CM Let = 2, and set the orthogonal code sequences Code1={1,1} and Code2={1,-1} with code length Loc=2, and the coding Doppler multiplexing number to be N. DOP_CD (1) = 1, N DOP_CD (2) Let's set it to 2, and the time multiplexing number N for a Doppler multiplexed signal ndm=1. DOP_TDM (1) = 2, time multiplexing number N for Doppler multiplexed signal ndm = 2 DOP_TDM Let's explain the case where (2)=1. In this case, the encoding unit 106 controls the encoding Doppler phase rotation amount ψ to the phase rotation unit 108. 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 (m) is output at each transmission cycle.

[0123] For example, the phase rotation unit PROT#[1, 1] rotates the chirp signal generated by the radar transmission signal generation unit 101 for each transmission period by a phase rotation amount ψ as shown in equation (22) below for each transmission period. 1, 1 Add (m).

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[0124] Furthermore, the output of the phase rotation unit PROT#[1, 1] is input to the transmission control unit TxSW#[1, 1]. The transmission control unit TxSW#[1, 1] switches between the transmitting antennas Tx#[1, 1, 1] and Tx#[2, 1, 1] in a time-division manner for each transmission cycle, and transmits the output of the phase rotation unit PROT#[1, 1]. For example, the transmitting antennas Tx#[1, 1, 1] and Tx#[2, 1, 1] output transmission signals as shown in equations (23) and (24), respectively, for each transmission cycle. Here, cp(t) represents the chirp signal for each transmission cycle, and Txoff indicates that no transmission output is produced during that transmission cycle.

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[0125] Similarly, the phase rotation unit PROT#[1, 2] rotates the chirp signal generated by the radar transmission signal generation unit 101 for each transmission period by the phase rotation amount ψ as shown in equation (25) below for each transmission period. 1, 2 (m) is added. Additionally, the output of the phase rotation unit PROT#[1, 2] is input to the transmit control unit TxSW#[1, 1, 2] and output from the transmit antenna Tx#[1, 1, 2].

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[0126] Similarly, the phase rotation unit PROT#[2, 2] rotates the chirp signal generated by the radar transmission signal generation unit 101 for each transmission period by a phase rotation amount ψ as shown in equation (26) below for each transmission period. 2, 2 (m) is added. Also, the output of the phase rotation unit PROT#[2, 2] is input to the transmit control unit TxSW#[1, 2, 2] and output from the transmit antenna Tx#[1, 2, 2].

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[0127] The above describes the encoded Doppler phase rotation amount ψ in the encoding unit 106. ndop_CD(ndm), ndm Examples of settings for (m), and examples of settings for the time multiplexing unit 107 and the transmission control unit 109 were described.

[0128] Thus, in this embodiment, the Doppler shift amount DOP is set for multiple transmitting antennas 110. ndm and orthogonal code sequence Code ncm At least one of the combinations (e.g., assignment) is different and is associated with each other, or Doppler shift amount DOP ndm and orthogonal code sequence Code ncm Even if the radar is identical, it is assigned different transmission cycles (different time-division multiplex transmission cycles) to transmit the radar signal.

[0129] Furthermore, in this embodiment, the Doppler shift amount DOP ndm and orthogonal code sequence Code ncm Each Doppler shift amount DOP in combination with ndm Corresponding orthogonal code sequence Code ncm The number of multiplexings (for example, the coded Doppler multiplexing number N) DOP_CD (ndm)) may be different, and time-division Doppler multiplexing has an encoded Doppler multiplexing number N. DOP_CD Use (ndm)=1.

[0130] For example, in this embodiment, the Nt transmitting antennas 110 may include at least a plurality of transmitting antennas 110 to which each transmits a transmission signal that is code-multiplexed by different orthogonal code sequences, and at least one transmitting antenna 110 to which a transmission signal with a different code-multiplexing number is transmitted. For example, the radar transmission signal transmitted from the radar transmitting unit 100 has at least the coding Doppler multiplexing number N DOP_CD (ndm) with code number N CM The encoded Doppler multiplexed signal set to and the number of encoded Doppler multiplexed signals N DOP_CD (ndm) with code number N CM A smaller encoded Doppler multiplexed signal may be included.

[0131] [Configuration of radar receiver 200] In Figure 1, the radar receiver 200 is equipped with Na receiving antennas 202, forming an array antenna. The radar receiver 200 also includes Na antenna system processing units 201-1 to 201-Na, a CFAR (Constant False Alarm Rate) unit 211, a separation unit 212, and a direction estimation unit 213.

[0132] Each receiving antenna 202 receives a reflected wave signal, which is a radar transmission signal reflected by a target, and outputs the received reflected wave signal as a received signal to the corresponding antenna system processing unit 201.

[0133] Each antenna system processing unit 201 includes a receiving radio unit 203 and a signal processing unit 206.

[0134] The receiving radio unit 203 includes a mixer unit 204 and an LPF (low-pass filter) 205. In the mixer unit 204, the receiving radio unit 203 mixes the received reflected wave signal with the chirp signal, which is the transmission signal input from the radar transmission signal generation unit 101, and passes it through the LPF 205. This extracts a beat signal whose frequency corresponds to the delay time of the reflected wave signal. For example, as shown in the lower part of Figure 2, the difference frequency between the frequency of the transmitted chirp signal (transmitted frequency modulated wave) and the frequency of the received chirp signal (received frequency modulated wave) is obtained as the beat frequency.

[0135] 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.

[0136] 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.

[0137] 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 FFT processing. 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). During FFT processing, the beat frequency analysis unit 208 may multiply by a window function coefficient, such as a Han window or a Hamming window. By using a window function coefficient, side lobes that occur around the beat frequency peak can be suppressed.

[0138] 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 RFT z (f b Let it be expressed as , m). Here, f bThis 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, 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.

[0139] Also, the beat frequency index f b The distance information R(f) is calculated using the following equation (27). b It can be converted to ). Therefore, below, the beat frequency index f b to "distance index f b They call it that.

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[0140] Here, B w C0 represents the frequency modulation bandwidth within the range gate in a chirp signal, and C0 represents the speed of light.

[0141] 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 output from the coding unit 106 of the phase rotation amount setting unit 104. For example, the output switching unit 209 selects the OC_INDEX-th Doppler analysis unit 210 in the m-th transmission period Tr.

[0142] 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 output from the beat frequency analysis unit 208).z (f b Using , m)), distance index f b Doppler analysis is performed for each step. Here, noc is the index of the sign element, and noc = 1, ~, Loc.

[0143] 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.

[0144] The following describes the case where Ncode is a power of 2 as an example. If Ncode is not a power of 2, for example, by including zero-padding data, it is possible to perform FFT processing with a data size (FFT size) that is a power of 2. In addition, the Doppler analysis unit 210 may multiply by window function coefficients such as a Han window or a Hamming window during FFT processing. By applying a window function, side lobes that occur around the beat frequency peak can be suppressed.

[0145] 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 (28). Note that j is the imaginary unit, and z = 1 to Na.

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[0146] The processing in each component of the signal processing unit 206 has been described above.

[0147] In Figure 1, 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.

[0148] The CFAR unit 211, for example, as shown in equation (29) 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 2D CFAR process consisting of a distance axis and a Doppler frequency axis (corresponding to relative velocity), or a CFAR process that combines a 1D CFAR process. For the 2D CFAR process or the CFAR process that combines a 1D CFAR process, for example, the process disclosed in Non-Patent Document 2 may be applied.

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[0149] 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 ) is output to the separation unit 212.

[0150] Note that the Doppler shift amount is DOP. ndm Phase rotation amount φ to impart ndm For example, when using equation (1), the interval ΔFD of the Doppler shift amount in the Doppler frequency domain in the output from the Doppler analysis unit 210 becomes equal, and ΔFD = Ncode / N DM Therefore, in the output from the Doppler analysis unit 210, in the Doppler frequency domain, peaks are detected for each Doppler-shifted multiplexed signal at intervals of ΔFD. Note that the phase rotation amount φ ndmWhen using formula (1), Ncode and N DM In some cases, ΔFD may not be an integer. In such cases, ΔFD can be made an integer value by using equation (35), which will be described later. Below, the reception processing operation will be explained assuming that ΔFD is an integer value.

[0151] Figure 6(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 6(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 with intervals of ΔFD for each of f1, f2, and f3 (e.g., f1+ΔFD, f2+ΔFD, f3+ΔFD).

[0152] 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, as shown in equation (30), combine the peak positions of each Doppler-shifted signal and sum the power (for example, called "Doppler region compression"), and then perform CFAR processing (for example, called "Doppler region compressed CFAR processing"). Here, f s_comp = -Ncode / 2, ~, -Ncode / 2 + ΔFD-1.

number

[0153] This allows the Doppler frequency range of CFAR processing to be 1 / N DM It can be compressed to reduce the amount of CFAR processing required and simplify the circuit configuration. In addition, in the CFAR section 211, N DM Since the power of each Doppler-shifted multiplexed signal can be added together, the SNR (Signal to Noise Ratio) can be increased to (N DM ) 1 / 2 This can improve the degree of improvement and enhance the radar detection performance of the radar device 10.

[0154] Figure 6(b) shows an example of the output after applying the Doppler region compression process shown in equation (30) to the output of the Doppler analysis unit 210 shown in Figure 6(a). As shown in Figure 6(b), N DM When = 2, the Doppler region compression process adds the power component of Doppler frequency index f1 and the power component of f1 + ΔFD to the output. Similarly, as shown in Figure 6(b), the power component of Doppler frequency index f2 and the power component of f2 + ΔFD are added to the output, and the power component of Doppler frequency index f2 and the power component of f3 + ΔFD are added to the output.

[0155] As a result of Doppler region compression, the range of the Doppler frequency index fs_comp in the Doppler frequency domain is reduced to -Ncode / 2 or greater, and -Ncode / 2+ΔFD-1 or less, compressing the range of CFAR processing and thus reducing the computational load of CFAR processing. Also, in Figure 6, for example, the reflected waves from the three targets are power-summed, improving the SNR of the signal component. Since the noise component is also power-summed, the improvement in SNR is, for example, (N DM ) 1 / 2 This represents an improvement of some degree.

[0156] 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 Received power information PowerFT(f(nfd-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-1)×ΔFD), nfd=1,~,N DM This is output to the separation unit 212.

[0157] Note that the Doppler shift amount is DOP. ndm Phase rotation amount φ to impart ndmThis is not limited to equation (1). For example, each Doppler-shifted multiplexed signal has a phase rotation amount φ at which peaks are detected at regular intervals in the Doppler frequency domain output from the Doppler analysis unit 210. ndm In that case, the CFAR unit 211 can apply Doppler region compression CFAR processing.

[0158] Furthermore, for example, when using equation (2), the intervals of the Doppler shift amounts in the Doppler frequency domain in the output from the Doppler analysis unit 210 become unequal, and ΔFD = Ncode / (N DM +1), or 2 × ΔFD. Even if the intervals of the Doppler shift amounts in the Doppler frequency domain are unequal, if the unequal intervals are an integer multiple of the interval ΔFD of the smallest Doppler shift amount, the CFAR unit 211 can apply Doppler domain compression CFAR processing.

[0159] Next, an example of the operation of the separation unit 212 shown in Figure 1 will be described. In the following, an example of the processing of the separation unit 212 when Doppler region compression CFAR processing is used in the CFAR unit 211 will be described.

[0160] The separation unit 212 receives 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 Received power information PowerFT(f(nfd-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-1)×ΔFD), nfd=1,~,N DMBased on this, the output of the Doppler analysis unit 210 is used to separate the transmitted signals that have been encoded Doppler multiplexed or time-division Doppler multiplexed, to determine the transmitting antenna 110 (for example, also called determination or identification), and to determine the Doppler frequency (for example, Doppler velocity or relative velocity), and to associate it with the transmitting antenna Tx#[ndop_TDM(ndm),ndop_CD(ndm), ndm]. Hereafter, the received signal from the transmitting antenna Tx#[ndop_TDM(ndm),ndop_CD(ndm), ndm] received by the z-th receiving antenna 202 is Y z This is written as (ndop_TDM(ndm), ndop_CD(ndm), ndm). Here, z=1,~,Na.

[0161] As described above, the encoding unit 106 of the phase rotation amount setting unit 104 is, for example, N DM The number of encoded Doppler multiplexers N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM The radar transmitter 100 transmits encoded Doppler multiplexed data, with at least one of the encoding Doppler multiplexed numbers set to 2 or more. The encoding unit 106 also sets N DM The number of encoded Doppler multiplexers N DOP_CD (1), N DOP_CD (2), ~, N DOP_CD (N DM Of these, at least one encoded Doppler multiplexing number is set to 1, and the radar transmission unit 100 transmits using time multiplexing by the time multiplexing unit 107 and the transmission control unit 109.

[0162] Here, when the encoding Doppler multiplexing number is set to 2 or more, multiple transmitting antennas 110 transmit simultaneously using the same Doppler multiplexed signal, and the average transmission power of the Doppler multiplexed signal increases in proportion to the encoding Doppler multiplexing number. For example, when the encoding Doppler multiplexing number is set to 2, the average transmission power of the Doppler multiplexed signal increases by about twice, and when the encoding Doppler multiplexing number is set to 3, it increases by about three times. As the average transmission power of the Doppler multiplexed signal increases, the received power of the Doppler multiplexed signal may also increase by a similar amount.

[0163] On the other hand, when the Doppler multiplexing number is set to 1 and time-multiplexed transmission is performed by the time-multiplexing unit 107 and the transmission control unit 109, multiple transmitting antennas 110 switch and transmit using the same Doppler multiplexed signal for each transmission cycle. Therefore, the transmission power of the Doppler multiplexed signal is the same as the transmission power of each individual transmitting antenna 110. Consequently, the received power of the Doppler multiplexed signal does not increase.

[0164] Thus, it is assumed that the average received power will differ between a Doppler multiplexed signal with an encoding Doppler multiplexing number of 2 or more and a Doppler multiplexed signal transmitted using time division multiplexing. For this reason, the separation unit 212 separates the signals transmitted using encoding Doppler multiplexing or time division multiplexing based on the difference in received power between the Doppler multiplexed signals, enabling the identification of the transmitting antenna 110 and the Doppler frequency (e.g., Doppler velocity or relative velocity).

[0165] For example, the output of the Doppler analysis unit 210 for a transmitted signal like the one in <Setting Example 1> described above is shown in Figure 7. Here, the distance index f is the output of the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar For example, the output VFT of the Doppler analysis unit 210 (e.g., the first Doppler analysis unit 210) of the z-th signal processing unit 206. z 1 (f b_cfar、 f s_comp_cfar ), VFT z 1 (f b_cfar、 f s_comp_cfar The upper part of Figure 7 shows the output VFT of the Doppler analysis unit 210 (for example, the second Doppler analysis unit 210) of the z-th signal processing unit 206, and the output VFT of the z-th signal processing unit 206. z 2 (f b_cfar、 f s_comp_cfar ), VFT z 2 (f b_cfar、 f s_comp_cfar The lower part of Figure 7 shows the Doppler frequency component (+ΔFD). The length of the arrows for each Doppler frequency component represents the magnitude of the received power.

[0166] For example, from equation (29), the separation unit 212 receives the received power information PowerFT(f b_cfar , f s_comp_cfar ) and received power information PowerFT(f b_cfar , f s_comp_cfar By comparing with +ΔFD), it is possible to distinguish between Doppler multiplexed signals with an encoded Doppler multiplexing number of 2 or more and Doppler multiplexed signals transmitted using time multiplexing. For example, as shown in Figure 7, the received power information PowerFT(f b_cfar , f s_comp_cfar )>PowerFT(f b_cfar , f s_comp_cfar In the case of +ΔFD), the separation unit 212 is the Doppler frequency index f s_comp_cfar This is an encoded Doppler multiplexed signal with an encoding Doppler multiplexing number of 2 or more, and one of the Doppler frequency indexes f s_comp_cfar It is determined that +ΔFD is a time-Doppler multiplexed signal.

[0167] Since there is a one-to-one correspondence between the switching period of the transmitting antenna 110 and the output of the Doppler analysis unit 210, the separation unit 212 identifies the transmitting antenna 110 based on the output of the Doppler analysis unit 210 when the Doppler frequency index, which has been determined to be a time-Doppler multiplexed signal, was transmitted in time division. For example, in the case of the example in Figure 7, the separated received signal for the first transmitting antenna 110 transmitted in time Doppler multiplexed is VFT z 1 (f b_cfar、 f s_comp_cfar The value is +ΔFD), and the separated received signal for the second transmitting antenna 110, which was time-doppler multiplexed, is VFT. z 2 (f b_cfar、 f s_comp_cfar The result is (+ΔFD). Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,1] set in Example 1 and received by the z-th receiving antenna 202 is VFT z 1 (f b_cfar、 f s_comp_cfar +ΔFD) and Y zIt is written as (1,1,1). Also, the received signal transmitted from the transmitting antenna Tx#[2, 1, 1] set in Example 1 and received by the z-th receiving antenna 202 is VFT z 2 (f b_cfar、 f s_comp_cfar +ΔFD) and Y z Let (2,1,1) be written as such. Here, z=1,~, and Na.

[0168] Furthermore, the separation unit 212 further decodes and receives the Doppler frequency index signal, which has been determined to be an encoded Doppler multiplexed signal, using the code used to encode the encoded Doppler multiplexed signal. For example, a signal transmitted from the transmitting antenna 110 encoded with Code1={1,1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (f s_comp_cfar The code is decoded and received at ). Here α corr (f s_comp_cfar ) is a coefficient that corrects the Doppler phase rotation due to the sampling time difference between the Doppler analysis units 210, and is determined by the Doppler frequency determination result obtained by subtracting the offset due to the Doppler shift amount applied during transmission from the received Doppler frequency, and the sampling time difference between the Doppler analysis units 210 (in this case, Tr) (for an example, see Patent Document 5, so a detailed explanation is omitted). Also, the signal transmitted from the transmitting antenna 110 encoded by Code2={1,-1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar )α corr (f s_comp_cfar The code is decoded and received.

[0169] Therefore, the received signal transmitted from the transmitting antenna Tx#[1, 1, 2] set in Example 1 and received by the z-th receiving antenna 202 is (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (f s_comp_cfar ) and Y z It is written as (1,1,2). Also, the received signal transmitted from the transmitting antenna Tx#[1, 2, 2] set in Example 1 and received by the z-th receiving antenna 202 is (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar )α corr (f s_comp_cfar ) and Y z Let's write it as (1,2,2). Here, z=1,~, and Na. The same applies to the following examples.

[0170] Furthermore, if the Doppler frequency range of the target exceeds ±1 / {2Tr×(Loc)}, the Doppler frequency range output from the Doppler analysis unit 210 also exceeds ±1 / {2Tr×(Loc)}, and therefore the Doppler frequency of the target is detected by aliasing. In such cases, the coded Doppler multiplexing number N DOP_CD (ndm) with code number N CM Smaller (for example, number of signs ≤ N) CM -1) By using the configured encoded Doppler multiplexed signal, the Doppler detection range can be further expanded. For example, the separation unit 212 has a code count ≤ N CM By setting it to -1, the Doppler detection range can be further expanded by performing aliasing detection based on unused codes (code sequences different from the code sequences used for code multiplexing).

[0171] For example, as shown in Figure 4(a), N CMWhen = 2, the time multiplexing unit 107 is N DOP_CD (2) = 1, N DOP_CD (3) Of the ones where N DOP_CD (2) When performing time multiplexing, N DOP_CD (3) = 1 <N CM By using encoded Doppler multiplexed signals, the Doppler detection range can be further expanded. Also, for example, as shown in Figure 5, N CM When = 4, N DOP_CD (1) = 3 <N CM By using coded Doppler multiplexed signals, the Doppler detection range can be further expanded. The number of coded Doppler multiplexed signals is N. DOP_CD (ndm) with code number N CM The reception processing for expanding the Doppler detection range by using a smaller encoded Doppler multiplexed signal is described in Patent Document 5, so a detailed explanation is omitted here.

[0172] Furthermore, the Doppler frequency obtained by subtracting the offset due to the Doppler shift amount applied during transmission from the received Doppler frequency is the result of determining (or identifying) the target's Doppler frequency, and this Doppler frequency can be output as positioning information for the target.

[0173] Also, each Doppler shift amount DOP ndm The phase rotation amount φ that imparts ndm If the intervals are unequal, for example, the Doppler shift amount DOP ndm Phase rotation amount φ to impart ndm By assigning the values ​​as shown in equation (2), it becomes possible to identify the transmitting antenna 110 based on the Doppler interval, as disclosed in Patent Document 4. Therefore, the separation 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 Received power information PowerFT(f(nfd-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-1)×ΔFD), nfd=1,~,N DMBased on this, by using the output of the Doppler analysis unit 210 to detect Doppler multiplexed signals with unequal intervals, it becomes possible to separate the transmitted signals that have been encoded or time-division multiplexed, and to identify the transmitting antenna 110 and the Doppler frequency (e.g., Doppler velocity or relative velocity).

[0174] Figure 8 shows, for example, that the phase rotation amount is φ divided 2π unequally, as shown in equations (18) to (21) of the setting example 2 described above. ndm =2π(ndm-1) / (N DM The output of the Doppler analysis unit 210 for the transmitted signal when set to +1) is shown. Here, the distance index f is the output of the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar For example, the output VFT of the Doppler analysis unit 210 (first Doppler analysis unit 210) of the z-th signal processing unit 206. z 1 (f b_cfar、 f s_comp_cfar ), VFT z 1 (f b_cfar、 f s_comp_cfar +ΔFD), VFT z 1 (f b_cfar、 f s_comp_cfar The upper part of Figure 8 shows the output VFT of the Doppler analysis unit 210 (second Doppler analysis unit 210) of the z-th signal processing unit 206. z 2 (f b_cfar、 f s_comp_cfar ), VFT z 2 (f b_cfar、 f s_comp_cfar +ΔFD), VFT z 2 (f b_cfar、 f s_comp_cfar The lower part of Figure 8 shows the Doppler frequency component (+2ΔFD). In Figure 8, the length of the arrows for each Doppler frequency component represents the magnitude of the received power.

[0175] The separation unit 212 uses the output of the Doppler analysis unit 210 to detect Doppler multiplexed signals at unequal intervals, thereby separating the transmitted signals that have been encoded or time-division multiplexed, and enabling the identification of the transmitting antenna 110 and the Doppler frequency (e.g., Doppler velocity or relative velocity).

[0176] For example, from equation (29), the separation unit 212 receives the received power information PowerFT(f b_cfar , f s_comp_cfar ), PowerFT(f b_cfar , f s_comp_cfar +ΔFD), PowerFT(f b_cfar , f s_comp_cfar +2ΔFD), and PowerFT(f b_cfar , f s_comp_cfar By comparing +3ΔFD), PowerFT(f b_cfar , f s_comp_cfar Because the received power of +3ΔFD is lower than the others, it is possible to detect Doppler multiplexed signals with unequal intervals. As a result, the separation unit 212 can distinguish between Doppler multiplexed signals that have been encoded and multiplexed, and Doppler multiplexed signals that are transmitted using time multiplexing.

[0177] Since there is a one-to-one correspondence between the switching period of the transmitting antenna 110 and the output of the Doppler analysis unit 210, the separation unit 212 identifies the transmitting antenna 110 based on the output of the Doppler analysis unit 210 when the Doppler frequency index, which has been determined to be a time-Doppler multiplexed signal, was transmitted in time division. For example, in the case of the example in Figure 8, the separated received signal for the first transmitting antenna 110 that was transmitted in time Doppler multiplexed is VFT z 1 (f b_cfar、 f s_comp_cfar ) and the separated received signal for the second transmitting antenna 110, which was transmitted via time Doppler multiplexing, is VFT z 2 (f b_cfar、 f s_comp_cfar Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,1] set in setting example 2 and received by the z-th receiving antenna 202 is VFT z1 (f b_cfar、 f s_comp_cfar ) and Y z This is denoted as (1,1,2). Also, the received signal transmitted from the transmitting antenna Tx#[2,1,1] and received by the z-th receiving antenna 202 is VFT z 2 (f b_cfar、 f s_comp_cfar ) and Y z This is written as (2,1,2).

[0178] Furthermore, the separation unit 212 determines the Doppler frequency index (N) of the encoded Doppler multiplexed signal. DOP_CD (2)=1) is further decoded and received using the code used to encode the coded Doppler multiplexed signal. For example, a signal transmitted from transmitting antenna 110 encoded with Code1={1,1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar (+ΔFD) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar (+ΔFD)×α corr (f s_comp_cfar The code is decoded and received using +ΔFD.

[0179] Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,2] set in Example 2 and received by the z-th receiving antenna 202 is (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar (+ΔFD) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar (+ΔFD)×α corr (f s_comp_cfar +ΔFD) and Y z This is denoted as (1,1,2). Furthermore, the transmitting antenna encoded by Code1={1,1} is (+1)×VFT. z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD) + (+1) × VFTz 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfar The code is decoded and received at +2ΔFD.

[0180] Also, for example, a signal transmitted from transmitting antenna 110 encoded by Code2={1,-1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD)+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfar The code is decoded and received at +2ΔFD.

[0181] Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,3] set in Example 2 and received by the z-th receiving antenna 202 is (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfar Y z This is denoted as (1,1,3). Furthermore, the received signal transmitted from the transmitting antenna Tx#[1,1,3] and received by the z-th receiving antenna 202 is (+1) × VFT. z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD)+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfar Y z It is denoted as (1,2,3).

[0182] Furthermore, if the Doppler frequency range of the target exceeds ±1 / {2Tr×(Loc)}, the Doppler frequency range output from the Doppler analysis unit 210 also exceeds ±1 / {2Tr×(Loc)}, and therefore the Doppler frequency of the target is detected by aliasing. In such cases, the coded Doppler multiplexing number N DOP_CD (ndm) with code number N CM By using a coded Doppler multiplexed signal with a smaller number of codes, the Doppler detection range can be further expanded. For example, the separation unit 212 has a code count ≤ N. CM By setting it to -1, the Doppler detection range can be further expanded by performing aliasing detection based on unused codes (code sequences different from the code sequences used for code multiplexing).

[0183] For example, in the case of the example in Figure 8, VFT z 1 (f b_cfar、 f s_comp_cfar +2ΔFD) and VFT z 2 (f b_cfar、 f s_comp_cfar For a transmitting antenna 110 encoded with Code1={1,1}, the decoder 212 calculates the received power (+1) × VFT when code-separated with Code1={1,1}. z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfar (+2ΔFD) and the received power when Code2={1,-1} is decoded (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD)+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfarBy comparing it with (+2ΔFD), Doppler aliasing can be detected. For example, if the received power of the former is large, the target's Doppler frequency ftarget is in the range of -1 / {2Tr×(Loc)}≦ftarget<-1 / {2Tr×(Loc)}. Also, if the received power of the latter is large, the Doppler frequency is detected through aliasing, so the target's Doppler frequency ftarget is in the range of -1 / (2Tr)≦ftarget<-1 / {2Tr×(Loc)} or 1 / {2Tr×(Loc)}≦ftarget<1 / (2Tr). Note that the encoded Doppler multiplexing number is N. DOP_CD (ndm) with code number N CM The reception processing for expanding the Doppler detection range by using a smaller encoded Doppler multiplexed signal is described in Patent Document 5, so a detailed explanation is omitted here.

[0184] The above describes an example of the operation of the separation unit 212.

[0185] In Figure 1, the direction estimation unit 213 performs target direction estimation processing based on the signals separated by the separation unit 212 from the multiplexed transmission signals using multiple transmitting antennas 110 into received signals for each transmitting antenna 110.

[0186] Note that the distance index f is the output of the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar Based on this, the received signal from the transmitting antenna Tx#[ndop_TDM(ndm),ndop_CD(ndm),ndm] separated and received at the z-th receiving antenna 202 is Y z (ndop_TDM(ndm), ndop_CD(ndm), ndm) can be mapped to these respectively. Therefore, the Y that is separated and received at the z-th receiving antenna 202 z By associating ndop_TDM(ndm), ndop_CD(ndm), and ndm in (ndop_TDM(ndm), ndop_CD(ndm), ndm) with one of Tx#1 to Tx#Nt, "YT zIt can also be written as "(nt)". Here, nt = 1 to Nt. The operation of the direction estimation unit 213 will be explained below using the latter notation.

[0187] For example, the direction estimation unit 213 uses the distance index f, which is the output of the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar Based on this, YT was separated and received at the z-th receiving antenna 202. z Based on (nt), the virtual receive array correlation vector h(f) of the direction estimation unit 213 is given by equation (31) below. b_cfar ,f s_comp_cfar A function is generated, and direction estimation is performed. Here, nt = 1 to Nt.

number

[0188] Here, the virtual receive array correlation vector h(f b_cfar , f s_comp_cfar The array contains Nt × Na elements, which is the product of the number of transmitting antennas Nt and the number of receiving antennas Na. The direction estimation unit 213 calculates the virtual received 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 receiving antenna 202.

[0189] The direction estimation unit 213, for example, performs direction estimation processing using a virtual received array correlation vector h(f b_cfar , f s_comp_cfar Using ), the direction estimation evaluation function value P H (θ, f b_cfar , f s_comp_cfar ) in the direction θ u The spatial profile is calculated by varying the angle within a defined range. 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).

[0190] Note that the direction estimation evaluation function value P H(θ, 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.

[0191] Furthermore, by using, for example, a MIMO virtual receiving antenna arrangement arranged in a rectangular grid, the direction estimation unit 213 can also estimate the direction of arrival in both the azimuth and elevation directions. For example, the direction estimation unit 213 may calculate the azimuth and elevation directions as estimated directions of arrival and output them as positioning values.

[0192] Through the above operations, the direction estimation unit 213 of the radar device 10 outputs, for example, f b_cfar and the received signal YT after separation processing. z Based on (nt), an estimated direction of arrival value may be output. Furthermore, the direction estimation unit 213 may output f as a positioning output. b_cfar The system may also output an estimated Doppler frequency of the target.

[0193] Also, PH b_cfar This may be converted into distance information using equation (27) and output.

[0194] Also, information input from the separation unit 212 (for example, f b_cfar , and the received signal YT after separation processing. z If there are multiple (nt) values, the direction estimation unit 213 may calculate estimated directions of arrival for each of them in the same manner as described above and output the positioning result.

[0195] For example, Nt × Na virtual receiving arrays are spaced equally apart d H When the beamformers are arranged in a straight line, the beamformer method can be expressed as shown in equations (32) and (33). Other methods such as Capon and MUSIC can also be applied in a similar manner.

number

number

[0196] Here, in equation (32), the superscript H is the Hermitian transpose operator. Also, a(θ u ) is the azimuth direction θ u This shows the direction vector of the virtual receiving array for the incoming wave.

[0197] Also, the azimuth direction θ u This is a vector obtained by changing the azimuth range for estimating the direction of arrival by an azimuth interval β1. For example, θ u It will be set as follows: θ u =θmin + uβ1, u=0,…, NU NU = floor[(θmax-θmin) / β1]+1 Here, floor(x) is a function that returns the largest integer value not exceeding the real number x.

[0198] Furthermore, in equation (32), Dcal is the following (Nt × Na) matrix which includes array correction coefficients that correct the phase and amplitude deviations between transmitting and receiving array antennas, and coefficients that reduce the effect of inter-element coupling between antennas. When the coupling between antennas of the virtual receiving array is negligible, Dcal becomes a diagonal matrix, and the diagonal components include array correction coefficients that correct the phase and amplitude deviations between transmitting and receiving array antennas.

[0199] The direction estimation unit 213, for example, provides the distance index f along with the direction estimation result as a positioning result. b_cfar Distance information based on this, and target Doppler velocity information based on the target's Doppler frequency determination result may also be output.

[0200] Note that Doppler frequency information may be converted to a relative velocity component and output. The Doppler frequency index f of the target Doppler frequency determination result. out The relative velocity component v d (f outTo convert to ), the following equation (34) can be used. Here, λ is the wavelength of the carrier frequency of the RF signal output from the transmitting radio unit (not shown). Note that when a frequency-modulated wave (chirp signal) is used as the radar transmission wave, the wavelength of the center frequency may be used as λ.

number

[0201] For example, Figure 9 shows an example of antenna configuration using Configuration Example 1. Figure 9 shows an example of antenna configuration that enables angle measurement in the horizontal direction (for example, the horizontal direction in Figure 9).

[0202] In Figure 9, the transmitting antennas 110 (Tx#1, Tx#2 in the example in Figure 9) that transmit coded Doppler multiplexed signals are arranged horizontally with an antenna spacing of 2DTH, and the receiving antennas 202 (Rx#1, Rx#2, Rx#3 in the example in Figure 9) are arranged horizontally with an antenna spacing of DRH. Here, the antenna spacing 2DTH may be set to a spacing wider than twice the horizontal aperture length of the receiving antennas 202 (2DRH in the case of Figure 9) (in the example in Figure 9, 2DTH = 6DRH > 4DRH).

[0203] Furthermore, in Figure 9, the transmitting antennas 110 that transmit time-division Doppler multiplexed signals (Tx#3, Tx#4 in the example of Figure 9) may be arranged alternately (nested) with the transmitting antennas 110 that transmit coded Doppler multiplexed signals (Tx#1, Tx#2 in the example of Figure 9) with an antenna spacing DTH. Here, the antenna spacing DRH may be set to, for example, half a wavelength (λ / 2).

[0204] With these transmitting and receiving antennas, the arrangement of virtual receiving antennas (VA#1 to VA#12) shown in Figure 9 can be obtained. The virtual receiving antennas VA#1 to VA#12 shown in Figure 9 are arranged horizontally with an antenna spacing of DRH (for example, λ / 2).

[0205] As described above, in this embodiment, the radar device 10 includes, in addition to the transmitting antenna 110 that transmits multiple coded Doppler multiplexed signals, a transmitting antenna 110 that transmits multiple (two or more) time-division Doppler multiplexed signals. For example, the radar device 10 code-multiplexes a Doppler multiplexed signal (transmitting signal) corresponding to a certain Doppler shift amount (e.g., a first Doppler shift amount), and time-multiplexes a Doppler multiplexed signal corresponding to a second Doppler shift amount different from the first Doppler shift amount (e.g., a Doppler shift amount not used for code-multiplexed Doppler multiplexing).

[0206] As a result, the radar device 10 can increase the number of transmitting antennas while reducing the number of Doppler multiplexing operations by using time multiplexing and code multiplexing in combination with Doppler multiplexing transmission. This allows for a wider aperture length in the virtual receiving antenna arrangement, improving angular resolution, suppressing grating lobes during angle measurement, or reducing sidelobe levels, thereby improving the angle measurement performance of the radar device 10 and enhancing radar detection performance.

[0207] Furthermore, the radar device 10 can further reduce the amount of code multiplexing separation processing (for example, the complexity of the code separation processing) by using code multiplexing and time multiplexing in combination. In addition, when using code multiplexing and time multiplexing for Doppler multiplexed signals, the radar device 10 makes the code multiplexed Doppler multiplexed signal (or Doppler shift amount, transmitting antenna 110) and the time multiplexed Doppler multiplexed signal (or Doppler shift amount, transmitting antenna 110) different. This suppresses the disruption of orthogonality between code multiplexed signals due to the switching of the transmitting antenna 110 by time multiplexing, and suppresses the occurrence of mutual interference between multiplexed signals. As a result, the radar device 10 can be properly separated and received in the radar receiving unit 200, and the radar detection performance can be improved.

[0208] (Variation 1) Doppler shift amount DOP ndm Phase rotation amount φ to impart ndm This is not limited to the values ​​shown in equation (1), for example. For example, the phase rotation amount φndm The value shown in equation (35) below may also be the value shown. Here, round(x) is a rounding function that outputs an integer value rounded to the nearest integer for a real number x. Note that round(N code / N DM By introducing the term ), the phase rotation amount can be set to an integer multiple of the Doppler frequency interval in the Doppler analysis unit 210. Also, in equation (35), the angle is expressed in radians.

number

[0209] (Variation 2) In the embodiment of the present disclosure described above, the encoding unit 106 outputs N from the Doppler shift setting unit 105. DM Phase rotation amounts φ1,~,φ that impart individual Doppler shift amounts NDM For each of them, 1 or N CM By applying a phase rotation based on a plurality of orthogonal code sequences of a certain magnitude or less, the encoded Doppler phase rotation amount ψ ndop_code(ndm), ndm (m) is set and output to the phase rotation unit 108. However, the processing of the encoding unit 106 is not limited to this.

[0210] Variation 2 describes the case where the correspondence between the transmitting antenna 110 and the Doppler multiplexed signal is set variably for each transmission cycle.

[0211] For example, the number of Doppler multiplexers used for coded Doppler multiplexing transmission may remain the same, while the allocation of Doppler multiplexing (e.g., Doppler shift amount) to the transmitting antenna 110 may be set variably for each transmission period. For example, the Doppler shift amount used for code multiplexing includes a Doppler shift amount corresponding to the first code element of the code sequence used for code multiplexing, and a Doppler shift amount corresponding to the second code element of the code sequence, and each Doppler shift amount may be different from the others.

[0212] For example, the encoding unit 106 sets the encoded Doppler phase rotation amount using a phase rotation amount that assigns a different Doppler shift amount to each code element of the orthogonal code sequence (for example, each transmission period Tr). For example, the encoding unit 106 assigns the encoded Doppler phase rotation amount ψ to the radar transmission signal transmitted from each transmitting antenna 110. ndop_code(ndm), ndm In (m), for each code element of the orthogonal code sequence (for example, each transmission period Tr), the Doppler shift amount DOP ndm The values ​​of can be different.

[0213] By setting the coding Doppler phase rotation amount in this manner, the same effects as those of the embodiment of the present disclosure described above can be obtained. Furthermore, for example, when receiving a signal under the influence of different interferences (e.g., intersymbol interference) for each transmitting antenna 110, the randomization effect of the interference can be obtained by making the transmitting antenna 110 variable.

[0214] For example, the encoding unit 106 encodes the Doppler phase rotation amount ψ using the following equation (36) instead of equation (6). ndop_CD(ndm), ndm You may also set (m).

number

[0215] The encoded Doppler phase rotation ψ shown in equation (36) ndop_CD(ndm), ndm In (m), the phase rotation amount that imparts the Doppler shift amount is φ during the transmission period of Loc times, which is the code length used for encoding. mod(ndm+OC_INDEX-2,NDM)+1 The transmission period is set variably so that this occurs (term 1 of equation (36)), and the code used for encoding is Code ndop_code(ndm) Each of the Loc code elements OC ndop_CD(ndm) (1), ~, OC ndop_CD(ndm) The phase rotation amount (Loc) is applied (second term of equation (36)). In equation (36), the phase rotation amount φ that applies the Doppler shift amount is mod(ndm+OC_INDEX-2,NDM)+1 This value is set variably for each sign element (e.g., OC_INDEX).

[0216] For example, Nt=4, N DM =2, NCM When = 2, the encoded Doppler phase rotation amount ψ in equation (36) ndop_CD(ndm), ndm This section explains how to set (m).

[0217] In this case, the assignment of Doppler shift amounts DOP1, DOP2 and orthogonal codes Code1, Code2 is, for example, as shown in Figure 10, N DOP_CD (1), N DOP_CD This is determined according to the setting in (2). In Figure 10, the horizontal axis represents the combination of the Doppler shift amount used for the first sign element (e.g., OC_INDEX=1) and the Doppler shift amount used for the second sign element (e.g., OC_INDEX=2).

[0218] As shown in Figure 10, for example, N CM In a code sequence with a code length of =2, the Doppler shift amount corresponding to the first code element and the Doppler shift amount corresponding to the second code element are different. The transmission control unit 109, as in <Setting Example 1>, has an encoding Doppler multiplexing number N. DOP_CD (1) = 1 encoded Doppler phase rotation ψ 1, 1 For a coded Doppler multiplexed signal with (m) assigned to it, time-division multiplexing (for example, time Doppler multiplexing) is performed by switching two transmitting antennas 110 at each transmission period. In this case, since the Doppler shift amount corresponding to the first code element and the Doppler shift amount corresponding to the second code element are different, when time-division multiplexing is performed using two transmitting antennas 110, the Doppler shift amount corresponding to the first transmitting antenna 110 and the Doppler shift amount corresponding to the second transmitting antenna 110 are different.

[0219] Furthermore, the transmission control unit 109 sets the encoding Doppler multiplexing number N DOP_CD (1) = 2 encoded Doppler phase rotation ψ 1, 2 (m), ψ 2, 2 For each encoded Doppler multiplexed signal assigned (m), no control is performed to switch the transmitting antenna 110; instead, each encoded Doppler multiplexed signal is transmitted from a single transmitting antenna 110.

[0220] The following describes the processing operation of the encoding unit 106 using configuration example 3.

[0221] <Setting Example 3> For example, in the encoding unit 106, when equation (36) is used, the number of transmitting antennas used for multiplex transmission Nt = 4, and the number of Doppler multiplexers N DM =2, code multiplex number N CM When we set = 2 and use orthogonal code sequences Code1={1,1} and Code2={1,-1} with code length Loc=2, the number of Doppler multiplexing numbers is N. DOP_CODE (1) = 1, N DOP_CODE The case where (2)=2 (see, for example, Figure 10(b)) will be explained. In this case, the encoding unit 106 has an encoded Doppler phase rotation amount ψ such that the following equations (37)~(39) 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 Set (m) and output it to the phase rotation unit 108.

number

number

number

[0222] Encoded Doppler phase rotation ψ in equations (37)~(39) 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 In each of (m), phase rotation amounts φ1 and φ2 that impart Doppler shift amounts DOP1 and DOP2 are used alternately with a period of code length Loc=2.

[0223] Furthermore, the ψ shown in equations (38) and (39) 1, 2 (m), ψ 2, 2 In (m), the phase rotation amounts φ1 and φ2 that impart the Doppler shift amounts DOP1 and DOP2 are assigned by the orthogonal code sequences Code1 and Code2, respectively, while maintaining a relationship where the phase rotation amounts are the same with a period of code length Loc=2. For example, ψ1, 2 (m), ψ 2, 2 In (m), code multiplexing is performed using multiple orthogonal code sequences by similarly changing the phase rotation amount that imparts the Doppler shift amount over a period of code length Loc.

[0224] Furthermore, the ψ shown in equations (37) and (38) 1, 1 (m) and ψ 1, 2 In (m), the phase rotation amounts φ1 and φ2 that impart the Doppler shift amounts DOP1 and DOP2 are different phase rotation amounts with a period of code length Loc=2. Equations (37) and (39) show ψ 1, 1 (m) and ψ 2, 2 Similarly, in (m), the phase rotation amounts φ1 and φ2 that impart the Doppler shift amounts DOP1 and DOP2 are set to different phase rotation amounts with a period of code length Loc=2.

[0225] Here, for example, the Doppler shift amount DOP ndm The phase rotation amount that imparts this is φ in equation (1). ndm =2π(ndm-1) / N DM The following describes the case where the phase rotation amount φ1=0 is used to impart the Doppler shift amount DOP1, and the phase rotation amount φ2=π is used to impart the Doppler shift amount DOP2. In this case, the encoding unit 106 uses the encoded Doppler phase rotation amount ψ as shown in the following equations (40)~(42). 1, 1 (m), ψ 1, 2 (m), ψ 2, 2 (m) is set and output to the phase rotation unit 108. Here, m = 1, ..., Nc.

number

number

number

[0226] Next, an example of the operation of the radar receiver 200 when the encoded Doppler phase rotation amount is set in the encoding unit 106 described above will be explained. In the radar receiver 200, the separation process in the separation unit 212 differs from the embodiment of the present disclosure described above.

[0227] The separation unit 212 receives the distance index f, which is the output of the CFAR unit 211. b_cfar N DM Doppler frequency index (f) of individual encoded Doppler multiplexed signals s_comp_cfar Separation processing is performed on the output of the Doppler analysis unit 210 in the z-th signal processing unit 206, which is indicated by +(nfd-1)×ΔFD).

[0228] For example, the output of the Doppler analysis unit 210 for a transmitted signal like the one in <Setting Example 3> described above is shown in Figure 11. Here, the distance index f is the output of the CFAR unit 211. b_cfar , Doppler frequency index f s_comp_cfar For example, the output VFT of the Doppler analysis unit 210 (first Doppler analysis unit 210) of the z-th signal processing unit 206. z 1 (f b_cfar、 f s_comp_cfar ), VFT z 1 (f b_cfar、 f s_comp_cfar The upper part of Figure 11 shows the output VFT of the Doppler analysis unit 210 (second Doppler analysis unit 210) of the z-th signal processing unit 206. z 2 (f b_cfar、 f s_comp_cfar ), VFT z 2 (f b_cfar、 f s_comp_cfar The lower part of Figure 11 shows the Doppler frequency component (+ΔFD). The length of the arrows for each Doppler frequency component represents the magnitude of the received power.

[0229] For example, the separation unit 212 outputs the VFT of the Doppler analysis unit 210 of the z-th signal processing unit 206. z 1 (f b_cfar、 f s_comp_cfar ), VFTz 1 (f b_cfar、 f s_comp_cfar +ΔFD) and the output VFT of the Doppler analysis unit 210 of the z-th signal processing unit 206. z 2 (f b_cfar、 f s_comp_cfar ), VFT z 2 (f b_cfar、 f s_comp_cfar By comparing the received power with (+ΔFD), it is possible to distinguish between Doppler multiplexed signals with an encoded Doppler multiplexing number of 2 or more and Doppler multiplexed signals transmitted using time multiplexing.

[0230] For example, as shown in Figure 11, VFT z 1 (f b_cfar、 f s_comp_cfar ) Received power > VFT z 1 (f b_cfar、 f s_comp_cfar The received power is +ΔFD), and the VFT z 2 (f b_cfar、 f s_comp_cfar ) Received power <VFT z 2 (f b_cfar、 f s_comp_cfar This is the received power of +ΔFD). In the case of setting example 3, the phase rotation amounts φ1 and φ2 that impart the Doppler shift amounts DOP1 and DOP2 alternately change with a period of code length Loc=2, so the separation unit 212 is VFT z 1 (f b_cfar、 f s_comp_cfar ) and VFT z 2 (f b_cfar、 f s_comp_cfar +ΔFD) is an encoded Doppler multiplexed signal with an encoded Doppler multiplexing number of 2 or more, and VFT z 1 (f b_cfar、 f s_comp_cfar +ΔFD) and VFT z 2 (f b_cfar、 f s_comp_cfar ) is determined to be a time-Doppler multiplexed signal.

[0231] Since there is a one-to-one correspondence between the switching period of the transmitting antenna 110 and the output of the Doppler analysis unit 210, the separation unit 212 can identify the transmitting antenna 110 from the output of the Doppler analysis unit 210 when the Doppler frequency index, which has been determined to be a time-Doppler multiplexed signal, is time-division multiplexed. For example, in the case of Figure 11, the separated received signal for the first transmitting antenna 110 that was time-Doppler multiplexed is VFT z 1 (f b_cfar、 f s_comp_cfar The value is +ΔFD), and the separated received signal for the second transmitting antenna 110, which was time-doppler multiplexed, is VFT. z 2 (f b_cfar、 f s_comp_cfar Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,1] set in setting example 3 and received by the z-th receiving antenna 202 is VFT z 1 (f b_cfar、 f s_comp_cfar +ΔFD) and Y z It is denoted as (1,1,1). Also, the received signal transmitted from the transmitting antenna Tx#[2,1,1] set in setting example 3 and received by the z-th receiving antenna 202 is VFT z 2 (f b_cfar、 f s_comp_cfar ) and Y z This is denoted as (2,1,1). Here, z=1,~, and Na.

[0232] Furthermore, the separation unit 212 receives the Doppler frequency index, which has been determined to be an encoded Doppler multiplexed signal, by code separation using the code used to encode the encoded Doppler multiplexed signal. For example, the signal from the transmitting antenna 110 encoded by Code1={1,1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar (+ΔFD)×αcorr (f s_comp_cfar The code is decoded and received by +ΔFD). Here, α corr (f s_comp_cfar +ΔFD) is a coefficient that corrects the Doppler phase rotation due to the sampling time difference between the Doppler analysis units 210, and is determined by the Doppler frequency obtained by subtracting the offset due to the Doppler shift amount applied during transmission from the received Doppler frequency, and the sampling time difference between the Doppler analysis units 210 (in this case, Tr) (for an example, see Patent Document 5, so a detailed explanation is omitted). Also, the signal from the transmitting antenna 110 encoded by Code2={1,-1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar +ΔFD)α corr (f s_comp_cfar The code is decoded and received by +ΔFD.

[0233] Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,2] set in Example 3 and received by the z-th receiving antenna 202 is (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar (+ΔFD)×α corr (f s_comp_cfar +ΔFD) and Y z This is denoted as (1,1,2). Also, the received signal transmitted from the transmitting antenna Tx#[1,2,2] set in Example 1 and received by the z-th receiving antenna 202 is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)VFT z 2 (f b_cfar、 f s_comp_cfar +ΔFD)α corr (f s_comp_cfar+ΔFD) and Y z This is denoted as (1,2,2), where z=1,~ and Na.

[0234] (Variation 3) In the embodiment of the present disclosure described above, a case was described in which the radar transmission signal generation unit 101 generates the same chirp signal as a radar transmission signal with a constant transmission period Tr, as shown in the upper part of Figure 2, for example, but the invention is not limited to this.

[0235] For example, as shown in Figure 12, the same chirp signal may be output at different transmission periods. The following describes an operation different from the embodiment of the present disclosure described above. For example, a transmission delay may be set in each of the multiple transmission periods of the time-multiplexed radar transmission signal to change the transmission timing of the radar transmission signal.

[0236] Figure 12 shows an example of a radar transmission signal (for example, a radar transmission wave) output from the radar transmission signal generation unit 101.

[0237] As shown in Figure 12, the radar transmission signal generation unit 101 generates a transmission delay d of the radar transmission signal for each code transmission period (e.g., Loc × Tr) relative to the timing for each transmission period Tr (e.g., called the "reference timing"). t1 d t2 ,~,d tLoc-1 This can be set on a cyclical basis. For example, the radar transmission wave has a transmission delay d for each transmission period Tr. t1 d t2 ,~,d tLoc-1 One of the following will be set. Note that each transmission delay d t1 d t2 ,~,d tLoc-1 Any of these values ​​may be set to 0 (for example, no transmission delay), but at least one transmission delay may contain a value other than 0. A positive transmission delay indicates a delay in time. A negative transmission delay also indicates an advance in time. For example, each transmission delay d t1 d t2 ,~,d tLoc-1The absolute value of can be set to be smaller than Tr, for example, it may be set to around Tr / 2, Tr / 3, or Tr / 4.

[0238] Except for the operation of the radar transmission signal generation unit 101, the operation of the radar transmission unit 100 may be the same as that of the embodiment of the present disclosure described above.

[0239] For each of the above-mentioned code transmission periods (e.g., Loc × Tr), the transmission delay d of the radar transmission signal is calculated. t1 d t2 ,~,d tLoc-1 When the settings are configured cyclically, the operation of the separation unit 212 in the radar receiving unit 200 differs from that of the embodiment of the present disclosure described above. An example of the operation of the separation unit 212 will be described below.

[0240] The separation unit 212 receives 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 Received power information PowerFT(f(nfd-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-1)×ΔFD), nfd=1,~,N DM Based on this, the output of the Doppler analysis unit 210 is used to separate the transmitted signals that have been encoded Doppler multiplexed or time-division Doppler multiplexed, to identify the transmitting antenna 110 and the Doppler frequency, and to associate them with the transmitting antenna Tx#[ndop_TDM(ndm),ndop_CD(ndm), ndm].

[0241] Here, for each code transmission period (e.g., Loc × Tr), the transmission delay d of the radar transmission signal is defined. t1 d t2 ,~,d tLoc-1 When set cyclically, the separation unit 212 can determine the Doppler frequency up to ±1 / (2Tr) of the Doppler frequency range. The following explanation will be based on setting example 1, but it is not limited to this and can be applied similarly under different conditions.

[0242] For example, the output of the Doppler analysis unit 210 for a transmitted signal like the one in <Setting Example 1> described above will be as shown in Figure 7. The separation unit 212 receives power information PowerFT(f b_cfar , f s_comp_cfar ) and received power information PowerFT(f b_cfar , f s_comp_cfar By comparing it with (+ΔFD), it is possible to distinguish between Doppler multiplexed signals with an encoded Doppler multiplexing number of 2 or more and Doppler multiplexed signals transmitted using time multiplexing.

[0243] As described in the embodiment of the present disclosure described above, for example, as shown in Figure 7, the received power information PowerFT(f b_cfar , f s_comp_cfar )>PowerFT(f b_cfar , f s_comp_cfar In the case of +ΔFD), the separation unit 212 is the Doppler frequency index f s_comp_cfar It is determined that this is an encoded Doppler multiplexed signal with an encoding Doppler multiplexing number of 2 or more, and the Doppler frequency index f s_comp_cfar +ΔFD is determined to be a time-Doppler multiplexed signal.

[0244] Here, the separation unit 212 further decodes and receives the Doppler frequency index, which has been determined to be an encoded Doppler multiplexed signal, using the code used to encode the encoded Doppler multiplexed signal. At that time, the separation unit 212 decodes the transmission delay d of the radar transmission signal for each code transmission period (e.g., Loc × Tr). t1 d t2 ,~,d tLoc-1 Sign separation is performed taking into account that the parameters are set cyclically.

[0245] For example, the signal from transmitting antenna 110 encoded by Code1={1,1} is (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (fs_comp_cfar ) is received with code separation. Here, α corr (f s_comp_cfar ) is a coefficient for correcting the Doppler phase rotation due to the sampling time shift between the Doppler analysis units 210, and is the Doppler frequency obtained by removing the offset due to the Doppler shift amount added at the time of transmission from the received Doppler frequency, and the sampling time shift between the Doppler analysis units 210 (in this case, Tr + d t1 ).) and is determined from.

[0246] Here, when there is a Doppler frequency foldover (when the Doppler frequency range of the target exceeds ±1 / {2Tr×(Loc)}), ξ Alias_plus (d t1 ) = 2π×(Tr + d t1 ), or ξ Alias_minus (d t1 ) = -2π×(Tr + d t1 ) / (2Tr) phase rotation is added. For example, (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(+1)×VFT z 2 (f b_cfar、 f s_comp_cfar )×α corr (f s_comp_cfar ) ×exp(-j×ξ Alias_plus (d t1 )) is received with code separation, or (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(+1)×VFT z 2 (f b_cfar、 f s_comp_cfar )×α corr (f s_comp_cfar ) ×exp(-j×ξ Alias_plus (d t1 )) is received with code separation.

[0247] In the case of the above-described embodiment of the present disclosure, d t1 = 0, ξ Alias_plus (0) = π or ξ Alias_minusSince (0) = -π, if there is Doppler frequency aliasing, it becomes difficult to distinguish between the sign elements of Code1={1,1} and Code2={1,-1}, and there is a possibility of misidentification of the sign.

[0248] On the other hand, for each code transmission period (e.g., Loc × Tr), there is a transmission delay d of the radar transmission signal. t1 d t2 ,~,d tLoc-1 When setting it cyclically, for example, d t1 If we set =Tr / 2, then ξ Alias_plus (Tr / 2) = 3π / 2 or ξ Alias_minus (Tr / 2) = -3π / 2. Therefore, for example, the signal from the transmitting antenna 110 encoded by Code1 = {1,1} may be one of the following three code-separated signals, depending on the Doppler frequency range of the target.

[0249] 1) When there is no Doppler frequency aliasing (the target's Doppler frequency range is within ±1 / {2Tr × (Loc)}), (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (f s_comp_cfar ) a signal decoded by 2) When there is aliasing of the Doppler frequency (ξ Alias_plus (In the case of Tr / 2), (+1) × VFT z 1 (f b_cfar、 f s_comp_cfar ) + (+1) × VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (f s_comp_cfar )×exp(-j×ξ Alias_plus A signal decoded by (Tr / 2), or 3) When there is aliasing of the Doppler frequency (ξ Alias_minus (In the case of Tr / 2), (+1) × VFT z1 (f b_cfar、 f s_comp_cfar )+(+1)×VFT z 2 (f b_cfar、 f s_comp_cfar )×α corr (f s_comp_cfar )×exp(-j×ξ Alias_minus (Tr / 2))

[0250] Similarly, for the signal of the transmission antenna 110 encoded by Code2 = {1, -1}, depending on the Doppler frequency range of the target, the following three separated signals can be candidates.

[0251] 1) When there is no Doppler frequency folding (the Doppler frequency range of the target is within the range of ±1 / {2Tr×(Loc)}), (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)×VFT z 2 (f b_cfar、 f s_comp_cfar )×α corr (f s_comp_cfar ) - separated signals 2) When there is Doppler frequency folding (ξ Alias_plus (Tr / 2)), (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)×VFT z 2 (f b_cfar、 f s_comp_cfar )×α corr (f s_comp_cfar )×exp(-j×ξ Alias_plus (Tr / 2)) - separated signals, 3) When there is Doppler frequency folding (ξ Alias_minus (Tr / 2)), (+1)×VFT z 1 (f b_cfar、 f s_comp_cfar )+(-1)×VFT z 2 (f b_cfar、 f s_comp_cfar )×αcorr (f s_comp_cfar )×exp(-j×ξ Alias_minus (Tr / 2)) Sign-separated signal

[0252] Therefore, there are three candidates for the signal to be decoded in cases 1), 2), and 3) of the target's Doppler frequency. The decoder 212 selects the candidate that maximizes the sum of the power of the decoded signals of Code1 and Code2 in each Doppler frequency case, thereby enabling not only decoded signaling but also determination of the Doppler frequency within the Doppler frequency range ±1 / (2Tr).

[0253] Note that transmission delay d t1 As a setting, d t1 Alternatively, we can use =-Tr / 2. In this case, ξ Alias_plus (-Tr / 2) = π / 2 or ξ Alias_minus (-Tr / 2) = -π / 2.

[0254] Also, transmission delay d t1 As a setting, d t1 It is also acceptable to use =Tr / 3. In this case, ξ Alias_plus (Tr / 3) = 4π / 3 or ξ Alias_minus (-Tr / 2) = -4π / 3.

[0255] Also, transmission delay d t1 As a setting, d t1 Alternatively, we can use =-Tr / 3. In this case, ξ Alias_plus (-Tr / 3) = 2π / 3 or ξ Alias_minus (-Tr / 2) = -2π / 3.

[0256] (Variation 4) In the embodiment of the present disclosure described above, the Doppler shift setting unit 105 sets the Doppler shift amount DOP ndm In order to impart a certain phase rotation amount φ ndm The case where the settings are configured and output to the encoding unit 106 has been described, but the method is not limited to this, and Doppler phase rotation may be used in which the Doppler multiplexed signal becomes a signal of multiple Doppler frequencies.

[0257] For example, the radar device 10 may assign multiple Doppler shift amounts used for code multiplexing to each of the transmitting antennas 110 to which the code multiplexed radar transmission signal is transmitted, in one transmission cycle.

[0258] For example, the Doppler shift setting unit 105 sets one Doppler shift amount DOP ndm Instead of assigning two Doppler shift amounts DOP ndm-1 and DOP ndm-2 The resulting phase rotation amount φ ndm (m) may be added. For example, the Doppler shift setting unit 105 rotates the phase Φ for each Tr of the chirp signal. ndm You can also output it with (m)=phseq[mod(m-1,4)+1] appended.

[0259] Here, phseq[ps] represents the ps-th element of phseq=[0, 0, π, π]. For example, phseq[1]=phseq[2]=0 and phseq[3]=phase[4]=π. Also, mod(x,y) is a modulo operation function that represents the remainder when x is divided by y. Note that the Doppler shift setting unit 105 has two Doppler shift amounts DOP ndm-1 and DOP ndm-2 Since a Doppler multiplexed signal with the Doppler shift amount DOP is generated, 2-1 and Doppler shift amount DOP 2-2 The electricity is then divided into two.

[0260] Note that the phase rotation amount φ generates two Doppler multiplexed signals. ndm The examples of setting (m) are not limited to those described above. For example, two Doppler multiplexed signals can also be generated using phseq=[0, π / 2, 0, π / 2], [0, -π / 2, 0, -π / 2], [π, -π / 2,π, -π / 2], or [π, π / 2,π, π / 2].

[0261] The following describes an example of the operation of the Doppler shift setting unit 105 and the encoding unit 106 using setting example 4.

[0262] <Setting Example 4> For example, the number of transmitting antennas used for multiplex transmission is Nt=4, and the number of Doppler multiplexers is N. DM =2, code multiplex number N CM Let = 2. The encoding unit 106 uses orthogonal code sequences Code1={1,1} and Code2={1,-1} with code length Loc=2. Here, the phase rotation amount to which the Doppler shift amount DOP1 is given by φ in equation (1). ndm =2π(ndm-1) / N DM Using this, the phase rotation amount φ1 = 0 for assigning the Doppler shift amount DOP1. In this case, the encoding unit 106 assigns the encoded Doppler phase rotation amount ψ shown in equation (6) to the phase rotation amount φ1 for assigning the first Doppler shift amount DOP1 in the mth transmission period Tr. ndop_CD(ndm), ndm Set (m) and output it to the phase rotation unit 108.

[0263] Furthermore, regarding the Doppler shift amount DOP2, instead of assigning one Doppler shift amount DOP2, two Doppler shift amounts DOP 2-1 and DOP 2-2 The output is obtained by adding a phase rotation Φ2(m) = phseq[mod(floor[(m-1) / Loc]-1,4)+1] which imposes the second Doppler shift amount DOP2. Here, as an example, phseq[ps] is used, where phseq=[0, 0, π, π]. In this case, the encoding unit 106, in the mth transmission period Tr, assigns the second Doppler shift amount DOP2 to the phase rotation amount φ2, and instead of equation (6), it assigns the encoded Doppler phase rotation amount ψ shown in the following equation (43). ndop_CD(ndm), ndm Set (m) and output it to the phase rotation unit 108.

number

[0264] For example, the number of encoded Doppler multiplexers is N DOP_CD (1) = 1, N DOP_CD If (2)=2, the encoding unit 106 has an encoded Doppler phase rotation amount ψ such that equations (44) to (46) 1, 1 (m), ψ 1, 2 (m), ψ2, 2 Set (m) and output it to the phase rotation unit 108.

number

number

number

[0265] Furthermore, as shown in equations (44) to (46), when the phase rotation Φ2(m) is set to phseq[mod(floor[(m-1) / Loc]-1,4)+1], phseq contains four elements, so 4×N CM It changes with a transmission period that equals 8.

[0266] The transmission control unit 109 sets the encoding Doppler multiplexing number to N. DOP_CD (1) = 1 encoded Doppler phase rotation ψ 1, 1 For an encoded Doppler multiplexed signal with (m) assigned to it, time-division multiplexing is performed, for example, by switching between two transmitting antennas 110 at each transmission cycle (e.g., time Doppler multiplexing). The transmission control unit 109 also sets the encoding Doppler multiplexing number N. DOP_CD (2) Encoded Doppler phase rotation ψ such that = 2 1, 2 (m), ψ 2, 2 For each encoded Doppler multiplexed signal assigned (m), no control is performed to switch the transmitting antenna 110; instead, each encoded Doppler multiplexed signal is transmitted from a single transmitting antenna 100.

[0267] As shown in the example setting 4 above, in the Doppler shift setting unit 105, one phase rotation amount φ ndm (m) is the amount of two Doppler shifts DOP ndm-1 and DOP ndm-2 In the case of settings including this, some of the operation of the CFAR unit 211 and the separation unit 212 differs from the embodiment of the present disclosure described above. Examples of the operation of the CFAR unit 211 and the separation unit 212 will be described below.

[0268] 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 ) is output to the separation unit 212.

[0269] As shown in setting example 4, the Doppler shift setting unit 105 sets two Doppler shift amounts DOP by a phase rotation amount φ2(m). 2-1 and DOP 2-2 When making settings that include the Doppler shift amount DOP 2-1 and DOP 2-2 The interval between them is 1 / (2Tr×Loc). Also, the output of the Doppler analysis unit 210 of the reflected wave received signal, where the relative velocity with the target is zero, is as shown in Figure 13. In Figure 13, the Doppler shift amount DOP1 = 0 due to the phase rotation amount φ1, and the Doppler shift amount DOP due to the phase rotation amount φ2 (m) 2-1 = 1 / (4Tr × Loc) and DOP 2-2 = -1 / (4Tr × Loc).

[0270] Therefore, the reflected wave received signal for one target has three DOPs at the output of the Doppler analysis unit 210. 2-2 , DOP1, DOP 2-1 Because it contains Doppler peaks, the CFAR section 211 extracts Doppler peaks that match the Doppler interval.

[0271] For example, in the case of setting example 4, DOP 2-2 , DOP1, DOP 2-1 The Doppler frequency interval is 1 / (4Tr×Loc)=1 / (8Tr), and the Doppler frequency index interval corresponds to ΔFD=Ncode / 4, so it can be considered as an unequal-interval Doppler multiplexed signal containing ΔFD or 2ΔFD. Therefore, the intervals of the Doppler shift amounts in the Doppler frequency domain are unequal, and the unequal intervals are integer multiples of the interval ΔFD of the smallest Doppler shift amount. For this reason, the CFAR unit 211 can be subjected to Doppler domain compression CFAR processing and can perform the same operation as in the embodiment of the present disclosure described above.

[0272] Next, we will describe an example of the operation of the separation unit 212 in the case of setting example 4. In the following, we will describe an example of the processing of the separation unit 212 when Doppler region compression CFAR processing is used in the CFAR unit 211.

[0273] The separation unit 212 operates in the same manner as described in the embodiment of the present disclosure described above, with respect to 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 Received power information PowerFT(f(nfd-1)×ΔFD) b_cfar , f s_comp_cfar +(nfd-1)×ΔFD), nfd=1,~,N DM Based on this, the output of the Doppler analysis unit 210 is used to separate the transmitted signals that have been encoded Doppler multiplexed or time-division Doppler multiplexed, and the transmitting antenna 110 and the Doppler frequency (e.g., Doppler velocity or relative velocity) are determined. In the case of setting example 4, the separation unit 212 is determined by the Doppler shift setting unit 105, which sets two Doppler shift amounts DOP based on the phase rotation amount φ2(m). 2-1 and DOP 2-2 The system performs separation processing that takes into account the setting that includes this feature.

[0274] In the case of setting example 4, each Doppler shift amount DOP ndm The phase rotation amount φ that imparts ndm The same processing as when the intervals are unequal can be applied. As a result, the separation unit 212 can detect the Doppler multiplexed signals with unequal intervals, separate the signals that have been transmitted using encoded Doppler multiplexing or time-division Doppler multiplexing, and determine the transmitting antenna 110 and the Doppler frequency.

[0275] Since there is a one-to-one correspondence between the switching period of the transmitting antenna and the output of the Doppler analysis unit 210, the separation unit 212 can, for example, identify the transmitting antenna from the output of the Doppler analysis unit 210 when a Doppler frequency index determined to be a time-Doppler multiplexed signal is transmitted.

[0276] For example, in the case of the example in Figure 13, the separated received signal for the first transmitting antenna 110 that was transmitted via time Doppler multiplexing is VFT z 1 (f b_cfar、 f s_comp_cfar The value is +ΔFD), and the separated received signal for the second transmitting antenna 110, which was time-doppler multiplexed, is VFT. z 2 (f b_cfar、 f s_comp_cfar (+ΔFD)

[0277] Therefore, the received signal transmitted from the transmitting antenna Tx#[1,1,1] set in setting example 4 and received by the z-th receiving antenna 202 is VFT z 1 (f b_cfar、 f s_comp_cfar +ΔFD) and Y z This is denoted as (1,1,1). Furthermore, the received signal transmitted from the transmitting antenna Tx#[2,1,1] and received by the z-th receiving antenna 202 is VFT. z 2 (f b_cfar、 f s_comp_cfar +ΔFD) and Y z This is written as (2,1,1).

[0278] In addition, in setting example 4, the Doppler shift setting unit 105 sets two Doppler shift amounts DOP by a phase rotation amount φ2(m). 2-1 and DOP 2-2 To configure the settings, the Doppler frequency index determined to be an encoded Doppler multiplexed signal will have two Doppler frequency indices (f s_comp_cfar , and, f s_comp_cfarThis includes +2ΔFD). Therefore, the decoupling unit 212 decodes and receives these encoded Doppler multiplexed signals using the codes used for encoding.

[0279] For example, the signal from transmitting antenna 110 encoded by Code1={1,1} is (+1)×{VFT z 1 (f b_cfar、 f s_comp_cfar )+ VFT z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD)}+(+1)×{VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (f s_comp_cfar )+ VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfar The signal is received with sign separation by (+2ΔFD). Here, the signal that is received with sign separation is the received signal Y transmitted from the transmitting antenna Tx#[1,1,2] and received at the z-th receiving antenna 202. z This corresponds to (1,1,2).

[0280] Also, for example, the signal from transmitting antenna 100 encoded by Code2={1,-1} is (+1)×{VFT z 1 (f b_cfar、 f s_comp_cfar )+ VFT z 1 (f b_cfar、 f s_comp_cfar (+2ΔFD)}+(-1)×{VFT z 2 (f b_cfar、 f s_comp_cfar ) × α corr (f s_comp_cfar )+ VFT z 2 (f b_cfar、 f s_comp_cfar (+2ΔFD)×α corr (f s_comp_cfarThe signal is received with sign separation by (+2ΔFD). Here, the signal that is received with sign separation is the received signal Y transmitted from the transmitting antenna Tx#[1,2,2] and received at the z-th receiving antenna 202. z This corresponds to (1,2,2).

[0281] Furthermore, if the Doppler frequency range of the target exceeds ±1 / {2Tr×(Loc)}, the Doppler frequency range output from the Doppler analysis unit 210 also exceeds ±1 / {2Tr×(Loc)}, and therefore the Doppler frequency of the target is detected by folding. In such cases, the number of encoded Doppler multiplexers is N. DOP_CD (ndm) with code number N CM By using a smaller encoded Doppler multiplexed signal, the Doppler detection range can be expanded to ±1 / {2Tr)}.

[0282] Alternatively, the same operation as in variation 4 can be applied, expanding the Doppler detection range to ±1 / {2Tr)}.

[0283] Note that in Figure 13, if DOP1 corresponds to a time-division Doppler multiplexed signal, DOP 2-2 , DOP 2-1 Because the power is divided in the frequency component of the corresponding Doppler peak, DOP 2-2 , DOP1, DOP 2-1 The received power of the corresponding Doppler peak frequency component will be approximately the same. Also, for example, if DOP1 corresponds to an encoded Doppler multiplexed signal, DOP 2-2 , DOP1, DOP 2-1 The received power of the corresponding Doppler peak frequency components becomes 1:4:1, widening the received power difference, and when the received SNR is low, DOP 2-2 , DOP 2-1 The probability of the corresponding Doppler peak frequency component being undetected increases. Therefore, the two Doppler shift amounts DOP 2-1 and DOP 2-2 When adding this, it is more preferable to use it as an encoded Doppler multiplexed signal.

[0284] (Variation 5) In the embodiment of the present disclosure described above, the output of the phase rotation unit PROT#[ndop_CD(ndm), ndm] is connected to the transmission control unit TxSW#[ndop_CD(ndm), ndm] and transmitted from the transmitting antenna Tx#[ndop_TDM(ndm),ndop_CD(ndm), ndm] is described, but the invention is not limited to this.

[0285] For example, the assignment of coded Doppler multiplexed signals (e.g., combination of Doppler shift amount and code sequence) may be set variably for each radar positioning operation in which the radar transmission signal is sent (e.g., every Nc transmission cycles (Nc × Tr)). For example, the Doppler shift amount in coded Doppler multiplexed signals may be set variably for each frame in which the radar transmission signal is sent. For example, if multiple targets exist within approximately the same distance, it may become difficult to properly separate them if their Doppler frequency intervals match the Doppler shift interval of the Doppler multiplexed signals. In contrast, by varying the Doppler shift amount for each frame, it is possible to avoid the difficulty in properly separating them.

[0286] For example, when radar positioning is performed continuously, the radar device 10 may vary the transmitting antenna 110 that transmits the output of the phase rotation unit PROT#[ndop_CD(ndm), ndm] for each radar positioning (for example, every Nc transmission cycles (Nc × Tr)). For example, when radar positioning is performed continuously, the radar device 10 may vary the transmitting antenna 110 that transmits the output of the transmission control unit TxSW#[ndop_CD(ndm), ndm] for each radar positioning (for example, every Nc transmission cycles (Nc × Tr)). Here, ndm = 1, ~, N DM And ndop_CD(ndm)=1,~, N DOP_CODE (ndm) is the case. Also, if the Doppler multiplexed signal ndm ≠ ndm_TDM, then ndop_TDM(ndm) = 1, and the Doppler multiplexed signal is output from one transmitting antenna 110. On the other hand, if the Doppler multiplexed signal ndm = ndm_TDM, then ndop_TDM(ndm_TDM) = 1, ~, N DOP_TD(ndm_TDM) is used, and the Doppler multiplexed signal is output in time division from multiple transmitting antennas 110.

[0287] The radar device 10 may maintain multiple assignment tables, for example, which assign which of the Nt transmitting antennas #1, ~, #Nt the output of the transmission control unit TxSW#[ndop_CD(ndm), ndm] should be used for transmission. For example, the radar device 10 can variably set the transmitting antenna 110 that transmits for each radar positioning by changing the assignment table for each radar positioning (for example, every Nc transmission cycles (Nc × Tr)).

[0288] Thus, when the radar device 10 performs radar positioning continuously, it sets the corresponding transmitting antenna 110 to be variable for each radar positioning operation by the transmitting control unit. This allows for a randomization effect of interference when the signal is received under different interference conditions (e.g., intersymbol interference) for each transmitting antenna 110, by making the transmitting antenna 110 variable.

[0289] (Variation 6) In the embodiment of the present disclosure described above, the transmitting antenna 110 that transmits the time-division Doppler multiplexed signal transmits fewer times than the transmitting antenna 110 that transmits the encoded Doppler multiplexed signal. Therefore, when signals are transmitted from each transmitting antenna 110 at equal power, the reception quality (e.g., reception SNR) for the time-division Doppler multiplexed signal may be reduced compared to the reception SNR for the encoded Doppler multiplexed signal.

[0290] Since encoded Doppler multiplexed signals can achieve a higher received signal-to-noise ratio (SNR) compared to time-division Doppler multiplexed signals, they may be used, for example, for far-range target detection. In such cases, the transmitting antenna 110 that transmits the encoded Doppler multiplexed signal may be an antenna with narrower horizontal or vertical directivity compared to the transmitting antenna 110 that transmits the time-division Doppler multiplexed signal. This allows the radar device 10 to improve the detection accuracy of far-range targets.

[0291] Furthermore, since coded Doppler multiplexed signals can achieve a higher received SNR compared to time-division Doppler multiplexed signals, they may be used, for example, for target detection with a wide detection range in the horizontal or vertical direction. For example, among a plurality of transmitting antennas 110, the transmitting antenna 110 to which coded multiplexed radar transmission signals are transmitted may be arranged in either the horizontal or vertical direction (for example, a first direction), and the transmitting antenna 110 to which time-multiplexed radar transmission signals are transmitted may be arranged in the other direction (a second direction different from the first direction). In such a case, the transmitting antenna 110 to transmit coded Doppler multiplexed signals may be an antenna with wider horizontal or vertical directivity compared to the transmitting antenna 110 to transmit time-division Doppler multiplexed signals. This allows the radar device 10 to detect objects over a wider range in the horizontal or vertical direction, thereby improving detection accuracy.

[0292] On the other hand, the transmitting antenna 100 that transmits the time-division Doppler multiplexed signal may be positioned, for example, for detecting targets in the height direction at relatively close distances. In such a case, the transmitting antenna 110 that transmits the time-division Doppler multiplexed signal may be an antenna with wider vertical directivity (broader) compared to the transmitting antenna 110 that transmits the encoded Doppler multiplexed signal. This allows the radar device 10 to further expand the height range of detectable targets.

[0293] Figure 14 shows an example of antenna configuration.

[0294] In Figure 14, the transmitting antenna 110 (Tx#1, Tx#2) that transmits the encoded Doppler multiplexed signal is arranged horizontally with an antenna spacing DTH. The receiving antenna 202 (Rx#1, Rx#2, Rx#3) is also arranged horizontally with an antenna spacing DRH. Here, the antenna spacing DTH of the transmitting antenna 110 (Tx#1, Tx#2) that transmits the encoded Doppler multiplexed signal is set to be wider than the aperture length of the receiving antenna 202 (2DRH) (DTH = 3DRH > 2DRH).

[0295] Furthermore, in Figure 14, the transmitting antennas 110 (Tx#3, Tx#4) that transmit time-division Doppler multiplexed signals are positioned at a different vertical position from the transmitting antennas 110 (Tx#1, Tx#2) that transmit encoded Doppler multiplexed signals. For example, in the example of Figure 14, the transmitting antennas (Tx#3, Tx#4) that transmit time-division Doppler multiplexed signals are positioned at a different vertical position from the vertical position where the transmitting antennas 110 (Tx#1, Tx#2) that transmit encoded Doppler multiplexed signals are positioned horizontally, with antenna spacings DTV3 and DTV4, respectively. For example, in the case of Figure 14, DTV3 = DTV4 or DTV3 ≠ DTV4.

[0296] The horizontal positions of the transmitting antennas 110 that transmit time-division Doppler multiplexed signals (Tx#3, Tx#4 in Figure 14) may be the same as or different from the horizontal positions of the transmitting antennas 110 that transmit encoded Doppler multiplexed signals (in Figure 14, Tx#3 and Tx#4 are positioned at different horizontal positions). Also, the horizontal positions between the transmitting antennas 110 that transmit time-division Doppler multiplexed signals (Tx#3, Tx#4 in Figure 14) may be the same or different (in Figure 14, Tx#3 and Tx#4 are at the same horizontal position).

[0297] With such transmitting and receiving antennas, the virtual receiving antenna configuration shown in Figure 15 can be obtained.

[0298] For example, at relatively long distances, the radar device 10 can perform horizontal target angle measurement using virtual receiving antennas VA#1 to VA#6. Also, at relatively short distances, the radar device 10 can perform horizontal and vertical target angle measurement using all virtual receiving antennas VA#1 to VA#12. In this way, by using coded Doppler multiplexed signals and time-division Doppler multiplexed signals, multiplexed transmission using more transmitting antennas 110 becomes possible, and the two-dimensional angle measurement performance in the horizontal and vertical directions can be improved.

[0299] Figure 16 shows another example of antenna configuration.

[0300] In Figure 16, the transmitting antenna 110 (Tx#1, Tx#2) that transmits the encoded Doppler multiplexed signal is arranged horizontally with an antenna spacing DTH. The receiving antenna 202 (Rx#1, Rx#2, Rx#3) is also arranged horizontally with an antenna spacing DRH. Here, the antenna spacing DTH of the transmitting antenna 110 (Tx#1, Tx#2) that transmits the encoded Doppler multiplexed signal is set to be wider than twice the aperture length (2DRH) of the receiving antenna 202 (DTH = 6DRH > 2 × 2DRH).

[0301] Furthermore, in Figure 16, the transmitting antennas 110 (Tx#3, Tx#4) that transmit time-division Doppler multiplexed signals are positioned at a different vertical position from the transmitting antennas 110 (Tx#1, Tx#2) that transmit encoded Doppler multiplexed signals. For example, in the example of Figure 16, the transmitting antennas (Tx#3, Tx#4) that transmit time-division Doppler multiplexed signals are positioned at a different vertical position from the vertical position where the transmitting antennas 110 (Tx#1, Tx#2) that transmit encoded Doppler multiplexed signals are positioned horizontally, with antenna spacings DTV3 and DTV4, respectively. For example, in the case of Figure 16, DTV3 = DTV4 or DTV3 ≠ DTV4.

[0302] The horizontal positions of the transmitting antennas 110 that transmit time-division Doppler multiplexed signals (Tx#3, Tx#4 in Figure 16) may be the same as or different from the horizontal positions of the transmitting antennas 110 that transmit coded Doppler multiplexed signals (in Figure 16, Tx#3 and Tx#4 are positioned at different horizontal positions). Also, the horizontal positions between the transmitting antennas 110 that transmit time-division Doppler multiplexed signals (Tx#3, Tx#4 in Figure 16) may be the same or different (in Figure 16, Tx#3 and Tx#4 are at different horizontal positions).

[0303] Here, the transmitting antenna 110 that transmits the time-division Doppler multiplexed signal may be used not only for the transmission of individual transmitting antennas, but also for the simultaneous transmission of two or more transmitting antennas. For example, in the case of Figure 16, the transmission may be a combination of three: transmission of transmitting antenna Tx#3, transmission of transmitting antenna Tx#4, and simultaneous transmission of transmitting antenna Tx#3 and transmitting antenna Tx#4. When simultaneous transmission of transmitting antenna Tx#3 and transmitting antenna Tx#4 is performed, the midpoint position of the arrangement of transmitting antenna Tx#3 and transmitting antenna Tx#4 becomes the phase center of transmitting antenna Tx#3 and transmitting antenna Tx#4 (indicated by the dotted circle near "Tx#3 & Tx#4" in Figure 16).

[0304] An example of the operation of the time multiplexing unit 107 when using the antenna configuration shown in Figure 16 will be described.

[0305] For example, N DM =2, N CM Let = 4, and as shown in Figure 5, N DOP_CD (1) = 3, N DOP_CD (2) When using 1, the time multiplexing unit 107 uses a Doppler multiplexed signal with an encoding Doppler multiplexing number of 1 (N in Figure 7). DOP_CD (2)) Time multiplexing is performed using this method. For example, transmission may be performed by combining three transmissions (Tx#3, Tx#4, and Tx#3 & Tx#4): transmission by transmitting antenna Tx#3, transmission by transmitting antenna Tx#4, and simultaneous transmission by transmitting antenna Tx#3 and transmitting antenna Tx#4. For example, the time multiplexing unit 107 controls the transmission control unit 109 to sequentially switch between transmission of Tx#3, transmission of Tx#4, and simultaneous transmission of Tx#3 & Tx#4 for each transmission period Tr. As a result, the operation of the transmission control unit 109 causes one of the transmitting antennas Tx#3, Tx#4, or Tx#3 & Tx#4 to switch sequentially for each transmission period Tr of Loc (=4), which is the code transmission period, and a Doppler multiplexed signal is transmitted. In this case, the transmitting antennas may be switched multiple times within the transmission period Loc × Tr.

[0306] For example, at Loc=4, the time multiplexing unit 107 is NDOP_TD When (ndm)=Loc is set, the transmission control unit 109 may be controlled to sequentially switch the four transmitting antennas (for example, Tx#3, Tx#3 & Tx#4, Tx#4, Tx#3 & Tx#4) with each transmission period Tr. As a result, the operation of the transmission control unit 109 causes the transmitting antennas Tx#3, Tx#3 & Tx#4, Tx#4, Tx#3 & Tx#4 to switch sequentially with each period Tr, and a Doppler multiplexed signal is transmitted.

[0307] Alternatively, a transmission period that is not connected to the transmitting antenna 110 may be included. For example, at Loc=4, the time multiplexing unit 107 is N DOP_TD When (ndm)=Loc-1=3 is set, the transmission control unit 109 may be controlled to sequentially switch the three transmitting antennas (for example, Tx#3, Tx#4, Tx#3 & Tx#4) with each transmission period Tr, and to set a no-transmission section in the next transmission period where the transmitting antennas are not connected. As a result, the operation of the transmission control unit 109 causes the transmission from transmitting antennas Tx#3, Tx#4, and Tx#3 & Tx#4, as well as the no-transmission section (Txoff), to be sequentially switched with period Tr for every Loc transmission period Loc × Tr, which is the code transmission period.

[0308] In the example above, we described an example where two transmitting antennas 110 are combined, but this is not the only option. For example, even more transmitting antennas 110 (e.g., three transmitting antennas 110) may be combined for simultaneous transmission.

[0309] In this way, when transmitting by switching between multiple transmitting antennas 110 in a time-division manner, the effect of increasing the number of transmitting antennas can be obtained by including simultaneous transmission of multiple (two or more) transmitting antennas 110 in addition to the transmission of each transmitting antenna 110. As a result, by appropriately arranging the antennas, it is possible to suppress grating lobes or reduce side lobe levels during angle measurement, for example.

[0310] For example, the transmitting and receiving antenna configuration shown in Figure 16 yields the virtual receiving antenna configuration shown in Figure 17.

[0311] In Figure 17, for example, the radar device 10 can perform horizontal target angle measurement using virtual receiving antennas VA#1 to VA#6 and VA#13 to VA#15 at relatively long distances. Also, for example, the radar device 10 can perform horizontal and vertical target angle measurement using all virtual receiving antennas VA#1 to VA#15 at relatively short distances. In this way, by using coded Doppler multiplexed signals and time-division Doppler multiplexed signals, multiplexed transmission using more transmitting antennas 110 becomes possible, and the two-dimensional angle measurement performance in the horizontal and vertical directions can be improved.

[0312] The above describes one embodiment relating to the present disclosure.

[0313] [Other embodiments] 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. Furthermore, 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.

[0314] Furthermore, the numerical values ​​used in one embodiment of this disclosure (for example, the number of transmitting antennas Nt, the number of receiving antennas Na, and the number of Doppler multiplexers N) DM , number of codes N CM , time multiplicity N TD These are just examples and are not limited to those values.

[0315] A radar system according to one embodiment of the present disclosure, although not shown, includes, for example, a CPU (Central Processing Unit), a storage medium such as ROM (Read Only Memory) storing a control program, and working memory such as 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 system is not limited to this example. For example, each functional part of the radar system 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.

[0316] 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.

[0317] 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.

[0318] 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.

[0319] 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.

[0320] 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.

[0321] <Summary of this disclosure> A radar device according to one embodiment of the present disclosure comprises a plurality of transmitting antennas that transmit a transmission signal, and a transmitting circuit that multiplexes the transmission signal from the plurality of transmitting antennas by applying a phase rotation amount corresponding to a Doppler shift amount to the transmission signal, wherein the transmitting circuit code multiplexes the transmission signal corresponding to a first Doppler shift amount and time multiplexes the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount.

[0322] In a radar device according to one embodiment of the present disclosure, the first Doppler shift amount includes a third Doppler shift amount corresponding to a first code element of the code sequence used for code multiplexing, and a fourth Doppler shift amount corresponding to a second code element of the code sequence, wherein the third Doppler shift amount and the fourth Doppler shift amount are different from each other.

[0323] In a radar device according to one embodiment of the present disclosure, the second Doppler shift amount includes a fifth Doppler shift amount corresponding to a first transmission signal used for time multiplexing, and a sixth Doppler shift amount corresponding to a second transmission signal used for time multiplexing, wherein the fifth Doppler shift amount and the sixth Doppler shift amount are different from each other.

[0324] In a radar device according to one embodiment of the present disclosure, the transmission circuit sets a transmission delay that changes the transmission timing of the transmission signal in each of the multiple transmission cycles of the time-multiplexed transmission signal.

[0325] In a radar device according to one embodiment of the present disclosure, the transmitting circuit assigns a plurality of first Doppler shift amounts to each of the transmitting antennas among the plurality of transmitting antennas to which the code-multiplexed transmission signal is transmitted, in one transmission cycle.

[0326] In a radar device according to one embodiment of the present disclosure, the transmission circuit sets the first Doppler shift amount to be variable for each frame in which the transmission signal is transmitted.

[0327] In a radar device according to one embodiment of the present disclosure, among the plurality of transmitting antennas, the first transmitting antenna to which the code-multiplexed transmission signal is transmitted is arranged in a first direction, and among the plurality of transmitting antennas, the second transmitting antenna to which the time-multiplexed transmission signal is transmitted is arranged in a second direction different from the first direction.

[0328] In a radar device according to one embodiment of the present disclosure, the first direction is horizontal, and the second direction is vertical.

[0329] In a radar device according to one embodiment of the present disclosure, the transmission circuit simultaneously transmits the time-multiplexed transmission signal from a plurality of second transmitting antennas.

[0330] A radar device according to one embodiment of the present disclosure further comprises a plurality of receiving antennas that receive a reflected wave signal obtained by reflecting the transmitted signal off a target, and a receiving circuit that determines aliasing in the Doppler frequency domain of the reflected wave signal based on a code sequence different from the code sequence used for code multiplexing.

[0331] A radar signal generation device according to one embodiment of the present disclosure comprises a signal generation circuit that generates a transmission signal, and a multiplexing circuit that multiplexes the transmission signal via a plurality of transmitting antennas by applying a phase rotation amount corresponding to a Doppler shift amount to the transmission signal, wherein the multiplexing circuit code multiplexes the transmission signal corresponding to a first Doppler shift amount and time multiplexes the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount.

[0332] In a radar signal generation device according to one embodiment of the present disclosure, the first Doppler shift amount includes a third Doppler shift amount corresponding to a first code element of the code sequence used for code multiplexing, and a fourth Doppler shift amount corresponding to a second code element of the code sequence, wherein the third Doppler shift amount and the fourth Doppler shift amount are different from each other.

[0333] In a radar signal generation device according to one embodiment of the present disclosure, the second Doppler shift amount includes a fifth Doppler shift amount corresponding to a first transmission signal used for time multiplexing, and a sixth Doppler shift amount corresponding to a second transmission signal used for time multiplexing, wherein the fifth Doppler shift amount and the sixth Doppler shift amount are different from each other.

[0334] In a radar signal generation device according to one embodiment of the present disclosure, the multiplexing circuit sets a transmission delay that changes the transmission timing of the transmission signal in each of the multiple transmission cycles of the time-multiplexed transmission signal.

[0335] In a radar signal generation device according to one embodiment of the present disclosure, the multiplexing circuit assigns a plurality of first Doppler shift amounts to each of the plurality of transmitting antennas from which the code-multiplexed transmission signal is transmitted in one transmission cycle.

[0336] In a radar signal generation method according to one embodiment of the present disclosure, a transmission signal is generated, the transmission signal is multiplexed by applying a phase rotation amount corresponding to a Doppler shift amount to the transmission signal, the transmission signal corresponding to a first Doppler shift amount is code-multiplexed, and the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount is time-multiplexed.

[0337] In a radar signal generation method according to one embodiment of the present disclosure, the first Doppler shift amount includes a third Doppler shift amount corresponding to a first code element of the code sequence used for code multiplexing, and a fourth Doppler shift amount corresponding to a second code element of the code sequence, wherein the third Doppler shift amount and the fourth Doppler shift amount are different from each other.

[0338] In a radar signal generation method according to one embodiment of the present disclosure, the second Doppler shift amount includes a fifth Doppler shift amount corresponding to a first transmission signal used for time multiplexing, and a sixth Doppler shift amount corresponding to a second transmission signal used for time multiplexing, wherein the fifth Doppler shift amount and the sixth Doppler shift amount are different from each other.

[0339] In a radar signal generation method according to one embodiment of the present disclosure, a transmission delay is set in each of the multiple transmission cycles of the time-multiplexed transmission signal to change the transmission timing of the transmission signal.

[0340] In a radar signal generation method according to one embodiment of the present disclosure, a plurality of first Doppler shift amounts are assigned to each of the plurality of transmitting antennas to which the code-multiplexed transmission signal is transmitted, in one transmission cycle. [Industrial applicability]

[0341] This disclosure is suitable as a radar device for detecting a wide-angle range. [Explanation of Symbols]

[0342] 10 Radar equipment 100 Radar Transmitter 101 Radar transmission signal generation unit 102 Modulated signal generation unit 103 VCO 104 Phase rotation amount setting unit 105 Doppler Shift Setting Section 106 Encoding section 107 Time multiplex section 108 Phase rotation section 109 Transmission Control Unit 110 Transmitting Antenna 200 Radar Receiver 201 Antenna System Processing Unit 202 Receiving Antenna 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 Separation section 213 Direction estimation part

Claims

1. Multiple transmitting antennas that transmit a transmission signal, A transmission circuit that multiplexes the transmission signal from the multiple transmitting antennas by applying a phase rotation amount corresponding to the Doppler shift amount to the transmission signal, It is equipped with, The transmission circuit code-multiplexes the transmission signal corresponding to a first Doppler shift amount, and time-multiplexes the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount. Radar device.

2. The first Doppler shift amount includes a third Doppler shift amount corresponding to the first code element of the code sequence used for code multiplexing, and a fourth Doppler shift amount corresponding to the second code element of the code sequence, wherein the third Doppler shift amount and the fourth Doppler shift amount are different from each other. The radar device according to claim 1.

3. The second Doppler shift amount includes a fifth Doppler shift amount corresponding to the first transmission signal used for time multiplexing, and a sixth Doppler shift amount corresponding to the second transmission signal used for time multiplexing, wherein the fifth Doppler shift amount and the sixth Doppler shift amount are different from each other. The radar device according to claim 1.

4. The transmission circuit sets a transmission delay in each of the multiple transmission cycles of the time-multiplexed transmission signal to change the transmission timing of the transmission signal. The radar device according to claim 1.

5. The transmitting circuit assigns a plurality of the first Doppler shift amounts to each of the transmitting antennas among the plurality of transmitting antennas to which the code-multiplexed transmission signal is transmitted, in one transmission cycle. The radar device according to claim 1.

6. The transmission circuit sets the first Doppler shift amount variably for each frame in which the transmission signal is transmitted. The radar device according to claim 1.

7. Of the plurality of transmitting antennas, the first transmitting antenna on which the code-multiplexed transmission signal is transmitted is arranged in a first direction. Of the plurality of transmitting antennas, the second transmitting antenna on which the time-multiplexed transmission signal is transmitted is arranged in a second direction different from the first direction. The radar device according to claim 1.

8. The first direction is horizontal, and the second direction is vertical. The radar device according to claim 7.

9. The transmission circuit simultaneously transmits the time-multiplexed transmission signal from a plurality of second transmitting antennas. The radar device according to claim 7.

10. Multiple receiving antennas that receive the reflected wave signal of the transmitted signal reflected from the target, The system further comprises a receiving circuit that determines aliasing in the Doppler frequency domain of the reflected wave signal based on a code sequence different from the code sequence used for the code multiplexing, The radar device according to claim 1.

11. A signal generation circuit that generates a transmission signal, A multiplexing circuit that multiplexes the transmitted signal via multiple transmitting antennas by applying a phase rotation amount corresponding to the Doppler shift amount to the transmitted signal, It is equipped with, The multiplexer circuit code-multiplexes the transmission signal corresponding to a first Doppler shift amount and time-multiplexes the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount. Radar signal generator.

12. The first Doppler shift amount includes a third Doppler shift amount corresponding to the first code element of the code sequence used for code multiplexing, and a fourth Doppler shift amount corresponding to the second code element of the code sequence, wherein the third Doppler shift amount and the fourth Doppler shift amount are different from each other. The radar signal generating device according to claim 11.

13. The second Doppler shift amount includes a fifth Doppler shift amount corresponding to the first transmission signal used for time multiplexing, and a sixth Doppler shift amount corresponding to the second transmission signal used for time multiplexing, wherein the fifth Doppler shift amount and the sixth Doppler shift amount are different from each other. The radar signal generating device according to claim 11.

14. The multiplexer sets a transmission delay in each of the multiple transmission cycles of the time-multiplexed transmission signal to change the transmission timing of the transmission signal. The radar signal generating device according to claim 11.

15. The multiplexing circuit assigns a plurality of first Doppler shift amounts to each of the plurality of transmitting antennas from which the code-multiplexed transmission signal is transmitted, in one transmission cycle. The radar signal generating device according to claim 11.

16. Generate a transmission signal, By applying a phase rotation amount corresponding to the Doppler shift amount to the transmitted signal, the transmitted signal is multiplexed. The transmission signal corresponding to a first Doppler shift amount is code-multiplexed, and the transmission signal corresponding to a second Doppler shift amount different from the first Doppler shift amount is time-multiplexed. Radar signal generation method.

17. The first Doppler shift amount includes a third Doppler shift amount corresponding to the first code element of the code sequence used for code multiplexing, and a fourth Doppler shift amount corresponding to the second code element of the code sequence, wherein the third Doppler shift amount and the fourth Doppler shift amount are different from each other. The radar signal generation method according to claim 16.

18. The second Doppler shift amount includes a fifth Doppler shift amount corresponding to the first transmission signal used for time multiplexing, and a sixth Doppler shift amount corresponding to the second transmission signal used for time multiplexing, wherein the fifth Doppler shift amount and the sixth Doppler shift amount are different from each other. The radar signal generation method according to claim 16.

19. In each of the multiple transmission cycles of the time-multiplexed transmission signal, a transmission delay is set to change the transmission timing of the transmission signal. The radar signal generation method according to claim 16.

20. Among the multiple transmitting antennas, a plurality of the first Doppler shift amounts are assigned to each of the multiple transmitting antennas to which the code-multiplexed transmission signal is transmitted, in one transmission cycle. The radar signal generation method according to claim 16.

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