RADAR DEVICE, METHOD FOR TRANSMITTING RADAR SIGNALS AND METHOD FOR RECEIVING RADAR SIGNALS

Abstract

This radar device includes: a plurality of transmission antennas including a first transmission antenna transmitting a first polarized wave and a second transmission antenna transmitting a second polarized wave different from the first polarized wave; and a transmission circuit that multiplexes transmission signals with a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence from the plurality of transmission antennas. Combinations in which at least one of the Doppler shift amount and the code sequence differs are respectively assigned to the plurality of transmission antennas, and a first pattern of the Doppler shift amount and the code sequence assigned to a first transmission antenna differs from a second pattern of the Doppler shift amount and the code sequence assigned to a second transmission antenna.

Description

Technical area

[0001] The present disclosure relates to a radar device, a method for transmitting a radar signal, and a method for receiving a radar signal. General state of the art

[0002] Recently, a study has been conducted on radar devices using a short-wavelength radar transmission signal, including a microwave or millimeter wave, which can achieve high resolution. Furthermore, a radar device has been proposed, for example, in which, in addition to a receiver, a transmitter with a plurality of antennas (array antenna) is provided and which is configured to perform beam scanning by signal processing using the transmitting and receiving array antennas (which may also be referred to as a multiple-input multiple-output (MIMO) radar). List of citationsPatent literature PTL 1 US Patent Application Publication No. US 2019 / 0064337 A1 PTL 2 US Patent Application Publication No. US 2020 / 0363497 A1 PTL 3 Unexamined Japanese Patent Application Publication No. JP 2008-304417 A PTL 4 Unexamined Japanese Patent Application Publication (Translation of PCT Application) No. JP 2011-526371 A PTL 5 Unexamined Japanese Patent Application Publication No. JP 2011-119344 A PTL 6 Japanese Patent Application, Examined Publication No. JP 2020-204603 A PTL 7 Japanese Patent Application, Laid-Open No. JP 2020-092247 A PTL 8 Japanese Patent Application, Examined Publication No. JP 2020-148754 A Non-patent literature Non-patent literature 1 J. Li and P. Stoica, “MIMO Radar with Colocated Antennas,” Signal Processing Magazine, IEEE Vol. 24, and Issue: 5, pp. 106-114, 2007 Non-patent literature 2 M. Kronauge, H. Rohling, “Fast two-dimensional CFAR procedure”, IEEE Trans. Aerosp. Electron. Syst., 2013, 49, (3), pp. 1817-1823 Non-patent literature 3 Direction-of-arrival estimation using signal subspace modeling Cadzow, JA; Aerospace and Electronic Systems, IEEE Transactions, Volume: 28, Issue: 1, published in: 1992, Page(s): 64 to 79 Brief description of the invention

[0003] However, methods for a radar device (e.g., MIMO radar) to detect a target object (or a target) have not been comprehensively investigated so far.

[0004] A non-limiting embodiment of the present disclosure contributes to providing a radar device that improves the detection accuracy of a target object, a method for transmitting a radar signal, and a method for receiving a radar signal.

[0005] A radar device according to an embodiment of the present disclosure comprises: a plurality of transmission antennas including a first transmission antenna for transmitting a first polarized wave and a second transmission antenna for transmitting a second polarized wave different from the first polarized wave;and a transmission circuit operative to multiplex, from the plurality of transmission antennas, a transmission signal to which a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence is applied, wherein the combination in which at least one of the Doppler shift amount and the code sequence is different is assigned to each of the plurality of transmission antennas, and a first pattern of the Doppler shift amount and the code sequence assigned to the first transmission antenna and a second pattern of the Doppler shift amount and the code sequence assigned to the second transmission antenna are different from each other.

[0006] Note that these generic or specific example embodiments may be achieved by a system, apparatus, method, integrated circuit, computer program, or recording medium, and also by a combination of the system, apparatus, method, integrated circuit, computer program, and recording medium.

[0007] According to an exemplary embodiment of the present disclosure, the accuracy of target object detection of a radar device can be improved.

[0008] Further advantages and benefits of the disclosed embodiments will become apparent from the description and the drawings. The advantages and / or benefits may be achieved individually by the various embodiments and features of the description and drawings, although not all of them need be provided to achieve one or more of these advantages and / or benefits. Short description of the drawings Fig. 1 illustrates an exemplary coded Doppler multiplex transmission; Fig. Figure 2 illustrates an example of a received signal in a coded Doppler multiplex transmission; Fig. Figure 3 illustrates an exemplary coded Doppler multiplex transmission; Fig. 4 is a block diagram illustrating an exemplary configuration of a radar device; Fig. 5 illustrates an example of a transmission signal for a case where a chirp signal is used; Fig. 6 illustrates a configuration example of a Doppler shift amount and a code sequence; Fig. 7 shows a configuration example of the coded Doppler phase rotation amount; Fig. Figure 8 illustrates an example of a received signal in a coded Doppler multiplex transmission; Fig. 9 shows a configuration example of the coded Doppler phase rotation amount; Fig. 10 illustrates an example of a received signal in a coded Doppler multiplex transmission; Fig. 11 shows a configuration example of the coded Doppler phase rotation amount; Fig. 12 illustrates an example of a received signal in a coded Doppler multiplex transmission; Fig. 13 shows a configuration example of the coded Doppler phase rotation amount; Fig. 14 is a flowchart illustrating an exemplary operation of demultiplexing a coded Doppler multiplexed signal; Fig. 15 is a block diagram illustrating an exemplary configuration of a radar receiver; Fig. 16 illustrates a configuration example of the coded Doppler phase rotation amount; and Fig. Figure 17 illustrates an example of a received signal in a coded Doppler multiplex transmission. Description of embodiments[Polarimetric radar]

[0009] There are techniques for improving radar detection or identification performance, for example, by using an antenna that emits differently polarized radio waves or an antenna that receives differently polarized radio waves (see, for example, PTL 1 or 2). A radar device using a plurality of polarized waves is also called a "polarimetric radar."

[0010] For example, PTL 1 or PTL 2 discloses a method for detecting and identifying an object by transmitting a transmission signal through an antenna using vertically polarized waves or horizontally polarized waves and using a signal received by an antenna using vertically polarized waves or horizontally polarized waves. For example, PTL 1 discloses a method for detecting and identifying an object by transmitting a transmission signal through an antenna using left-hand circularly polarized waves or right-hand circularly polarized waves and using a signal received by an antenna using left-hand circularly polarized waves or right-hand circularly polarized waves. It should be noted that an antenna using polarized waves, such aslinearly polarized waves, including linearly polarized waves or horizontally polarized waves, or circularly polarized waves, including left-hand circularly polarized waves or right-hand circularly polarized waves, can also be called a "polarized antenna".

[0011] Such polarimetric radars use a variety of different types of polarized antennas (e.g., polarized transmitting antennas or polarized receiving antennas).

[0012] The following describes the multiplex transmission method in a MIMO radar using a plurality of different types of polarized antennas (e.g. referred to as “polarimetric MIMO radar”).

[0013] For example, as an example of a multiplex transmission method for a MIMO radar with a plurality of transmitting antennas, transmission by time division multiplexing (TDM) (see, for example, PTLs 3 and 4) or transmission by Doppler division multiplexing (DDM) (see, for example, PTL 5) is known.

[0014] The aforementioned time-division multiplexing or Doppler multiplexing can separate the reflected waves corresponding to the transmission signals from a plurality of transmission antennas using the allocated transmission time or Doppler frequency domain. However, with time-division multiplexing and Doppler multiplexing, the detection range of Doppler frequencies is likely to narrow as the number of transmission antennas increases. For example, with time-division multiplexing and Doppler multiplexing, the Doppler frequency range in which detection can be successful is -1 / (2Nt x Tr) - f d< 1 / (2Nt x Tr), and the Doppler frequency detection range narrows inversely proportional to the number of transmitting antennas. Here, Nt is the number of transmitting antennas and Tr is the transmission period of a transmitted signal. [Coded Doppler multiplex transmission]

[0015] The PTL 6 (e.g. Fig. 1 of PTL 6) discloses a multiplex transmission method in which Doppler multiplexing and code division multiplexing are combined (hereinafter referred to as “coded Doppler multiplex transmission” or “coded DDM transmission (abbreviated to CDDM transmission)”).

[0016] For example, Fig. 1 a case where a radar transmission wave (e.g., a chirp signal) is transmitted in each transmission period Tr. Fig. Figure 1 illustrates an example of the assignment of Doppler transmission frequencies and codes in a case where signals code-multiplexed with orthogonal codes (e.g., Code #1, Code #2) with a code length Loc = 2 are transmitted over three transmit antennas (e.g., Tx #1 to Tx #3) using two DDM (Doppler Multiplexing) signals (e.g., DOP1, DOP2). In the example of Fig. 1 is the number N CM of code multiplexing = 2 and is the number N DM of Doppler multiplexing = 2.

[0017] The phase rotation based on the codes is achieved, for example, by cyclically repeating the operation of applying the phase rotation to a chirp signal in the transmission periods Loc × Tr (in Fig. 1, two transmission periods (2Tr)), the number of times according to the code length. At this time, the phase rotation is performed based on the DDM signals in the code length times of the transmission periods Loc (in Fig. 1, two transmission periods (2Tr)) for the application of codes with a code length of Loc constant. For example, the phase shift can be varied based on the DDM signals and applied for each 2Tr transmission period.

[0018] For example in Fig. 1, the Doppler transmission shift amounts to be assigned are set to DOP1 = 0 and DOP2 = -1 / (4Tr) [Hz]. For example, since DOP1 is applied every m-th transmission period, the phase rotation ϕ1(m) = Δϕ1 × (floor(m / Loc) + 1) is applied to the radar transmission wave (chirp signal). Since DOP2 is applied every m-th transmission period, the phase rotation ϕ2(m) = Δϕ2 × (floor(m / Loc) + 1) is applied to the radar transmission wave. Here, Δϕ1 = 0 and Δϕ2 = -π. The Doppler multiplexing interval is Δf d = 1 / (4Tr). Furthermore, orthogonal codes with a code length of 2 can be used, such as Code1 = [1, 1] and Code2 = [1, -1]. In Fig. For example, DopCode #1 = (DOP2, Code1), DopCode #2 = (DOP2, Code2), and DopCode #3 = (DOP1, Code1) are assigned to Tx #1 through Tx #3, respectively, and transmitted as coded Doppler-multiplexed (CDDM) signals, which combine Doppler-multiplexed signals and codes. Note that floor[x] is a function that returns the largest integer not greater than the real number x.

[0019] Here DopCode #n represents the assignment of a CDDM signal for n-th Tx #n (assignment with Doppler shift amount DOP ndm and code code ncm ). The character “n” is 1 to Nt, “ndm” is an integer value in the range 1 to N DM and “ncm” is an integer value in the range 1 to N CM For Nt transmitting antennas, a CDDM signal of a different combination of DOP ndm and code ncm assigned.

[0020] These signals, which are simultaneously multiplexed, are received by a radar device (e.g., a received signal processor). In the radar device, for example, Doppler frequency analysis is performed on a radar reflected wave received signal on a single Doppler analyzer (e.g., V-FFT #1, #2, ... #Loc) for each received signal for each element of the code to be transmitted. The multiplexed transmitted signal is demultiplexed and received by performing code demultiplexing and Doppler demultiplexing based on the Doppler frequency analysis output.In an exemplary case where the code length Loc = 2, the number of elements of the code is 2, and the radar device demultiplexes and receives the multiplexed transmission signal by code demultiplexing and Doppler demultiplexing of reception signals based on the output of the Doppler frequency analysis performed for each odd-numbered transmission signal and each even-numbered transmission signal in a single FT-Doppler analyzer (V-FET #1, #2).

[0021] Since the radar device (e.g. the Doppler analyzer) uses received signals with Loc times (code length) of the transmission periods (in Fig. 1, Fig. 2 transmission periods (2Tr) since Loc = 2), a Doppler frequency greater than ±1 / (2 Loc Tr) (±1 / (4Tr) in Fig. 1) as having aliasing. Whether the received signal of a radar reflected wave contains a component in the frequency range of aliasing can be detected, for example, by multiplexing transmission from a plurality of transmitting antennas with an odd number of code division multiplexes between the DDM signals, as disclosed in PTL 6. Thus, the radar device can expand the Doppler frequency range (maximum Doppler) in which Doppler frequency detection is possible without aliasing to ±1 / (2Tr) and can also determine the transmitting antenna.

[0022] For example in Fig. 1 is the number of code multiplexing for the Doppler shift amount DOP1 is 1, the number of code multiplexing for DOP2 is 2, and the number of code multiplexing between the DDM signals is configured as odd. By using a CDDM signal (DopCode = (DOP1, Code2) in Fig. 1) with respect to which no transmitting antenna is assigned and which is a combination of an unused code and a Doppler signal, the radar device detects, from the demultiplexed received signals for the multiplexed transmitted signals, whether a received signal of a radar reflected wave contains a component in a frequency range of aliasing (hereinafter, the detection is also referred to as "aliasing determination").

[0023] For example, (a) of Fig. 2 the Doppler reception signal in a case where the target object Doppler frequency f dtg 0 and the CDDM signal in Fig. 1 is demultiplexed with each Code1 and Code2. In the DDM reception signal demultiplexed by Code1, the reception levels at two Doppler frequencies of a Doppler frequency interval corresponding to the Doppler multiplex interval Δf dbetween DOP1 and DOP2 is detected as high, and the radar device can determine these components as received signals from Tx #1 and Tx #3. Furthermore, in the Doppler received signal demultiplexed by Code2, a Doppler frequency with a high received level is detected at Doppler received frequency f d = -1 / 4Tr). It should be noted that the reception level of the Doppler frequency (Doppler reception frequency f d = 0) in the Doppler frequency interval corresponding to the Doppler multiplex interval Δf d between DOP1 and DOP2 for the detected Doppler frequency, approximately corresponds to the noise level.

[0024] For this reason, the radar device under (a) of Fig. 2, determine that the Doppler frequency component with a high reception level detected in the Doppler reception signal demultiplexed by Code2 is the reception signal of Tx #2. Furthermore, the radar device can determine the Doppler frequency of the target object because the amount of deviation from the Doppler shift amount at the time of transmission for each transmitting antenna is the Doppler frequency of the target object.

[0025] For example, under (b) in Fig. Figure 2 illustrates the received Doppler signal in a case where the CDDM signal from Fig. 1 was demultiplexed with each of Code1 and Code2 when the Doppler frequency f dtg = -1 / (2Tr) of the target object. In the Doppler reception signal demultiplexed by Code2, the reception levels at two Doppler frequencies of a Doppler frequency interval corresponding to the Doppler multiplex interval Δf dbetween DOP1 and DOP2 is detected as high, and the radar device can determine these components as the received signals of Tx #1 and Tx #3. In addition, a Doppler frequency with a high reception level is detected in the Doppler reception signal demultiplexed by Code1. It should be noted that the reception level of the Doppler frequency (Doppler reception frequency f d = 0) in the Doppler frequency interval corresponding to the Doppler multiplex interval Δf d between DOP1 and DOP2 for the detected Doppler frequency, approximately corresponds to the noise level.

[0026] For this reason, the radar device under (b) may Fig. 2, determine that the Doppler frequency component with a high reception level detected in the Doppler reception signal demultiplexed by Code 1 is the reception signal of Tx #2. Furthermore, the radar device can determine the Doppler frequency of the target object because a deviation amount from the Doppler shift amount at the time of transmission for each transmitting antenna is the Doppler frequency of the target object.

[0027] It is noted that in a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg< 1 / (2Tr), the Doppler analyzers (e.g., V-FFT #1 and V-FFT #2) observe a Doppler frequency with aliasing. The actual Doppler frequency is determined by adding a π phase rotation to the Doppler frequency detected in the Doppler analyzers (V-FFT #1 and V-FFT #2) in the case of a detection time difference Tr between V-FFT #1 and V-FFT #2 due to a 2π phase difference between the transmission periods of 2Tr. Accordingly, in the case of the code length Loc = 2, the radar device can determine that Doppler frequency aliasing exists when a received signal corresponding to Code2 is determined upon demultiplexing Code1, as in b) of Fig. 2 illustrates.

[0028] Through the demultiplexed reception processing of the CDDM signal described above, the radar device can estimate the Doppler frequency of the radar reflected wave in the Doppler frequency range of ±1 / (2Tr). As described above, CDDM transmission expands the Doppler frequency range in which detection can be successful to ±1 / 2Tr. For example, the Doppler frequency range in which detection can be successful is expanded by Nt times compared to PTL 5. [Application of coded Doppler division multiplexing (CDDM) transmission to polarimetric MIMO radar]

[0029] As described above, in a MIMO radar using coded Doppler multiplexing, for example, demultiplexing a CDDM signal (hereinafter referred to as “coded Doppler demultiplexing” or “CDDM demultiplexing”) is performed to estimate the Doppler frequency of a target object based on the received power at the Doppler reception frequency after code demultiplexing the reflected wave from the target object.

[0030] For this reason, the following can be assumed when applying CDDM to a polarimetric MIMO radar.

[0031] For example, in polarimetric MIMO radar, the reception level of reflected waves can vary significantly depending on the polarization of the transmitting and receiving antennas. In polarimetric MIMO radar, when transmitting antennas of different polarizations are used, the reception level of reflected waves from a transmitting antenna with one polarization can be significantly attenuated compared to that from a transmitting antenna with a different polarization. Therefore, in polarimetric MIMO radar, when multiplexing with CDDM, the difference (or ratio) in the reception levels of reflected waves between transmitting antennas with different polarizations can become large, making CDDM demultiplexing difficult.If CDDM demultiplexing is made difficult, the target detection performance in a MIMO radar may degrade or CDDM demultiplexing may be faulty, which may result in incorrect Doppler estimation or degradation of angle measurement performance.

[0032] The following describes an example where CDDM demultiplexing is difficult in a polarimetric MIMO radar that applies CDDM.

[0033] Here, the exemplary case of a MIMO radar configuration with two transmit antennas for each of both left-circular polarization (hereinafter also referred to as "LC") and right-circular polarization (hereinafter also referred to as "RC") (designated as LC-2Tx and RC-2Tx, respectively) is described (e.g., with a total of Nt = 4 transmit antennas). For example, the polarization antenna corresponding to left-circular polarization is referred to as the "LC polarization antenna" (e.g., LC-polarized transmit antenna or LC-polarized receive antenna), and the polarization antenna corresponding to right-circular polarization is referred to as the "RC polarization antenna" (e.g., RC-polarized transmit antenna or RC-polarized receive antenna).

[0034] For example, the case where the MIMO radar receives a single-reflection wave (a reflected wave that is reflected once off a target object) using an LC-polarized receiving antenna is described. The reflected wave signal corresponding to the transmission signal from the RC-polarized transmitting antenna (e.g., also called "reception signal corresponding to the RC-polarized transmitting antenna") is a reception signal as an RC-polarized wave, and when the reception signal corresponding to the RC-polarized transmitting antenna is received by the LC-polarized receiving antenna, the reception is cross-polarized reception. For this reason, the reception levels of the reception signals corresponding to the RC-polarized transmitting antennas are lower at the LC-polarized receiving antenna (e.g.,By 10 dB or more, depending on the difference in the antenna's cross-polarization, the reception levels of the reflected wave signals corresponding to the transmission signals from the LC-polarized transmit antennas (e.g., also called the "received signal corresponding to the LC-polarized receive antenna") are lower than the reception levels of the reflected wave signals corresponding to the transmission signals from the LC-polarized transmit antennas. For example, depending on the reception quality (e.g., signal-to-noise ratio (SNR)), the reception levels of the received signals corresponding to the RC-polarized transmit antennas may reach or fall below the noise level, making it difficult to detect Doppler frequency peaks in the MIMO radar.

[0035] Fig. Figure 3 illustrates an example of a signal that has undergone CDDM transmission in a polarimetric MIMO radar. Fig. 3, two transmit antennas with LC polarization and two transmit antennas with RC polarization are used as differently polarized transmit antennas, and a MIMO radar is configured with a total of four Tx #1 to #4. Here, Tx #1 and Tx #2 are LC-polarized transmit antennas, and Tx #3 and Tx #4 are RC-polarized transmit antennas. In the example of Fig. 3 The receiving antenna performs reception via an LC-polarized receiving antenna.

[0036] For example, CDDM signals in which the number N DM of Doppler multiplexing = 3 and the number N CM of code multiplexing = 2 four Tx #1 to Tx #4 are assigned as under (a) in Fig. 3. In CDDM, each transmitting antenna is assigned a different combination of a DDM signal (DOP1, DOP2, or DOP3) and a code (Code1 or Code2).

[0037] Furthermore, Fig. 3 black circles (•) indicate the assignment of CDDM signals to LC-polarized transmit antennas (Tx #1 and Tx #2) and the pairs of DopCode #1 = (DOP1, Code1) and DopCode #2 = (DOP2, Code1) are assigned to Tx #1 and Tx #2, respectively. Fig. 3, the white circles (◯) also indicate the assignment of CDDM signals to RC polarization transmit antennas (Tx #3 and Tx #4) and the combinations of DopCode #3 = (DOP3, Code2) and DopCode #4 = (DOP1, Code2) are assigned to Tx #3 and Tx #4, respectively.

[0038] For example, in a case where the CDDM signals as in (a) of Fig. 3 and the LC-polarized receiving antenna once receives reflected waves, the reception levels of the reception signals (R) corresponding to the RC-polarized transmitting antennas may be lower than the reception levels of the reception signals (L) corresponding to the LC-polarized Sen, as described in (b) of Fig. 3 illustrates.

[0039] In Fig. 3, the sizes of the black circles (•) and the white circles (◯) represent the reception power. The smaller the sizes of the black circle (•) and the white circle (◯), the lower the reception power (for example, the reception power is as low as the noise level).

[0040] Further, for example, a case will be explained where the MIMO radar receives a twice-reflected wave (a reflected wave reflected twice by an object) using an LC-polarized receiving antenna. The received signals corresponding to the LC-polarized transmitting antennas, which are received by the LC-polarized receiving antenna, become received signals as RC-polarized waves because they are reflected twice, and the reception by the LC-polarized receiving antenna becomes cross-polarized reception. For this reason, the received signals corresponding to the LC-polarized transmitting antennas may have a lower reception level than the received signals corresponding to the RC-polarized transmitting antennas (e.g., by 10 dB or more, depending on the difference in the cross-polarization of the antenna's reception level).For example, depending on the reception quality (SNR), the reception levels of the receive signals corresponding to the LC-polarized transmit antennas may fall below the noise level, making it difficult to detect Doppler frequency peaks in the MIMO radar.

[0041] For example, in a case where the CDDM signals as in (a) of Fig. 3 and the LC-polarized receiving antenna receives twice reflected waves, the reception levels of the reception signals (L) corresponding to the LC-polarized transmitting antennas may be lower than the reception levels of the reception signals (R) corresponding to the RC-polarized transmitting antennas, as in (c) of Fig. 3 illustrates.

[0042] In a case where the Doppler frequency of the reflected wave from the target object and the number of times of reflections are unknown in advance, it is difficult for the MIMO radar to calculate the Doppler frequency based on the results given in part (b) or (c) of Fig. 3, to determine whether the reception levels of the received signals corresponding to the RC-polarized transmitting antennas have decreased or whether the reception levels of the received signals corresponding to the LC-polarized transmitting antennas have decreased. Furthermore, it is difficult for the MIMO radar, for example, to determine which transmitting antenna the detected Doppler frequency peak in the signal corresponds to based on the reception levels, as described in part (b) or (c) in Fig. 3 when CDDM transmission is used. For this reason, it is difficult for the MIMO radar to demultiplex the CDDM signal and it is difficult to determine the Doppler frequency f dtgthe reflection wave (e.g. referred to as “wave reflected from the target object”) from the target object within a range of -1 / (2Tr) ≤ f dtg < 1 / (2Tr) to be determined.

[0043] For example, if the wave reflected from the target object is a once reflected wave and the Doppler frequency f dtg = 0 (case i in the upper part of (b) of Fig. 3, where the reception levels of the reception signals corresponding to the RC-polarized transmitting antennas decrease to a noise level), and in a case where the wave reflected from the target object is a twice-reflected wave and the Doppler frequency f dtg = -1 / (2Tr) + Δf d(where the reception levels of the received signals corresponding to the LC-polarized transmit antennas drop to a noise level), the peak frequencies are observed in the same way as DOP1 and DOP2 at the Doppler reception frequency after code division multiplexing with Code1. Therefore, the results of CDDM demultiplexing in these cases are not clear, and it is difficult for the radar device to distinguish between these cases.

[0044] As described above, the demultiplexing of the multiplexed transmission signal in the coded Doppler multiplexing MIMO radar is performed under the assumption that the reception levels of the CDDM signals assigned to the transmitting antennas are similar to each other and that the reception level of the coded Doppler signal not assigned to any transmitting antenna is sufficiently low and close to the noise level. In a polarimetric MIMO radar using CDDM, the assumption can be broken during the demultiplexing of CDDM, as described in (b) and (c) of Fig. 3, and there is a possibility that the CDDM demultiplexing processing is faulty.

[0045] In one non-limiting exemplary embodiment of the present disclosure, a method for improving the detection performance of a polarimetric MIMO radar using coded Doppler division multiplexing (CDDM) transmission is described.

[0046] It should be noted that although the example described here includes a configuration of the MIMO radar using two transmit antennas for each of both left-hand circular polarization (LC) and right-hand circular polarization (RC) (e.g., number Nt of transmit antennas = 4), the polarizations used in the polarimetric MIMO radar are not limited to these.

[0047] For example, polarimetric MIMO radar can use different linear polarizations that are orthogonal to each other. For example, linear polarizations that are orthogonal to each other can be used, for example, vertical polarization can be used instead of left-circular polarization (LC) and horizontal polarization can be used instead of right-circular polarization (RC). When radar transmission waves are transmitted using such vertically and horizontally polarized transmit antennas, the reflected wave of one of the vertical polarization and the horizontal polarization can have a weaker reception level than the other polarization, the closer the angle of incidence is to the Brewster angle when the radar transmission waves are reflected by the target object.For example, in MIMO radar, when such reflected waves are received using a polarization receiving antenna with either vertical polarization or horizontal polarization, the received signal corresponding to the transmitting antenna with either vertical polarization and horizontal polarization becomes cross-polarized reception and may have a lower reception level of reflected waves (e.g., 10 dB or more lower, depending on the cross-polarization discrimination of the antenna) than the received signal corresponding to the other polarized receiving antenna. The received signal with the reduced reception level may fall below the noise level depending on the reception quality (SNR), making it difficult to detect Doppler frequency peaks in MIMO radar.

[0048] For example, if vertical polarization is applied instead of left-hand circular polarization (LC) and horizontal polarization is applied instead of right-hand circular polarization (RC) and the CDDM signals are assigned as described in part (a) of Fig. 3, the received signals could be as described in part (b) of Fig. 3 and (c) of Fig. 3 be.

[0049] Even when vertically and horizontally polarized transmit antennas are used, it is difficult for the MIMO radar to determine the position based on the reception levels, such as in part (b), (c), (e) or (f) in Fig. 3, to determine whether the reception level of the transmission signal from the horizontally polarized transmitting antenna has decreased or whether the reception level of the transmission signal from the vertically polarized transmitting antenna has decreased. For this reason, for example, in a MIMO radar, it is difficult to demultiplex CDDM signals, and it is difficult to determine the Doppler frequency fd of the wave reflected from the target object in a range of -1 / (2Tr) ≤ f d < 1 / (2Tr) to be determined.

[0050] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the embodiments, the same individual elements are identified by the same numerals, and their descriptions are omitted for redundancy.

[0051] The following describes a configuration of a radar device (e.g., MIMO radar configuration) having a transmit branch on which multiplexed different transmit signals are transmitted simultaneously from a plurality of transmit antennas, and a receive branch on which the transmit signals are separately subjected to receive processing.

[0052] Furthermore, a configuration of a radar system using a frequency-modulated pulse wave such as a chirp pulse (e.g., also referred to as chirp pulse transmission (fast chirp modulation)) will be described below by way of example. However, the modulation scheme is not limited to frequency modulation. For example, an exemplary embodiment of the present disclosure is also applicable to a radar system using a pulse compression radar configured to transmit a pulse train after performing phase modulation or amplitude modulation on the pulse train.

[0053] In addition, the radar device performs, for example, Doppler multiplexing. Furthermore, in Doppler multiplexing, the radar device multiplexes and transmits signals by encoding the signals (e.g., by performing code division multiplexing (CDM) on the signals) to which various phase rotations (e.g., phase shifts) have been applied, the number of which corresponds to the number of Doppler multiplexings (hereinafter, such signals are referred to as "Doppler multiplexed (DDM) transmission signals" or "Doppler multiplexed (DDM) signals") (hereinafter, such multiplexing is referred to as "coded Doppler division multiplexing (CDDM)"). [Radar device configuration]

[0054] The radar device 10, which is Fig. 4, comprises a radar transmitter (transmitting branch) 100 and a radar receiver (receiving branch) 200.

[0055] The radar transmitter 100 generates radar signals (radar transmission signals) and transmits the radar transmission signals in a defined transmission period (hereinafter referred to as “radar transmission period”) using a transmission antenna section 109 (e.g., a transmission array antenna) composed of a plurality of transmission antennas (e.g., Nt transmission antennas).

[0056] The radar receiver 200 receives a reflected wave signal, which is a radar transmission signal reflected from a target object (target; (not illustrated)), using a receiving antenna section 202 (e.g., a receiving array antenna) including a plurality of receiving antennas 202-1 to 202-Na. The radar receiver 200 performs signal processing on the reflected wave signal received by each receiving antenna and outputs information (e.g., positioning information) related to the estimation result, for example, by detecting the presence or absence of a target object or estimating the incident distance, Doppler frequency (e.g., relative velocity), and incident direction of the reflected wave signal.

[0057] It should be noted that the radar device 10 may be installed on, for example, a mobile unit such as a vehicle, and that a positioning output of a radar receiver 200 (information on the estimation result) may be connected to an electronic control unit (ECU) (not illustrated) such as an advanced driver assistance system (ADAS) or an autonomous driving system to improve collision safety, and may be used for vehicle driving control or alarm call control.

[0058] The radar device 10 can also be installed on a structure at a relatively high height (not shown), such as a utility pole or traffic light. The radar device 10 can also be used, for example, as a sensor of an assistance system for improving the safety of passing vehicles or pedestrians, or as a sensor of a system for preventing the entry of suspicious persons (not shown). The positioning output of the radar receiver 200 can also be connected, for example, to a control device (not shown) in the assistance system or the system for preventing the entry of suspicious persons, and can be used for alarm call control or anomaly detection control. The use of the radar device 10 is not limited to the above and can also be used for other purposes.

[0059] In addition, the target object is an object to be detected by the radar device 10. Examples of the target object include vehicles (including four-wheeled and two-wheeled vehicles), a person, and a blockage or curb. [Configuration of radar transmitter 100]

[0060] The radar transmitter 100 includes a radar transmission signal generator 101, a phase rotation amount setting unit 105, phase rotators 108, and a transmission antenna section 109.

[0061] The radar transmission signal generator 101 generates a radar transmission signal. The radar transmission signal generator 101 includes, for example, a transmission signal generation controller 102, a modulation signal generator 103, and a voltage-controlled oscillator (VCO) 104. The components of the radar transmission signal generator 101 are described below.

[0062] The transmission signal generation controller 102 configures, for example, a transmission signal generation timing for each radar transmission period and outputs information about the configured transmission signal generation timing to the modulation signal generator 103 and the phase shift amount setting unit 105 (e.g., Doppler shift setting unit 106). The radar transmission period is represented herein by Tr.

[0063] the modulation signal generator 103 periodically generates, for example, sawtooth modulation signals based on the information input from the transmission signal generation controller 102 at the time of transmission signal generation for each radar transmission period Tr.

[0064] The VCO 104 outputs frequency-modulated signals (hereinafter referred to as frequency chirp signals or chirp signals, for example) to the phase rotators 108 and the radar receiver 200 (mixer 204, described below) as radar transmission signals (radar transmission waves) based on the modulation signals input from the modulation signal generator 103, as shown in Fig. 5 illustrates.

[0065] The phase rotation amount setting unit 105 configures phase rotation amounts applied to the radar signals for each radar transmission period Tr at phase rotators 108 (e.g., phase rotation amounts corresponding to CDDM transmission) based on the transmission signal generation timing information for each radar transmission period Tr input from the transmission signal generation controller 102. The phase rotation amount setting unit 105 includes, for example, the Doppler shift setting unit 106 and the encoder 107.

[0066] The Doppler shift setting unit 106 configures phase rotation amounts applied to the radar transmission signals (e.g., chirp signals) and corresponding to the Doppler shift amounts, for example, based on the information at the time of transmission signal generation for each radar transmission period Tr.

[0067] The encoder 107 configures a phase rotation amount corresponding to the coding, for example, based on the information at the time of transmission signal generation for each radar transmission period Tr. The encoder 107 calculates the phase rotation amounts for the phase rotators 108, for example, based on the phase rotation amounts output from the Doppler shift setting unit 106 and the phase rotation amount corresponding to the coding, and outputs the phase rotation amounts to the phase rotators 108. Furthermore, the encoder 107 outputs, for example, information about code sequences used for coding (e.g., elements of orthogonal code sequences) to the radar receiver 200 (e.g., output switch 209).

[0068] The phase rotators 108 apply the phase rotation amounts input from the encoder 107 to the chirped signals input from the VCO 104 and output the phase-rotated signals to the transmitting antenna section 109. For example, each of the phase rotators 108 includes a phase shifter, a phase modulator, etc. (not shown). The output signals of the phase rotators 108 are amplified to a defined transmission power and transmitted into space from transmitting antennas. For example, radar transmission signals are multiplexed by applying the phase rotation amounts corresponding to the combinations of the Doppler shift amounts and the code sequences and transmitted from a plurality of transmitting antennas 109.

[0069] Next, an exemplary configuration method for the phase rotation amount setting unit 105 for configuring the phase rotation amounts will be described.

[0070] The Doppler shift setting unit 106 configures the phase shift φ ndm for the application of the Doppler shift amount DOP ndm and outputs the phase shift amount to the encoder 107. Here ndm = 1 to N DM . N DM is the configured number of different Doppler shift amounts and is referred to as the “number of Doppler multiplexing” below.

[0071] Since the coding by the encoder 107 in the radar device 10 is used in combination, the number N DM Doppler multiplexing should be set to a smaller number than the number Nt of transmitting antennas used for multiplexing. Note that the number N DM of Doppler multiplexing is greater than or equal to 2.

[0072] Doppler shift amounts at equal intervals or Doppler shift amounts at unequal intervals can be written as DOP1, DOP2 ... DOP N_DM be configured (where “N_DM” is also known as “N pnn Each DOP1, DOP2 ... DOP N_DM can be configured to be, for example, 0 ≤ DOP1, DOP2 ... DOP N_DM < 1 / (TrL oc ) in order to be used in combination with the coding described later by the encoder 107. Alternatively, DOP1, DOP2 ... DOP N_DM be configured to satisfy, for example, expression 1. [1] −12TrLoc≤DOP1,DOP2,…,DOPN_DM<12TrLoc

[0073] In addition, for example, the minimum Doppler shift interval Δf MinInterval between DOP1, DOP2 ... and DOP N_DMsatisfy the following expression 2. It should be noted that the Doppler shift interval (also called Doppler multiplex interval or Doppler interval) is defined as the absolute value of the difference between any two Doppler shift amounts between DOP1, DOP2 ... and DOP N_DM can be defined. Here, Loc represents the number of code elements. Example: Loc represents the code length of a code used in encoder 107. [2] 0<ΔfMinInterval≤1TrNDMLoc

[0074] In addition, the phase shift amount φ ndm for the application of each DOP1, DOP2 ... DOP N_DM for example, as in the following expression 3: [3] ϕndm=2πDOPndm / (1TrLoc)

[0075] In a case where Doppler shift magnitudes are calculated with an interval of Δf MinIntervalconfigured (hereinafter referred to as “equal interval Doppler shift amount configuration”), phase rotation amounts φ ndm for the application of DOP ndm assigned as described in the following expression 4: [4] ϕndm=2π(ndm−1)ΔfMinInterval / (1TrLoc)

[0076] The narrower the minimum Doppler shift interval Δf MinInterval is, the more likely interference between DDM signals is, and the more likely target detection accuracy is to be reduced (e.g., deteriorated). Therefore, it is preferable to further widen the intervals between Doppler shift amounts within the range that satisfies the limiting condition of Expression 2. For example, if the equality in Expression 2 holds (e.g., Δf MinInterval = 1 / (T r N DM L OC)), the interval in the Doppler domain between DDM signals can be maximized (hereinafter referred to as “maximum configuration of Doppler shift amounts with equal intervals”). In this case, the phase rotation range greater than or equal to 0 and less than 2π becomes uniform in N DM different DM Phase rotation amounts, and DOP1, DOP2 ... and DOP N_DM are assigned different phase shift amounts. For example, the phase shift amount φ ndm for the application of DOP ndm as given in the following expression 5. Note that in the following the angle is expressed in radians. [5] ϕndm=2π(ndm−1)NDM

[0077] It should be noted that the assignment of the phase rotation amounts for the application of DOP1, DOP2 ... and DOP N_DMis not limited to this assignment method. For example, the phase rotation amounts φ1, φ2 ... (φ N_DM randomly DOP1, DOP2 ... DOP N_DM (where “N_DM” is N DM ), using an assignment table with phase rotation amounts.

[0078] In addition, when configuring the Doppler shift amounts with equal intervals, the phase rotation amount can be configured as given in the following Expression 6 by setting Δf MinInterval = 1 / (T r (N DM + N int )L OC ) in Expression 4. Here, N int an integer value. [6] ϕndm=2π(ndm−1)NDM+Nint

[0079] The encoder 107 configures for each of the phase rotation amounts φ1 to φ N_DM to apply the N entered by the Doppler shift setting unit 106 DMDoppler shift amounts the phase rotation amounts based on one or more code sequences (at most N CM ). In addition, the encoder 107 configures the phase rotation amounts, e.g., "coded Doppler phase rotation amounts" (hereinafter abbreviated as CDP amounts), which generate coded Doppler multiplexed signals (CDDM signals) based on the Doppler shift amounts and the code sequences, and outputs the CDP amounts to the phase rotator 108.

[0080] An example of the operation of encoder 107 is described below.

[0081] For example, it is preferred that the encoder 107 N CMCode sequences (e.g., number of code multiplexing) are used, each with a code length of Loc, which are less correlated or uncorrelated. For example, the encoder uses orthogonal code sequences. Note that code elements that form an orthogonal code sequence are not limited to real numbers and can contain complex numbers.

[0082] In the following, N CM orthogonal code sequences with a code length Loc as code ncm = {OC ncm (1), OC ncm (2) ... OC ncm (Loc)}. OC nem (noc) represents the noc-th code element in the ncm-th orthogonal code sequence Code ncm Here noc is an index of the code element and noc = 1 to Loc.

[0083] The orthogonal code sequence used in encoder 107 can be, for example, a Walsh-Hadamard code. Encoder 107 generates an orthogonal code sequence using a predefined code length L OC , the orthogonal N CM can generate code sequences.

[0084] In the encoder 107, the number of code division multiplexing (hereinafter referred to as the number of coded Doppler multiplexing) for encoding a DDM signal using the ndm-th Doppler shift amount DOP ndm , which is input by the Doppler shift setting unit 106, as “N CDDM (ndm)”. Here ndm = 1 to N DM .

[0085] The encoder 107 configures the number N CDDM (ndm) of the coded Doppler multiplexing such that the sum of the numbers N CDDM (1), N CDDM (2) ... and N CDDM (N DM) of coded Doppler multiplexing for encoding the DDM signals corresponds to the number Nt of transmitting antennas used for multiplexing. Thus, the radar device 10 is capable of performing multiplexed transmission (hereinafter referred to as coded Doppler multiplexing (CDDM transmission)) in the Doppler domain and the code domain using Nt transmitting antennas.

[0086] Further, using, for example, a Doppler shift amount configuration with equal intervals including a maximum Doppler shift amount configuration with equal intervals, the encoder 107 may configure the number of coded Doppler multiplexing to have different numbers of coded Doppler multiplexing in a range from one or more to N CM or less in terms of the numbers N CDDM (1), N CDDM (2) ... N CDDM (N DM) of coded Doppler multiplexing. For example, the encoder 107 does not configure the number of codes N CM for all numbers of coded Doppler multiplexing, but configures the number of codes N CDDM (ndm) that have at least one DOP ndm so that it is smaller than N CM Therefore, a variety of combinations between DOP ndm and orthogonal code sequences the number of N CDDM (ndm) of the multiplexing (number of coded Doppler multiplexing) by the orthogonal code sequence corresponding to the at least one DOP ndmmay differ from the numbers of coded Doppler multiplexing associated with other Doppler shift amounts. For example, the encoder 107 configures the numbers of coded Doppler multiplexing for the DDM signals unevenly. With this configuration, for example, the aliasing determination processing in the reception processing described in PTL 6 and PTL 7 enables the radar device 10 to individually demultiplex and receive signals transmitted by CDDM from a plurality of transmission antennas over a Doppler range of ±1 / 2Tr.

[0087] The encoder 107 configures a CDP amount ψ ndc(ndm),ndm (m), which in the following expression 7 for a phase rotation amount φ ndm is shown to calculate the ndm-th Doppler shift amount DOP ndm in the m-th transmission period Tr, and gives the CDP amount ψ ndc(ndm),ndm (m) to the phase rotator 108: [7] ψndc(ndm),ndm(m)=floor[(m−1)Loc]×φndm+angle[OCndc(ndm)(OC_INDEX)]

[0088] Here the subscript “ndc(ndm)” represents an index that is less than or equal to the number N CDDM (ndm) of the coded Doppler multiplexing for the phase shift amount φ ndm for the application of the Doppler shift amount DOP ndm For example, ndc(ndm) = 1 ... N CDDM (ndm). Furthermore, angle[x] is an operator that returns the radian phase of the real number x, and is, for example, angle[1] = 0, angle[-1] = π, and angle[j] = π / 2.

[0089] For example, as stated in Expression 7, the CDP amount ψ ndc(ndm), ndm (m) a constant phase rotation amount for the application of the Doppler shift amount DOP ndmin the duration of the Loc transmission periods (“Loc” is the code length used for coding) (for example, the first term in Expression 7) and applies a phase rotation amount that is equal to each of Loc code elements OC ndc(ndm) (1) ... OC ndc(ndm)( Loc) of the code Code ndc(ndm) as used for encoding (the second term in Expression 7).

[0090] Furthermore, the transmitter 107 outputs an orthogonal code element index OC_INDEX to the radar receiver 200 (output switch 209, as described below) in each transmission period (Tr). OC_INDEX is an orthogonal code element index that represents an element of the orthogonal code sequence Code ndc(ndm) and is cyclically variable in a range from 1 to Loc in each transmission period (Tr), as given in the following expression 8: [8] OC_INDEX=mod(m−1,Loc)+1

[0091] Here, mod(x, y) denotes a modulo operator and is a function that returns the remainder after dividing x by y. Furthermore, m = 1 to Nc. Nc denotes the number of transmission periods used for radar positioning (hereinafter referred to as "radar transmission signal transmission times"). In addition, the radar transmission signal transmission times Nc are set to an integer multiple of Loc (by a factor of Ncode). For example, Nc = Loc × Ncode.

[0092] Next, an example of a procedure for configuring numbers N CDDM (ndm) of the non-uniformly coded Doppler multiplexing for the DDM signals in the encoder 107.

[0093] For example, encoder 107 configures the number N CM orthogonal code sequences (e.g., the number of code multiplexing or the number of codes) that satisfy the following condition. For example, the number N CMof orthogonal code sequences and the number N DM Doppler multiplexing, the following relationship for the number Nt of transmitting antennas used for multiplex transmission: (Number of NCMs of orthogonal code sequences)×(number of NDMs of Doppler multiplexing)>Number of transmitting antennas Nt used for multiplexed transmission.

[0094] Next, a configuration example for the CDP amount ψ ndc(ndm),ndm (m) described.

[0095] For example, a case is described where in the encoder 107, the number Nt of transmitting antennas used for multiplexing is 3, the number N DM of Doppler multiplexing is 2 and the number N CM of code multiplexing is 2 and orthogonal code sequences Code1 = {1, 1} and Code2 = {1, -1} with code length Loc = 2 are used. As in Fig. 6, the encoder 107 configures in this case, for example, when the number of coded Doppler multiplexing N CDDM (1) = 1 and N CDDM (2) = 2, CDP amounts ψ 1, 1 (m), ψ 1, 2 (m) and ψ 2, 2 (m) and outputs it to the phase rotator 108. For example, when configuring the CDP amount ψ 1, 1 (m) the encoder 107 executes the configuration as in the following expression 9. It is noted that in Fig. 6, “◯” represents the used Doppler shift amount and the used orthogonal code, and “×” represents the allocation of the unused Doppler shift amount and the unused orthogonal code. [9] {ψ1.1(1),ψ1.1(2),ψ1.1(3),ψ1.1(4),ψ1.1(5),ψ1.1(6),ψ1.1(7),ψ1.1(8),…}={0,0,ϕ1,ϕ1,2ϕ1,2ϕ1,3ϕ1,3ϕ1,…}

[0096] The configuration procedure for the phase rotation amount setting unit 105 for configuring the phase speed values ​​has been described above.

[0097] In Fig. 4, the phase rotators 108 apply the phase rotation amounts in each transmission period Tr to the chirp signals input from the radar transmission signal generator 101 based on CDP amounts ψ ndc(ndm), ndm (m) configured by the phase rotation amount setting unit 105. Here, ndm = 1 for N DM and ndc(ndm) = 1 for N CDDM (ndm).

[0098] The outputs of the Nt phase rotators 108 (e.g. called CDDM signals) are amplified to a defined transmission power and then radiated into the room by the Nt transmitting antennas of the transmitting antenna section 109.

[0099] It is noted that in the following the phase rotator 108, which determines the CDP value ψ ndc(ndm), ndm(m) is also called a “phase rotator PROT #[ndc(ndm), ndm]”. Similarly, a transmitting antenna for radiating the phase rotator PROT #[ndc(ndm), ndm] into space is also called a “transmitting antenna Tx #[ndc(ndm), ndm]”. Here, ndm = 1 for N DM and ndc(ndm) = 1 for N CDDM (ndm). Alternatively, the Nt transmit antennas are also referred to as Tx #1, Tx #2 ... and Tx #Nt. The CDP amounts applied to the radar transmit signals transmitted by Tx #1, Tx #2 ... and Tx #Nt can be assigned using a previously known table or similar. For example, by determining (or detecting) the CDP amount ψ ndc(ndm), ndm (m) the transmitting antenna can be determined (or detected).

[0100] For example, in the case of Fig. 6, the CDP amounts ψ 1, 1 (m), ψ 1, 2 (m) and ψ 2, 2(m) for each transmission period from the transmitter 107 to the phase rotator 108.

[0101] For example, the phase rotator PROT #[1, 1] gives a signal exp[jψ 1, 1 (m)]cp(t), to which the phase rotation amount ψ 1, 1 (m) applied every m-th transmission period to the chirp signal cp(t) generated by the radar transmission signal generator 101 in each transmission period. The output of the phase rotator PROT #[1, 1] is output from the transmitting antenna Tx #[1, 1]. Here, cp(t) denotes a chirp signal for each transmission period. Similarly, the output of the phase rotator PROT #[1, 2] is output from Tx #[1, 2], and the output of the phase rotator PROT #[2, 2] is output from Tx #[2, 2].

[0102] The configuration example for the CDP amount ψ ndc(ndm), ndm (m) described.

[0103] Further, in the present embodiment, when the numbers N CDDM(ndm) of the coded Doppler multiplexing for the DDM signals are not uniformly configured, the number of multiplexing (e.g. number N CDDM (ndm) of coded Doppler multiplexing) by orthogonal code sequences Code ncm , which correspond to the Doppler shift amounts DOP ndm correspond to the combinations of Doppler shift amounts DOP ndm and the orthogonal code sequences Code ncm be different.

[0104] Further, in the present embodiment, when the numbers N CDDM (ndm) of the coded Doppler multiplexing for the DDM signals are uniformly configured, the numbers of multiplexing can be achieved by orthogonal code sequences Code ncm (e.g. numbers N CDDM (ndm) of coded Doppler multiplexing), the DOP ndm respectively, among the combinations of DOP ndm and orthogonal code sequences Code ncmIn this case, the number of combinations of DOP ndm and the orthogonal code sequences and the number Nt of transmitting antennas must be equal (e.g. N DM × N CM = Nt).

[0105] Furthermore, in the present embodiment, for example, Tx #1 to Tx #Nt of the transmitting antenna section 109 include transmitting antennas with at least two different polarizations and form a polarimetric radar. For example, Tx #1 to Tx #Nt may include transmitting antennas that are orthogonal to each other as different polarizations. Furthermore, a plurality of transmitting antennas of at least one of the polarizations and at least one transmitting antenna for the other polarizations may be provided.

[0106] The radar device 10 (e.g., phase rotation amount setting unit 105) configures different CDP amounts ψ ndc(ndm), ndm(m) for each transmitting antenna, for example, taking into account transmitting antennas with different polarizations. The radar device 10 (e.g., the phase rotator 108) can thus configure CDP values ​​ψ ndc(ndm), ndm (m) to the chirp signals and output the chirp signals to the transmitting antenna section 109.

[0107] Even in a case where the reception levels between reception signals corresponding to the transmission antennas of different polarizations differ significantly (e.g., in a case where the reception level difference or the reception level ratio is greater than or equal to a threshold value), the radar device 10 enables demultiplexing of CDDM signals and prevents deterioration of positioning performance and radar detection performance (an exemplary operation will be described later).

[0108] The following describes an exemplary operation of the unit 105 for setting the phase rotation amount in the radar transmitter 100 when configuring a polarimetric MIMO radar with at least two transmit antennas of different polarizations.

[0109] It is noted that the number Nt of transmitting antennas ≥ 3, the number N DM of Doppler multiplexing ≥ 2, the number N CM of code multiplexing ≥ 2 or more and Nt < N DM x N CM As described above, the number Nt of different transmitting antennas can be smaller than the total number of combinations of Doppler shift amount and code sequence (N DM x N CM ). It should be noted that Nt is proportional to the total number of combinations of Doppler shift magnitude and code sequence (N DM x N CM ) can be identical.

[0110] In addition, the number of different polarizations included in the transmit antennas (hereinafter referred to as the "number of transmit polarizations") is represented as "NPL." Furthermore, the q-th polarization is denoted as "PLq." The symbol "q" is an integer value within the number of transmit polarizations NPL (e.g., any value from q = 1 to NPL).

[0111] In addition, the number of transmitting antennas with PLq polarization is defined as “N PLq “ N PLq ≥ 1 and the total number of transmitting antennas of the respective PLq polarizations is Nt. For example, in a case of NPL = 2, Np L1 of transmitting antennas with PL1 polarization N PL1 ≥ 1, N is PL2 of transmitting antennas with PL2 polarization N PL2 ≥ 1 and is N PL1 + N PL2 = Nt.

[0112] In addition, the number of Doppler multiplexing assigned to the transmitting antenna of PLq polarization is called “N DM-PLq“ Here N DM_PLq ≤ N DM For example, in a case of NPL = 2 N DM_PL1 and N DM_PL2 ≤ N DM .

[0113] The radar device 10 has N PL1 and N PL2 Transmitting antennas with different PL1 polarization or PL2 polarization and uses at least two polarizations. The phase rotation amount setting unit 105 in the radar transmitter 100 of the radar device 10 (e.g., a polarimetric MIMO radar) configures the number N CDDM (ndm) of the coded Doppler multiplexing for the DDM signal is non-uniform and configures the CDP amount ψ ndc(ndm),ndm (m) which satisfies the following condition 1. Here ndm = 1 for N DM and ndc(ndm) = 1 for N CDDM (ndm). <Bedingung 1>

[0114] For example, the patterns of the Doppler shift amount and the code sequence assigned to the transmitting antenna with PL1 polarization are different (e.g., the pattern of coded Doppler division multiplexing (CDDM) and the pattern of CDDM assigned to the transmitting antenna with PL2 polarization are different). For example, the phase rotation amount setting unit 105 configures the CDP amount ψ ndc(ndm),ndm (m) that satisfies a condition of a different Doppler multiplexing (DDM) pattern (e.g., an allocation pattern of a Doppler shift amount), a condition of a different code division multiplexing (CDM) pattern (e.g., a different number of code division multiplexing between DDM signals), or a condition of different patterns of DDM and CDM for each of the transmitting antennas with PL1 polarization and the transmitting antenna with PL2 polarization.

[0115] For example, the condition for different DDM patterns can be one of the following conditions (e.g. also called “Condition 1A” or “1Aof Condition 1”). 1A) Different conditions for the DDM signal pattern: (A-1) The number of Doppler multiplexing corresponding to polarizations (e.g., the number of Doppler multiplexing of transmit signals sent from transmit antennas of the polarizations) is equal to (e.g., N DM_PL1 = N DM_PL2 , however N DM_PL1 = N DM_PL2 ≥ 2) and includes different Doppler shift intervals for the polarizations (e.g. intervals of Doppler shift amounts assigned to transmitting antennas of the respective polarizations). (A-2) The number of Doppler multiplexing for each polarization (e.g., the number of Doppler multiplexing for a transmission signal sent from a transmission antenna for each polarization) is different (N DM_PL1 ≠ NDM_PL2 ). (A-3) In a case where N DM_PL1 ≥ 3 and N DM_PL2 ≥ 3 and in which the Doppler shift intervals for the respective polarizations enclose the same Doppler shift interval, the orders of the Doppler shift intervals differ from each other (cyclic mismatch).

[0116] In addition, the condition of another CDM pattern can be any of the following conditions (e.g. also referred to as “Condition 1 B”). (B-1) The code intervals (e.g., code index intervals) assigned to the respective DDM signals differ from each other (cyclic mismatch). (B-2) The numbers of code division multiplexing assigned to the respective DDM signals are different from each other (cyclic mismatch).

[0117] In addition, the phase rotation amount setting unit 105 may determine the CDP amount ψ ndc(ndm),ndm(m) to satisfy, for example, the following condition 2. <Bedingung 2>

[0118] Signals transmitted from transmitting antennas of the same polarization are multiplexed and transmitted with numbers of code division multiplexing that are inconsistent between DDM signals, and the numbers of code division multiplexing include any value in the range from 1 to N CM - 1 or less (the number of code multiplexing of 1 is in the case of N CM = 2 included). For example, in a plurality of combinations of a Doppler shift amount and a code sequence, the number of code multiplexing by a code sequence associated with at least one Doppler shift amount differs from the number of code multiplexing by a code sequence associated with another Doppler shift amount with respect to at least one transmitting antenna with PL1 polarization and the PL2 polarization.

[0119] For example, under A-3 of Condition 1, when each value of a plurality of intervals of the Doppler shift amount to be allocated (for example, a combination of Doppler shift intervals) between the transmitting antenna of the PL1 polarization and the transmitting antenna of the PL2 polarization is the same, the order of the plurality of Doppler shift intervals corresponding to the transmitting antenna of the PL1 polarization on the Doppler frequency axis and the order of the plurality of Doppler shift intervals corresponding to the transmitting antenna of the PL2 polarization on the Doppler frequency axis may be different from each other.For example, the combination of intervals included in an array in which the intervals of Doppler shift amounts assigned to the transmitting antenna of PL1 polarization are arranged in increasing order on the Doppler frequency axis and the combination of intervals included in an array in which the intervals of Doppler shift amounts assigned to the transmitting antenna of PL2 polarization are arranged in increasing order on the Doppler frequency axis coincide, and the first array and the second array are different arrays in a cyclic permutation. If A-3 of Condition 1 is satisfied, the Doppler shift interval of the transmitting antenna of PL1 polarization and the Doppler shift interval of the transmitting antenna of PL2 polarization do not coincide (become cyclically mismatched), even if both are cyclically shifted in the Doppler frequency domain.

[0120] Furthermore, for example, under B-1 of Condition 1, the order of the code sequences assigned to the transmitting antenna of PL1 polarization on the Doppler frequency axis and the order of the code sequences assigned to the transmitting antenna of PL2 polarization on the Doppler frequency axis may differ. For example, an array in which the indices of the code sequences corresponding to the Doppler shift amounts assigned to the transmitting antennas of PL1 polarization are arranged in increasing order on the Doppler frequency axis and an array in which the indices of the code sequences corresponding to the Doppler shift amounts assigned to the transmitting antennas of PL2 polarization are arranged in increasing order on the Doppler frequency axis are different arrays in cyclic permutation.In a case where B-1 of Condition 1 is satisfied, the indices of the code sequences corresponding to the Doppler shift amounts for the transmitting antennas of the PL1 polarization and the indices of the code sequences corresponding to the Doppler shift amounts for the transmitting antennas of the PL2 polarization do not match (become cyclically mismatched), even if both are cyclically shifted in the Doppler frequency domain.

[0121] Furthermore, for example, under B-2 of Condition 1, the order of the numbers of code division multiplexing by the code sequences assigned to the transmitting antennas of the PL1 polarization on the Doppler frequency axis and the order of the numbers of code division multiplexing by the code sequences assigned to the transmitting antennas of the PL2 polarization on the Doppler frequency axis may be different from each other. For example, an array in which the numbers of code division multiplexing corresponding to the Doppler shift amounts assigned to the transmitting antennas of the PL1 polarization are arranged in increasing order on the Doppler frequency axis and an array in which the numbers of code division multiplexing corresponding to the Doppler shift amounts assigned to the transmitting antennas of the PL2 polarization are arranged in increasing order on the Doppler frequency axis are different arrays in cyclic permutation.In a case where B-2 of Condition 1 is satisfied, the numbers of code division multiplexing corresponding to the Doppler shift amounts for the transmitting antennas of the PL1 polarization and the numbers of code division multiplexing corresponding to the Doppler shift amounts for the transmitting antennas of the PL2 polarization do not match (become cyclically mismatched) even if both are cyclically shifted in the Doppler frequency domain.

[0122] The radar device 10 achieves the following effects by applying CDP amounts satisfying the above condition 1 to the transmitting antennas.

[0123] For example, the Doppler frequency of the received signal includes the encoded Doppler phase shift at the time of transmission, as described above, and also includes the Doppler frequency of an unknown target. Therefore, there is a possibility that the Doppler frequencies of the DDM signals may change in a positive or negative direction while the intervals between the DDM signals remain constant.For example, by satisfying 1A of Condition 1, the radar device 10 can distinguish between a case where a CDDM signal assigned to a transmitting antenna of the PL1 polarization is received and a CDDM signal assigned to a transmitting antenna of the PL2 polarization is not received, and a case where a CDDM signal assigned to a transmitting antenna of the PL1 polarization is received and a CCD signal assigned to a storage unit of the PL1 polarization is not received, because the intervals or the numbers of Doppler multiplexing (e.g., DDM patterns) of the DDM signals in these cases are different from each other.

[0124] Further, for example, by satisfying 1B of Condition 1, the radar device 10 can distinguish between a case where a CDDM signal assigned to a transmission antenna of the PL1 polarization is received and a CDDM signal assigned to a transmission antenna of the PL2 polarization is not received, and a case where a CDDM signal assigned to a transmission antenna of the PL1 polarization is received and a CDDM signal assigned to a transmission antenna of the PL1 polarization is not received, because the code intervals or the numbers of code division multiplexing (e.g., CDM patterns) in which the reception level becomes high after each DDM signal is code-demultiplexed are different from each other.

[0125] Thus, to satisfy Condition 1, by configuring the CDP amounts by the phase rotation amount setting unit 105, the radar device 10 can demultiplex CDDM signals and prevent the deterioration of positioning performance and radar detection performance even in cases where the reception levels between reception signals corresponding to transmission antennas of different polarizations vary significantly.

[0126] By satisfying Condition 2 in addition to Condition 1, the configuration of the CDP amounts by the phase rotation amount setting unit 105 further enables the Doppler frequency range in which detection can be performed in the radar device 10 to be -1 / (2Tr) ≤ f d < 1 / (2Tr); thus, it is possible to extend the range to a range equivalent to the Doppler detection range in the case of a transmitting antenna (an example will be described later).

[0127] For example, during a CDDM transmission by radar device 10, both Condition 1 and Condition 2 may be satisfied, or Condition 1 may be satisfied and Condition 2 may not be satisfied. Examples of the case where Condition 1 is satisfied but Condition 2 is not satisfied include the following three cases.

[0128] Case 1 is a case where neither PL1 polarization nor PL2 polarization satisfy condition 2 and the Doppler frequency range f d , in which the detection can be successful, the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) or the range of -1 / (2Loc N DM_PL1 Tr) ≤ f d < 1 / (2Loc N DM_PL1 Tr) or the range of -1 / (2Loc N DM_PL2 Tr) ≤ f d < 1 / (2Loc N DM-PL2 Tr). Case 2 is a case where the PL2 polarization does not satisfy condition 2 and the Doppler frequency range f d, in which the detection can be successful, the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) or the range of -1 / (2Loc N DM_PL2 Tr) ≤ f d < 1 / (2Loc N DM_PL2 Tr). Case 3 is a case where the PL1 polarization does not satisfy condition 2 and the Doppler frequency range f d , in which the detection can be successful, the range of -1 / (2Tr) ≤ f d < 1 / (2LocN DM_PL1 Tr) or the range of -1 / (2LocN DM_PL1 Tr) ≤ f d < 1 / (2LocN DM_PL1 Tr).

[0129] In each of the cases 1 to 3, the Doppler frequency range in which the acquisition can be successful, while satisfying Nt > Loc N DM_P\L1 or Nt > Loc N DM_PL2 over the Doppler detection range of -1 / (2NtTr) ≤ f d < 1 / (2NtTr) when Doppler multiplexing is performed at equal intervals.

[0130] The following describes an example of the CDP amount configuration in the phase rotation amount setting unit 105.

[0131] In the following, the interval of Doppler shift amounts to be applied to Tx #n1 and Tx #n2 is referred to as the Doppler shift interval “Δf d(n1, n2) “ Here Δf d(n1, n2) the interval (DOP n2 - DOP n1 ) between the Doppler shift amount applied to Tx #n2 and the Doppler shift amount applied to Tx #n1 for reference. It is noted that in a case where the Doppler shift interval Δf d(n1, n2) is a negative value (e.g. in a case where (DOP n2 - DOP n1 ) < 0), the Doppler shift interval Δf d(n1, n2) using Δf d(n1, n2) = 1 / Loc Tr - Δf d(n1, n2)taking into account aliasing in a range from -1 / (2 Loc Tr) to 1 / (2 Loc Tr), which is an observation range in the Doppler analyzer 210, as described later, and is represented as a positive value. When describing the Doppler shift interval Δf d(n1, n2) The same notation is also used in the following explanation. <Konfigurationsbeispiel 1>

[0132] Configuration example 1 is a configuration example for the CDP amount in a case where Condition 1 (condition of different CDM patterns) is met and Condition 2 is met.

[0133] Fig. Fig. 7 illustrates an example of the configuration of the CDP amount in the phase rotation amount setting unit 105 in a case where the number Nt of the transmitting antennas is 4, N PL1 2 and N PL2 2 is. In Fig. 7, black circles (•) indicate the assignment of CDDM signals for transmitting antennas (Tx #1 and Tx #2) of PL1 polarization, and white circles (◯) indicate the assignment of CDDM signals for transmitting antennas (Tx #3 and Tx #4) of PL2 polarization.

[0134] Furthermore, in Fig. 7 the number N DM of Doppler multiplexing = 3 and the Doppler shift setting unit 106 can configure three DOP1 to DOP3, for example, with the configuration of a maximum Doppler shift amount with equal intervals as shown in Expression 5. In Fig. 7 is a phase rotation amount φ1 = 0 for the application of DOP1 = 0, is a phase rotation amount φ2 = 2π / 3 for the application of DOP2 = Δf d and is a phase rotation amount φ3 = 4π / 3 (φ3 = -2π / 3 can be used) for the application of DOP3 = -Δf d . As in Fig. 7, the interval (also called Doppler multiplex interval, Doppler shift interval or Doppler interval) Δf d between DDM signals an equal interval and is Δf d = 1 / (6Tr).

[0135] Furthermore, in Fig. 7 the number N CM of code multiplexing = 2 and the encoder 107 uses Code1 = {1, 1} and Code2 = {1, -1}, which are orthogonal code sequences with code length Loc = 2. In addition, in the configuration examples 2 to 3 described later, the number N CM of code multiplexing 2 and the same codes can be used.

[0136] In Fig. 7 is the number Nt of transmitting antennas 4, is the number N DM of Doppler multiplexing 3 and is the number N CM of code multiplexing 2, and therefore the phase rotation amount setting unit 105 can set the numbers N CDDM(ndm) of the coded Doppler multiplexing for the DDM signals can be configured inconsistently (here ndm = 1 to ndm), since Nt < N DM x N CM is.

[0137] As in Fig. 7, the numbers of coded Doppler multiplexing for the DDM signals using three DOP1 to DOP3, as inputted from the Doppler shift setting unit 106 to the encoder 107, are N CDDM (1) = 1, N CDDM (2) = 1 or N CDDM (3) = 2. As described above, the phase rotation amount setting unit 105 configures the number of coded Doppler multiplexing for the DDM signals non-uniformly.

[0138] Furthermore, Fig. 7 the Doppler shift setting unit 106 assigns DDM signals to the transmitting antennas Tx #1 and Tx #2 of the PL1 polarization, for which, for example, the Doppler shift amounts DOP1 and DOP3 are used (N DM_pl1 = 2), from the DDM signals, where the number NDM of Doppler multiplexing = 3. Furthermore, the encoder 107 assigns DOP1 and DOP3 to Code2 and Code1, which are assigned to Tx #1 and Tx #2 of the PL1 polarization, respectively. In the following, such an assignment is referred to as the configuration of CDP magnitudes ψ 2, 1 (m) and ψ1, 3(m) for Tx #1 and Tx #2 of the PL1 polarization by the phase rotation amount setting unit 105. In Fig. 7, the Doppler shift setting unit 106 further assigns DDM signals to the transmitting antennas Tx #3 and Tx #4 of the PL2 polarization, for which, for example, the Doppler shift amounts DOP2 and DOP3 are used (N DM_pl2 = 2), from the DDM signals, where the number N DM of Doppler multiplexing = 3. For example, the phase rotation amount setting unit 105 configures CDP amounts ψ 2, 2 (m) or ψ 2, 3(m) for Tx #3 and Tx #4 of PL2 polarization.

[0139] In Fig. 7 are the numbers of Doppler multiplexing that the Doppler shift setting unit 106 assigns to the transmitting antennas of the PL1 polarization and the transmitting antennas of the PL2 polarization, N DM_PL1 = N OM_PL2 = 2 and are equal. In addition, the Doppler shift intervals of the DDM signals assigned to Tx #1 to #2 of the PL1 polarization are Δ2fd(1,2) = Δf d and Δf d (2,1) = Δf d , and are the Doppler shift intervals of the DDM signals associated with Tx #3 to #4 of the PL2 polarization, Δf d (3,4) = Δf d and Δf d (4,3) = 2Δf d and are equal (cyclically adjusted).

[0140] Thus, the configuration of the CDP amounts specified in Fig. 7, does not match any of the conditions for DDM patterns under Condition 1A.

[0141] Furthermore, Fig. 7 are the codes assigned to the transmitting antennas of PL1 polarization for DDM signals using DOP1 to DOP3 [Code2, no assignment, Code1], and is the number of code division multiplexing assigned to each DDM signal, 0 or 1.

[0142] Below, the code indices assigned to the transmitting antennas of PL1 polarization for DDM signals using Doppler shift amounts DOP1 to DOP3 are described as "CiPL1 = (2, *, 1)". In CiPL1, "*" represents a case where no code is assigned. Furthermore, in a case where multiple codes are assigned to a DDM signal, the codes are represented by "&". For example, when Code1 and Code2 are assigned to a DDM signal, the notation is represented as "1&2". The code index is also called a "code interval".

[0143] Further, in the following, the numbers of code division multiplexing assigned to the transmitting antennas of the PL1 polarization, respectively, for DDM signals using the Doppler shift amounts DOP1 to DOP3 are described as “NcPL1 = (1, 0, 1)” (in the case of Fig. 7).

[0144] In Fig. 7, the codes assigned to the transmitting antennas of the PL2 polarization for DDM signals using DOP1 to DOP3 are [No Assignment, Code2, Code2], and the number of code division multiplexing assigned to each DDM signal is 0 or 1. Note that, similar to the PL1 polarization, the code indices assigned to the transmitting antennas of the PL2 polarization for DDM signals using DOP1 to DOP3 are represented as "CiPL2 = (*, 2, 2)". Furthermore, the number of code division multiplexing assigned to the transmitting antennas of the PL2 polarization for the DDM signals using DOP1 to DOP3 is represented as "NcPL2 = (0, 1, 1)".

[0145] As described above, the numbers of code division multiplexing assigned to DDM signals for the transmitting antennas of PL1 polarization and the transmitting antennas of PL2 polarization are NcPL1 = (1, 0, 1) and NcPL2 = (0, 1, 1), respectively, and are cyclically coincident, so B-2 of Condition 1 is not satisfied.

[0146] The code indices assigned to the DDM signals for the transmit antennas of PL1 polarization and the transmit antennas of PL2 polarization, however, are CiPL1 = (2, *, 1) and CiPL2 = (*, 2, 2), respectively, and are different from each other (or cyclically mismatched). In the following, the difference in the INDEX interval is referred to as the different INDEX interval.

[0147] Furthermore, in a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg< 1 / (2Tr), a Doppler frequency with aliasing is observed in the Doppler analyzers 210, as described later. In this case, the code indices CiPL1 alias = (1, *, 2) and CiPL2 alias = (*, 1, 1), which are different from each other (cyclically mismatched). In the example of Fig. 7, the code indices thus exhibit a cyclic mismatch, and the code intervals differ in a range of -1 / (2Tr) ≤ f dtg < -1 / (2Tr) of the Doppler frequency of the target object.

[0148] Accordingly, the code intervals assigned to the DDM signals differ between the polarizations, thus satisfying B-1 of Condition 1 as well as the condition of a different CDM pattern.

[0149] The configuration of the CDP amounts as in Fig. 7 is thus an example of a configuration that satisfies condition 1.

[0150] Furthermore, in Fig. 7 is the number of code division multiplexings assigned to each DDM signal in the transmitting antenna of PL1 polarization, NcPL1 = (1, 0, 1), and is the number of code division multiplexings assigned to each DDM signal in the transmitting antenna of PL2 polarization, NcPL2 = (0, 1, 1). The multiplexing of both signals occurs with the number of code division multiplexings that is non-uniform between the DDM signals, and the number of code division multiplexings is in a range from 1 to N inclusive. CM - 1 included.

[0151] In the example of Fig. 7 Thus, the signals transmitted from the transmitting antennas of the same polarization (e.g., PL1 polarization and PL2 polarization, respectively) are multiplexed and transmitted with the number of code division multiplexing that is non-uniform between DDM signals, and the number of code division multiplexing is in a range from 1 to N inclusive CM - 1 included. The configuration of the CDP amounts, as in Fig. 7 is accordingly an example of a configuration that satisfies condition 2 for both the PL1 polarization and the PL2 polarization.

[0152] Based on the configuration of the CDP amounts in the phase rotation amount setting unit 105 as shown in Fig. 7, an example of a reception signal in the outputs of the Doppler analyzers 210 in a case that, for example, the transmission antenna section 109 in which PL1 polarization is left-hand circular polarization (LC) and PL2 polarization is right-hand circular polarization (RC) is used and the reception antenna section 202 uses an LC-polarization antenna (PL1 polarization) will be described below.

[0153] Fig. Figure 8 illustrates an example of the outputs of the Doppler analyzers 210 for a wave reflected from the target object at a certain distance index. For example, the wave reflected from the target object includes the Doppler frequency of f dtg of the target object. Accordingly, the radar device 10 receives a signal that is dependent on the Doppler shift amount configured in the radar transmitter 100 by f dtg Doppler shifted. Fig. Figure 8 illustrates an example case where the Doppler frequency f dtg the wave reflected from the target object is 0, and a case where f dtg -1 / (2Tr).

[0154] It is pointed out that in Fig. 8 The received power is represented by the size of the black circles (•) and the white circles (◯). The smaller the size of the black circles (•) and the white circles (◯), the lower the received power (for example, the received power is as low as the noise level) (the same notation is used in the configuration examples below).

[0155] In this case, if the reflected wave of the radar transmission wave reflected from the target object includes many scattered waves or is a reflected wave with many reflections, the reflected wave may contain many different polarizations. For this reason, the reception level of the reception signal in the radar device 10 is less likely to vary significantly between reception signals corresponding to differently polarized transmission antennas (e.g., PL1-polarized transmission antenna and PL2-polarized transmission antenna). Thus, the radar device 10 receives the reception signal corresponding to the transmission antenna with RC polarization (PL2 polarization) and the reception signal corresponding to the transmission antenna with LC polarization (PL1 polarization) at approximately the same reception level.

[0156] For example, in the configuration of the CDP amounts, as in Fig. 7, if the received signal does not include a wave reflected from the target object that is cross-polarized with respect to the polarization of the receiving antenna (e.g., LC polarization (PL1 polarization)), no received signal such as that under part (a) of Fig. 8. As under (a) of Fig. As illustrated in Figure 8, the reception levels of the reception signals corresponding to Tx #1 and Tx #2 (PL1 polarization) and Tx #3 and Tx #4 (PL2 polarization), respectively, are substantially the same.

[0157] Furthermore, for example, when the radar device 10 receives a reflected wave of a radar transmission wave that has been specularly reflected from the target object (e.g., from a slightly uneven surface) (e.g., a specular reflection), the reception level may vary between polarized transmission antennas. For example, the reception signal corresponding to the transmission antenna with LC polarization (PL1 polarization) becomes a signal with the same polarization as the reception antenna with LC polarization (PL1 polarization). On the other hand, the reception signal corresponding to the transmission antenna with RC polarization (PL2 polarization), for example, becomes a signal that is cross-polarized with respect to the reception antenna with LC polarization (PL1 polarization). Thus, the reception signal corresponding to the transmission antenna with RC polarization (PL2 polarization) may have a lower reception level (e.g.,By 10 dB or more, depending on the difference in the antenna's cross-polarization, than the received signal corresponding to the transmitting antenna with LC polarization (PL1 polarization). For example, depending on the received SNR, the received signal corresponding to the transmitting antenna with RC polarization (PL2 polarization) may fall below the noise level, making it difficult for the radar device 10 to detect the peak Doppler frequency.

[0158] For example, in the case of Fig. 7, when waves reflected from the target object, wherein the RC polarization (PL2 polarization) is cross-polarized with respect to the polarization of the receiving antenna (e.g., LC polarization (PL1 polarization)), are included, a reception signal such as that under part (b) of Fig. 8. As provided under part (b) of Fig. As shown in Figure 8, the reception levels of the reception signals corresponding to Tx #3 and Tx #4 (PL2 polarization) become lower compared to the reception levels of the reception signals corresponding to Tx #1 and Tx #2 (PL1 polarization).

[0159] Furthermore, for example, when radar device 10 receives a reflected wave of a radar transmission wave that has been specularly reflected from the target object and then further specularly reflected from a surface such as a road (e.g., two specular reflections), the reception level may vary between polarized transmitting antennas. For example, the received signal corresponding to the transmitting antenna with RC polarization (PL2 polarization) becomes a signal with the same polarization as the receiving antenna with LC polarization (PL1 polarization). On the other hand, the received signal corresponding to the transmitting antenna with LC polarization (PL1 polarization), for example, becomes a signal cross-polarized with respect to the receiving antenna with LC polarization (PL1 polarization).For this reason, the received signal corresponding to the transmitting antenna with LC polarization (PL1 polarization) may have a lower reception level than the received signal corresponding to the transmitting antenna with RC polarization (PL2 polarization) (e.g., by 10 dB or more, depending on the cross-polarization discrimination level of the antenna's reception level). For example, depending on the received SNR, the received signal from the transmitting antenna with LC polarization (PL1 polarization) may fall below the noise level, making it difficult for the radar device 10 to detect the peak Doppler frequency.

[0160] For example, in the case of Fig. 7, when reflected waves from the target object, wherein the LC polarization (PL2 polarization) is cross-polarized with respect to the polarization of the receiving antenna (e.g., LC polarization (PL1 polarization)) are included, a reception signal such as that under part (b) of Fig. 8. As described under part (c) of Fig. 8, the reception levels of the reception signals corresponding to Tx #1 and Tx #2 (PL1 polarization) become lower compared to the reception levels of the reception signals corresponding to Tx #3 and Tx #4 (PL2 polarization).

[0161] For example, as described in part (a) of Fig. As shown in Fig. 8, when no reflected wave from the target object is included that is cross-polarized with respect to the polarization of the receiving antenna, the radar device 10 receives the received signal corresponding to each of the transmitting antennas (Tx #3 and Tx #4) with RC polarization (PL2 polarization) and the transmitting antennas (Tx #1 and Tx #2) with LC polarization (PL1 polarization) at almost the same level or at a level within a range of approximately several dB to 6 dB. As in (a) of Fig. 8 Here, the signals transmitted by the number Nt from Tx #1 to Tx #4, which consist of transmitting antennas of RC polarization (PL2 polarization) and transmitting antennas of LC polarization (PL1 polarization), are CDDM-transmitted using CDP amounts that represent the numbers N CDDM(ndm) of coded Doppler multiplexing for the respective DDM signals. Thus, radar device 10 can demultiplex CDDM signals based on the existing demultiplexing operation on CDDM signals (see, for example, PTL 7).

[0162] As provided for in parts (b) and (b) of Fig. 8, the radar device 10 further receives when a wave reflected from the target object that is cross-polarized with respect to the polarization of the receiving antenna receives different CDDM signals (e.g., CDDM signals that satisfy B-1 of Condition 1), provided that the PL2 polarization includes waves reflected from the target object that are cross-polarized (part (b) of Fig. 8) and provided that the PL1 polarization includes waves reflected from the target object that are cross-polarized (part (c) of Fig. 8), to prevent.

[0163] For example, i) under (b) of Fig. 8 a received signal in which the Doppler frequency of the wave reflected from the target object with PL2 polarization is defined as cross polarization f dtg = 0. At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. With respect to the code index assigned to each DDM signal, the Doppler frequency of the target object is -1 / (4Tr) ≤ f dtg < -1 / (4Tr) and CiPL1 = (2, *, 1).

[0164] Furthermore, ii) under (b) of Fig. 8 a received signal in which the Doppler frequency of the wave reflected from the target object, where the PL2 polarization is a cross polarization, f dtg= -1 / (2Tr). At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. With respect to the code index assigned to each DDM signal, the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr) and CiPL1 alias = (1,*,2).

[0165] For example, i) under (c) of Fig. 8 furthermore a received signal in which the Doppler frequency of the wave reflected from the target object with PL1 polarization is defined as cross polarization f dtg = 0. At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. With respect to the code indices assigned to each DDM signal, the Doppler frequency of the target object is -1 / (4Tr) ≤ fdtg < -1 / (4Tr) and CiPL2 = (*, 2, 2).

[0166] Furthermore, ii) under (c) of Fig. 8 a received signal in which the Doppler frequency of the wave reflected from the target object, in which the PL1 polarization is a cross polarization, f dtg = -1 / (2Tr). At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. With respect to the code indices assigned to the DDM signals, the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr) and CiPL2 alias = (*, 1, 1).

[0167] As described above, in a case where the reflected wave from the target object is cross-polarized with respect to the polarization of the receiving antenna, the radar device 10 receives a reflected wave signal that is a CDDM signal that differs in a pattern (e.g., pattern of code indices or code intervals) between a case where the reception level of the reception signal corresponding to the transmitting antenna of the PL1 polarization decreases and a case where the reception level of the reception signal corresponding to the transmitting antenna with the PL2 polarization decreases, even if a DDM signal having a cyclic shift on the Doppler frequency axis by the Doppler frequency of the target object is received.

[0168] Consequently, the radar device 10 becomes capable of determining, for example, based on the detected peaks of the Doppler frequency after code demultiplexing, whether there has been a decrease in the reception level of the reception signal corresponding to the PL1-polarized (e.g., LC-polarized) transmission antenna in the coded Doppler demultiplexer 212, as described later, or a decrease in the reception level of the reception signal corresponding to the PL2-polarized (e.g., RC-polarized) transmission antenna.

[0169] Furthermore, for example, the DDM signals of PL1 polarization are multiplexed and transmitted with the number of code division multiplexings NcPL1 = (1, 0, 1), which is non-uniform between the DDM signals (for example, the number of code division multiplexings is 0 or 1 for three DDM signals, and thus the transmission can be regarded as CDDM transmission, which is non-uniform). For example, in a case where the received signal is determined to be a received signal corresponding to a transmitting antenna with LC polarization (PL1 polarization) based on the result of the determination by the coded Doppler demultiplexer 212, the radar device 10 can demultiplex the CDDM signal by using the existing demultiplexing operation on the CDDM signal.

[0170] Similarly, for example, the DDM signals of PL2 polarization are multiplexed and transmitted with the number of code division multiplexings NcPL2 = (0, 1, 1) that is non-uniform between the DDM signals (for example, the number of code division multiplexings is 0 or 1 for three DDM signals, and thus the transmission can be regarded as CDDM transmission that is non-uniform). Thus, for example, in a case where the received signal is determined to be a received signal corresponding to a transmitting antenna with PL2 polarization based on the result of the determination by the coded Doppler demultiplexer 212, the radar device 10 can demultiplex the CDDM signal using the existing demultiplexing operation on the CDDM signal.

[0171] By operating the coded Doppler demultiplexer 212 as described above, the radar device 10 can determine the Doppler frequency f d of the target object in a range of -1 / (2Tr) ≤ f d< 1 / (2Tr) and obtain an output in which a transmit antenna is assigned to each CDDM signal. <Konfigurationsbeispiel 2>

[0172] Configuration example 2 is a configuration example for the CDP amount in a case where Condition 1 (fulfillment of the condition of the different CDM patterns (B-1 and B-2)) and Condition 2 are met. Fig. Fig. 9 illustrates an example of the configuration of the CDP amount in the phase rotation amount setting unit 105 in a case where the number Nt of the transmitting antennas is 6, N PL1 3 and N PL2 3 is. In Fig. 9, black circles (•) indicate the assignment of CDDM signals to transmit antennas (Tx #1 to #3) of PL1 polarization, and white circles (◯) indicate the assignment of CDDM signals to transmit antennas (Tx #4 and #6) of PL2 polarization.

[0173] In Fig. 9 can also be the number N DMof Doppler multiplexing = 4 and the Doppler shift setting unit 106 can configure four DOP1 to DOP4, for example, with the configuration of a maximum Doppler shift amount with equal intervals as shown in Expression 5. In Fig. 9 are the phase rotation amounts for the application of DOP1 = 0, DOP2 = Δf d , DOP4 = -2Δf d and DOP4= -Δf d φ1 = 0, φ2 = π / 2, φ3 = -π and φ4 = 3π / 2 (φ4 = -π / 2 can also be used). As in Fig. 9 illustrates the Doppler multiplex interval Δf d an equal interval and Δf d = 1 / (8Tr).

[0174] In Fig. 9 is the number Nt of transmitting antennas 6, is the number N DM of Doppler multiplexing 4 and is the number N CM of code multiplexing 2, and therefore the phase rotation amount setting unit 105 can set the numbers N CDDM(ndm) of the coded Doppler multiplexing for the DDM signals can be configured inconsistently (where ndm = 1 to ndm), since Nt < N DM x N CM is.

[0175] As in Fig. 9, the numbers of coded Doppler multiplexing for the DDM signals using four DOP1 to DOP4 as inputted from the Doppler shift setting unit 106 to the encoder 107 are set to N CDDM (1) = 1, N CDDM (2) = 2, N CDDM (3) = 2 and N CDDM (4) = 1. As described above, the phase rotation amount setting unit 105 configures the number of coded Doppler multiplexing for the DDM signals non-uniformly.

[0176] Furthermore, Fig. 9 the Doppler shift setting unit 106 assigns DDM signals to the transmitting antennas Tx #1 to #3 of the PL1 polarization, for which, for example, the Doppler shift amounts DOP1 and DOP2 are used (N DM_PL1= 2), from the DDM signals, where the number N DM of Doppler multiplexing = 4. For example, the phase rotation amount setting unit 105 configures the CDP amounts ψ 1,1 (m), ψ 1,2 (m) and Ψ2,2(m) for Tx #1 to #3 of the PL1 polarization, respectively.

[0177] Furthermore, Fig. 9 the Doppler shift setting unit 106 assigns DDM signals to the transmitting antennas Tx #4 to #6 of the PL2 polarization, for which, for example, the Doppler shift amounts DOP3 and DOP4 are used (N DM_PL2 = 2), from the DDM signals, where the number N DM of Doppler multiplexing = 4. For example, the phase rotation amount setting unit 105 configures the CDP amounts ψ 1, 3 (m), ψ 2, 3 (m) and ψ 1, 4 (m) for Tx #4 to #6 of PL2 polarization.

[0178] In Fig. 9 are the numbers of Doppler multiplexing that the Doppler shift setting unit 106 assigns to the transmitting antennas of the PL1 polarization and the transmitting antennas of the PL2 polarization, N DM_PL1 = N DM_PL2 = 2 and are equal. In addition, the Doppler shift intervals of the DDM signals assigned to Tx #1 to #3 of the PL1 polarization are Δf d (1,2) = Δf d and Δf d (2,1) = 3Δf d , and are the Doppler shift intervals of the DDM signals associated with Tx #4 to #6 of the PL2 polarization, Δf d (3,4) = Δf d and Δf d (4,3) = 3Δf d and are equal (cyclically adjusted).

[0179] Thus, the configuration of the CDP amounts that are in Fig. 9 does not match any of the conditions for DDM patterns under Condition 1A.

[0180] Furthermore, Fig. 9 the code indices assigned to the transmitting antennas of PL1 polarization and the transmitting antennas of PL2 polarization for DDM signals using DOP1 to DOP4 are CiPL1 = (1, 1&2, *, *) and CiPL2 = (*, *, 1&2, 1), respectively, which results in cyclic mismatch and different code index intervals, thus satisfying B-1 of Condition 1.

[0181] Furthermore, Fig. 9, the numbers of code division multiplexing assigned to the transmitting antennas of PL1 polarization and the transmitting antennas of PL2 polarization for DDM signals using DOP1 to DOP4 are NcPL1 = (1, 2, 0, 0) and NcPL2 = (0, 0, 2, 1), respectively, resulting in cyclic mismatch and different numbers of code division multiplexing. Accordingly, B-2 of Condition 1 is satisfied.

[0182] It is noted that in a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg< 1 / (2Tr), the Doppler analyzers 210 described later observe the Doppler frequency with aliasing. In this case, the code indices CiPL1 alias = (2, 1&2, *, *) and CiPL2 alias = (*, *, 1&2, 2), which are different from each other (cyclically mismatched). In the example of Fig. 9, the code indices accordingly exhibit a cyclic mismatch and the code intervals differ in a range of the Doppler frequency of the target object of -1 / (2Tr) ≤ f dtg < -1 / (2Tr) from each other. Accordingly, B-1 and B-2 of Condition 1 are met, and the condition of different CDM patterns is met.

[0183] The configuration of the CDP amounts as in Fig. 9 is thus an example of a configuration that satisfies condition 1.

[0184] Furthermore, in Fig. 9 is the number of code division multiplexing assigned to DDM signals in the transmitting antennas of PL1 polarization, NcPL1 = (1, 2, 0, 0), and is the number of code division multiplexing assigned to DDM signals in the transmitting antennas of PL2 polarization, NcPL2 = (0, 0, 2, 1), and both signals are multiplexed and transmitted with the number of code division multiplexing that is inconsistent between the DDM signals, and is the number of code division multiplexing in a range from 1 to N inclusive CM - 1 included.

[0185] In the example of Fig. 9 Thus, the signals transmitted from the transmitting antennas of the same polarization (e.g., PL1 polarization and PL2 polarization) are multiplexed and transmitted with the number of code division multiplexing that is non-uniform between DDM signals, and the number of code division multiplexing is in a range from 1 to N inclusive CM - 1 included. The configuration of the CDP amounts, as in Fig. 9 is accordingly an example of a configuration that satisfies condition 2 for both the PL1 polarization and the PL2 polarization.

[0186] In a case where the wave reflected from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, according to the configuration of the CDP amounts specified in Fig. 9, the radar device 10 receives the reception signals corresponding to the transmitting antennas of the PL1 polarization and the transmitting antennas of the PL2 polarization, respectively, at substantially the same level or at a level within a range of approximately several dB to 6 dB. In Fig. 9 Here, the signal transmitted by Nt (= 6) transmitting antennas, including transmitting antennas of PL1 polarization and transmitting antennas of PL2 polarization, is CDDM transmitted using CDP amounts that make the numbers of coded Doppler multiplexing for the DDM signals non-uniform.

[0187] Thus, the radar device 10 can demultiplex CDDM signals based on the existing demultiplexing operation on CDDM signals (see, for example, PTL 7).

[0188] For example, in the configuration of the CDP amounts, as in Fig. 9, the radar device 10 receives mutually different CDDM signals (e.g., CDDM signals satisfying B-1 and B-2 of Condition 1) in a case where the wave reflected from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, is included, between a case where the wave reflected from the target object in which the PL2 polarization is cross-polarization is included, as in (a) of Fig. 10, and a case where the wave reflected from the target object, in which the PL1 polarization is a cross polarization, is included as in (b) of Fig. 10 illustrates.

[0189] For example, (a) of Fig. 10 an example of a received signal in which the Doppler frequency of the wave reflected from the target object with PL2 polarization is defined as cross polarization f dtg = 0. At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. The code indices assigned to the DDM signals are CiPL1 = (1, 1 and 2, *, *) when the Doppler frequency of the target object is -1 / (4Tr) ≤ f dtg < -1 / (4Tr). In a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr), the code indices assigned to the DDM signals are CiPL1 alias = (2, 1&2, *, *).

[0190] For example, (b) of Fig. 10 an example of a received signal in which the Doppler frequency of the wave reflected from the target object with PL1 polarization is defined as cross polarization f dtg = 0. At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. The code indices assigned to the DDM signals are CiPL2 = (*, *, 1&2, 1) when the Doppler frequency of the target object is -1 / (4Tr) ≤ f dtg < -1 / (4Tr). In a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr), the code indices assigned to the DDM signals are CiPL2 alias = (*, *, 1&2, 2).

[0191] As described above, in a case where the receiving antenna includes a wave reflected from the target object that is cross-polarized with respect to the polarization (e.g., LC polarization) of the receiving antenna, the radar device 10 receives a reflected wave signal that is a CDDM signal that differs in a pattern (e.g., pattern of code indices or code intervals) between a case where the reception level of the reception signal corresponding to the transmitting antenna with PL1 polarization decreases and a case where the reception level of the reception signal corresponding to the transmitting antenna with PL2 polarization decreases, even if the DDM signal is received with a cyclic shift on the Doppler frequency axis by the Doppler frequency of the target object.

[0192] Consequently, the radar device 10 becomes capable of determining, for example, based on the detected peaks of the Doppler frequency after code demultiplexing, whether there has been a decrease in the reception level of the reception signal corresponding to the PL1-polarized (e.g., LC-polarized) transmission antenna in the coded Doppler demultiplexer 212, as described later, or a decrease in the reception level of the reception signal corresponding to the PL2-polarized (e.g., RC-polarized) transmission antenna.

[0193] Furthermore, for example, the DDM signal of PL1 polarization is multiplexed and transmitted with the number NcPL1 of code division multiplexing = (1, 2, 0, 0) which is non-uniform between the DDM signals (for example, the number of code division multiplexing is 0, 1 or 2 for four DDM signals, and thus the transmission can be regarded as CDDM transmission which is non-uniform).

[0194] For example, in a case where the reception signal is determined to be a reception signal corresponding to a transmission antenna with LC polarization (PL1 polarization) based on the result of the determination by the coded Doppler demultiplexer 212, the radar device 10 may demultiplex the CDDM signal by using the existing demultiplexing operation on the CDDM signal.

[0195] Similarly, for example, the DDM signal of PL2 polarization is multiplexed and transmitted with the number NcPL2 of code division multiplexing = (0, 0, 2, 1), which is non-uniform between the DDM signals (for example, the number of code division multiplexing is 0, 1, or 2 for four DDM signals, and thus the transmission can be regarded as CDDM transmission, which is non-uniform).

[0196] Thus, for example, in a case where the reception signal is determined to be a reception signal corresponding to a transmission antenna with PL2 polarization based on the result of the determination by the coded Doppler demultiplexer 212, the radar device 10 may demultiplex the CDDM signal using the existing demultiplexing operation on the CDDM signal.

[0197] By operating the coded Doppler demultiplexer 212 as described above, the radar device 10 can determine the Doppler frequency f d of the target object in a range of -1 / (2Tr) ≤ f d < 1 / (2Tr) and obtain an output in which a transmit antenna is assigned to each CDDM signal. <Konfigurationsbeispiel 3>

[0198] Configuration example 3 is a configuration example for the CDP amount in a case, in which condition 1 (condition of different CDM patterns) is met and condition 2 is not met. Fig. Fig. 11 illustrates an example of the configuration of the CDP amount in the phase rotation amount setting unit 105 in a case where the number Nt of the transmitting antennas is 3, N PL1 2 and N PL2 1 is. In Fig. 11, black circles (•) indicate the assignment of CDDM signals to transmitting antennas (Tx #1 and Tx #2) of PL1 polarization, and the white circle (◯) indicates the assignment of a CDDM signal to transmitting antenna (Tx #3) of PL2 polarization.

[0199] Furthermore, in Fig. 11 furthermore the number N DM of Doppler multiplexing = 2 and the Doppler shift setting unit 106 can configure two DOP1 and DOP2, for example, with the configuration of a maximum Doppler shift amount with equal intervals, as shown in Expression 5. In Fig. 11 is the phase rotation φ1 for the application of DOP1 = 0 0 and is the phase rotation φ2 for the application of DOP2 = -Δf d-π. As in Fig. 11, the Doppler multiplex interval Δf d an equal interval and is Δf d = 1 / (4Tr).

[0200] In Fig. 11 is the number Nt of transmitting antennas 3, is the number N DM of Doppler multiplexing 2 and is the number N CM of code multiplexing 2, and therefore the phase rotation amount setting unit 105 can set the numbers N CDDM (ndm) of the coded Doppler multiplexing for the DDM signals can be configured inconsistently (where ndm = 1 to ndm), since Nt < N DM x N CM is.

[0201] As in Fig. 11, the numbers of coded Doppler multiplexing for the DDM signal using two DOP1 and DOP2 input from the Doppler shift setting unit 106 to the encoder 107 are N CDDM (L) = 1 and N CDDM(2) = 2. As described above, the phase rotation amount setting unit 105 configures the number of coded Doppler multiplexing for the DDM signals non-uniformly.

[0202] Furthermore, Fig. 11, the unit 106 for determining the Doppler shift Tx #1 and Tx #2 of the PL1 polarization assigns DDM signals, for which, for example, the Doppler shift amounts DOP1 and DOP2 (NDN_PL1 = 2) are used, from the DDM signals, where the number N DM of Doppler multiplexing = 2. For example, the phase rotation amount setting unit 105 configures the CDP amounts ψ1, 1(m) and ψ1, 2(m) for Tx #1 to #2 of the PL1 polarization, respectively.

[0203] Furthermore, Fig. 11 the Doppler shift setting unit 106 Tx #3 of the PL2 polarization assigns a DDM signal for which, for example, the Doppler shift amount DOP2 is used (N OM_PL2 = 1), from the DDM signals with the number N DMof Doppler multiplexing = 2, and the phase rotation amount setting unit 105 configures the CDP amount ψ 2, 2 (m) for Tx #3 of PL2 polarization.

[0204] In Fig. 11 are the numbers of Doppler multiplexing that the Doppler shift setting unit 106 assigns to the transmitting antennas of the PL1 polarization and the transmitting antenna of the PL2 polarization, N DM_PL1 = 2 or N OM_PL2 = 1 and are different numbers of Doppler multiplexing. The configuration of the CDP amounts, as in Fig. 11, is consistent with the condition of different DDM patterns of A-2 in Condition 1.

[0205] Furthermore, Fig. 11 the code indices assigned to the transmitting antennas of PL1 polarization and the transmitting antenna of PL2 polarization for DDM signals using DOP1 and DOP2 are CiPL1 = (1, 1) and CiPL2 = (*, 2), respectively, resulting in cyclic mismatch and different code index intervals.

[0206] Furthermore, in a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr), the Doppler frequency with aliasing is observed in the Doppler analyzers 210, as described later. In this case, the code indices CiPL1 alias = (2,2) and CiPL2 alias = (*,1), which leads to a cyclic mismatch. In the example of Fig. 11, the code indices accordingly exhibit a cyclic mismatch and the code intervals differ in a range of the Doppler frequency of the target object of -1 / (2Tr) ≤ f dtg< -1 / (2Tr) from each other. Accordingly, B-1 of condition 1 is satisfied.

[0207] Furthermore, Fig. 11, the numbers of code division multiplexing assigned to the transmitting antennas of PL1 polarization and the transmitting antenna of PL2 polarization for DDM signals using DOP1 and DOP2 are NcPL1 = (1, 1) and NcPL2 = (0, 1), respectively, resulting in a cyclic mismatch and different numbers of code division multiplexing. Accordingly, B-2 of Condition 1 is satisfied. Thus, the configuration of the CDP amounts specified in Fig. 11, B-1 and B-2 of condition 1 and agrees with the condition of different CDM patterns.

[0208] The configuration of the CDP amounts as in Fig. 11 is thus an example of a configuration that satisfies condition 1.

[0209] Furthermore, in Fig. 11 the number of code division multiplexing assigned to each DDM signal in the transmitting antennas of PL1 polarization, NcPL1 = (1, 1), and the DDM signals are multiplexed and transmitted with a uniform number of code division multiplexings.

[0210] In Fig. 11, on the other hand, is the number of code division multiplexing assigned to each DDM signal in the transmitting antenna of PL2 polarization, NcPL1 = (0, 1) and the DDM signals are multiplexed and transmitted with the number of code division multiplexing that is inconsistent between the DDM signals, and is the number of code division multiplexing in a range from 1 to N inclusive CM - 1 included.

[0211] In the example of Fig. 11 Thus, the signal transmitted from the transmitting antenna of PL2 polarization is multiplexed and transmitted with the number of code division multiplexing which is non-uniform between DDM signals, and the number of code division multiplexing is in a range from 1 to N inclusive CM - 1 included, and the signal transmitted by the transmitting antennas of PL1 polarization is such that the number of code division multiplexing assigned to each DDM signal is uniform. The configuration of the CDP amounts, as in Fig. 11 is thus an example of a configuration that satisfies condition 2 for the PL2 polarization and does not satisfy condition 2 for the PL1 polarization.

[0212] In a case where the wave reflected from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, according to the configuration of the CDP amounts specified in Fig. 11, the radar device 10 receives the reception signals corresponding to each of the transmitting antenna of the PL1 polarization and the transmitting antenna of the PL2 polarization at substantially the same level or at a level within a range of approximately several dB to 6 dB. Fig. 11, here the signal transmitted by Nt (= 3) transmitting antennas composed of the transmitting antennas with PL1 polarization and transmitting antennas with PL2 polarization is CDDM transmitted using CDP amounts that make the numbers of coded Doppler multiplexing non-uniform for DDM signals.

[0213] Thus, the radar device 10 can demultiplex CDDM signals based on the existing demultiplexing operation on CDDM signals (see, for example, PTL 7).

[0214] For example, in the configuration of the CDP amounts, as in Fig. 11, the radar device 10 receives mutually different CDDM signals (e.g., CDDM signals satisfying 1A and 1B of Condition 1) in a case where the wave reflected from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, is included, between a case where the wave reflected from the target object in which the PL2 polarization is cross-polarization is included, as in (a) of Fig. 12, and a case where the wave reflected from the target object, in which the PL1 polarization is a cross polarization, is included as in (b) of Fig. 12 illustrates.

[0215] For example, (a) of Fig. 12 an example of a received signal in which the Doppler frequency of the wave reflected from the target object with PL2 polarization is defined as cross polarization f dtg= 0. At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. The code indices assigned to the DDM signals are CiPL1 = (1, 1) when the Doppler frequency of the target object is -1 / (4Tr) ≤ f dtg < -1 / (4Tr), and the code indices assigned to the DDM signals are CiPL1 alias = (2, 2), if the Doppler frequency of the target object -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr).

[0216] For example, (b) of Fig. 12 an example of a received signal in which the Doppler frequency of the wave reflected from the target object, where the PL1 polarization is a cross polarization, f dtg= 0. At radar device 10, each DDM signal is received with a cyclic shift on the Doppler frequency axis that depends on the Doppler frequency of the target object. The code indices assigned to the DDM signals are CiPL2 = (*, 2) when the Doppler frequency of the target object is -1 / (4Tr) ≤ f dtg < -1 / (4Tr). In a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg < 1 / (2Tr), the code indices assigned to the DDM signals are CiPL2 alias = (*, 1).

[0217] As described above, in a case where the receiving antenna includes a reflected wave from the target object that is cross-polarized with respect to the polarization (e.g., LC polarization) of the receiving antenna, the radar device 10 receives a reflected wave signal that is a CDDM signal that differs in a pattern (e.g., pattern, numbers of Doppler multiplexing, code intervals, or numbers of code division multiplexing) between a case where the reception level of the reception signal corresponding to the transmitting antenna with PL1 polarization decreases and a case where the reception level of the reception signal corresponding to the transmitting antenna with PL2 polarization decreases, even if the DDM signal is received with a cyclic shift on the Doppler frequency axis by the Doppler frequency of the target object.

[0218] Consequently, the radar device 10 becomes capable of determining, for example, based on the detected peaks (e.g., the number of peaks) of the Doppler frequency after code demultiplexing, whether there has been a decrease in the reception level of the reception signal corresponding to the PL1-polarized (e.g., LC-polarized) transmission antenna or a decrease in the reception level of the reception signal corresponding to the PL2-polarized (e.g., RC-polarized) transmission antenna in the coded Doppler demultiplexer 212, as described later.

[0219] Further, for example, the DDM signal of PL1 polarization is multiplexed and transmitted with the number of code division multiplexings NcPL1 = (1, 1), which is uniform between the DDM signals (for example, the number of code division multiplexings is 1 for two DDM signals, and thus the transmission can be regarded as CDDM transmission, which is uniform). For example, in a case where the reception signal is determined to be a reception signal corresponding to a transmission antenna with LC polarization (PL1 polarization) based on the result of the determination by the coded Doppler demultiplexer 212, the radar device 10 can demultiplex the DDM signal by using the existing demultiplexing operation on the DDM signal (see, for example, PTL 5). In this case, the radar device 10 can demultiplex the Doppler frequency f d of the target object in a range of -1 / (2LocN DM_PL1 Tr) ≤ f d < 1 / (2LocN DM_PL1Tr) and obtain an output in which a transmit antenna is assigned to each CDDM signal.

[0220] Furthermore, for example, the DDM signal of PL2 polarization is multiplexed and transmitted with the number of code division multiplexings NcPL2 = (0, 1), which is non-uniform between the DDM signals (for example, the number of code division multiplexings is 0 or 1 for two DDM signals, and thus the transmission can be regarded as CDDM transmission, which is non-uniform). Thus, for example, in a case where the received signal is determined to be a received signal corresponding to a transmitting antenna with PL2 polarization based on the result of the determination by the coded Doppler demultiplexer 212, the radar device 10 can demultiplex the CDDM signal using the existing demultiplexing operation on the CDDM signal.

[0221] By operating the coded Doppler demultiplexer 212 as described above, the radar device 10 can determine the Doppler frequency f d of the target object in a range of -1 / (2LOCN DM_PL1 Tr) ≤ f d < 1 / (2LOCN DM_PL1 Tr) when the received signal is determined as a received signal corresponding to the transmitting antenna of PL1 polarization and can obtain an output in which the transmitting antenna is associated with each CDDM signal.

[0222] Furthermore, in a determination other than the case where the reception signal is determined as a reception signal corresponding to a transmission antenna with PL1 polarization, the radar device 10 may determine the Doppler frequency f d of the target object in a range of -1 / (2Tr) ≤ f d < 1 / (2Tr) and obtain an output where the transmit antenna is assigned to each CDDM signal. <Konfigurationsbeispiel 4>

[0223] In the configuration examples 1 to 3 described above, a configuration example with codes with the number N CM of code multiplexing = 2, but the number of code multiplexing is not limited to N CM = 2 and can be any other value. For example, as in Fig. 13 illustrates, number N CM of code multiplexing = 4.

[0224] Configuration example 4 is a configuration example that satisfies Condition 1 (condition of different DDM patterns and condition of different CDM patterns) and Condition 2 with a code length of 4. The following describes an example of configuring the CDP amount in the phase rotation amount setting unit 105 in a case where the number N CM of code multiplexing = 4.

[0225] Fig. Fig. 13 illustrates an example of the configuration of the CDP amount in the phase rotation amount setting unit 105 in a case where the number Nt of the transmitting antennas is 6, N PL1 3 and N PL2 3 is. In Fig. 13, black circles (•) indicate the assignment of CDDM signals to transmit antennas (Tx #1 to #3) of PL1 polarization, and white circles (◯) indicate the assignment of CDDM signals to transmit antennas (Tx #4 and #6) of PL2 polarization.

[0226] Furthermore, in Fig. 13 the number N DM of Doppler multiplexing = 2 and the Doppler shift setting unit 106 can configure two DOP1 and DOP2, for example, with the configuration of a maximum Doppler shift amount with equal intervals, as shown in Expression 5. In Fig. 13 is the phase rotation φ1 = 0 for the application of DOP1 = 0 and is phase rotation φ2 = -π for the application of DOP2 = -Δf d . As in Fig. 13 illustrates that the interval Δf d between DDM signals is equal and is Δf d = 1 / (4Tr).

[0227] Furthermore, in Fig. 13 the number N CM of code multiplexing 4 and the encoder 107 uses, for example, orthogonal code sequences of Walsh-Hadamard codes with a code length Loc = 4, such as Code1 = {1, 1, 1, 1}, Code2 = {1, -1, 1, -1}, Code3 = {1, 1, -1, -1} and Code4 = {1, -1, -1, 1}.

[0228] In Fig. 13, the phase rotation amount setting unit 105 configures the CDP amounts ψ 1, 1 (m), ψ 1, 2 (m) and ψ 2, 2 (m) for Tx #1 to Tx #3 of the PL1 polarization and configures the CDP amounts ψ 2, 1 (m), ψ 3, 1 (m) and ψ 4, 1 (m) for Tx #4 to Tx #6 of the PL2 polarization. In Fig. 13 are the numbers of Doppler multiplexing that the Doppler shift setting unit 106 assigns to the transmitting antennas of the PL1 polarization and the transmitting antennas of the PL2 polarization, respectively, N DM_PL1 = 2 or N DM_PL2 = 1 and are different numbers of Doppler multiplexing. The configuration of the CDP amounts, as in Fig. 13, is consistent with the condition of different DDM patterns of A-2 in Condition 1.

[0229] Furthermore, Fig. 13 The code indices assigned to the transmit antennas of PL1 polarization and the transmit antennas of PL2 polarization for DDM signals using DOP1 and DOP2 are CiPL1 = (1, 1&2) and CiPL2 = (2&3&4, *), respectively, resulting in a cyclic mismatch and different code index intervals. In Fig. 13, the numbers of code division multiplexing assigned to the transmitting antennas of PL1 polarization and PL2 polarization for DDM signals using DOP1 and DOP2 are NcPL1 = (1, 2) and NcPL2 = (3, 0), respectively, which results in cyclic mismatch and different numbers of code division multiplexing. Thus, the configuration of the CDP amounts specified in Fig. 13, B-1 and B-2 of condition 1 and agrees with the condition of different CDM patterns.

[0230] The configuration of the CDP amounts as in Fig. 13 is thus an example of a configuration that satisfies condition 1.

[0231] Furthermore, in Fig. 13 is the number of code division multiplexing assigned to each DDM signal in the transmitting antenna of PL1 polarization, NcPL1 = (1, 2), and is the number of code division multiplexing assigned to each DDM signal in the transmitting antenna of PL2 polarization, NcPL2 = (3, 0), and both signals are multiplexed and transmitted with the number of code division multiplexing that is inconsistent between the DDM signals, and is the number of code division multiplexing in a range from 1 to N inclusive CM - 1 (= 3) included.

[0232] Furthermore, Fig. 13 the signals transmitted from the transmitting antennas of PL1 polarization and PL2 polarization are multiplexed and transmitted with the numbers of code division multiplexing that are non-uniform between the DDM signals, and the number of code division multiplexing n is in a range from 1 to N inclusive CM - 1 included. The configuration of the CDP amounts, as in Fig. 13 is accordingly an example of a configuration that satisfies condition 2 for both the PL1 polarization and the PL2 polarization.

[0233] The above description describes an example of configuring the CDP amount in the phase rotation amount setting unit 105. [Configuration of the radar receiver 200]

[0234] In Fig. 4, the radar receiver 200 includes a receiving antenna section 202 with Na receiving antennas Rx #1 to Rx #Na. The radar receiver 200 further includes Na antenna system processors 201-1 to 201-Na, a constant false alarm rate (CFAR) section 211, a coded Doppler multiplexer 212, and a direction estimator 213. Note that the Na antenna system processors 201-1 to 201-Na, the CFAR section 211, the coded Doppler demultiplexer 212, and the direction estimator 213 may be collectively referred to as a receiving circuit. Note that the receiving circuit estimates the target direction based on a reflected wave signal, which is a transmitted signal reflected from a target object.

[0235] The receiving antennas Rx #1 to Rx #Na of the receiving antenna section 202 each receive a reflected wave signal, which is a radar transmission signal reflected from a target object (target), and output the received wave signal to the corresponding antenna system processor 201 as a received signal.

[0236] Each of the antenna system processors 201 includes a receiving radio unit 203 and a signal processor 206.

[0237] Signals received by Na receiving antennas Rx #1 to Rx #Na are output to Na receiving radio units 203, respectively. Furthermore, the output signals from Na receiving radio units 203 are output to Na signal processors 206, respectively.

[0238] Each of the receiving radio units 203 includes a mixer 204 and a low-pass filter (LPF) 205. The mixer 204 mixes the received reflected wave signal with a chirp signal, which is a transmission signal, input from the radar transmission signal generator 101. For example, the receiving radio unit 203 passes the output of the mixer 204 through the LPF 205. As a result, a beat signal is output whose frequency varies depending on a delay time of the reflected wave signal. For example, the difference in frequency between the chirp transmission signal (frequency-modulated transmission wave), which is the transmission signal (radar transmission wave), and the chirp reception signal (received frequency-modulated wave), which is the reception signal (radar reflected wave), is obtained as the beat frequency.

[0239] In each antenna system processor 201-z (where z is any one from 1 to Na), the signal processor 206 includes an analog-to-digital (A / D) converter (207), a beat frequency analyzer (208), an output switch 209, and Doppler analyzers 210.

[0240] The signal output from the LPF 205 (e.g., beat signal) is converted into separately sampled data by the A / D converter 207 in the signal processor 206.

[0241] The beat frequency analyzer 208 performs frequency analysis processing (e.g., FFT processing) to the N data Elements of the obtained separately sampled data within a specified time range (range gate) for each transmission period Tr. The signal processor 206 thus outputs a frequency spectrum in which a peak occurs at a beat frequency depending on the delay time of the reflected wave signal (radar reflected wave).

[0242] Here, the beat frequency response output from the beat frequency analyzer 208 in the z-th signal processor 206 and obtained by the m-th chirp pulse transmission is called “RFT z (f b , m)”. Here f denotes b the beat frequency index and corresponds to an FFT index (bin number). For example, f b = 0 ..., is(N data / 2) - 1, z = 1 to Na and m = 1 to NC. A beat frequency with a smaller beat frequency index f b indicates a shorter delay time of the reflected wave signal (e.g. a shorter distance to the target object).

[0243] Furthermore, a beat frequency index f b using the following expression 10 in distance information R(f b ). Thus, the beat frequency index f b hereinafter also referred to as “distance index f b " designated.

[10] R(fb)=C02Bwfb

[0244] Here B denotes w a frequency modulation bandwidth within the range gate for a chirp signal and C0 denotes the speed of light. Furthermore, C0 / (2B w ) in expression 10 is the distance resolution.

[0245] The output switch 209 performs selective switching to output the output of the beat frequency analyzer 208 for each transmission period to the OC_INDEX-th Doppler analyzer 210 among the Loc Doppler analyzers 210 based on an orthogonal code element index OC_INDEX input from the encoder 107 of the phase rotation amount setting unit 105.

[0246] The signal processor 206 includes Loc Doppler analyzers 210-1 to 210-Loc. For example, the data is input via the output switch 209 to the noc-th Doppler analyzer 210 in each of the Loc transmission periods (Loc x Tr). Accordingly, the noc-th Doppler analyzer 210 performs Doppler analyses for each distance index f. b using data from Ncode transmission periods between Nc transmission periods (e.g. using the beat frequency response RFT z (f b , m) input from the beat frequency analyzer 208). Here, noc is an index of the code element and noc = 1 to Loc.

[0247] For example, if Ncode is a power of 2, FFT processing is applicable in Doppler analysis. In this case, the FFT size is Ncode and is a maximum Doppler frequency derived from the sampling theorem at which no aliasing occurs, ±1 / (2Loc x Tr). In addition, the Doppler frequency interval for the Doppler frequency index f is s 1 / (Ncode x Loc x Tr) and is the range of the Doppler frequency index f s f s = -Ncode / 2 ... 0 ... Ncode / 2 - 1.

[0248] The following is an example description of a case where Ncode is a power of 2. Note that when Ncode is not a power of 2, data is padded with zero, e.g., to enable FFT processing, where the data size (FFT size) is equal to the power of 2.

[0249] For example, an output VFT z noc (f b , f s) of the Doppler analyzer 210 of the z-th signal processor 206 is given by the following expression 11. Note that j is the imaginary unit and z = 1 to Na.

[11] VFT2noc(fb,fs)=∑s=0Ncode−1RFTz(fb,LOC×s+noc)exp[−j2πsfsNcode]

[0250] The processing in each component of the signal processor 206 has been described above. [Example Operation of CFAR Section 211]

[0251] In Fig. 4, the CFAR section 211 performs the CFAR processing (e.g., determining the adaptive thresholds) using the outputs of Loc Doppler analyzers 210 of the first to Na-th signal processors 206, respectively, and extracts distance indices (hereinafter referred to as f b_cf referred to) and Doppler frequency indices (hereinafter referred to as f s_cf ) that provide peak signals. CFAR Section 211 introduces the power summation of the VFT outputs z noc (fb , f s ) of Doppler analyzers 210 in the first to Na-th signal processors 206, and two-dimensional CFAR processing with the distance axis and the Doppler frequency axis (corresponding to the relative velocity) or CFAR processing which is a combination of one-dimensional CFAR processing (e.g., the processing mentioned in NPL 2 can be applied).

[0252] For example, if the phase shift amount φ ndm for the application of the Doppler shift amount DOP ndm determined with Expression 5, the intervals between the Doppler shift amounts in the Doppler frequency domain output by Doppler analyzers 210 are equal intervals and ΔFD = Ncode / N DM, when intervals ΔFD of the Doppler shift magnitudes are represented by the intervals of the Doppler frequency indices. Accordingly, in the outputs of the Doppler analyzers 210, a peak is detected for each DDM signal at an interval of ΔFD in the Doppler frequency domain.

[0253] Accordingly, as indicated in the following Expression 12, the CFAR section 211 may perform power addition (e.g., called "Doppler domain compression") on the outputs of Doppler analyzers 210 while adjusting the peak positions of Doppler-multiplexed signals to the respective ranges resulting from dividing the Doppler shift amounts by the range of the interval ΔFD. Subsequently, the CFAR section 211 may perform CFAR processing (e.g., "CFAR processing for Doppler domain compression"). In the reception processing, f sc = -ΔFD / 2 ... -ΔFD / 2 - 1. For example, in the case of ΔFD = Ncode / N DM, f sc = Ncode / (2N DM ) ... Ncode / (2N DM ) - 1. It should be noted that the CFAR processing for Doppler domain compression is described in, for example, PTL 6 and PTL 7, and a detailed description of this processing is omitted.

[12] PowerFT(fb,fsc)=∑nfd=1NDM∑2=1Na∑noc=1Loc|VFTznoc(fb,fsc+(nfd−ceil(NDM2)−1)×ΔFD)|2

[0254] For example, the CFAR section 211, which uses the Doppler domain CFAR processing, adaptively configures a threshold and outputs f b_cf , f sc_cf and information on received power PowerFT(f b_cf , f sc_cf + (nfd - ceil(N DM / 2 - 1) × ΔFD (where nfd = 1 ... N DM )) for Doppler frequency indices (f sc_cf + (nfd - ceil(N DM / 2) - 1) × ΔFD) of N DMDDM signals to the coded Doppler demultiplexer 212 that provide a received power above the threshold. [Example operation of the coded Doppler demultiplexer 212]

[0255] Next, an exemplary operation of the coded Doppler demultiplexer 212 as shown in Fig. 4. The following describes an example of the processing by the coded Doppler demultiplexer 212 when the CFAR section 211 uses CFAR processing for Doppler domain compression. Fig. 14 is a flowchart showing an example of demultiplexing operation in the coded Doppler demultiplexer 212. <Schritt A-1 >

[0256] The coded Doppler demultiplexer 212 performs coded Doppler demultiplexing for Nt CDDM signals, assuming the case that the wave reflected from the target object, the PL2 polarization, is cross-polarized with respect to the polarization of the receiving antenna, is not included.

[0257] For example, the coded Doppler demultiplexer 212 demultiplexes Nt CDDM transmitted signals and performs discrimination (e.g., determination or identification) of the transmitting antenna and discrimination of the Doppler frequency (e.g., Doppler velocity or relative velocity), wherein the outputs of the Doppler analyzers 210 are based on f b_cf and f sc_cf and the received power information for the Doppler frequency indices of the N DM -Signals entered from CFAR Section 211.

[0258] As described above, when the encoder 107 of the phase rotation amount setting unit 105 uses, for example, the equal-interval Doppler shift amount configuration, including the maximum Doppler shift amount configuration, at least one of the N DM -Numbers N CDDM (1), N CDDM (2) ... N CDDM (N DM ) of the coded Doppler multiplexing to a value less than N CM (configures the number of coded Doppler multiplexing to a non-uniform value) instead of all N CM Numbers of coded Doppler multiplexing on N CM to be determined.

[0259] For example, the coded Doppler demultiplexer 212 (1) performs code demultiplexing, detects a CDDM signal in which the number of coded Doppler multiplexing is set to less than N CMis determined (e.g., an unused CDDM signal not used for multiplexed transmission) and performs aliasing determination. Then, the coded Doppler demultiplexer 212 (2) performs Doppler code demultiplexing of CDDM signals used for multiplexed transmission based on the result of the aliasing determination.

[0260] The operation of the coded Doppler demultiplexer 212 as described above is identical to the operation of the coded Doppler demultiplexer in a MIMO radar using an existing coded Doppler multiplex transmission and is described, for example, in PTL 7, so a detailed description of the operation is omitted.

[0261] It should be noted that in a case where the configuration of a Doppler shift amount with equal intervals, including the configuration of a maximum Doppler shift amount with equal intervals, for example, not all of the N DM Numbers N CDDM (1), N CDDM (2) ... and N CDDM (N DM ) of coded Doppler multiplexing on N CM and at least one number of coded Doppler multiplexing is set to a value less than N CM is set, the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) can be detected by the operation of the coded Doppler demultiplexer 212 as described above (see, for example, PTL 7). <Schritt A-2>

[0262] The coded Doppler demultiplexer 212 determines whether Nt CDDM signals were detected normally. If Nt CDDM signals are detected normally, the coded Doppler demultiplexer 212 performs the processing in step A-3, and if the Nt CDDM signals are detected abnormally, the coded Doppler demultiplexer 212 performs the processing in step B-1.

[0263] For example, in the processing of step A-1, if the wave reflected from the target object includes PL1 polarization or PL2 polarization, which is cross-polarization with respect to the polarization of the receiving antenna, there is a possibility that the Nt CDDM signals are not detected normally.

[0264] For example, in a case where a polarimetric MIMO radar is configured using transmitting antennas with two polarizations of PL1 polarization and PL2 polarization, the configuration of the phase rotation amount setting unit 105 is N DM_PL1 < N DM or N DM_PL2 < N DM , and the wave reflected from the target object, in which PL1 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is included, a component in which the received power is different by a value greater than or equal to a predetermined value, or a component in which the received power is as low as the noise level is included, among the received powers for the Doppler frequency indices of N DM DDM signals. In such a case, the coded Doppler demultiplexer detects 212 CDDM signals less than N DMand thus determines that the detection is abnormal and performs the processing in step B-1.

[0265] Further, for example, in a case where the configuration of the phase rotation amount setting unit 105 is N DM_PL1 = N DM for the transmitting antennas of the PL1 polarization and the wave reflected from the target object, wherein the PL2 polarization is a cross-polarization with respect to the polarization of the receiving antenna, or in a case where the configuration of the unit 105 for setting the phase rotation amount N DM_PL2 = N DM = N DMfor the transmitting antennas of the PL2 polarization and the wave reflected from the target object, where the PL1 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is included, the received power is received within a predetermined range, among the received powers for the Doppler frequency indices of N DM DDM signals.

[0266] In this case, the number of unused CDDM signals not used for multiplexing will be larger than the expected number (N CM × N DM - Nt) during code demultiplexing processing, and thus the coded Doppler demultiplexer 212 fails in aliasing determination, making it difficult to normally detect Nt CDDM signals.

[0267] Accordingly, the coded Doppler demultiplexer 212 determines that the detection is abnormal when the number of unused CDDM signals not used for multiplex transmission is greater than the expected number (N CM × N DM - Nt) and performs the processing in step B-1. <Schritt A-3>

[0268] The coded Doppler demultiplexer 212 outputs a received signal Y z (f b_cf , f sc_cf , ncm, ndm) resulting from the CDDM demultiplexing processing based on the result of the aliasing determination on the CDDM signal used for multiplex transmission, together with f b_cf and f sc_cf to the direction estimator 213.

[0269] Here are Y z (f b_cf , f sc_cf , ndc(ndm), ndm) Outputs (e.g. CDDM demultiplexing results) for f b_cf and f sc_cfresulting from the demultiplexing of the Doppler analyzers 210 in the z-th antenna system processor 201 on the CDDM signals with DOP ndm and the orthogonal code ndc(ndm) For example, Y z (f b_cf , f sc_cf , ndc(ndm), ndm) represent received signals transmitted from the transmitting antenna Tx #[ndc(ndm), ndm], is reflected from the target object and is received by the z-th antenna system processor 201.

[0270] It is noted that z = 1 to Na and ncm = 1 to N CM . Furthermore, ndm = 1 for N DM and ndc(ndm) = 1 for N CDDM (ndm).

[0271] Furthermore, the coded Doppler demultiplexer 212 can output information about the Doppler frequency of the detected target object to the direction estimator 213.

[0272] It is noted that in cases where condition 2 is satisfied, the coded Doppler demultiplexer 212 can detect the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) is estimated based on the aliasing determination result. <Schritt B-1 >

[0273] The coded Doppler demultiplexer 212 performs CDDM demultiplexing on N PL1 -CDDM signals, assuming the case that the wave reflected from the target object, where the PL2 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is included.

[0274] For example, the coded Doppler demultiplexer demultiplexes 212 N PL1CDDM transmitted signals and performs discrimination (e.g., determination or identification) of the transmitting antenna and discrimination of the Doppler frequency (e.g., Doppler velocity or relative velocity), wherein the outputs of the Doppler analyzers 210 are based on f b_cf and f sc_cf and the received power information for the Doppler frequency indices of the N DM -Signals entered from CFAR Section 211.

[0275] Here, there is a case where the received power is greater than or equal to a predetermined value among the received powers for the Doppler frequency indices of N DM DDM signals is different, or a case where (N DM - N OM_PL1) Components having a reception power as low as the noise level are included. It should be noted that in a case where the configuration of the phase rotation amount setting unit 105 N DM = N DM_PL1 a component with a received power as low as the noise level is not included.

[0276] Accordingly, the coded Doppler demultiplexer 212 extracts, for example, the upper N DM_PL1 DDM signals in terms of power from the received powers for the Doppler frequency indices of the N DM DDM signals.

[0277] For example, in a case where the Doppler multiplex interval of the extracted upper N DM_PL1DDM signals in terms of power matches the Doppler multiplexing interval assigned to the transmitting antennas of PL1 polarization, the coded Doppler demultiplexer 212 (1) performs code demultiplexing to detect a CDDM signal (e.g., an unused CDDM signal not used for multiplex transmission of the transmitting antenna with PL1 polarization) with respect to which the number of coded Doppler multiplexing is set to less than N CM is determined, among the CDDM signals assigned to the transmitting antennas with PL1 polarization to perform aliasing determination. Subsequently, the coded Doppler demultiplexer 212 (2) performs Doppler code demultiplexing on the CDDM signals used for multiplexed transmission based on the result of the aliasing determination.

[0278] The operation of the coded Doppler demultiplexer 212 as described above is identical to the operation of the coded Doppler demultiplexer in a MIMO radar using an existing coded Doppler multiplex transmission and is described, for example, in PTL 7, so a detailed description of the operation is omitted.

[0279] It should be noted that by configuring the CDP amounts that satisfy condition 2, for example, the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) can be detected by the operation of the coded Doppler demultiplexer 212 described above (see, for example, PTL 7). <Schritt B-2>

[0280] The coded Doppler demultiplexer 212 determines whether N PL1 CDDM signals that support the N PL1 transmitting antennas corresponding to the PL1 polarization are normally detected. In a case where NPL1 CDDM signals are normally detected, the coded Doppler demultiplexer 212 performs the processing in step B-3, and in a case where the N PL1 If CDDM signals are not detected normally, the coded Doppler demultiplexer 212 performs the processing in step C-1. By configuring the CDP amount by the phase rotation amount setting unit 105 to satisfy Condition 1, the following determination processing can be performed.

[0281] For example, in the processing of step B-1, if the wave reflected from the target object, in which the PL2 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is not included, there is a possibility that N PL1 CDDM signals are not detected normally.

[0282] For example, the coded Doppler demultiplexer 212 determines that the wave reflected from the target object, in which the PL2 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is not included when the power difference (or power ratio) between the extracted upper N DM_PL1 DDM signals in terms of power and the other (N DM - N DM_PL1 ) lower power DDM signals are not greater than or equal to a predetermined level, and performs the processing in step C-1.

[0283] In a case where the configuration of the CDP amounts by the phase rotation amount setting unit 105 (A-2) satisfies the condition 1A, the coded Doppler demultiplexer 212 may perform such determination processing.

[0284] In a case where the Doppler multiplex intervals of the extracted upper N DM_PL1DDM signals do not match in power with the Doppler multiplexing intervals assigned to the transmitting antennas of PL1 polarization, the coded Doppler demultiplexer 212 determines that a wave reflected from the target object in which the PL2 polarization is a cross-polarization with respect to the receiving antenna is not included, and performs the processing in step C-1.

[0285] In a case where the configuration of the CDP amounts by the phase rotation amount setting unit 105 (A-1) or (A-3) satisfies the condition 1A, the coded Doppler demultiplexer 212 may perform such determination processing.

[0286] For example, the configuration of the phase rotation amount setting unit 105 is N DM_PL1 = N DM_PL2for the transmitting antennas of the PL1 polarization. In this case, if the wave reflected from the target object, in which the PL1 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is included, the received power is received within a given range, from the received powers for the Doppler frequency indices of the N DM DDM signals. In such a case, during code demultiplexing, a signal is obtained with a code interval or the number of code multiplexing that differs from the assumed N PL1 CDDM signals, and thus the coded Doppler demultiplexer 212 fails to determine the aliasing, making it difficult to determine the N PL1 CDDM signals normally. In such a case, the coded Doppler demultiplexer 212 determines that the detection of the N PL1 CDDM signals are not normal and performs the processing in step C-1.

[0287] In a case where the configuration of the CDP amounts by the phase rotation amount setting unit 105 (B-1) or (B-2) satisfies the condition 1B, the coded Doppler demultiplexer 212 may perform such determination processing. <Schritt B-3>

[0288] The coded Doppler demultiplexer 212 outputs receive signals YPL1 z (f b_cr , f sc_cf , ncm, ndm) resulting from the CDDM demultiplexing processing based on the processing result of step B-2 on the CDDM signals for the multiplex transmission of N PL1 Transmitting antennas corresponding to the PL1 polarization to the direction estimator 213 together with f b_cf and f sc_cf out of.

[0289] This is YPL1 z (f b_cr , f sc_cf , ndc(ndm), ndm) Outputs (e.g. CDDM demultiplexing results) for f b_cf and f sc_cfresulting from the demultiplexing of the Doppler analyzers 210 in the z-th antenna system processor 201 on the CDDM signals with DOP ndm and the orthogonal code ndc(ndm) For example, YPL1 z (f b_cr , f sc_cf , ndc(ndm), ndm) represent received signals from N PL1 Transmitting antennas Tx #[ndc(ndm), ndm] corresponding to the PL1 polarization are transmitted, reflected by the target object, and received by the z-th antenna system processor 201. Note that z = 1 to Na, ndm = 1 to N DM , ndc(ndm) = 1 to N CDDM (ndm) and other signals than those that the N PL1 Signals assigned to transmitting antennas corresponding to PL1 polarization are output as zero.

[0290] Furthermore, the coded Doppler demultiplexer 212 can output the Doppler frequency of the detected target object to the direction estimator 213.

[0291] It is noted that in cases where condition 2 is satisfied, the coded Doppler demultiplexer 212 can detect the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) is estimated based on the aliasing determination result. <Schritt C-1 >

[0292] The coded Doppler demultiplexer 212 performs CDDM demultiplexing on N PL2 CDDM signals, assuming the case that the wave reflected from the target object, the PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna.

[0293] For example, the coded Doppler demultiplexer demultiplexes 212 N PL2CDDM transmitted signals and performs discrimination (e.g., determination or identification) of the transmitting antenna and discrimination of the Doppler frequency (e.g., Doppler velocity or relative velocity), wherein the outputs of the Doppler analyzers 210 are based on f b_cf and f sc_cf and the received power information for the Doppler frequency indices of the N DM -signals that are the outputs of CFAR Part 211.

[0294] Here, there is a case where the received power is greater than or equal to a predetermined value among the received powers for the Doppler frequency indices of N DM DDM signals is different, or a case where (N DM - N DM_PL2) Components having a reception power as low as the noise level are included. It should be noted that in a case where the configuration of the phase rotation amount setting unit 105 N DM = N DM_PL2 a component with a received power as low as the noise level is not included.

[0295] Accordingly, the coded Doppler demultiplexer 212 extracts, for example, the upper N DM_PL2 DDM signals in terms of power from the received powers for the Doppler frequency indices of the N DM DDM signals.

[0296] For example, in a case where the Doppler multiplex interval of the extracted upper N DM_PL2DDM signals in terms of power matches the Doppler multiplexing interval assigned to the transmitting antennas of PL2 polarization, the coded Doppler demultiplexer 212 (1) performs code demultiplexing to detect a CDDM signal (e.g., an unused CDDM signal not used for multiplex transmission of the transmitting antenna with PL2 polarization) with respect to which the number of coded Doppler multiplexing is set to less than N CM is determined, among the CDDM signals assigned to the transmit antennas with PL2 polarization to perform aliasing determination. Then, the coded Doppler demultiplexer 212 (2) performs Doppler code demultiplexing on the CDDM signals used for multiplexed transmission based on the result of the aliasing determination.

[0297] The operation of the coded Doppler demultiplexer 212 as described above is identical to the operation of the coded Doppler demultiplexer in a MIMO radar using an existing coded Doppler multiplex transmission and is described, for example, in PTL 7, so a detailed description of the operation is omitted.

[0298] It should be noted that by configuring the CDP amounts that satisfy condition 2, for example, the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) can be detected by the operation of the coded Doppler demultiplexer 212 described above (see, for example, PTL 7). <Schritt C-2>

[0299] The coded Doppler demultiplexer 212 determines whether N PL2 CDDM signals that support the N PL2 transmitting antennas corresponding to the PL2 polarization are normally detected. In a case where NPL2 CDDM signals are normally detected, the coded Doppler demultiplexer 212 performs the processing in step C-3, and in a case where N PL1 When CDDM signals are not normally detected, the coded Doppler demultiplexer 212 performs the processing in step D. This is because the coded Doppler demultiplexer 212 considers the received signal to have a high noise component (e.g., low SNR) or to include an interference component.

[0300] For example, the coded Doppler demultiplexer 212 determines that the wave reflected from the target object, in which the PL1 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is not included when the power difference (or power ratio) between the extracted upper N DM_PL2 DDM signals in terms of power and the other (N DM - N DM_PL2) lower power DDM signals are not greater than or equal to a predetermined level, and performs the processing in step D.

[0301] In a case where the Doppler multiplex intervals of the extracted upper N DM_PL2 DDM signals do not match in power with the Doppler multiplexing intervals assigned to the transmitting antennas of PL2 polarization, the coded Doppler demultiplexer 212 determines that a wave reflected from the target object in which the PL1 polarization is cross-polarization with respect to the receiving antenna is not included, and performs the processing in step D.

[0302] Furthermore, the coded Doppler demultiplexer 212 determines, for example, whether the code intervals or the numbers of code division multiplexing match the code intervals or the numbers of code division multiplexing determined by the N PL2CDDM signals are expected based on the reception powers of signals obtained by performing code division multiplexing on the extracted upper N DM_PL2 DDM signals are obtained in terms of power. In a case where the code intervals or the numbers of code division multiplexing do not match, it is determined that the reflected wave from the target object, in which PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna, is not included, and the processing in step D is performed. <Schritt C-3>

[0303] The coded Doppler demultiplexer 212 outputs received signals YPL2 z (f b_cf , f sc_cf , ncm, ndm) resulting from the CDDM demultiplexing based on the processing result of step C-2 on the CDDM signals for the multiplex transmission of N PL2Transmitting antennas corresponding to the PL2 polarization to the direction estimator 213 together with f b_cf and f sc_cf out of.

[0304] Here is YPL2 z (f b_cf , f sc_cf , ndc(ndm), ndm) Outputs (e.g. CDDM demultiplexing results) for f b_cf and f sc_cf resulting from the demultiplexing of the Doppler analyzers 210 in the z-th antenna system processor 201 on the CDDM signals with DOP ndm and the orthogonal code ndc(ndm) For example, YPL2 z (f b_cf , f sc_cf , ndc(ndm), ndm) represent received signals from N PL2 Transmitting antennas Tx #[ndc(ndm), ndm] corresponding to the PL2 polarization are reflected from the target object and received by the z-th antenna system processor 201. Note that z = 1 to Na, ndm = 1 to N DM , ndc(ndm) = 1 to N CDDM (ndm) and other signals than those that the N PL2Signals assigned to transmitting antennas corresponding to PL2 polarization are output as zero.

[0305] Furthermore, the coded Doppler demultiplexer 212 can output the Doppler frequency of the detected target object to the direction estimator 213.

[0306] It is noted that in cases where condition 2 is satisfied, the coded Doppler demultiplexer 212 can detect the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) is estimated based on the aliasing determination result. <Schritt D>

[0307] In a case where the condition of step C-2 is not satisfied, the coded Doppler demultiplexer 212 may determine that the received signal is a noise component or an interference component and may not output the received signal to the direction estimator 213.

[0308] An example of the operation of the coded Doppler demultiplexer 212 has been described above.

[0309] It is noted that in a case where a plurality of f b_cf , Doppler frequency index f sc_cf and received power information input from the CFAR section 211, the coded Doppler demultiplexer 212 may perform the above-described CDDM demultiplexing operation multiple times for, for example, each of the distance index, the Doppler frequency index, and the received power information. [Example operation of the direction estimator 213]

[0310] Next, an exemplary operation of the direction estimator 213 as shown in Fig. 4 illustrates and describes.

[0311] The direction estimator 213 performs, for example, processing for target object direction estimation based on a signal input from the coded Doppler demultiplexer 212 (e.g., fb_cf , Receive signal Y z (f b_cf , f sc_cf , ndc(ndm), ndm) or YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm), which has undergone CDDM demultiplexing. Here, q = 1 to NPL.

[0312] It should be noted that since the received signal Y z (f b_cf , f sc_cf , ndc(ndm), ndm), on which the CDDM demultiplexing is to be performed, is a received signal from a transmitting antenna for which the CDP magnitude ψ ndc(ndm) , ndm (m) is used, Y z (f b_cf , f sc_cf , ndc(ndm), ndm) Tx #1, Tx #2 ... and Tx #Nt. Accordingly, the CDP amount ψ ndc(ndm) , ndm (m) in the received signal Y z (f b_cf , f sc_cf , ndc(ndm), ndm) also as “YT z (f b _ cf , f sc_cf, nt)" assigned to one of Tx #1 to Tx #Nt. Here, nt = 1 to Nt.

[0313] Analogously, the CDP amount ψ ndc(ndm) , ndm (m) in the received signals YPLq,(f b_cf , f sc_cf , ndc(ndm), ndm) also as “YPLT z (f b _ cf , f sc_cf , nt)” assigned to one of Tx #1 to Tx #Nt.

[0314] An example operation 1 and an example operation 2 of the direction estimator 213 are described below. <Beispielbetrieb 1 des Richtungsschätzers 213>

[0315] For example, in Example Operation 1, the direction estimator 213 generates the virtual receive array correlation vector h(f b_cf , f sc_cf ) of the direction estimator 213 based on f b_cf and the received signal Y z (f b_cf , f sc_cf, ndc(ndm), ndm) at which the CDDM demultiplexing processing was performed, and performs direction estimation processing.

[0316] Here, the information input from the coded Doppler demultiplexer 212 includes a CDDM demultiplexed receive signal for Nt transmit antennas when the receive signal Y z (f b_cf , f sc_cf , ndc(ndm), ndm) that has undergone CDDM demultiplexing. For this reason, the virtual receive array correlation vector h(f b_cf , f sc_cf ) Nt × Na elements, which is the product of the number Nt of transmitting antennas and the number Na of receiving antennas. Based on the phase difference between the transmitting / receiving antennas, the direction estimator 213 performs a direction estimation of the reflected wave signal from the target object, using the virtual receiving array correlation vector (f b_cf , f sc_cf) is used.

[0317] For example, to perform the direction estimation processing, the direction estimator 213 extracts, for each polarization antenna, received signals corresponding to transmitting antennas of the same polarization from the virtual receive array correlation vector h(f b_cf , f sc_cf ) and generates the virtual receive array correlation vector h PLq (f b_cf , f sc_cf ) through the transmitting antennas of the PLq polarization. Here, h PLq (f b_cf , f sc_cf ) a column vector containing N PLq × Contains Na elements.

[0318] The direction estimator 213 calculates the spatial profile of the PLq polarization by varying the azimuth direction θ u within a given angle range in the direction estimation evaluation function P H-PLq (θ u , f b_cf , f sc_cf ), e.g., using the virtual receive array correlation vector h PLq(f b_cf , f sc_cf ) by the transmitting antennas of the PLq polarization.

[0319] The direction estimator 213 can extract a predefined number of maximum peaks of the spatial profile for each calculated PLq polarization in descending order and can output the azimuth direction of the maximum peaks as arrival direction estimates (e.g., positioning outputs) of the PLq polarizations. Here, q = 1 to NPL.

[0320] It is noted that depending on the incidence direction estimation algorithm, there are various methods for the direction estimation evaluation function value P H-PLq (θu, f b_cf , f sc_cf ). For example, an estimation method using an array antenna as disclosed in NPL 3 may be used.

[0321] By using a virtual MIMO receiving antenna array in which the antennas are arranged in a rectangular grid, it is further possible to estimate the azimuth direction of arrival and the elevation direction. For example, the direction estimator 213 can calculate the azimuth direction and the elevation direction as the estimated direction of arrival for each transmitting antenna with different polarizations and output the azimuth direction and the elevation direction as the position output. Note that the same applies to Example Operation 2 of the direction estimator 213, which will be described later.

[0322] Through the above operation, the direction estimator 213 of the radar device 10 can output, for example, the incidence direction estimation value based on f b_cf and the received signal Y z (f b_cf , f sc_cf, ndc(ndm), ndm) which has undergone CDDM demultiplexing as the positioning output. In addition, the direction estimator 213 can use f b_cf and output the Doppler frequency estimate of the target object. Note that the same applies to Example Operation 2 of the direction estimator 213, which will be described later.

[0323] In addition, f b_cf after conversion to distance information using Expression 10. Note that the same applies to Example Operation 2 of the direction estimator 213, which will be described later.

[0324] Furthermore, in a case where multiple information items (e.g., f b_cf and received signal Y z (f b_cf , f sc_cf, ndc(ndm), ndm) on which the CDDM demultiplexing was performed) input from the coded Doppler demultiplexer 212, calculate the arrival direction estimate for each of them in the same manner as the processing described above, and output the positioning results. Note that the same applies to Example Operation 2 of the direction estimator 213, which will be described later. <Beispielbetrieb 2 des Richtungsschätzers 213>

[0325] For example, in Example Operation 2, the direction estimator 213 generates the virtual receive array correlation vector hq(f b_cf , f sc_cf , ndc(ndm), ndm) of the direction estimator 213 based on f b_cf and the received signals YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) that have undergone CDDM demultiplexing, and performs the direction estimation processing on the antenna transmission of the PLq polarization.

[0326] The direction estimator 213 performs the direction estimation processing for the PLq polarization corresponding to q, which is consistent with the polarization of the received signal YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) that has undergone CDDM demultiplexing, which is different from the operation in Example Operation 1. The operation in this case is the same as the processing in which Y z (f b_cf , f sc_cf , ndc(ndm), ndm) in the operation of the example operation 1 by the received signal YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) and thus the detailed description of the operation is omitted.

[0327] Through the above operation, the direction estimator 213 of the radar device 10 can output, for example, as a positioning output, the arrival direction estimation value based on f b_cf and YPLq z (f b_cf , f sc_cf, ndc(ndm), ndm), which is a received signal obtained by performing CDDM demultiplexing on a received signal from a transmitting antenna with PLq polarization.

[0328] The above describes Example Operation 1 and Example Operation 2 of the direction estimator 213.

[0329] The direction estimator 213 can perform the direction estimation processing based on the output according to the demultiplexing operation of the coded Doppler demultiplexer 212 by the operation described above.

[0330] For example, the direction estimator 213 may perform the direction estimation processing based on the output of the coded Doppler demultiplexer 212 in each of the cases where a wave reflected from the target object that is cross-polarized with respect to the polarization of the receiving antenna is not included, a wave reflected from the target object where the PL2 polarization is cross-polarized with respect to the polarization of the receiving antenna is included, and a wave reflected from the target object where the PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna is included.

[0331] For example, in the case where the reflected wave from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, is not included, the direction estimator 213 may further perform direction estimation processing for each of the polarizations included in the transmitting antennas. For example, in the case where the reflected wave from the target object, where the PL2 polarization is cross-polarized with respect to the polarization of the receiving antenna, is included, the direction estimator 213 may further perform direction estimation processing on the PL1 polarization transmission. For example, in the case where the reflected wave from the target object, where the PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna, is included, the direction estimator 213 may further perform direction estimation processing on the PL2 polarization transmission.

[0332] By operating the direction estimator 213 as described above, a direction estimation processing result is obtained for each transmission polarization or a direction estimation result for a portion of the transmission polarizations depending on the reflected wave situation, and a direction estimation result is obtained depending on the transmission polarization. Since the response of the reflected waves from the target object may vary depending on the transmission polarization, the radar device 10 can improve the detection or identification performance with respect to the target object based on such direction estimation results that depend on the transmission polarization.

[0333] The example operation of the direction estimator 213 was described above.

[0334] As described above, in the present embodiment, the radar device 10 assigns CDDM signals that differ between polarizations and satisfy at least Condition 1 in the phase rotation amount setting unit 105 in a polarimetric transmission MIMO radar using CDDM (e.g., signals where at least one of the DDM pattern and the CDM pattern is different). Thus, the radar device 10 can distinguish the transmission antenna in the coded Doppler demultiplexer 212, and CDDM demultiplexing is possible even in a case where the reception levels between reflection waves corresponding to transmission antennas of different polarizations are significantly different. Therefore, according to the present embodiment, it is possible to prevent deterioration of target detection performance, misestimation of the Doppler frequency, or deterioration of angle measurement performance.

[0335] In addition, for example, when assigning the CDDM signal in the phase rotation amount setting unit 105 while satisfying the above-described condition 1 and condition 2, the radar device 10 can set the Doppler frequency range f d , in which the detection can be successful, to a range of -1 / (2Tr) ≤ f d < 1 / (2Tr), which is similar to the range in the case where a single transmitting antenna is used, even in the case where the reception levels between reflection waves corresponding to transmitting antennas with different polarizations are significantly different.

[0336] For this reason, according to the present embodiment, it is possible to improve the detection performance of a polarimetric MIMO radar using coded Doppler multiplex transmission.

[0337] In the present embodiment, the radar device 10 further includes a receiving antenna that receives a reflected wave signal of a radar transmission signal reflected from a target object using one of a plurality of polarizations (e.g., PL1 polarization and PL2 polarization). Then, the radar device 10 performs direction estimation based on the reflected wave signal received by the receiving antenna. Thus, the radar device 10 can distinguish the transmission antenna corresponding to the DDM signal and resolve the Doppler frequency ambiguity even when a reflected wave having a cross-polarization relationship with the polarization of the receiving antenna is included.Furthermore, in the present embodiment, CDDM demultiplexing is possible even when the receiving antenna is a receiving antenna having the same polarization, and it is not necessary to additionally use a receiving antenna having a different polarization type in the radar receiver 200, and the number of receiving antennas can be reduced. (Variation 1)

[0338] In the embodiment described above, an example operation of the CFAR section 211, the coded Doppler demultiplexer 212, and the direction estimator 213 in the case where a plurality of receiving antennas of the receiving antenna section 202 are receiving antennas having the same polarization has been described by way of example.

[0339] The plurality of receiving antennas of the receiving antenna section 202 may include receiving antennas with different polarizations. In Modification 1, an example operation of the CFAR section, the coded Doppler demultiplexer, and the direction estimator will be described in the case where the plurality of receiving antennas of the receiving antenna section 202 include receiving antennas with different polarizations.

[0340] For example, if the plurality of receiving antennas includes receiving antennas with different polarizations, the reception level of the reflected waves from the target object may differ significantly for each polarization. For this reason, the radar device 10 may individually perform, for example, CFAR processing, Doppler separation processing, and direction estimation processing for the outputs (e.g., reflected wave signals received by the receiving antennas of the polarizations, respectively) of the Doppler analyzers 210 corresponding to the receiving antennas with different polarizations. Furthermore, the direction estimation processing may be performed using the output of the Doppler separation processing by receiving antennas of a plurality of polarizations.

[0341] The following describes, as an example, the case where the receiving antenna section 202 includes receiving antennas with at least two different polarizations, from Rx #1 to Rx #Na.

[0342] For example, two different polarizations are called "RxPL1 polarization" and "RxPL2 polarization." Furthermore, the number of receiving antennas consisting of Na receiving antennas with RxPL1 polarization is N RxPL1 and the number for RxPL2 polarization is NRxPL2. Here, N RxPL1 + NRxPL2 = Na.

[0343] Fig. 15 is a block diagram showing an example configuration of CFAR sections 211a, Doppler demultiplexers 212a, and direction estimators 213a of a radar receiver 200a in the radar device 10 according to Modification 1. In Fig. 15 are the receiving antennas Rx #1 to Rx #N RxPL1 for example, receiving antennas of RxPL1 polarization and are Rx #N RxPL1+1 to Rx #Na receive antennas of RxPL2 polarization. It should be noted that the relationship between the number of receive antennas and polarizations does not apply to the Fig. 15 is limited to the example illustrated.

[0344] As in Fig. 15, Doppler demultiplexing is possible using peak detection results of the receiving antennas having the same polarization, and since power addition operations between receiving antennas having different polarizations do not need to be performed, a reduction in the computational load in the radar receiver 200a can be achieved.

[0345] For example, from the outputs of the Na Doppler analyzers 210, the outputs from first to N RxPL1-th Doppler analyzers 210 apply the received signals to receiving antennas with RxPL1 polarization and are input to a first CFAR section 211a-1, which performs CFAR processing on the received signals with the RxPL1 polarization.

[0346] For example, from the outputs of the Na Doppler analyzers 210, the outputs of Rx #N RxPL1 +1 to Na-th Doppler analyzers 210 are applied to the received signals with RxPL2 polarization and are input to a second CFAR section 211a-2, which performs CFAR processing on the received signals with the RxPL2 polarization.

[0347] The first coded Doppler demultiplexer 212a-1, for example, based on f b_cf , f sc_cf and reception power information PowerFT RxPL1 (f b_cf , f sc_cf + (nfd - ceil(N DM / 2) - 1) x ΔFD) (where nfd = 1 to N DM ) for the Doppler frequency index (f sc_cf + (nfd - ceil(N DM / 2) - 1) × ΔFD) of the N DM DDM signals input from, for example, the first CFAR section 211a-1, demultiplexes Nt CDDM transmitted signals using the outputs of the first to N RxPL1 Doppler analyzers 210, which are received signals from the transmitting antennas of the RxPL1 polarization, and performs a discrimination (e.g., also referred to as determination or identification) of the transmitting antenna and a discrimination of the Doppler frequency (e.g., also referred to as Doppler velocity or relative velocity). The operation of the first coded Doppler demultiplexer 212a-1 thus differs from the operation of the coded Doppler demultiplexer 212 of Fig. 4, that the operation of the first coded Doppler demultiplexer 212a-1 uses the received power information based on the outputs of the first to N RxPL1-th Doppler analyzers 210, and the other operations may be identical to the operation of the coded Doppler demultiplexer 212.

[0348] The second coded Doppler demultiplexer 212a-2, e.g. based on f b_cf , f sc_cf and reception power information PowerFT RxPL2 (f b_cf , f sc_cf + (nfd - ceil(N DM / 2) - 1) × ΔFD) (where nfd = 1 to N DM ) for the Doppler frequency indices (f sc_cf + (nfd - ceil(N DM / 2) - 1) x ΔFD) of the N DM DDM signals, which are, for example, the outputs of the second CFAR section 211-2, Nt demultiplexes CDDM-transmitted signals using the outputs of the N RxPL1+ 1st to Nath Doppler analyzers 210, which are received signals from the transmitting antennas of the RxPL2 polarization, and performs a discrimination (e.g., also referred to as determination or identification) of the transmitting antenna and a discrimination of the Doppler frequency (e.g., Doppler velocity or relative velocity). The second coded Doppler demultiplexer 212a-2 differs from the coded Doppler demultiplexer 212 in Fig. 4 in that the second coded Doppler demultiplexer 212a-2 uses received power information based on the outputs of the N RxPL1 +1-th to Na-th Doppler analyzers 210, and the other operations may be identical to the operations of the coded Doppler demultiplexer 212.

[0349] Next, an exemplary operation of a first direction estimator 213a-1 and a second direction estimator 213a-2 will be described. Hereinafter, the first direction estimator 213a-1 and the second direction estimator 213a-2 will be collectively referred to as the "y-th direction estimator 213a" and described together. Here, y is 1 or 2. The y-th direction estimator 213a performs, for example, target object direction estimation processing based on the signal input from the y-th coded Doppler demultiplexer 212a.

[0350] An example operation 1 and an example operation 2 of the y-th direction estimator 213a are described below. <Beispielbetrieb 1 des y-ten Richtungsschätzers 213a>

[0351] For example, the y-th direction estimator 213a generates the virtual receive array correlation vector h RxPLy (f b_cf , f b_comp_cf ) of the y-th direction estimator 213a based on f b_cfand the received signal Y z (f b_cf , f sc_cf , ndc(ndm), ndm) that has undergone CDDM demultiplexing, which are signals input from the y-th coded Doppler demultiplexer 212a, and performs direction estimation processing. Here, y is 1 or 2.

[0352] The virtual receive array correlation vector h RxPLy (f b_cf , f b_comp_cf ) includes Nt x N RxPLy elements, which is a product of the number Nt of transmitting antennas and the number N RxPLy of the receiving antennas of the RxPLy polarization. The y-th direction estimator 213a performs a direction estimation based on the phase difference between the transmitting / receiving antennas for the reflected wave signals from the target object, where the virtual receiving array correlation vector h RxPLy (f b_cf , f b_comp_cf ) is used.

[0353] For example, the y-th direction estimator 213a for performing the direction estimation processing for each polarization antenna extracts received signals corresponding to transmitting antennas of the same polarization from the virtual receive array correlation vector h RxPLy (f b_cf , f sc_cf ) and generates the virtual receive array correlation vector h PLq , RxPLy (f b_cf , f sc_cf ) through the transmitting antennas of the PLq polarization. Here, h PLq, RxPLy (f b_cf ,f sc_cf ) a column vector with N PLq x N RxPLy elements.

[0354] For example, the y-th direction estimator 213a may perform the direction estimation processing using the virtual receive array correlation vector h PLq, RxPLy (f b_cf , f sc_cf) through the transmitting antennas of PLq polarization and can output the arrival direction estimation value (e.g., the positioning output) through the receiving antennas of RxPLy polarization for each PLq polarization.

[0355] Through the above operations, y-th direction estimator 213a can, for example, as positioning output, obtain the estimated direction of arrival through the receiving antennas of RxPLy polarization for each differently polarized transmitting antenna for f b_cf and received signal Y z (f b_cf , f sc_cf , ndc(ndm) on which the CDDM demultiplexing was performed, which are signals input from the y-th coded Doppler demultiplexer 212a. In addition, the y-th direction estimator 213a may output f b_cf output as positioning output. <Beispielbetrieb 2 des y-ten Richtungsschätzers 213a>

[0356] For example, the y-th direction estimator 213a generates the virtual receive array correlation vector h PLq , RxPLy (f b_cf , f sc_cf ) by the transmitting antennas of the PLq polarization based on f b_cf and the received signals YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) that have undergone CDDM demultiplexing, which are input from the y-th coded Doppler demultiplexer 212a, and performs direction estimation processing. The y-th direction estimator 213a, for example, performs direction estimation processing of a polarization (PLq polarization) corresponding to q, which is consistent with the polarization of the received signals YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) that have undergone CDDM processing.

[0357] This operation differs from the operation in Example Operation 1 in that the y-th direction estimator 213a performs the direction estimation processing of a polarization (PLq polarization) corresponding to the polarization of the reception signals YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) that have undergone CDDM processing. The operation in this case is the same as the operation in which the processing in which Y z (f b_cf , f sc_cf , ndc(ndm), ndm) in the operation of the example operation 1 by the received signals YPLq z (f b_cf , f sc_cf , ndc(ndm), ndm) and thus the detailed description of the operation is omitted.

[0358] Through the above operation, the y-th direction estimator 213a can, for example, based on reception signals from the transmitting antenna of the PLq polarization for f b_cf and the received signals YPLq z (fb_cf , f sc_cf , ndc(ndm), ndm) subjected to CDDM demultiplexing, which are input from the y-th Doppler demultiplexer 212a, output the arrival direction estimation value through the RxPLq polarization receiving antennas for the PLq polarization transmission as a positioning output. In addition, the y-th direction estimator 213a f b_cf output as positioning output.

[0359] In the above, the example operation 1 and the example operation 2 of the y-th direction estimator 213a are described.

[0360] Through such operations, the y-th direction estimator 213a can obtain the results of the direction estimation processing with the RxPLy-polarized receiving antenna for each transmission polarization or the direction estimation results with the RxPLy-polarized receiving antenna for some transmission polarizations, depending on the reflected wave situation, thereby obtaining direction estimation results that depend on the transmission and reception polarization antennas. Since the response of the reflected waves from the target object may vary depending on the transmission and reception polarizations, the radar device 10 can improve the detection or identification performance with respect to the target object based on such direction estimation results that depend on the transmission and reception polarizations.

[0361] It should be noted that a case has been described here in which the y-th direction estimator 213a performs the processing for target object direction estimation based on the signal input of the y-th coded Doppler demultiplexer 212a (e.g., f b_cf , Receive signal Y z (f b_cf , f sc_cf , ndc(ndm), ndm) that has undergone CDDM demultiplexing, or f sc_cf ) and the output of the Doppler analyzer 210 corresponding to these distances, and performs Doppler demultiplexing indices, but the present invention is not limited thereto.

[0362] For example, the y-th direction estimator 213a may perform the processing of the target object direction estimation based on the signal input of the first coded Doppler demultiplexer 212a-1 and the signal input of the second coded Doppler demultiplexer 212a-2.

[0363] For example, the y-th direction estimator 213a calculates the virtual receive array correlation vector h PL1, RxPL1 (f b_cf , f sc_cf ) based on the received signal transmitted by a transmitting antenna with PL1 polarization and received by a receiving antenna with RxPL1 polarization, using the signal input of the first coded Doppler demultiplexer 212a-1. Further, the y-th direction estimator 213a calculates the virtual receive array correlation vector h PL2, RxPL2 (f b_cf , f sc_cf ) based on the reception signal transmitted from a transmitting antenna with PL2 polarization and received by a transmitting antenna with RxPL2 polarization, using the signal input of the second coded Doppler demultiplexer 212a-2. Thereafter, the y-th direction estimator 213a can perform the target object direction estimation processing based on the virtual receive array correlation vector h PL1, RxPL1 (f b_cf , f sc_cf) and the virtual receive array correlation vector h PL2, RxPL2 (f b_cf , f sc_cf ) carry out.

[0364] For example, the y-th direction estimator 213a calculates the virtual receive array correlation vector h PL2, RxPL1 (f b_cf , f sc_cf ) alternatively, based on the received signal transmitted by a transmitting antenna with PL2 polarization and received by a receiving antenna with PxPL1 polarization, using a signal input of the first coded Doppler demultiplexer 212a-1. Further, the y-th direction estimator 213a calculates the virtual receive array correlation vector h PL1, RxPL2 (f b_cf , f sc_cf) based on the reception signal transmitted from a transmitting antenna with PL1 polarization and received by a transmitting antenna with RxPL2 polarization, using the signal input of the second coded Doppler demultiplexer 212a-2. Further, the y-th direction estimator 213a can perform the target object direction estimation processing based on the virtual receive array correlation vectors h PL2, RxPL1 (f b_cf , f sc_cf ) and h PL1, RxPL2 (f b_cf , f sc_cf ) carry out. (Variation 2)

[0365] Regarding the transmission polarizations of different polarizations, Embodiment 1 described above is described with reference to the example of two polarizations, PL1 polarization and PL2 polarization, which are in an orthogonal polarization relationship. However, the present disclosure is not limited to this, and the number of polarizations may be three or more. For example, in addition to the two polarizations, PL1 polarization and PL2 polarization, which are in an orthogonal polarization relationship, a transmission antenna with a polarization other than PL1 polarization and PL2 polarization may be used.

[0366] For example, the radar device 10 (e.g., the polarimetric MIMO radar) may use Nt transmit antennas, which include transmit antennas with three or more different polarizations, including two polarizations that are in an orthogonal polarization relationship.

[0367] Hereinafter, the first polarization is referred to as PL1 polarization, and the second polarization is referred to as PL2 polarization. The q-th polarization is referred to as PLq polarization. Furthermore, combinations of different polarizations that are in an orthogonal polarization relationship, e.g., PL1 polarization and PL2 polarization, may include right-hand circular polarization and left-hand circular polarization, horizontal polarization and vertical polarization, right-diagonal 45° polarization and left-diagonal 45° polarization.

[0368] Furthermore, the number Nt of transmitting antennas can be set to 3 or higher. For example, the number N DM of Doppler multiplexing ≥ 2 and is the number N CM of code multiplexing ≥ 2. For example, Nt < N DM × N CM . In addition, the number of transmitting antennas with PLq polarization is defined as “N PLq“ Here the number N PLq of PLq polarization antennas N PLq ≥ 1 and Np L1 + N PL2 + ... + NPL_NPL = Nt, where q = 1 to NPL. The transmitting antennas include, for example, N PL1 PL1-polarized antennas and N PL2 PL2-polarized antennas and N PL1 + N PL2 < Nt. In addition, the number of Doppler multiplexing assigned to the transmitting antennas of the PLq polarization is defined as “N DM_PLq “ Here N DM_PLq ≤ N DM .

[0369] The radar device 10 performs CDDM transmission, e.g., using Nt transmit antennas.

[0370] Further, the radar device 10 performs simultaneous multiplex transmission of Nt transmission antennas using CDDM transmission that satisfies Condition 1a and Condition 2a described later for Nt transmission antennas including transmission antennas with PL1 polarization and PL2 polarization that are cross-polarizations with respect to each other, and a transmission antenna with a polarization other than PL1 polarization and PL2 polarization.

[0371] For example, Conditions 1a and 2a are conditions for the case where, in addition to the two polarizations, PL1 polarization and PL2 polarization, which are in an orthogonal polarization relationship, a transmitting antenna with a polarization other than PL1 polarization and PL2 polarization is included. For example, if there is no transmitting antenna with a different polarization besides the transmitting antennas of the two polarizations, PL1 polarization and PL2 polarization, which are in an orthogonal polarization relationship, then Conditions 1a and 2a become equivalent to Conditions 1 and 2.

[0372] For example, the reflected waves corresponding to the radar transmission signals from the transmitting antennas with PL1 polarization and PL2 polarization, which are in an orthogonal polarization relationship, are cross-polarized with respect to the receiving antenna section 202, which may lead to cases where the reception levels of the received signals differ significantly. On the other hand, among the Nt transmitting antennas, the transmitting antennas with a polarization other than PL1 polarization and PL2 polarization do not become an orthogonal polarization relationship with PL1 polarization and PL2 polarization. For this reason, the reflected waves corresponding to the radar transmission signals from the transmitting antennas with other polarizations are less likely to differ significantly in the reception level of the received signals from the receiving antennas corresponding to the transmitting antennas with PL1 polarization and PL2 polarization.

[0373] Thus, for example, in condition 1a, instead of “transmitting antenna with PL1 polarization” in condition 1, the condition “polarization transmitting antenna except transmitting antennas with PL2 polarization (e.g. (Nt - N PL2 ))" can be used. Likewise, in condition 1a, instead of the "transmitting antenna with PL2 polarization" in condition 1, the condition "polarization transmitting antenna except transmitting antennas with PL1 polarization (e.g. (Nt - N PL1 ))" be used.

[0374] Furthermore, for example, in Condition 2a, instead of “a transmitting antenna with the same polarization” in Condition 2, the condition “any of a polarization transmitting antenna other than a PL2 polarization antenna and a polarization transmitting antenna other than a PL1 polarization antenna” may be used.

[0375] For example, condition 1a and condition 2a can be defined as follows. <Bedingung 1a>

[0376] For example, the phase rotation amount setting unit 105 configures the CDP amount ψ for each of a polarization transmitting antenna other than PL2 polarization and a polarization transmitting antenna other than PL1 polarization. ndc(ndm), ndm (m) that satisfies a condition of a different DDM pattern (e.g., an allocation pattern of a Doppler shift amount), a condition of a different CDM pattern (e.g., the numbers of code division multiplexing differ between DDM signals), or a condition of a different pattern of Doppler division multiplexing and code division multiplexing. <Bedingung 2a>

[0377] The multiplex transmission of each of the signals transmitted from the polarization transmission antenna other than the PL2 polarization antenna and the polarization transmission antenna other than the PL1 polarization antenna is performed with the numbers of code division multiplexing that are non-uniform between the DDM signals, and the numbers of code division multiplexing include any of the ranges from 1 to N inclusive. CM - 1.

[0378] By applying a CDP amount that satisfies the above condition 1a to the transmitting antenna, the radar device 10 achieves the following effects.

[0379] For example, the Doppler frequency of the received signal includes the coded Doppler phase shift at the time of transmission, as described above, and also includes the Doppler frequency of an unknown target object. For this reason, the intervals between the DDM signals can be maintained while their Doppler frequencies can change in a positive or negative direction. For example, by satisfying condition 1A of condition 1a (e.g., at least one of A-1, A-2, or A-3), the radar device 10 can distinguish between a case where a CDDM signal assigned to a transmitting antenna with PL1 polarization is not received and a case where a CDDM signal assigned to a transmitting antenna with PL2 polarization is not received, because the intervals or the number of Doppler multiplexing for the DDM signals are different in these cases.

[0380] For example, by satisfying 1B of condition 1a (e.g., at least one of B-1 or B-2), the radar device 10 can distinguish between a case where a CDDM signal assigned to a transmission antenna with PL1 polarization is not received and a case where a CDDM signal assigned to a transmission antenna with PL2 polarization is not received, because the code intervals or the numbers of code division multiplexing at which the reception level becomes high are different after each DDM signal is code division multiplexed.

[0381] Thus, to satisfy condition 1a, by configuring the CDP amounts by the phase rotation amount setting unit 105, the radar device 10 can demultiplex CDDM signals and prevent the deterioration of positioning performance and radar detection performance even in cases where the reception levels vary significantly between reception signals corresponding to transmission antennas of different polarizations.

[0382] By satisfying Condition 2a in addition to Condition 1a, the configuration of the CDP amounts by the phase rotation amount setting unit 105 further enables the Doppler frequency range in which detection can be performed in the radar device 10 to be -1 / (2Tr) ≤ f d < 1 / (2Tr); thus, it is possible to extend the range to a range equivalent to the Doppler detection range in the case of a transmitting antenna.

[0383] The following describes an example of the CDP amount configuration in the phase rotation amount setting unit 105. <Konfigurationsbeispiel 5>

[0384] Fig. Fig. 16 illustrates an example of the configuration of the CDP amount in the phase rotation amount setting unit 105 in a case where the number Nt of the transmitting antennas is 6, N PL1 = 2, N PL2 = 2 and NPL3 = 3.

[0385] In Fig. In Figure 16, the black circles indicate the assignment of CDDM signals to the transmit antennas (Tx #1 and Tx #2) of PL1 polarization, the white circles indicate the assignment of CDDM signals to the transmit antennas (Tx #3 and Tx #4) of PL2 polarization, and the shaded circles indicate the assignment of CDDM signals to the transmit antennas (Tx #5 and Tx #6) of PL3 polarization (e.g., vertical (V) polarization). For example, PL1 polarization and PL2 polarization are polarizations that are orthogonal to each other. For example, PL1 polarization can be LC polarization, and PL2 polarization can be RC polarization. In addition, the PL3 polarization can be a polarization (e.g., vertical (V) polarization) that does not become an orthogonal polarization with respect to the PL1 polarization and the PL2 polarization.

[0386] In Fig. 16 can also be the number N DMof Doppler multiplexing = 4 and the Doppler shift setting unit 106 can configure four DOP1 to DOP4, for example, with the configuration of a maximum Doppler shift amount with equal intervals, as illustrated in Expression 5. In Fig. 16, the phase rotation amount φ1 = 0 for the application of DOP1 = 0, the phase rotation amount φ2 = π / 2 for the application of DOP2 = Δf d , the phase shift amount φ3 = π for the application of DOP3 = -2Δf d and the phase rotation amount φ4 = 3π / 2 (φ4 = -π / 2 can be used) for application of DOP4 = -Δf d . As in Fig. 16, the interval (also called Doppler multiplex interval, Doppler shift interval or Doppler interval) Δf d between DDM signals an equal interval and is Δf d = 1 / (8Tr).

[0387] In Fig. 16 is the number N CMof code multiplexing 2 and the encoder 107 uses, for example, Code1 = {1, 1} and Code2 = {1, -1}, which are orthogonal code sequences with code length Loc = 2.

[0388] In Fig. 16 is the number Nt of transmitting antennas 6, is the number N DM of Doppler multiplexing 4 and is the number N CM of code multiplexing 2, and therefore the phase rotation amount setting unit 105 can set the numbers N CDDM (ndm) of the coded Doppler multiplexing for the DDM signals can be configured inconsistently (where ndm = 1 to ndm), since Nt < N DM × N CM is.

[0389] As in Fig. 16, the numbers of coded Doppler multiplexing for the DDM signals using four DOP1 to DOP4, as inputted from the Doppler shift setting unit 106 to the encoder 107, are N CDDM (L) = 2, N CDDM (2) = 1, N CDDM (3) = 2 or N CDDM(4) = 1. As described above, the phase rotation amount setting unit 105 configures the number of coded Doppler multiplexing for the DDM signals non-uniformly.

[0390] In Fig. 16, the Doppler shift setting unit 106 for the transmitting antennas Tx #1 and Tx #2 of the PL1 polarization assigns DDM signals for which, for example, the Doppler shift amounts DOP2 and DOP3 are used (N OM_PL1 = 2), from the DDM signals with the number N DM of Doppler multiplexing = 4, assigns DDM signals for Tx #3 and TD #4 of the PL2 polarization, for example, the Doppler shift amounts DOP3 and DOP4 are used (N DM_PL2 = 2), from the DDM signals with the number N DM of Doppler multiplexing = 4, and assigns DDM signals for Tx #5 and Tx #6 of the PL3 polarization, for which, for example, the Doppler shift amount DOP1 is used (N DM_PL2 = 1), from the DDM signals with the number N DMof Doppler multiplexing = 4.

[0391] The phase rotation amount setting unit 105 configures, for example, the CDP amounts ψ 2, 2 (m) and ψ 1, 3 (m) for Tx #1 and Tx #2 of the PL1 polarization, the CDP values ​​ψ 2, 3 (m) and ψ 2, 4 (m) for Tx #3 and Tx #4 of the PL2 polarization and the CDP values ​​ψ 1, 1 (m) and ψ 2, 1 (m) for Tx #5 or Tx #6 of the PL3 polarization.

[0392] For example in Fig. 16, the number of Doppler multiplexing that the Doppler shift setting unit 106 assigns to the transmitting antennas (transmitting antennas of PL1 polarization and PL3 polarization) other than the transmitting antenna of PL2 polarization is 3, and the number of Doppler multiplexing that the Doppler shift setting unit 106 assigns to the transmitting antennas (transmitting antennas of PL2 polarization and PL3 polarization) other than the transmitting antenna of PL1 polarization is 3, and these numbers are equal.

[0393] Furthermore, the Doppler shift intervals of the DDM signals assigned to the transmitting antennas except the transmitting antenna of PL2 polarization are Δf d (1,2) = Δf d , Δf d (2,3) = Δf d and Δf d (3,1) = 2Δf d , and are the Doppler shift intervals of the DDM signals associated with the transmitting antennas other than the transmitting antenna of PL1 polarization, Δf d (1,3) = 2Δf d , Δfd (3,4) = Δf d and Δf d (4,1) = Δf d , and are cyclically consistent and identical and thus do not satisfy the condition of different DDM patterns of 1A in Condition 1a.

[0394] It should be noted that the code indices assigned to the transmitting antennas (PL1 polarization and PL3 polarization) except for the transmitting antennas with PL2 polarization for DOP1 to DOP4 are represented as “CiNoPL2”. Fig. 16, CiNoPL2 = (2, 1, 1, *). Furthermore, the code indices assigned to the transmitting antennas (PL2 polarization and PL3 polarization) except for the PL1 polarization transmitting antennas for DOP1 to DOP4 are represented as "CiNoPL1". In the case of Fig. 16 is CiNoPL1 = (2, *, 1, 1).

[0395] It should be noted that the numbers of code division multiplexing assigned to the transmitting antennas (PL1 polarization and PL3 polarization) other than the PL2 polarization transmitting antennas for DOP1 to DOP4 are represented as “NcNoPL2”. Fig. 16, NcNoPL2 = (2, 1, 1, 0). Furthermore, the numbers of code division multiplexing assigned to the transmitting antennas (PL2 polarization and PL3 polarization transmitting antennas) other than the PL1 polarization transmitting antennas for DOP1 to DOP4 are represented as "NcNoPL1." In the case of Fig. 16 is NcNoPL1 = (2, 0, 1, 1).

[0396] As described above, the code indices assigned to the DDM signals for the transmitting antennas other than the transmitting antennas of PL2 polarization and the transmitting antennas other than the transmitting antennas of PL1 polarization are CiNoPL2 = (2, 1, 1, *) and CiNoPL1 = (2, *, 1, 1), respectively, and the code indices are cyclically mismatched and the code index intervals are different, and thus B-1 of Condition 1a is satisfied.

[0397] Furthermore, numbers of code division multiplexing assigned for DDM signals to the transmitting antennas other than the transmitting antennas of PL2 polarization and the transmitting antennas other than the transmitting antennas of PL1 polarization are NcNoPL2 = (2, 1, 1, 0) and NcNoPL1 = (2, 0, 1, 1), respectively, which results in cyclic mismatch and satisfies B-2 of Condition 1a.

[0398] In a case where the Doppler frequency of the target object is -1 / (2Tr) ≤ f dtg < -1 / (4Tr) or 1 / (4Tr) ≤ f dtg< 1 / (2Tr), the Doppler analyzers 210 described later observe the Doppler frequency with aliasing. In this case, the code indices CiNoPL2 alias = (1, 2, 2, *), CiNoPL1 alias = (1, *, 2, 2) and are different from each other (cyclically mismatched). In the example of Fig. 16, the code indices accordingly exhibit a cyclic mismatch and the code intervals differ in a range of the Doppler frequency of the target object of -1 / (2Tr) ≤ f dtg < -1 / (2Tr) from each other.

[0399] Accordingly, 1B satisfies condition 1a, and the condition of different CDM patterns is satisfied.

[0400] The configuration of the CDP amounts as in Fig. 16 is thus an example of a configuration that satisfies condition 1a.

[0401] In Fig. 16 is further the number of code division multiplexing assigned to each DDM signal in the transmitting antenna other than the transmitting antenna of PL2 polarization, NcNoPL2 = (2, 1, 0), and is the number of code division multiplexing assigned to each DDM signal in the transmitting antenna other than the transmitting antenna of PL1 polarization, NcNoPL1 = (2, 0, 1, 1), and in both cases, the multiplex transmission is performed with numbers of code division multiplexing that are non-uniform between the DDM signals, and the numbers of code division multiplexing are in a range from 1 to N inclusive. CM - 1 included.

[0402] In the example of Fig. 16, the signals transmitted from the transmitting antennas other than the transmitting antennas of PL2 polarization and the transmitting antennas other than the transmitting antennas of PL1 polarization are multiplexed and transmitted with the numbers of code division multiplexing that are non-uniform between the DDM signals, and the numbers of code division multiplexing are in a range from 1 to N inclusive. CM - 1 included. The configuration of the CDP amounts as in Fig. 16 is thus an example of a configuration that satisfies condition 2a.

[0403] In a case where the wave reflected from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, according to the configuration of the CDP amounts specified in Fig. 16, the radar device 10 receives the reception signals corresponding respectively to the transmitting antennas (Tx #1 and Tx #2) of the PL1 polarization, the transmitting antennas (Tx #3 and Tx #4) of the PL2 polarization, and the transmitting antennas (Tx #5 and Tx #6) of the PL3 polarization, at substantially the same level or at a level within a range of approximately several dB to 6 dB. In Fig. 16, the signals transmitted from Tx #1 to Tx #6, which consist of Nt (= 6) transmitting antennas with PL1 polarization, PL2 polarization, and PL3 polarization, are transmitted by CDDM transmission using CDP amounts that make the numbers of coded Doppler multiplexing for the DDM signals non-uniform.

[0404] Thus, the radar device 10 can demultiplex CDDM signals based on the existing demultiplexing operation on CDDM signals.

[0405] For example, in the configuration of the CDP amounts, as in Fig. 16, the radar device 10 receives mutually different CDDM signals (e.g., CDDM signals satisfying 1B of Condition 1a) in a case where the wave reflected from the target object, which is cross-polarized with respect to the polarization of the receiving antenna, is included, between a case where the wave reflected from the target object in which the PL2 polarization is cross-polarization is included, as in (a) of Fig. 17, and a case where the wave reflected from the target object, in which the PL1 polarization is a cross polarization, is included as in (b) of Fig. 17 illustrates.

[0406] As described above, in a case where the reflected wave from the target object which is cross-polarized with respect to the polarization of the receiving antenna is included, the radar device 10 receives reflected wave signals including Doppler frequency components having mutually different patterns of between a case as shown in (a) of Fig. 17, wherein the reception levels of the reception signals corresponding to the transmission antennas of the PL2 polarization decrease (e.g., corresponding to a case where reflection waves corresponding to transmission antennas other than the transmission antennas of the PL2 polarization are received), and a case as in (b) of the Fig. 17, wherein the reception levels of the reception signals corresponding to the transmission antennas of the PL1 polarization decrease (e.g., corresponding to a case where reflection waves corresponding to transmission antennas other than the transmission antennas of the PL1 polarization are received).

[0407] Thus, a radar device 10 can determine, for example, in a coded Doppler demultiplexer 212, based on the detected peak of the Doppler frequency after code demultiplexing, whether a reception level decrease of a reception signal corresponding to a transmission antenna with PL1 polarization (e.g., LC polarization) has occurred or whether a reception level decrease of a reception signal corresponding to a transmission antenna with PL2 polarization (e.g., RC polarization) has occurred.

[0408] For example, the DDM signals of polarizations other than PL2 polarization are code multiplexed with non-uniform numbers of code multiplexing between N DM DDM signals are sent (the numbers of code division multiplexing cover a range from 1 to N CM - 1).

[0409] For example, in a case where the reception signals are determined to be reception signals corresponding to transmission signals of the polarization transmission antennas other than the PL2 polarization transmission antennas based on the determination result by the coded Doppler demultiplexer 212, the radar device 10 may demultiplex the CDDM signals using the existing demultiplexing operation on the CDDM signal.

[0410] Similarly, for example, the DDM signals of polarizations other than the PL1 polarization are multiplexed and transmitted with the numbers of code division multiplexing specified under the N DM DDM signals are non-uniform (the number of code multiplexing covers a range from 1 to N CM - 1).

[0411] For example, in a case where the reception signals are determined to be reception signals corresponding to transmission signals of the polarization transmission antennas other than the PL1 polarization transmission antennas based on the detection result by the coded Doppler demultiplexer 212, the radar device 10 may demultiplex the CDDM signals using the existing demultiplexing operation on the CDDM signals.

[0412] By operating the coded Doppler demultiplexer 212 as described above, the radar device 10 can determine the Doppler frequency f d of the target object in a range of -1 / (2Tr) ≤ f d < 1 / (2Tr) and obtain an output in which a transmit antenna is assigned to each DDM signal.

[0413] The above description describes an example of configuring the CDP amount in the phase rotation amount setting unit 105. [Example operation of the coded Doppler demultiplexer 212]

[0414] In a case where, in addition to the two polarizations of PL1 polarization and PL2 polarization, which are in orthogonal polarization relationship, a transmitting antenna with a polarization different from PL1 polarization and PL2 polarization, and a transmitting antenna with a polarization different from PL1 polarization and PL2 polarization (e.g., PL3 polarization) is used, a DDM signal to which the CDP amount configured by the phase rotation amount setting unit 105 is applied can be demultiplexed by the operation of the coded Doppler demultiplexer 212 as follows. An operation of the coded Doppler demultiplexer 212 according to Modification 2, which is different from the operation in the above-described embodiment, will be described below.

[0415] In Variation 2, the operations in step B and step C of the demultiplexing operation on the CDDM signal in the coded Doppler demultiplexer 212 differ, as shown in Fig. 14 illustrates the operations in the above-described embodiment as follows. <Schritt B-1 >

[0416] When demultiplexing the CDDM signal in the coded Doppler demultiplexer 212, as shown in Fig. 14, the CDDM demultiplexing for N PL1 PL1 polarizations, but in variation 2, CDDM demultiplexing is performed on DDM signals from polarization transmit antennas other than (Nt - N PL2 ) PL2 polarizations. The other operations are identical, so their description is omitted. <Schritt B-2>

[0417] The coded Doppler demultiplexer 212 determines whether the (Nt - N PL2 ) CDDM signals that represent the (Nt - N PL2) transmitting antennas other than the transmitting antenna assigned to the PL2 polarization can be detected normally. In a case where the (Nt - N PL2 ) CDDM signals are normally detected, the coded Doppler demultiplexer 212 performs the processing in step B-3, and in a case where the (Nt - N PL2 ) CDDM signals are not normally detected, the coded Doppler demultiplexer 212 performs the processing in step C-1.

[0418] For example, in the processing of step B-1, if the wave reflected from the target object, in which the PL2 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is not included, there is a possibility that (Nt - N PL2 ) CDDM signals are not detected normally.

[0419] For example, the coded Doppler demultiplexer 212 determines that the wave reflected from the target object, in which the PL2 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is not included when the power difference (or power ratio) between the extracted upper N DM_ NotPL2 DDM signals in terms of power and the other (N DM - N DM_ NotPL2) DDM signals with lower power are not greater than or equal to a predetermined level, and performs the processing in step C-1.

[0420] In a case where the configuration of the CDP amounts by the phase rotation amount setting unit 105 (A-2) satisfies the condition 1a, the coded Doppler demultiplexer 212 may perform such determination processing.

[0421] Here is N DM_NotPL2 is the number of DDM signals where CDDM signals are assigned to transmit antennas other than the transmit antennas of PL2 polarization. For example, N DM_ NotPL2 the number of DDM signals for which the number of code multiplexing, which for N DM DDM signals to the transmitting antennas except the transmitting antennas of PL2 polarization is assigned, greater than or equal to 1. For example, in the configuration example of Fig. 16 is NcNoPL2 = (2, 1, 1, 0) and N DM_ NotPL2 = 3.

[0422] In a case where the Doppler multiplex interval of the extracted upper N DM_NotPL2 DDM signals match in power with the Doppler multiplexing interval assigned to the polarization transmitting antennas other than the PL2 polarization, the coded Doppler demultiplexer 212 determines that the reflected wave from the target object in which the PL2 polarization is a cross-polarization with respect to the receiving antenna is not included, and performs the processing in step C-1.

[0423] If the CDP amount configuration by the phase rotation amount setting unit 105 satisfies (A-1) or (A-3) of Condition 1a, the coded Doppler demultiplexer 212 is capable of performing such determination processing.

[0424] For example, the configuration of the phase rotation amount setting unit 105 is N DM_ NotPL1 = N DM_ NotPL2 for (Nt - N PL2) Transmitting antennas except the transmitting antennas of PL2 polarization. In this case, when the wave reflected from the target object, in which the PL1 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is included, a received power within a predetermined range is received, from the received powers PowerFT (f b_cf , f sc_cf + (nfd - ceil(N DM / 2) - 1) s ΔFD) for the Doppler frequency indices (f sc_cf + (nfd - ceil(N DM / 2) - 1) × ΔFD) of the N DM DDM signals. In such a case, during code demultiplexing, a signal is obtained with a code interval or number of code divisions that differs from the expected N DM_ NotPL2 CDDM signals, and thus the coded Doppler demultiplexer 212 fails to determine the aliasing, making it difficult to determine the N DM_NotPL2 CDDM signals normally. In this case, the coded Doppler demultiplexer 212 determines that the acquisition of the N DM_ NotPL2 CDDM signals are not normal and performs the processing in step C-1.

[0425] If the CDP amount configuration by the phase rotation amount setting unit 105 satisfies (B-1) or (B-2) of Condition 1a, the coded Doppler demultiplexer 212 is capable of performing such determination processing. <Schritt B-3>

[0426] Based on the processing result in step B-2, the coded Doppler demultiplexer 212 outputs the reception signals YPL1 z (f b_cr , f sc_cf , ncm, ndm) resulting from the CDDM demultiplexing on the CDDM signals used for the multiplex transmission of (Nt - N PL2 ) transmitting antennas other than the transmitting antennas of the PL2 polarization were used, together with f b_cf and f sc_cfto the direction estimator 213.

[0427] Here is YPL1z(f b_cf , f sc_cf , ndc(ndm), ndm) Outputs (e.g. CDDM demultiplexing results) for f b_cf and f sc_cf resulting from the demultiplexing of the Doppler analyzers 210 in the z-th antenna system processor 201 on the CDDM signals with DOP ndm and the orthogonal code ndc(ndm) For example, YPL1 z (f b_cr , f sc_cf , ndc(ndm), ndm) represent received signals from (Nt - N PL2 ) transmitting antennas Tx #[ndc(ndm), ndm], except for the transmitting antennas of PL2 polarization, are reflected from the target object and received by the z-th antenna system processor 201.

[0428] It is noted that z = 1 to Na, ndm = 1 to N DM , ndc(ndm) = 1 to N CDDM (ndm) and the signals that determine the N PL2 assigned to transmit antennas corresponding to the PL2 polarization are output as zero. <Schritt C-1>

[0429] The coded Doppler demultiplexer 212 performs CDDM demultiplexing on the CDDM signals of the polarization transmit antennas except (Nt - N PL1 ) PL1 polarizations, assuming the case that the wave reflected from the target object, where the PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna, is included.

[0430] When demultiplexing the CDDM signal in the coded Doppler demultiplexer 212, as shown in Fig. 14 illustrates the CDDM demultiplexing for N PL2 PL2 polarizations, but in variation 2 the CDDM demultiplexing is carried out on DDM signals from polarization transmit antennas without (Nt - N PL1 ) PL2 polarizations. The other operations are identical, so their description is omitted. <Schritt C-2>

[0431] The coded Doppler demultiplexer 212 determines whether the (Nt - N PL1 ) CDDM signals that represent the (Nt - N PL1 ) transmitting antennas other than the transmitting antennas assigned to the PL1 polarization can be detected normally. In a case where the (Nt - N PL1 ) CDDM signals are normally detected, the coded Doppler demultiplexer 212 performs the processing in step C-3, and in a case where the (Nt - N PL1 ) CDDM signals are not normally detected, the coded Doppler demultiplexer 212 considers the received signals as having a large amount of noise components (e.g., the SNR is low) or as a signal having interference components, and performs the processing of step D.

[0432] For example, the coded Doppler demultiplexer 212 determines that the wave reflected from the target object, in which the PL1 polarization is a cross-polarization with respect to the polarization of the receiving antenna, is not included when the power difference (or power ratio) between the extracted upper N DM_ NotPL1 DDM signals in terms of power and the other (N DM - N DM_ NotPL1) DDM signals with lower power are not greater than or equal to a predetermined level, and performs the processing in step D.

[0433] Here is N DM_ NotPL1 is the number of DDM signals where CDDM signals are assigned to transmit antennas other than the transmit antennas of PL1 polarization. For example, N DM_ NotPL1 the number of DDM signals for which the number of code multiplexing, which for N DMDDM signals to the transmit antennas except the transmit antennas of PL1 polarization is assigned, greater than or equal to 1. For example, in the configuration example of Fig. 16 is NcNoPL1 = (2, 0, 1, 1) and N DM_ NotPL1 = 3.

[0434] In a case where the Doppler multiplex intervals of the extracted upper N DM_ NotPL1 DDM signals do not match in power with the Doppler multiplexing intervals assigned to the polarization transmitting antennas other than the PL1 polarization, the coded Doppler demultiplexer 212 determines that the wave reflected from the target object in which the PL1 polarization is a cross-polarization with respect to the receiving antenna is not included, and performs the processing in step D.

[0435] Furthermore, the coded Doppler demultiplexer 212 determines, for example, whether the code intervals or the numbers of code division multiplexing match the code intervals or numbers of code division multiplexing determined by the (Nt - N PL1 ) CDDM signals are expected based on the reception powers of signals obtained by performing code division multiplexing on the extracted upper N DM_ NotPL1 DDM signals are obtained in terms of power. In a case where the code intervals or the numbers of code division multiplexing do not match, the coded Doppler demultiplexer 212 determines that the wave reflected from the target object, in which PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna, is not included, and performs the processing of step D. <Schritt C-3>

[0436] The coded Doppler demultiplexer 212 outputs received signals YPL2 z (f b_cf, f sc_cf , ncm, ndm) resulting from the CDDM demultiplexing based on the processing result of step C-2 on the CDDM signals for the multiplex transmission of (Nt - N PL1 ) Transmitting antennas other than the transmitting antennas of the PL1 polarization to the direction estimator 213 together with f b_cf and f sc_cf out of.

[0437] Here is YPL2,(f b_cf , f sc_cf , ndc(ndm), ndm) Outputs (e.g. CDDM demultiplexing results) for f b_cf and f sc_cf resulting from the demultiplexing of the Doppler analyzers 210 in the z-th antenna system processor 201 on the CDDM signals with DOP ndm and the orthogonal code ndc(ndm) For example, YPL2 z (f b_cf , f sc_cf , ndc(ndm), ndm) represent received signals from (Nt - N PL1) Tx #[ndc(ndm), ndm] are transmitted, except for the transmitting antennas of the PL1 polarization, reflected from the target object and received by the z-th antenna system processor 201.

[0438] It is noted that z = 1 to Na, ndm = 1 to N DM , ndc(ndm) = 1 to N CDDM (ndm) and the signals that determine the N PL1 assigned to transmit antennas corresponding to the PL1 polarization are output as zero.

[0439] Furthermore, the coded Doppler demultiplexer 212 can output the Doppler frequency of the detected target object to the direction estimator 213.

[0440] It is noted that in cases where condition 2a is satisfied, the coded Doppler demultiplexer 212 can detect the Doppler frequency of the target object, which is in the range of -1 / (2Tr) ≤ f d < 1 / (2Tr) is estimated based on the aliasing determination result.

[0441] An example of the operation of the coded Doppler demultiplexer 212 has been described above. [Example operation of the direction estimator 213]

[0442] The direction estimator 213 may perform direction estimation processing based on the outputs according to the demultiplexing operation of the coded Doppler demultiplexer 212 as in the above-described embodiment.

[0443] For example, the direction estimator 213 may perform the direction estimation processing based on the output of the coded Doppler demultiplexer 212 in each of the cases where a wave reflected from the target object that is cross-polarized with respect to the polarization of the receiving antenna is not included, a wave reflected from the target object where the PL2 polarization is cross-polarized with respect to the polarization of the receiving antenna is included, and a wave reflected from the target object where the PL1 polarization is cross-polarized with respect to the polarization of the receiving antenna is included.

[0444] By operating the direction estimator 213 as described above, a direction estimation processing result is obtained for each transmission polarization or a direction estimation result for a portion of the transmission polarizations depending on the reflected wave situation, and a direction estimation result is obtained depending on the transmission polarization. Since the response of the reflected waves from the target object may vary depending on the transmission polarization, the radar device 10 can improve the detection or identification performance with respect to the target object based on such direction estimation results that depend on the transmission polarization. Variation 2 has been described so far.

[0445] In the above, the embodiments of the present disclosure have been described. [Other embodiments]

[0446] (1) Prerequisites for the above-described embodiment are that, in a polarimetric MIMO radar using CDDM transmission, the numbers of code division multiplexing between DDM signals are non-uniformly configured for Nt transmitting antennas including differently polarized transmitting antennas, and CDDM transmission is performed by a plurality of transmitting antennas to expand the Doppler frequency range in which detection can be successful to the range of ±1 / (2Tr). In the above embodiment, a method for further improving the detection performance of the polarimetric MIMO radar by applying CDDM transmission that satisfies conditions 1 and 2 was described.For example, the conditions described above do not need to be applied if the assumed speed of movement of the target object is relatively low or if the relative speed between the radar device and the target object is limited to a narrow range.

[0447] For example, the encoder 107 can determine the numbers N CDDM (1), N CDDM (2) ... N CDDM (N DM ) of coded Doppler multiplexing to provide the same numbers of coded Doppler multiplexing in a range Form 1 up to and including N CM by using a Doppler shift amount configuration with equal intervals (e.g., Expression 6) whose interval is narrower than the maximum Doppler shift amount configuration with equal intervals. For example, the encoder 107 N CMConfigure codes for all numbers of coded Doppler multiplexing. Therefore, in a variety of combinations of DOP ndm and orthogonal code sequences the numbers N CDDM (ndm) of multiplexing (number of coded Doppler multiplexing) by the orthogonal code sequences assigned to each DOP ndmassigned to the DDM signals are identical. For example, the encoder 107 may uniformly configure the numbers of coded Doppler multiplexing for the DDM signals. With such a configuration, for example, in a case where the DDM signal is Doppler multiplexing with unequal intervals, the aliasing provision in PTL 8 can be applied, and the radar device 10 can individually demultiplex and receive signals CDDM-transmitted from a plurality of transmission antennas over a Doppler range of ±1 / (2 × Loc × Tr). By adopting such a CDDM transmission configuration and further applying CDDM transmission that satisfies Condition 1, the effect of Condition 1 described in Embodiment 1 can be achieved, and it is possible to improve the detection performance of a polarimetric MIMO radar.

[0448] Alternatively, the encoder 107 can all numbers N CDDM (1), N CDDM (2) ... N CDDM (N DM) of coded Doppler multiplexing to provide the same numbers of coded Doppler multiplexing in a range from 1 to N inclusive CM by using, for example, the configuration of a maximum Doppler shift amount with equal intervals. For example, the encoder 107 N CM Configure codes for all numbers of coded Doppler multiplexing. In this case, the number of combinations of DOP ndm and the orthogonal code sequences and the number Nt of transmitting antennas must be equal (e.g. N DM × N CM= Nt). For example, the encoder 107 may uniformly configure the number of coded Doppler multiplexings for the DDM signal. In this configuration, the aliasing determination processing in the reception processing of the radar device 10 is not applied. Furthermore, the radar device 10 may individually demultiplex and receive signals CDDM-transmitted from a plurality of transmission antennas over a Doppler range of, for example, ±1 / (2Loc × N DM × TR). By adopting such a CDDM transmission configuration and further applying CDDM transmission that satisfies Condition 1, the effect of Condition 1 described in Embodiment 1 can be achieved, and it is possible to improve the detection performance of a polarimetric MIMO radar.

[0449] (2) In an exemplary embodiment of the present disclosure, the radar device 10 may perform code division multiplex transmission using a part of the Nt transmission antennas instead of using all of the Nt transmission antennas.

[0450] Furthermore, in a case where code division multiplexing is applied in the above-described embodiment using a part of the Nt transmission antennas provided in the radar device 10, the radar device 10 can configure (or change) at least one of the combinations of transmission antennas or the number of multiplexed transmissions used for code Doppler multiplexing by time division, and perform the transmission. In this case, for example, the radar device 10 can switch the combination of transmission antennas for each transmission period or for each code transmission period (for example, each period corresponding to the code length of a code sequence) by time division. Alternatively, for example, the radar device 10 can switch the combinations of transmission antennas or the number of transmission antennas to be multiplexed for each measurement period (for each period of Nc radar transmission signal transmissions).Even if such an operation is employed, the effects of the above-described embodiment can also be achieved.

[0451] In a case where a portion of the Nt transmission antennas provided in the radar device 10 is used instead of all of the Nt transmission antennas and code division multiplex transmission is applied in the above-described embodiment, the radar device 10 can configure (e.g., change) the combinations of transmission antennas used for coded Doppler multiplex transmission by time division, and can transmit different chirp signals. For example, the radar device 10 can change at least one of the transmission bands, the frequency sweep time, or the center frequency of the chirp signal, or transmit with different chirp signals by combining these parameters in various ways.

[0452] (3) In the radar devices according to an exemplary embodiment of the present disclosure, the radar transmitter and the radar receiver may be individually arranged at physical demultiplexing locations from each other. Furthermore, the direction estimator and any other components in the radar receiver according to the exemplary embodiments of the present disclosure may be individually arranged at physical demultiplexing locations from each other.

[0453] (4) The numerical values ​​of parameters such as number Nt of transmitting antennas, number Na of receiving antennas, number N DM of Doppler multiplexing, number N PLq of transmitting antennas with PLq polarization, number of polarizations, Doppler shift amount, Doppler shift interval, number N CMThe code division multiplexing and code interval (code index) used in an exemplary embodiment of the present disclosure are examples and are not limited to these values. Further, for example, the number of some of the transmitting antennas included in the radar device may be used as the number Nt of transmitting antennas, and the number of some of the receiving antennas included in the radar device may be used as the number Na of receiving antennas.

[0454] A radar device according to an exemplary embodiment of the present disclosure includes, for example, a central processing unit (CPU), a storage medium such as a read-only memory (ROM) on which a control program is stored, and a working memory such as a random access memory (RAM), which are not illustrated. In this case, the functions of the above-described sections are implemented by the CPU, which executes the control program. However, the hardware configuration of the radar device is not limited to that in this example. For example, the functional sections of the radar device may be implemented as an integrated circuit (IC). Each functional section may be formed as a single chip, or some or all of them may be formed into a single chip.

[0455] In the above, various embodiments were described with reference to the drawings. The present disclosure is obviously not limited to these examples. Obviously, those skilled in the art can achieve variations and modifications within the scope of the claims, and these variations and modifications are intended to fall within the technical scope of the present disclosure. Each constituent element of the above-mentioned embodiments can be optionally combined without departing from the spirit of the disclosure.

[0456] The term "portion" used in the above-described embodiments may be replaced with another term such as "circuit," "device," "unit," or "module."

[0430] The above embodiments were described using an example of a configuration using hardware, but the present disclosure may also be implemented by software in combination with hardware.

[0457] Each functional block used in the description of each embodiment described above is typically implemented by an LSI, an integrated circuit. The integrated circuit controls each functional block used in the description of the above embodiments and may include an input terminal and an output terminal. The LSI may be formed individually as chips, or a chip may be formed to include part or all of the functional blocks. The LSI may refer herein to an IC, a system LSI, a super LSI, or an ultra LSI, depending on a difference in the degree of integration.

[0458] However, the technology for implementing an integrated circuit is not limited to LSIs and can be implemented using a dedicated circuit, a general-purpose processor, or a special-purpose processor. In addition, a field-programmable gate array (PFGA), which can be programmed after the LSI is fabricated, or a reconfigurable processor can be used, in which the connections and settings of circuit cells arranged within the LSI can be reconfigured.

[0459] If LSIs are replaced by future integrated circuit technology as a result of advances in semiconductor technology or other derivative technologies, the functional blocks could be integrated using the future integrated circuit technology. Biotechnology can also be used. <Kurzdarstellung der vorliegenden Offenbarung>

[0460] A radar device according to an exemplary embodiment of the present disclosure includes: a plurality of transmission antennas including a first transmission antenna for transmitting a first polarized wave and a second transmission antenna for transmitting a second polarized wave different from the first polarized wave;and a transmission circuit that, in operation, applies multiplexed transmission to a transmission signal from the plurality of transmission antennas to which a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence is applied, wherein the combination in which at least one of the Doppler shift amount and the code sequence is different is assigned to each of the plurality of transmission antennas, and a first pattern of the Doppler shift amount and the code sequence assigned to the first transmission antenna and a second pattern of the Doppler shift amount and the code sequence assigned to the second transmission antenna are different from each other.;

[0461] In one embodiment of the present disclosure, a number of the plurality of transmitting antennas is less than a total number of the combinations.

[0462] In an exemplary embodiment of the present disclosure, the first pattern and the second pattern relate to an interval of the Doppler shift amount, a number of Doppler multiplexing for the transmission signal transmitted by the first transmission antenna and a number of Doppler multiplexing for the transmission signal transmitted by the second transmission antenna are the same, and at least one of the plurality of intervals of the Doppler shift amount associated with the first transmission antenna is different from the interval of the Doppler shift amount associated with the second transmission antenna.

[0463] In an exemplary embodiment of the present disclosure, the first pattern and the second pattern refer to a number of Doppler multiplexing, and the number of Doppler multiplexing for the transmission signal transmitted from the first transmission antenna and the number of Doppler multiplexing for the transmission signal transmitted from the second transmission antenna are different from each other.

[0464] In an exemplary embodiment of the present disclosure, the first pattern and the second pattern relate to an order of an interval of the Doppler shift amount, a plurality of first Doppler shift amounts between a plurality of the Doppler shift amounts assigned to the first transmitting antenna and a plurality of second Doppler shift intervals between a plurality of the Doppler shift amounts assigned to the second transmitting antenna are the same, and the order of the plurality of first Doppler shift intervals on a Doppler frequency axis is different from the order of the plurality of second Doppler shift intervals on the Doppler frequency axis.

[0465] In an exemplary embodiment of the present disclosure, the first pattern and the second pattern relate to the code sequence, and an order of the code sequence assigned to the first transmitting antenna on a Doppler frequency axis and an order of the code sequence assigned to the second transmitting antenna on the Doppler frequency axis are different from each other in a plurality of combinations.

[0466] In an exemplary embodiment of the present disclosure, the first pattern and the second pattern refer to a number of code division multiplexing by the code sequence, and an order on a Doppler frequency axis of the number of code division multiplexing by the code sequence assigned to the first transmitting antenna and an order on the Doppler frequency axis of the number of code division multiplexing by the code sequence assigned to the second transmitting antenna are different from each other in a plurality of combinations.

[0467] In an exemplary embodiment of the present disclosure, a number of code multiplexing by the code sequence associated with at least one of the plurality of Doppler shift amounts or a number of code multiplexing by the code sequence associated with another one of the plurality of Doppler shift amounts differs from each other in a plurality of combinations with respect to at least one of the first transmitting antenna or the second transmitting antenna.

[0468] In an exemplary embodiment of the present disclosure, a receiving antenna that receives a reflected wave signal, which is the transmission signal reflected from a target object, using one of the first polarized waves and the second polarized wave; and a direction estimation circuit that, in operation, performs direction estimation for the target object based on the reflected wave signal are further included.

[0469] In one embodiment of the present disclosure, a plurality of receiving antennas including a first receiving antenna and a second receiving antenna, which receive a reflected wave signal that is the transmission signal reflected from a target object, the first receiving antenna being configured to receive the first polarized wave, the second receiving antenna being configured to receive the second polarized wave; and a direction estimation circuit operative to individually perform direction estimation for the target object on the reflected wave signal received by each of the first receiving antenna and the second receiving antenna.

[0470] In an exemplary embodiment of the present disclosure, a combination of transmission antennas from the plurality of transmission antennas for use in multiplexing the transmission signal is switched for each transmission period of the transmission signal, for each period corresponding to a code length of the code sequence, or for each measurement period in the radar device.

[0471] In an exemplary embodiment of the present disclosure, a plurality of transmitting antennas including a first transmitting antenna for transmitting a first polarized wave, a second transmitting antenna for transmitting a second polarized wave different from the first polarized wave, and a third transmitting antenna for transmitting a third polarized wave different from the first polarized wave and the second polarized wave;and a transmission circuit operative to multiplex transmission from the plurality of transmission antennas on a transmission signal to which a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence has been applied, wherein the combination in which at least one of the Doppler shift amount and the code sequence is different is assigned to each of the plurality of transmission antennas, and a third pattern of the Doppler shift amount and the code sequence assigned to the first transmission antenna and the third transmission antenna is different from a fourth pattern of the Doppler shift amount and the code sequence assigned to the second transmission antenna and the third transmission antenna.

[0472] The disclosure of Japanese Patent Application No. 2022-202052, filed on December 19, 2022, including the description, drawings and abstract thereof, is incorporated herein by reference in its entirety. Industrial applicability

[0473] The present disclosure is suitable as a radar device for wide-angle range detection. List of reference symbols 10 Radar device 100 radar transmitters 101 radar transmit signal generator 102 Control of transmission signal generation 103 modulation signal generators 104 VCO 105 Unit for setting the phase rotation amount 106 Unit for setting the Doppler shift 107 donors 108 phase shifters 109 Transmitting antenna section 200, 200a radar receiver 201 Antenna system processor 202 receiving antenna section 203 Receiving radio unit 204 mixers 205 LPF 206 Signal Processor 207 A / D converters 208 Beat Frequency Analyzer 209 Issue switch 210 Doppler Analyzer 211, 211a CFAR Section 212, 212a Coded Doppler demultiplexer 213, 213a Direction estimator QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2019 / 0064337 A1

[0002] US 2020 / 0363497 A1

[0002] JP 2008-304417 A

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[0472] Cited non-patent literature

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[0002] M. Kronauge, H. Rohling, “Fast two-dimensional CFAR procedure,” IEEE Trans. Aerosp. Electron. Syst., 2013, 49, (3), pp. 1817-1823

[0002] Direction-of-arrival estimation using signal subspace modeling Cadzow, JA; Aerospace and Electronic Systems, IEEE Transactions, Volume: 28, Issue: 1, published in: 1992, Page(s): 64 to 79

[0002]

Claims

[1] Radar device comprising: a plurality of transmitting antennas having a first transmitting antenna that transmits a first polarized wave and a second transmitting antenna that transmits a second polarized wave that is different from the first polarized wave; and a transmission circuit operative to multiplex a transmission signal to which a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence is applied from the plurality of transmission antennas, wherein the combination in which at least one of the Doppler shift amount or the code sequence differs is assigned to each of the plurality of transmitting antennas, and a first pattern of the Doppler shift amount and the code sequence assigned to the first transmitting antenna and a second pattern of the Doppler shift amount and the code sequence assigned to the second transmitting antenna differ from each other. [2] The radar device according to claim 1, wherein a number of the plurality of transmitting antennas is smaller than a total number of the combinations. [3] Radar device according to claim 1, wherein: the first pattern and the second pattern refer to an interval of the Doppler shift amount, a number of Doppler multiplexings for the transmission signal transmitted by the first transmission antenna and a number of Doppler multiplexings for the transmission signal transmitted by the second transmission antenna are identical, and at least one of a plurality of the intervals of the Doppler shift amount associated with the first transmitting antenna differs from the interval of the Doppler shift amount associated with the second transmitting antenna. [4] Radar device according to claim 1, wherein: the first pattern and the second pattern refer to the number of Doppler multiplexing, and the number of Doppler multiplexings for the transmission signal transmitted by the first transmission antenna and the number of Doppler multiplexings for the transmission signal transmitted by the second transmission antenna differ from each other. [5] Radar device according to claim 1, wherein: the first pattern and the second pattern refer to an order of an interval of the Doppler shift amount, a plurality of first Doppler shift intervals between a plurality of Doppler shift amounts associated with the first transmitting antenna and a plurality of second Doppler shift intervals between a plurality of Doppler shift amounts associated with the second transmitting antenna are equal, and the order of the plurality of first Doppler shift intervals on a Doppler frequency axis differs from the order of the plurality of second Doppler shift intervals on the Doppler frequency axis. [6] Radar device according to claim 1, wherein: the first pattern and the second pattern refer to the code sequence, and an order of the code sequence assigned to the first transmitting antenna on a Doppler frequency axis and an order of the code sequence assigned to the second transmitting antenna on the Doppler frequency axis differ from each other in a plurality of the combinations. [7] Radar device according to claim 1, wherein: the first pattern and the second pattern refer to a number of code multiplexing through the code sequence, and an order on a Doppler frequency axis of the number of code multiplexing by the code sequence assigned to the first transmitting antenna and an order on the Doppler frequency axis of the number of code multiplexing by the code sequence assigned to the second transmitting antenna differ from each other in a plurality of the combinations. [8] Radar device according to claim 1, wherein a number of code multiplexing by the code sequence associated with at least one of a plurality of Doppler shift amounts or a number of code multiplexing by the code sequence associated with another of the plurality of Doppler shift amounts differ from each other in a plurality of combinations with respect to at least one of the first transmitting antenna or the second transmitting antenna. [9] Radar device according to claim 1, further comprising: a receiving antenna that receives a reflected wave signal, which is the transmission signal reflected from a target object, using one of the first polarized waves and the second polarized waves; and a direction estimation circuit which, in operation, performs a direction estimation for the target object based on the reflected wave signal. [10] Radar device according to claim 1, further comprising: a plurality of receiving antennas including a first receiving antenna and a second receiving antenna, which receive a reflected wave signal that is the transmission signal reflected from a target object, wherein the first receiving antenna is configured to receive the first polarized wave, wherein the second receiving antenna is configured to receive the second polarized wave; and a direction estimation circuit operative to perform direction estimation individually for the target object on the reflected wave signal received by each of the first receiving antenna and the second receiving antenna. [11] Radar device according to claim 1, wherein a combination of transmitting antennas from the plurality of transmitting antennas for use in multiplexing the transmitting signal is switched for each transmitting period of the transmitting signal, for each period corresponding to a code length of the code sequence, or for each measuring period in the radar device. [12] Radar device comprising: a plurality of transmitting antennas comprising a first transmitting antenna transmitting a first polarized wave, a second transmitting antenna transmitting a second polarized wave different from the first polarized wave, and a third transmitting antenna transmitting a third polarized wave different from the first polarized wave and the second polarized wave; and a transmitting circuit operative to perform multiplex transmission on a transmitting signal to which a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence has been applied, from the plurality of transmitting antennas, wherein the combination in which at least one of the Doppler shift amount and the code sequence is different is assigned to each of the plurality of transmitting antennas, and a third pattern of the Doppler shift amount and the code sequence assigned to the first transmitting antenna and the third transmitting antenna is different from a fourth pattern of the Doppler shift amount and the code sequence assigned to the second transmitting antenna and the third transmitting antenna. [13] A method for transmitting a radar signal, the method comprising: Applying a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence to a radar signal; and Performing multiplex transmission on the radar signal to which the phase rotation amount is applied from a plurality of transmitting antennas, wherein the plurality of transmitting antennas includes a first transmitting antenna that transmits a first polarized wave and a second transmitting antenna that transmits a second polarized wave that is different from the first polarized wave, the combination in which at least one of the Doppler shift amount or the code sequence differs is assigned to each of the plurality of transmitting antennas, and a first pattern of the Doppler shift amount and the code sequence assigned to the first transmitting antenna and a second pattern of the Doppler shift amount and the code sequence assigned to the second transmitting antenna differ from each other. [14] A method for transmitting a radar signal according to claim 13, wherein a number of the plurality of transmitting antennas is smaller than a total number of the combinations. [15] A method of transmitting a radar signal according to claim 13, wherein: the first pattern and the second pattern refer to an interval of the Doppler shift amount, a number of Doppler multiplexing for the radar signal transmitted from the first transmitting antenna and a number of Doppler multiplexing for the radar signal transmitted from the second transmitting antenna are the same, and at least one of a plurality of the intervals of the Doppler shift amount associated with the first transmitting antenna differs from the interval of the Doppler shift amount associated with the second transmitting antenna. [16] A method of transmitting a radar signal according to claim 13, wherein: the first pattern and the second pattern refer to the number of Doppler multiplexing, and the number of Doppler multiplexing for the radar signal transmitted by the first transmitting antenna and the number of Doppler multiplexing for the radar signal transmitted by the second transmitting antenna differ from each other. [17] A method of transmitting a radar signal according to claim 13, wherein: the first pattern and the second pattern refer to an order of an interval of the Doppler shift amount, a plurality of first Doppler shift intervals between a plurality of Doppler shift amounts associated with the first transmitting antenna and a plurality of second Doppler shift intervals between a plurality of Doppler shift amounts associated with the second transmitting antenna are equal, and the order of the plurality of first Doppler shift intervals on a Doppler frequency axis differs from the order of the plurality of second Doppler shift intervals on the Doppler frequency axis. [18] A method for transmitting a radar signal, the method comprising: Applying a phase rotation amount corresponding to a combination of a Doppler shift amount and a code sequence to a radar signal; and Performing multiplex transmission on the radar signal to which the phase rotation amount is applied from a plurality of transmitting antennas, wherein the plurality of transmitting antennas includes a first transmitting antenna transmitting a first polarized wave, a second transmitting antenna transmitting a second polarized wave different from the first polarized wave, and a third transmitting antenna transmitting a third polarized wave different from the first polarized wave and the second polarized wave; the combination in which at least one of the Doppler shift amount and the code sequence differs is assigned to each of the plurality of transmitting antennas, and a third pattern of the Doppler shift amount and the code sequence assigned to the first transmitting antenna and the third transmitting antenna is different from a fourth pattern of the Doppler shift amount and the code sequence assigned to the second transmitting antenna and the third transmitting antenna. [19] A method for receiving a radar signal, the method comprising: Receiving a reflected wave signal by a receiving antenna, which is a radar signal transmitted by the method of transmitting a radar signal according to claim 13 and reflected by a target object; and Performing a direction estimation for the target object based on the reflected wave signal, wherein the receiving antenna receives the reflected wave signal using one of the first polarized wave and the second polarized wave. [20] A method for receiving a radar signal, the method comprising: Receiving a reflected wave signal by a receiving antenna, wherein the reflected wave signal is a radar signal transmitted by the method for transmitting a radar signal according to claim 13 and reflected by a target object, wherein the receiving antenna comprises a first receiving antenna for receiving the first polarized wave, a second receiving antenna for receiving the second polarized wave; and Performing direction estimation individually for the target object on the reflected wave signal received by each of the first receiving antenna and the second receiving antenna.

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