Radar signal processing device, radar signal processing method, radar signal processing program, and recording medium

Abstract

The radar signal processing device includes a target detection unit that obtains a distance to a target, an angle of arrival, and a speed of the target using transmission waves transmitted in a time-division manner from a plurality of transmission antennas and reception signals received from a plurality of reception antennas that receive reflected waves from the target; an angle measurement compensation processing unit that corrects the spatial signal using a phase element that depends on the azimuth angle with respect to the target and is not affected by a phase element due to the velocity of the target, to obtain an angle-compensated spatial signal; a velocity estimation unit that determines whether or not velocity aliasing occurs using a processing result obtained from the angle-compensated spatial signal, and obtains an estimated velocity of the target; a velocity compensation processing unit that corrects the spatial signal using a phase element that depends on the velocity of the target and is not affected by a phase element due to an azimuth angle with respect to the target, to obtain a velocity-compensated spatial signal; an angle measurement unit that performs angle measurement signal processing on the velocity-compensated spatial signal to obtain an azimuth angle with respect to the target; Equipped with.

Description

[Technical Field]

[0001] The present disclosure relates to TDM-MIMO (Time Division Multiplexing). The present invention relates to a radar signal processing device, a radar signal processing method, a radar signal processing program, and a recording medium for a MIMO (Multiple-Input Multiple-Output) radar device. [Background technology]

[0002] In recent years, TDM-MIMO radar systems have been adopted for applications such as automotive radar systems due to their wide frequency resource and simple hardware. However, one of the issues with TDM-MIMO radar devices is that because the TDM-MIMO radar device switches over time, the velocity measurement range (Nyquist frequency) that can be measured by the radar device is reduced. Therefore, aliasing (also known as velocity ambiguity, hereinafter referred to as velocity ambiguity) occurs for targets moving at speeds beyond the velocity measurement range, and the velocity of the target may be estimated inaccurately. .

[0003] Patent Document 1 is an example of a prior art document that focuses on this issue. Patent Document 1 discloses a method for estimating velocity without aliasing, based on the assumption that when the target velocity is within the velocity measurement range, the ideal corrected virtual array signal Sc will be a curve with a single peak in the angle FFT, whereas when the target velocity is outside the velocity measurement range, the erroneous virtual array signal Sc will likely be a curve with two peaks in the angle FFT. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2019-522220 Summary of the Invention [Problem to be solved by the invention]

[0005] The data reproduction device disclosed in Patent Document 1 has a problem in that it is difficult to obtain the velocity of the target and the azimuth angle to the target with high accuracy when there is velocity ambiguity.

[0006] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a radar signal processing device that can obtain the target speed over an expanded speed measurement range and the azimuth angle to the target with high accuracy even when there is speed ambiguity. [Means for solving the problem]

[0007] A radar signal processing device according to the present disclosure includes a target detection unit that obtains a distance to the target, an angle of arrival, and a velocity of the target using received signals corresponding to incoming waves from the multiple receiving antennas that receive the reflected waves from the target when the transmitted waves are reflected by the target; an angle measurement compensation processing unit that estimates a phase element that depends on an azimuth angle with respect to the target, which is not affected by a phase element due to the velocity of the target, for a spatial signal obtained by a combination of the multiple transmitting antennas and the multiple receiving antennas, and corrects the spatial signal using the phase element that depends on the azimuth angle, to obtain an angle-compensated spatial signal that is not affected by a phase element that depends on the azimuth angle with respect to the target; and a velocity estimation unit that performs fast Fourier transform processing on the angle-compensated spatial signal obtained by the angle measurement compensation processing unit, determines whether or not there is aliasing in the velocity obtained by the target detection unit, using the processing result obtained by the fast Fourier transform processing, and obtains an estimated velocity of the target from the velocity of the target obtained by the target detection unit based on the determination result. The target detection unit combines multiple transmitting antennas and multiple receiving antennas. There is no influence of phase elements due to the azimuth angle to the target on the spatial signal Obtained by the speed estimation unit Goal Estimate Estimate the velocity-dependent phase element, Target estimation obtained by the velocity estimator Using velocity-dependent phase elements The target detection unit combines multiple transmitting antennas and multiple receiving antennas.The system includes a velocity compensation processing unit that corrects the spatial signal to obtain a velocity-compensated spatial signal that is not affected by a phase element that depends on the velocity relative to the target, and an angle measurement unit that performs angle measurement signal processing on the velocity-compensated spatial signal obtained by the velocity compensation processing unit to obtain an azimuth angle relative to the target. [Effects of the Invention]

[0008] According to the present disclosure, even when there is velocity ambiguity, it is possible to obtain the velocity of a target with an expanded velocity measurement range and the azimuth angle to the target with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram showing a radar signal processing device according to a first embodiment. [Figure 2] 2 is an explanatory diagram showing a schematic diagram of the relationship between the transmitting antenna and the receiving antenna of the radar device and the transmitted waves and the received waves of the target; FIG. [Figure 3] 4 is a schematic diagram illustrating time switching of a transmission signal of the radar device according to the first embodiment. FIG. [Figure 4] 5 is a flowchart showing the operation of the radar signal processing device according to the first embodiment. [Figure 5] 1 is a configuration diagram showing a hardware configuration of a radar signal processing device according to a first embodiment. [Figure 6] FIG. 10 is a configuration diagram showing a radar signal processing device according to a second embodiment. [Figure 7] 10 is a flowchart showing the operation of the radar signal processing device according to the second embodiment. [Figure 8] FIG. 10 is a configuration diagram showing a radar signal processing device according to a third embodiment. [Figure 9] 10 is a flowchart showing the operation of the radar signal processing device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiment 1 A radar signal processing device 1 according to the first embodiment will be described with reference to FIGS. 1 to 4. FIG. The radar signal processing device 1 according to the first embodiment is a radar signal processing device applied to an in-vehicle TDM-MIMO radar device mounted on a moving object such as an automobile or indoor mobility device. As shown in FIG. 2, the TDM-MIMO radar device (hereinafter simply referred to as the radar device) has N transmitting antennas 21 to 23 and M receiving antennas 31 to 34, and in addition to a radar signal processing device 1 that forms part of a receiving device, also has a transmitting device (not shown), a control unit (not shown) that controls the transmitting device and the receiving device, and an overall control unit (not shown) that controls the entire radar device.

[0011] It should be noted that M and N are plural numbers, and in the radar device to which the first embodiment is applied, N is 3 and M is 4, for example. That is, although three elements are shown as transmitting antennas 21 to 23 and four elements are shown as receiving antennas 31 to 34, the numbers are not limited to these, and it is sufficient that each of the transmitting antennas 21 to 23 and receiving antennas 31 to 34 has a plurality of elements.

[0012] The transmitting device causes transmission antennas 21 to 23 to emit transmission waves (radio waves) Tx1 to Tx3, which are transmission signals, in a time-division manner in time series order. The transmitter is a commonly known transmitter used in an on-board TDM-MIMO radar device, and a detailed description thereof will be omitted. The receiving device generates received signals consisting of digital information corresponding to the incoming waves (received waves) Rx1 to Rx4 from receiving antennas 31 to 34, which receive the transmitted waves transmitted in a time-division manner in time series from transmitting antennas 21 to 23 in time division order and reflected by a target 100, which is an object.

[0013] The transmitter uses FMCW (Frequency Modulated Continuous Wave) and Fast-Chirp methods. The transmission waves Tx1 to Tx3 are emitted from the transmission antennas 21 to 23 by a commonly known method such as the Doppler method or the pulse Doppler method, and a detailed description thereof will be omitted. The receiving device processes the signals of the waves received by the receiving antennas 31 to .

[0014] The radar device to which the first embodiment is applied will be described taking an up-chirp fast-chirp method as an example. The transmitting antennas 21 to 23 transmit chirp signals Tx1-1, Tx2-1, Tx3-1, Tx1-2, ..., Tx1-Nc, Tx2-Nc, and Tx3-Nc, respectively, which are switched sequentially in chronological order by the transmitting device and whose frequencies increase over time, as shown in Figure 3. Nc indicates the number of chirps in each of the transmitting antennas 21 to 23.

[0015] Chirp signals Tx1-1, Tx1-2, . . . , Tx1-Nc indicate the first, second, . . . , Nc-th transmission waves transmitted from the transmitting antenna 21. Chirp signals Tx2-1, . . . , Tx2-Nc indicate the 1st, . . . , Ncth transmission waves transmitted from the transmitting antenna 22. Chirp signals Tx3-1, . . . , Tx3-Nc indicate the 1st, . . . , Ncth transmission waves transmitted from the transmitting antenna 23.

[0016] Transmitting Antenna 2 1、 Transmitting Antenna 2 2、 Chirp signals Tx1-nc, Tx2-nc, and Tx3-nc are transmitted in this order from the transmitting antennas 23 at time intervals (signal transmission intervals) Tc, where nc ranges from 1 to Nc. Considering the entire radar system, the signal transmission interval for the chirp signal is Tc, but the number of transmitting antennas is 2. 1、 Transmitting Antenna 2 2、 The signal transmission interval between signals transmitted from the same transmitting element of each transmitting antenna 23 is NTx×Tc. NTx is the number of transmitting antennas, and in the radar device to which the first embodiment is applied, the number of elements is 3. is used as an example.

[0017] The transmitting antennas 21 to 23 are arranged in an array with element spacing ΔdTx between adjacent transmitting antennas at equal or unequal intervals. 2, the transmission angles of the transmission waves Tx1 to Tx3 from the transmission antennas 21 to 23 to the target 100 are indicated as θ. θ corresponds to the azimuth angle of the target in the radar device.

[0018] The receiving antennas 31 to 34 receive the incoming waves Rx1 to Rx4 reflected by the target 100, respectively. The receiving antennas 31 to 34 are arranged in an array with element spacing ΔdRx between adjacent receiving antennas at equal or unequal intervals. However, the element spacing ΔdRx is used to estimate the DOA (Direction of Arrival) of radio waves. When processing, this interval is set so that estimation errors due to grating lobes do not occur. 2, the angles of arrival of the waves Rx1 to Rx4 arriving from the target 100 at the receiving antennas 31 to 34 are indicated as θ.

[0019] The angle of departure and the angle of arrival are assumed to be θ, and it is assumed that the transmitted waves Tx1 to Tx3 and the arriving waves Rx1 to Rx4 do not take different paths, ie, they are not so-called multipath waves. Furthermore, the target 100 approaches the radar device at a speed V (approaching) or moves away from the radar device at a speed V (leaving), and the speed V of the target 100 may exceed the speed measurement range of the radar device.

[0020] In the radar device to which the first embodiment is applied, the maximum velocity Vmax in the velocity measurement range is as follows: It is expressed by equation (1). Vmax=λ / (4NTx×Tc) (1) In equation (1), λ is the wavelength of the transmission wave, NTx is the number of transmission antennas, and Tc is the signal transmission interval. As is clear from equation (1), the velocity measurement range narrows in proportion to the number of elements NTx.

[0021] Moreover, the velocity V of the target 100 that exceeds the velocity measurement range of the radar device is expressed by the following equation (2). |V|>Vmax (2) The velocity V of the target 100 is given an absolute value because the target 100 approaches the radar device at velocity V or moves away from the radar device at velocity V, and therefore takes a positive or negative value.

[0022] If the speed V of the target 100 exceeds the maximum speed Vmax of the speed measurement range, the chirp signal When trying to determine the target's Doppler velocity using signal-direction FFT (= slow-time direction FFT, FFT: Fast Fourier Transform), aliasing of the Doppler velocity occurs because the signal exceeds the Nyquist frequency. In a TDM-MIMO radar device, due to time division transmission, signals for a target 100 approaching the radar device at a speed V or moving away from the radar device at a speed V are received with their phase rotated by the signal transmission interval Tc, so velocity compensation processing is required to perform MIMO signal processing such as angle measurement signal processing.

[0023] This velocity compensation process generally uses the detected Doppler velocity, so if velocity compensation is performed using a signal with velocity aliasing, the phase rotation will not be canceled out, causing an erroneous angle measurement in the subsequent MIMO signal processing. Therefore, in a TDM-MIMO radar system, it is necessary to accurately estimate the velocity V of the target 100. The radar signal processing device 1 according to the first embodiment can estimate the velocity V of the target 100 with high accuracy even when the velocity V of the target 100 exceeds the maximum velocity Vmax of the velocity measurement range, and can prevent erroneous This prevents angle measurement from occurring.

[0024] The radar signal processing device 1 according to the first embodiment includes a target detection unit 11, an angle measurement compensation processing unit 12, a speed estimation unit 13, a speed compensation processing unit 14, and an angle measurement unit 15, as shown in FIG. The target detection unit 11 receives received signals consisting of digital information corresponding to the incoming waves Rx1 to Rx4 from the receiving antennas 31 to 34, and calculates the relative distance between the radar device and the target 100, the relative speed with respect to the target 100, and the direction of the target 100 using the received signals and transmitted signals consisting of digital information corresponding to the transmitted waves Tx1 to Tx3 from the transmitting antennas 21 to 23 at each set observation period.

[0025] In the following description, the relative distance and the direction of the target 100 may be referred to as a signal indicating the position of the target 100, and the relative distance, direction and relative speed may be referred to as a signal for the target 100. Furthermore, the relative distance and relative velocity are simply referred to as distance and velocity.

[0026] The position and velocity are calculated as the number of combinations of the plurality of transmitting antennas 21 to 23 and the plurality of receiving antennas 31 to 34, that is, N×M, or 3×4 in the first embodiment, in the signal transmission interval NTx×Tc. For speed, if the speed V of the target 100 exceeds the maximum speed Vmax of the speed measurement range, It may contain velocity ambiguities (folding). The calculation of the position and velocity may be performed by a method for calculating the position and velocity that is generally known in radar devices, and a detailed description thereof will be omitted.

[0027] For example, in the case of transmission signals and reception signals of the up-chirp Fast-Chirp method, the position and velocity are calculated by performing 2D-FFT processing for each combination of multiple transmission antennas 21 to 23 and multiple reception antennas 31 to 34, creating a range-Doppler map by incoherent integration, and then performing CFAR (Constant False Alarm Rate) signal processing. This is done by detecting the position and velocity of the target 100. It should be noted that any method other than the Fast-Chirp method may be used as long as it can obtain a reflected signal from the target 100 under conditions that match the format of the radar signal.

[0028] The target detection unit 11 uses information indicating the position and velocity of the target 100 to extract information about the target 100 from the range-Doppler map, thereby extracting spatial signals S for the combinations of the transmitting antennas 21-23 and the receiving antennas 31-34. In the first embodiment, in the case of 4×3 MIMO using three elements as transmitting antennas 21 to 23 and four elements as receiving antennas 31 to 34, the spatial signal S extracted by the target detection unit 11 is expressed in matrix form by the following equation (3).

[0029] TIFF0007752813000001.tif32166

[0030] In the above equation (3), the columns indicate transmission and the rows indicate reception. Each element in M ​​rows and N columns corresponds to the nth transmitting element (transmitting antenna 2 n ) and the mth receiving element (receiving antenna 3 m ), where n ranges from 1 to N and m ranges from 1 to M.

[0031] In addition, in the above equation (3), Φmn is a range-azimuth angle phase element based on the range to the target 100 and the azimuth angle θ to the target 100 at the nth transmitting element and the mth receiving element, and is expressed by the following equation (4). Φmn=exp(i2πΔdmn Sin(θ) / λ) (4) In equation (4), Δdmn is the element spacing with respect to a reference element selected from among the receiving antennas 31 to 34. The reference element can be selected from any combination of antenna elements.

[0032] In the above equation (3), Φvn is a velocity phase element resulting from the velocity V of the target 100 corresponding to the n-th transmitting element, and is expressed by the following equation (5). Φvn=exp(i2π 2(n-1)V Tc / λ) (5)

[0033] In short, the target detection unit 11 has a first function of calculating the position of the target 100 and the velocity of the target 100 using received signals corresponding to the incoming waves Rx1 to Rx4 from the receiving antennas 31 to 34 and transmitted signals corresponding to the transmitted waves Tx1 to Tx3 from the transmitting antennas 21 to 23, and a second function of obtaining a spatial signal S expressed in a matrix format, where the columns indicate transmission and the rows indicate reception, and each element in the matrix has a range / azimuth phase element and a velocity phase element.

[0034] By using the spatial signal S obtained by the above equation (3) to compensate for the velocity phase element Φvn in the spatial signal S from the Doppler frequency (velocity), when angle measurement is performed using the range and azimuth phase element Φmn, the velocity V of target 100 is the maximum velocity Vmax of the velocity measurement range. If the velocity exceeds φvn, the velocity may contain velocity ambiguity (folding). Therefore, if the velocity has velocity ambiguity, the velocity phase element Φvn may not be compensated correctly, and correct MIMO signal processing for the angle measurement may not be possible.

[0035] Therefore, in the first embodiment, the following processing is performed. The angle measurement compensation processor 12 has a third function of performing a process of estimating the direction of arrival (DOA estimation) from the spatial signal S obtained by the above equation (3) without being affected by the velocity of the target 100, and provisionally estimating the azimuth angle θ relative to the target 100, and a fourth function of performing a process of canceling the range-azimuth phase element Φmn from the spatial signal S obtained by the above equation (3) and leaving only the velocity phase element Φvn, thereby obtaining an angle-compensated spatial signal Scmp. The angle measurement compensation processing unit 12 has an azimuth angle estimation unit 12a and a spatial signal compensation unit 12b, with the azimuth angle estimation unit 12a taking charge of the third function and the spatial signal compensation unit 12b taking charge of the fourth function.

[0036] That is, by having the third and fourth functions, the angle measurement compensation processing unit 12 estimates a phase element that depends on the arrival angle θ of the target 100 without being affected by the phase element due to the velocity V of the target 100, and then corrects the spatial signal S obtained by the above equation (3) using the phase element that depends on the arrival angle θ to obtain an angle-compensated spatial signal Scmp. In short, the angle measurement compensation processing unit 12 estimates the range / azimuth angle phase element Φmn and performs processing to cancel the range / azimuth angle phase element Φmn from the spatial signal S obtained by the above equation (3) and leave only the velocity phase element Φvn, thereby obtaining an angle-compensated spatial signal Scmp that is not affected by the angle of arrival θ with respect to the target 100.

[0037] The third function of the angle measurement compensation processor 12 will be described. The angle measurement compensation processor 12 obtains a reception correlation matrix R shown in the following equation (6) for the spatial signal S obtained by the above equation (3). This processing is for provisionally estimating a phase element that depends on the arrival angle θ of the target 100 without being affected by the phase element due to the velocity V of the target 100.

[0038] TIFF0007752813000002.tif33166

[0039] As can be seen from the above equation (6), in the reception correlation matrix R, the velocity phase element Φvn is cancelled out during the correlation matrix calculation, and only the range-azimuth phase element Φmn remains. Therefore, regardless of whether or not there is velocity ambiguity, the DOA estimation process can be performed using the reception correlation matrix R to provisionally obtain the azimuth angle θ with respect to the target 100.

[0040] Therefore, the angle measurement compensation processor 12 uses the reception correlation matrix R to perform signal correction using a signal correction method such as DBF (digital beamforming), Capon method, MUSIC (Multiple Signal Classification) method, or ESPRIT (Estimation of Signal Parameter via Rotational Invariance Techniques) method. A DOA estimation process is performed using a signal processing technique, and the azimuth angle (arrival angle) θ with respect to the target 100 is tentatively estimated. The tentatively estimated azimuth angle θ is obtained by estimating the direction of arrival using the array of receiving antennas 31 to 34, and is therefore not affected by phase rotation due to the velocity V of the target 100, making it possible to estimate the direction (arrival angle θ) relative to the target 100 with high accuracy.

[0041] The angle measurement compensation processing unit 12 may temporarily estimate the azimuth angle θ with respect to the target 100 by the following method. That is, the first column of the spatial signal S obtained by the above equation (3) has a velocity phase element of Φv1. Therefore, if only the first column of the signal is extracted, the azimuth angle (arrival angle) θ for the target 100 can be estimated regardless of whether or not there is velocity ambiguity. Therefore, the angle measurement compensation processing unit 12 uses the signal shown in the first column of the spatial signal S obtained by the above equation (3) and performs angle FFT, DBF, Capon method, MUSIC method, or ESPRIT method. The DOA estimation process is performed using a signal processing method such as the above, and the result of the DOA estimation process is tentatively estimated as the azimuth angle θ with respect to the target 100. The azimuth angle θ obtained by this method is also not affected by the phase rotation due to the velocity V of the target 100, and therefore can be provisionally estimated as the direction (arrival angle θ) relative to the target 100 with high accuracy.

[0042] In short, as a third function, the angle measurement compensation processing unit 12 performs DOA estimation processing from the spatial signal S obtained by the above equation (3) in a manner that is not affected by the velocity phase element Φvn, and tentatively estimates the azimuth angle θ with respect to the target 100. The fourth function of the angle measurement compensation processor 12 is processed as follows. The angle measurement compensation processing unit 12 uses the azimuth angle θ estimated by the third function and the element spacing Δdmn with respect to the reference element to cancel the distance-azimuth angle phase element Φmn from the spatial signal S obtained by the above equation (3) and leave only the velocity phase element Φvn, thereby obtaining an angle-compensated spatial signal Scmp that is not affected by the azimuth angle θ with respect to the target 100, as shown in the following equation (7), i.e., An angle-compensated spatial signal Scmp is obtained, which is free from the influence of the phase element due to the azimuth angle.

[0043] TIFF0007752813000003.tif32166

[0044] In the above equation (7), if we focus on the row direction, we get the velocity phase element Φvn resulting from the velocity V of the target 100 corresponding to the transmitting antennas 21 to 23 sampled at the signal transmission interval Tc, so it is possible to estimate the phase rotation, including FFT processing. In the above equation, the column direction corresponds to the receiving antennas 31 to 34.

[0045] The velocity estimation unit 13 estimates the velocity V of the target 100 using the angle-compensated spatial signal Scmp obtained from the angle measurement compensation processing unit 12, in which the range-azimuth phase element Φmn is cancelled. The speed estimation unit 13 estimates the angle-compensated spatial signal Scmp in the direction of the transmitting antenna (row vector direction). By performing FFT processing in the direction of the velocity, it becomes possible to calculate the maximum velocity Vmax_ex in the velocity measurement range of the radar device using the following equation (8).

[0046] That is, the velocity estimation unit 13 uses the angle-compensated spatial signal Scmp to estimate the target velocity. The velocity V of the target 100 is estimated based on the velocity Vamb of the target 100 calculated by the target detection unit 11. The speed measurement range is extended from the maximum speed Vmax to the maximum speed Vmax_ex. This also increases the resolution for estimating the velocity V of the target 100. Vmax_ex=λ / (4Tc) (8)

[0047] The speed estimation unit 13 performs FFT processing on the angle-compensated spatial signal Scmp in the direction of the transmitting antenna. and a sixth function of obtaining an estimated velocity V using the maximum value Vp of the FFT processing result. The speed estimation unit 13 has an FFT processing unit 13a and an estimation unit 13b, with the FFT processing unit 13a taking charge of the fifth function and the estimation unit 13b taking charge of the sixth function.

[0048] The FFT processing by the fifth function in the speed estimation unit 13 is angle The maximum value Vp of the FFT processing result may be calculated by performing FFT processing on velocity phase elements extracted from one row of the compensated spatial signal Scmp in the transmitting antenna direction, or the maximum value Vp of the FFT processing result may be calculated by averaging each column of the angle-compensated spatial signal Scmp and performing FFT processing on the velocity phase elements in each averaged column in the transmitting antenna direction, or further, the maximum value Vp of the FFT processing result may be calculated by performing FFT processing on the velocity phase elements in each row of the angle-compensated spatial signal Scmp in the transmitting antenna direction and averaging the processed results.

[0049] The speed estimation unit 13 performs FFT processing and estimates the speed based on the number of transmitting antennas 21 to 23, so the accuracy may be degraded. Therefore, in the sixth function, the velocity estimation unit 13 uses the maximum value Vp of the FFT processing result obtained by the FFT processing by the fifth function to determine whether or not there is velocity aliasing and whether the aliasing is positive or negative, and calculates the velocity of the target 100 using the velocity Vamb of the target 100 calculated by the target detection unit 11. Estimate the estimated speed V of

[0050] The velocity estimation unit 13 uses the maximum value Vp of the FFT processing result obtained by the fifth function to determine whether or not there is velocity aliasing and whether the aliasing is positive or negative, using the following method. That is, the speed estimation unit 13 calculates the maximum value Vp of the FFT processing result and the maximum speed of the speed measurement range shown in the above formula (1) for the speed Vamb of the target 100 calculated by the target detection unit 11. When the relationship between the value Vmax (=λ / (4NTx × Tc)) and the maximum velocity value Vmax_ex (=λ / (4Tc)) of the velocity measurement range shown in the above equation (8) for the result of FFT processing of the angle-compensated spatial signal Scmp in the direction of the transmitting antenna satisfies the relationship of the following equation (9), The value Vp determines that the velocity is in the positive aliasing direction, and if the relationship of the following equation (10) is satisfied, the maximum value Vp of the FFT processing result determines that the velocity is in the negative aliasing direction, and if the relationship of the following equation (11) is satisfied, the maximum value Vp of the FFT processing result determines that the velocity does not have positive or negative aliasing.

[0051] That is, the velocity Vamb of the target 100 calculated by the target detection unit 11 has a maximum velocity value of Since it is found in the speed measurement range where the maximum speed Vmax is, the maximum value Vp of the FFT processing result is calculated using the following formula: Depending on which of the following equations (9) to (12) is satisfied, the speed estimation unit 13 can determine whether or not there is a speed alias and whether the alias is positive or negative.

[0052] Vmax <Vp≦Vmax_ex (9) -Vmax_ex≦Vp<-Vmax (10) -Vmax <Vp<Vmax (11)

[0053] If the maximum value Vp of the FFT processing result satisfies the relationship of the above equation (9), the velocity estimation unit 13 can obtain the estimated velocity V of the target 100 by the following equation (12). V=Vamb+2Vmax (12) That is, the estimated speed V of the target 100 is calculated by adding twice the maximum speed Vmax of the speed measurement range for the speed Vamb to the speed Vamb of the target 100 calculated by the target detection unit 11. Let's say.

[0054] If the maximum value Vp of the FFT processing result satisfies the relationship of the above equation (10), the velocity estimation unit 13 can obtain the estimated velocity V of the target 100 by the following equation (13). V=Vamb-2Vmax (13) That is, the estimated speed V of the target 100 is calculated by multiplying the speed Vamb (negative value) of the target 100 calculated by the target detection unit 11 by twice the maximum speed Vmax of the speed measurement range for the speed Vamb. The subtracted value is used.

[0055] If the maximum value Vp of the FFT processing result satisfies the relationship of the above equation (11), the velocity estimation unit 13 can obtain the estimated velocity V of the target 100 by the following equation (14). V=Vamb (14)

[0056] That is, the estimated speed V of the target 100 is set to the speed Vamb of the target 100 calculated by the target detection unit 11. The velocity estimation unit 13 performs FFT processing on the angle-compensated spatial signal Scmp in the direction of the transmitting antenna. When performing the FFT processing, the roughness of the FFT processing result may be interpolated by discriminative processing and output.

[0057] In short, the velocity estimation unit 13 performs FFT processing on the angle-compensated spatial signal Scmp. , the velocity Vamb obtained by the target detection unit 11 using the processing result Vp obtained by the FFT processing The presence or absence of a return is determined, and an estimated velocity V of the target 100 is obtained from the velocity Vamb obtained by the target detection unit 11 based on the result of the determination. The estimated velocity V of the target 100 obtained by the velocity estimation unit 13 is output as the velocity V of the target.

[0058] The maximum estimated velocity V of the target 100 is determined by the angle-compensated spatial signal Scmp in the direction of the transmitting antenna. Since the result of FFT processing in the direction is the maximum velocity value Vmax_ex in the velocity measurement range shown in equation (8) above, the problem of velocity ambiguity is resolved.

[0059] The velocity compensation processing unit 14 estimates a phase element that depends on the velocity V of the target 100 without being affected by the phase element due to the angle of arrival θ of the target 100, and then corrects the spatial signal S obtained by the above equation (3) using the phase element that depends on the velocity V to obtain a velocity-compensated spatial signal Svcmp. In the first embodiment, the estimated velocity V of the target 100 estimated by the velocity estimation unit 13 is used to compensate for the velocity phase element Φvn of the spatial signal S obtained by the above equation (3), that is, a process is performed to cancel the velocity phase element Φvn from the spatial signal S and leave only the range-azimuth phase element Φmn, thereby obtaining a velocity-compensated spatial signal Svcmp shown in the following equation (15).

[0060] At this time, the velocity phase element Φvn for the spatial signal S is compensated using the estimated velocity V of the target 100 estimated by the velocity estimation unit 13, so that the velocity phase element Φvn of the spatial signal S can be correctly compensated, and the velocity-compensated spatial signal Svcmp can be correctly obtained. The velocity compensation processing unit 14 converts the velocity Vamb of the target 100 obtained by the target detection unit 11 into the velocity of the target 10 Compensate for phase rotation with an estimated velocity V of 0.

[0061] TIFF0007752813000004.tif38166

[0062] In the above equation (15), the row direction represents the distance-azimuth phase element Φmn resulting from the distance and azimuth angle to the target 100 corresponding to the transmitting antennas 21 to 23 sampled at the signal transmission interval Tc, and the column direction corresponds to the receiving antennas 31 to 34. As shown in the above equation (15), the velocity-compensated spatial signal Svcmp is a spatial signal that is not affected by the velocity V relative to the target 100 and contains only the range-azimuth phase element Φmn, by canceling out the velocity phase element Φvn from the spatial signal S obtained by the above equation (3).

[0063] The angle measurement unit 15 estimates the azimuth angle θ of the target using the velocity-compensated spatial signal Svcmp obtained from the velocity compensation processing unit 14, in which the velocity phase element Φvn has been cancelled. The angle measurement unit 15 obtains a high-resolution angle measurement value, i.e., the azimuth angle (angle of arrival) θ relative to the target 100, by MIMO signal processing of the velocity-compensated spatial signal Svcmp using an angle measurement signal processing method such as angle FFT, DBF, or a super-resolution signal processing method such as the MUSIC method. The azimuth angle θ relative to the target 100 obtained by the angle measurement unit 15 is output as the azimuth angle θ of the target.

[0064] Next, the operation of the radar signal processing device 1 according to the first embodiment will be described with reference to the flowchart shown in FIG. In step ST1, the target detection unit 11 calculates the distance to the target 100, the angle of arrival (azimuth angle), and the speed of the target 100 using a received signal consisting of digital information corresponding to the incoming waves Rx1 to Rx4 from the receiving antennas 31 to 34 and a transmitted signal consisting of digital information corresponding to the transmitted waves Tx1 to Tx3 from the transmitting antennas 21 to 23.

[0065] Step ST1 is a target signal detection step for a signal for the target 100. In step ST1, the target detection unit 11 uses the calculated distance and angle of arrival (indicating the position of the target 100) for the target 100 and the velocity of the target 100 to obtain a spatial signal S shown in the above equation (3), which is expressed in matrix form, with the columns indicating transmission and the rows indicating reception, and each element in the matrix having a range / azimuth phase element and a velocity phase element. Step ST1 is also a step of acquiring a spatial signal S for the target 100.

[0066] In step ST2, the azimuth angle estimation unit 12a in the angle measurement compensation processing unit 12 performs a direction of arrival (DOA estimation) process on a signal having a range-azimuth angle phase element and a velocity phase element for the target 100, which is the spatial signal S in the first embodiment, without being affected by the velocity of the target 100, and tentatively estimates the azimuth angle θ for the target 100. Step ST2 is a DOA estimation processing step for provisionally estimating the azimuth angle θ with respect to the target 100, which is performed using the array of receiving antennas 31 to .

[0067] In step ST3, the spatial signal compensation unit 12b in the angle measurement compensation processing unit 12 obtains an angle-compensated spatial signal Scmp in which the range-azimuth phase element Φmn is cancelled out from the spatial signal S for the target 100 using the azimuth angle θ obtained by the azimuth angle estimation unit 12a. Step ST3 is a step for obtaining an angle-compensated spatial signal Scmp in which the range-azimuth phase element Φmn is cancelled. Steps ST2 and ST3 together constitute an angle-of-arrival compensation step in which the angle measurement compensation processing unit 12 obtains an angle-compensated signal in which the range-azimuth phase element Φmn is cancelled out from a signal having a range-azimuth phase element Φmn and a velocity phase element Φvn.

[0068] In step ST4, the FFT processing unit 13a in the velocity estimation unit 13 performs FFT processing on the angle-compensated signal, in the first embodiment, the angle-compensated spatial signal Scmp, and the estimation unit 13b is calculated by the target detection unit 11 using the FFT processing result. The wraparound is determined. Step ST4 is a step of calculating the velocity Vamb of the target 100 calculated by the target detection unit 11. This is a wrap-around presence / absence determination step in which the presence or absence of wrap-around is determined.

[0069] In step ST5, the estimation unit 13b in the speed estimation unit 13 obtains an estimated speed of the target 100 from the speed Vamb of the target 100 based on the determination of whether or not there is a return, and calculates the estimated speed as the target The velocity V is output.

[0070] That is, if the processing result by the FFT processing unit 13a exceeds the positive value of the maximum speed Vmax of the speed measurement range for the speed Vamb of the target 100, the estimation unit 13b determines that a positive aliasing has occurred, and calculates a value obtained by adding twice the maximum speed Vmax to the speed Vamb of the target 100 as the estimated speed V of the target 100. If the processing result by the FFT processing unit 13a is less than the negative value of the maximum speed Vmaxb of the speed measurement range for the speed Vam of the target 100, the estimation unit 13b determines that a negative aliasing has occurred, and calculates a value obtained by subtracting twice the maximum speed Vmax from the speed Vamb (negative value) of the target 100 as the estimated speed V of the target 100. If the speed measurement range is between the positive and negative values ​​of the maximum speed Vmax, there will be no folding. The estimated speed V of the target 100 is set to the speed Vamb of the target 100.

[0071] Steps ST4 and ST5 are combined to determine the speed Vamb for the target 100. Determine whether or not there is a repeat, and based on the result of the determination, change the speed Vamb from target 100 to target 10 This is the velocity acquisition step to obtain an estimated velocity V of 0.

[0072] In step ST6, the velocity compensation processing unit 14 obtains a velocity-compensated spatial signal Svcmp in which the velocity phase element Φvn is cancelled out using the estimated velocity V of the target 100 obtained by the velocity estimation unit 13 for a signal having a range / azimuth phase element and a velocity phase element for the target 100, which is the spatial signal S in embodiment 1. Step ST6 is a velocity compensation step in which the velocity compensation processor 14 obtains a velocity-compensated signal in which the velocity phase element Φvn is cancelled from the signal having the range-azimuth phase element Φmn and the velocity phase element Φvn.

[0073] In step ST7, the angle measurement unit 15 obtains an azimuth angle (arrival angle) θ with respect to the target 100 by MIMO signal processing using the velocity-compensated signal and an angle measurement signal processing technique. Step ST7 is an angle measurement step for obtaining the azimuth angle θ relative to the target 100. The position of the target 100 is estimated based on the azimuth angle θ for the target 100 obtained in step ST7 and the distance to the target 100 obtained in step ST1, and the estimated position of the target 100 is output.

[0074] The radar signal processing device 1 according to the first embodiment, which includes a target detection unit 11, an angle measurement compensation processing unit 12, a speed estimation unit 13, a speed compensation processing unit 14, and an angle measurement unit 15, is realized by a hardware configuration using a computer, and as shown in FIG. 5, includes a CPU (Central Processing Unit) 1A, 1B of large-capacity semiconductor memory (RAM: Random Access Memory) and hard disk drive The device includes a storage device (ROM: Read only memory) 1C such as a nonvolatile storage device or an SSD device, an input interface unit 1D, an output interface unit 1E, and a signal path (bus) 1F.

[0075] The CPU 1A controls and manages the RAM 1B, the ROM 1C, the input interface section 1D, and the output interface section 1E. The CPU 1A loads the program stored in the ROM 1C into the RAM 1B, and executes various processes based on the program loaded into the RAM.

[0076] The target detection unit 11, the angle measurement compensation processing unit 12, the velocity estimation unit 13, the velocity compensation processing unit 14, and the angle measurement unit 15 are each components that represent functions executed by the CPU 1A based on a program stored in the ROM 1C and loaded into the RAM 1B. The signal path 1F is a bus that interconnects the CPU 1A, RAM 1B, ROM 1C, input interface unit 1D, and output interface unit 1E.

[0077] The program stored in ROM 19 and executed by CPU 18 includes: a target signal detection procedure for acquiring the distance, angle of arrival, and velocity of the target using received signals corresponding to the incoming waves from the multiple receiving antennas that receive the reflected waves from the target when the transmitted waves transmitted in a time-division manner from the multiple transmitting antennas are reflected by the target; an angle of arrival compensation procedure for acquiring an angle-compensated signal in which the range-azimuth phase element is cancelled out from a signal having a range-azimuth phase element and a velocity phase element obtained by combining the multiple transmitting antennas and the multiple receiving antennas; a velocity acquisition procedure for performing fast Fourier transform processing on the angle-compensated signal, determining whether or not the target velocity is aliased using the processing result obtained by the fast Fourier transform processing, and acquiring an estimated velocity of the target from the target velocity based on the determination result; a velocity compensation procedure for acquiring a velocity-compensated signal in which the velocity phase element is cancelled out from the signal having the range-azimuth phase element and the velocity phase element; and an angle measurement procedure for performing signal angle measurement processing on the velocity-compensated signal to acquire the azimuth angle of the target.

[0078] In the radar signal processing device 1 according to the first embodiment, the velocity estimation unit performs fast Fourier transform processing on the angle-compensated spatial signal obtained by the angle measurement compensation processing unit, which is not affected by a phase element that depends on the azimuth angle relative to the target, determines whether or not there is velocity aliasing using the processing result obtained by the fast Fourier transform processing, and obtains an estimated velocity of the target from the velocity of the target based on the determination result. The angle measurement unit performs angle measurement signal processing on the velocity-compensated spatial signal obtained by the velocity compensation processing unit, which is not affected by a phase element that depends on the velocity relative to the target, to obtain the azimuth angle relative to the target. Therefore, even when there is velocity ambiguity, it is possible to obtain the velocity of the target with an expanded velocity measurement range and the azimuth angle relative to the target with high accuracy.

[0079] Embodiment 2 The radar signal processing device 1 according to the second embodiment will be described with reference to FIGS. The radar signal processing device 1 according to the second embodiment is the same as the radar signal processing device 1 according to the first embodiment except for the method of signal compensation in the angle measurement compensation processor 12. Therefore, the following description will focus on signal compensation in angle measurement compensation processing section 12A, which corresponds to angle measurement compensation processing section 12 in the first embodiment. 6 and 7, the same reference numerals as those shown in FIGS. 1 to 5 indicate the same or corresponding parts.

[0080] The angle measurement compensation processing unit 12A has an azimuth angle estimation unit 12a and a signal compensation unit 12c. The azimuth angle estimating unit 12a performs the same function as the third function performed by the azimuth angle estimating unit 12a in the radar signal processing device 1 according to the first embodiment. The signal compensation unit 12c performs a function similar to the fourth function performed by the spatial signal compensation unit 12b in the radar signal processing device 1 according to the first embodiment. In short, the angle measurement compensation processing unit 12A obtains an angle-compensated signal that is not affected by the angle of arrival θ relative to the target 100.

[0081] The signal compensator 12c performs phase compensation on the received signals corresponding to the waves arriving from the receiving antennas 31 to 34 using the azimuth angle θ obtained by the azimuth angle estimator 12a and the element spacing ΔdRx of the receiving antennas 31 to 34. The received signal for phase compensation at this time has the distance to the target 100 obtained by the target detection unit 11, so a signal having the distance-azimuth phase element Φmn corresponding to the distance to the target 100 and the velocity phase element Φvn is extracted.

[0082] The signal corresponding to the distance to the target 100 has (Nc × NTx) elements for each of the receiving antennas 31 to 34. Nc is the number of elements for each of the transmitting antennas 21 to 23. is the number of chirps in the antenna, and NTx is the number of transmitting antennas 21 to 23. The angle compensation processing unit 12A obtains an angle-compensated signal from the entire received signal, that is, a signal having (Nc×NTx×NRx) elements, by the azimuth angle estimation unit 12a and the signal compensation unit 12c. NRx is the number of receiving antennas 31 to 34.

[0083] The signal compensation unit 12c performs phase compensation processing on the extracted signal having the distance-azimuth phase element Φmn corresponding to the distance to the target 100 and the velocity phase element Φvn, using the estimated azimuth angle θ, which is the result of the DOA estimation processing obtained by the azimuth angle estimation unit 12a, to obtain an angle-compensated spatial signal. By using signals extracted corresponding to the range to the target 100, the phase compensation process extends the signal compensation range to signals extracted at the range to the target 100.

[0084] The velocity estimation unit 13 performs FFT processing on the signal angle-compensated by the angle measurement compensation processing unit 12A, and the estimation unit 13b uses the FFT processing result to determine whether or not the velocity Vamb of the target 100 calculated by the target detection unit 11 is aliased. The angle measurement compensation processing unit 12A performs phase compensation on the entire received signal, and the velocity estimation unit 13 performs FFT processing on the entire phase-compensated received signal, so the velocity measurement range is expanded by the signal transmission interval Tc at which the chirp signal is transmitted. Furthermore, the observation time increases to {(N+NTx-1)×Tc} due to the signal transmission interval Tc and the number NTx of the transmitting antennas 21 to 23, improving the frequency resolution.

[0085] Although the example shows that the transmission signals sent from the transmitting antennas 21 to 23 are sent at equal intervals, the signals may not be sent at equal intervals, and a time may be provided after the transmission signal to stop transmission, or the transmission intervals may be unequal. In such a case, the Doppler frequency can be obtained by FFT processing or DFT (discrete Fourier transform) processing with zero padding according to the transmission interval of the transmission signal.

[0086] The estimated velocity V of the target 100 obtained by the velocity estimation unit 13 is output as the velocity V of the target. Furthermore, the estimated velocity V of the target 100 obtained by the velocity estimation unit 13 is used by the velocity compensation processing unit 14, and the azimuth angle θ for the target 100 obtained by the angle measurement unit 15 is output as the azimuth angle θ of the target.

[0087] Next, the operation of the radar signal processing device 1 according to the second embodiment will be described with reference to the flowchart shown in FIG. The target signal detection step ST1 and the DOA estimation processing step ST2 are the same as the target signal detection step ST1 and the DOA estimation processing step ST2 in the radar signal processing device 1 according to the first embodiment.

[0088] In step ST3a, the signal compensation unit 12c in the angle measurement compensation processing unit 12A performs phase compensation on the entire received signal corresponding to the incoming waves from the receiving antennas 31 to 34 using the azimuth angle θ obtained by the azimuth angle estimation unit 12a and the element spacing ΔdRx of the receiving antennas 31 to 34. Step ST3a is a step of performing phase compensation on the entire received signal to obtain an angle-compensated signal. Steps ST2 and ST3a are performed in combination by the angle measurement compensation processor 12A to obtain an angle-compensated signal from the entire received signal, that is, a signal having (Nc×NTx×NRx) elements. NRx is the number of receiving antennas 31 to 34.

[0089] In step ST4a, the FFT processing unit 13a in the velocity estimation unit 13 performs FFT processing on the angle-compensated signal in the direction of the transmitting antenna (row direction), and the estimation unit 13b uses the FFT processing result to calculate the aliasing for the velocity Vamb of the target 100 calculated by the target detection unit 11. A judgment is made as to whether or not the Step ST4a is a step of calculating the velocity Vamb of the target 100 calculated by the target detection unit 11. This is a folding presence / absence determination step in which a determination is made as to whether or not there is a folding.

[0090] Since the entire received signal is phase compensated in step ST3a and the entire phase-compensated received signal is subjected to FFT processing in step ST4a, the velocity measurement range is expanded by the signal transmission interval Tc at which the chirp signal is transmitted. Furthermore, the observation time increases to {(N+NTx-1)×Tc} by the signal transmission interval Tc and the number NTx of the transmitting antennas 21 to 23, improving the frequency resolution.

[0091] Step ST5, velocity compensation step ST6, and angle measurement step ST7 are the same as step ST5, velocity compensation step ST6, and angle measurement step ST7 in the radar signal processing device 1 according to the first embodiment. Step ST4a and step ST5 are performed together to achieve a target speed of 100, Vamb. Based on the result of the judgment, the target speed Vamb is changed from 100. This is a speed acquisition step in which an estimated speed V of the target 100 is obtained.

[0092] Similar to the radar signal processing device 1 according to the first embodiment, the hardware configuration of the radar signal processing device 1 according to the second embodiment is realized by a computer including a CPU 1A, a RAM 1B, a ROM 1C, an input interface unit 1D, an output interface unit 1E, and a signal path (bus) 1F, as shown in FIG. 5.

[0093] The radar signal processing device 1 according to the second embodiment, like the radar signal processing device 1 according to the first embodiment, calculates a phase element that depends on the azimuth angle θ with respect to the target 100 and the velocity Vamb of the target 100. By separating and estimating the phase elements due to the above, the velocity V of the target 100 with the velocity measurement range expanded and the azimuth angle θ relative to the target 100 can be obtained, so even when there is velocity ambiguity, the velocity of the target with the velocity measurement range expanded and the azimuth angle relative to the target with high accuracy can be obtained.

[0094] Embodiment 3 The radar signal processing device 1 according to the third embodiment will be described with reference to FIGS. The radar signal processing device 1 according to the third embodiment differs from the radar signal processing device 1 according to the first embodiment in that it includes a target number detection unit 16 that detects the number of targets 100, but is otherwise the same. Therefore, the target number detection unit 16 will be mainly described. 8 and 9, the same reference numerals as those shown in FIGS. 1 to 5 indicate the same or corresponding parts.

[0095] The target number detection unit 16 includes a reception correlation matrix processing unit 16a, an eigenvalue decomposition unit 16b, and a target number determination unit 16c. The reception correlation matrix processing unit 16a obtains the reception correlation matrix R shown in the above equation (6) using the spatial signal S obtained by the target detection unit 11 according to the above equation (3), and performs spatial averaging of the reception correlation matrix R.

[0096] If the number of receiving antennas 31 to 34 is greater than three, the receiving correlation matrix processing unit 16a divides the receiving antennas 31 to 34 into subarrays and performs forward spatial averaging to calculate the average of multiple receiving correlation matrices R created for each subarray, thereby obtaining the spatially averaged receiving correlation matrix R. Or, by performing forward / backward (F / B) spatial averaging processing that combines the average of the correlation matrix in which the relationship between the signal order of the received signal and the arrival angle (arrival direction) of the received signal is inverted, A spatially averaged receive correlation matrix may be obtained. By performing forward spatial averaging or forward / backward (F / B) spatial averaging, the rank of the degenerate matrix can be restored even when the signal of the target 100 detected by the target detection unit 11 is a combination of coherent waves.

[0097] The eigenvalue decomposition unit 16b obtains eigenvalues ​​and corresponding eigenvectors in the spatially averaged reception correlation matrix, which has had its rank restored. Since the rank of the receiving correlation matrix that has been subjected to spatial averaging processing is restored, even when coherent waves are incident on the receiving antennas 31 to 34, it is possible to obtain not only one eigenvalue and one eigenvector corresponding to that eigenvalue, but also two or more corresponding eigenvalues ​​and two or more eigenvectors corresponding to those eigenvalues.

[0098] The target number determination unit 16c determines the number of targets 100 based on the eigenvalues ​​obtained using the reception correlation matrix that has been spatially averaged by the eigenvalue decomposition unit 16b. The eigenvalues ​​and eigenvectors obtained by performing eigenvalue decomposition using the spatially averaged reception correlation matrix by the eigenvalue decomposition unit 16b are separated into those corresponding to arriving waves and noise according to the number of elements of the reception antennas 31 to 34 used in the eigenvalue decomposition.

[0099] For example, if the number of elements in the receiving antenna of the subarray is three and the number of arriving waves is two, two eigenvalues ​​correspond to the arriving waves and the remaining one corresponds to noise. The target number determination unit 16c determines the number of targets 100 based on the magnitude relationship of the eigenvalues. For example, the number of incoming waves corresponding to the number of targets 100 is determined by using the power of noise that has been checked in advance as a threshold and comparing it with the eigenvalue to obtain the number of incoming waves, or by determining the number from the ratio of the eigenvalues.

[0100] The target number determination unit 16c branches the process depending on whether the number of targets 100 obtained by the target number determination is one or two or more. When the target number determination unit 16c determines that the number of targets is 1, it separates the spatial signal S into a phase element that depends on the azimuth angle θ with respect to the target 100 and a phase element that depends on the velocity Vamb of the target 100. Since calculations can be performed separately, processing is performed by the angle measurement compensation processing unit 12, the speed estimation unit 13, the speed compensation processing unit 14, and the angle measurement unit 15, respectively. If the number of targets is two or more, the target number determination unit 16c causes the radar signal processing device 1 to suspend processing of the current signal and move on to processing of the received signal at the next time.

[0101] In short, the target number detection unit 16 performs spatial averaging of the reception correlation matrix obtained using the spatial signal S, determines the number of targets 100 based on the eigenvalues ​​obtained using the spatially averaged reception correlation matrix, and if the number of targets 100 is one, executes subsequent processing, but if the number of targets 100 is two or more, interrupts subsequent processing.

[0102] Next, the operation of the radar signal processing device 1 according to the third embodiment will be described with reference to the flowchart shown in FIG. The target signal detection step ST1 is the same as the target signal detection step ST1 in the radar signal processing device 1 according to the first embodiment. In step ST11, the reception correlation matrix processing unit 16a in the target number detection unit 16 obtains the reception correlation matrix R shown in the above equation (6) using the spatial signal S obtained by the target detection unit 11 using the above equation (3), and performs spatial averaging processing of the reception correlation matrix R. Step ST11 is a reception correlation matrix acquisition step for obtaining a reception correlation matrix that has been subjected to spatial averaging processing.

[0103] In step ST12, the eigenvalue decomposition unit 16b in the target number detection unit 16 obtains eigenvalues ​​and eigenvectors corresponding to the eigenvalues ​​in the spatially averaged reception correlation matrix. Step ST12 is an eigenvalue decomposition step for obtaining eigenvalues ​​and eigenvectors corresponding to the eigenvalues.

[0104] In step ST13, the target number determination unit 16c in the target number detection unit 16 determines the number of targets 100 based on the eigenvalues ​​obtained by the eigenvalue decomposition unit 16b, and the process proceeds to step ST14. In step ST14, if the target number determination unit 16c determines that the number of targets 100 is 1, the process proceeds to step ST2.

[0105] The operations after step ST2 are the same as those after step ST2 in the first embodiment, and therefore the explanation will be omitted. On the other hand, in step ST14, if the target number determination unit 16c determines that the number of targets 100 is two or more, the processing of the current signal is interrupted, and processing is shifted to the processing of the received signal at the next time, and so on.

[0106] Similar to the radar signal processing device 1 according to the first embodiment, the hardware configuration of the radar signal processing device 1 according to the third embodiment is realized by a computer including a CPU 1A, a RAM 1B, a ROM 1C, an input interface unit 1D, an output interface unit 1E, and a signal path (bus) 1F, as shown in FIG. 5.

[0107] The radar signal processing device 1 according to the third embodiment determines the number of targets 100, and after determining in the target number detection unit 16 that the signal being handled is for one target 100, the radar signal processing device 1 according to the third embodiment separates and estimates a phase element that depends on the azimuth angle θ with respect to the target 100 and a phase element that depends on the velocity Vamb of the target 100, in the same way as the radar signal processing device according to the first embodiment. Since the velocity V of the target 100 and the azimuth angle θ relative to the target 100 are obtained with an expanded velocity measurement range, even when there is velocity ambiguity, the velocity of the target with an expanded velocity measurement range and the azimuth angle relative to the target with high accuracy can be obtained.

[0108] The target number detection unit 16 shown in the third embodiment may be configured to be included in the radar signal processing device 1 according to the second embodiment. When the radar signal processing device 1 according to the second embodiment includes the target number detection unit 16 described in the third embodiment, in the radar signal processing device 1 according to the second embodiment, after the target signal detection step ST1 in the flow shown in FIG. 7, the target number detection unit 16 performs the processes of steps ST11 to ST14 shown in FIG. 9, and when the target number detection unit 16 determines in step ST14 that the number of targets 100 is 1, the process proceeds to step ST2, and the processes of steps ST2, ST3, ST4a, ST5, ST6, and ST7 shown in FIG. 7 are performed.

[0109] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted. [Industrial Applicability]

[0110] The radar signal processing device according to the present disclosure is suitable for applications including an in-vehicle radar device. [Explanation of symbols]

[0111] 1 radar signal processing device, 21-23 transmitting antennas, 31-34 receiving antennas, 11 target detection unit, 12, 12A angle measurement compensation processing unit, 13 speed estimation unit, 14 speed compensation processing unit, 15 angle measurement unit, 16 target number detection unit, 100 target.

Claims

1. a target detection unit that receives transmission waves transmitted in a time-division manner from a plurality of transmission antennas and reflected by a target, and obtains a distance to the target, an angle of arrival, and a velocity of the target using reception signals corresponding to the arrival waves from the plurality of reception antennas that receive the reflected waves from the target, and transmission signals corresponding to the transmission waves from the plurality of transmission antennas; an angle measurement compensation processing unit that estimates a phase element that depends on an azimuth angle with respect to the target and is not affected by a phase element due to the velocity of the target, for a spatial signal obtained by a combination of the plurality of transmitting antennas and the plurality of receiving antennas, and corrects the spatial signal using the phase element that depends on the azimuth angle to obtain an angle-compensated spatial signal that is not affected by a phase element that depends on the azimuth angle with respect to the target; a velocity estimation unit that performs a fast Fourier transform process on the angle-compensated spatial signal obtained by the angle measurement compensation processing unit, determines whether or not there is aliasing in the velocity obtained by the target detection unit using the processing result obtained by the fast Fourier transform process, and obtains an estimated velocity of the target from the velocity of the target obtained by the target detection unit based on the result of the determination; a velocity compensation processing unit that estimates a phase element dependent on an estimated velocity of the target obtained by the velocity estimation unit, which is not affected by a phase element due to an azimuth angle relative to the target, for a spatial signal obtained by the target detection unit due to a combination of the multiple transmitting antennas and the multiple receiving antennas, and corrects the spatial signal obtained by the target detection unit due to a combination of the multiple transmitting antennas and the multiple receiving antennas using the phase element dependent on the estimated velocity of the target obtained by the velocity estimation unit, to obtain a velocity-compensated spatial signal that is not affected by a phase element dependent on the velocity relative to the target; an angle measurement unit that performs angle measurement signal processing on the velocity-compensated spatial signal obtained by the velocity compensation processing unit to obtain an azimuth angle with respect to the target; A radar signal processing device comprising:

2. A spatial signal obtained by the combination of the plurality of transmitting antennas and the plurality of receiving antennas by the target detection unit is expressed in a matrix format, with columns indicating transmission and rows indicating reception, and each element in the matrix having a range / azimuth phase element and a velocity phase element, the angle-compensated spatial signal obtained by the angle measurement compensation processing unit is obtained by processing to cancel distance and azimuth phase elements from the spatial signal obtained by the target detection unit through a combination of the plurality of transmitting antennas and the plurality of receiving antennas, and leave only a velocity phase element; the velocity-compensated spatial signal obtained by the velocity compensation processing unit is obtained by processing to cancel velocity phase elements from the spatial signal obtained by the combination of the plurality of transmitting antennas and the plurality of receiving antennas obtained by the target detection unit, and to leave only distance / azimuth phase elements; 2. The radar signal processing device according to claim 1.

3. The spatial signal obtained by the combination of the plurality of transmitting antennas and the plurality of receiving antennas by the target detection unit is expressed in a matrix format, with columns indicating transmission and rows indicating reception, and each element in the matrix having a range / azimuth phase element and a velocity phase element, The angle-compensated spatial signal obtained by the angle measurement compensation processing unit is obtained by performing a DOA estimation process for the direction of arrival from the spatial signal obtained by the target detection unit due to the combination of the multiple transmitting antennas and the multiple receiving antennas in a manner that is not affected by the speed of the target, estimating an azimuth angle relative to the target, and using the estimated azimuth angle that is a result of the DOA estimation process, canceling out distance / azimuth phase elements from the spatial signal obtained by the target detection unit due to the combination of the multiple transmitting antennas and the multiple receiving antennas and leaving a speed phase element.

2. The radar signal processing device according to claim 1.

4. A spatial signal obtained by the combination of the plurality of transmitting antennas and the plurality of receiving antennas by the target detection unit is expressed in a matrix format, where columns indicate transmission and rows indicate reception, and each element in the matrix has a distance / azimuth phase element and a velocity phase element, The angle-compensated spatial signal obtained by the angle measurement compensation processing unit is obtained by performing a DOA estimation process for the direction of arrival from the spatial signal obtained by the combination of the plurality of transmitting antennas and the plurality of receiving antennas, without being affected by the speed of the target, estimating an azimuth angle to the target, extracting a signal having a distance / azimuth angle phase element and a speed phase element corresponding to the distance to the target, expanding the signal compensation range to the signal extracted at the distance to the target, and performing a phase compensation process using the estimated azimuth angle that is a result of the DOA estimation process.

2. The radar signal processing device according to claim 1.

5. The estimated velocity of the target obtained by the velocity estimation unit is When the result of the determination by the speed estimation unit as to whether or not there is a return indicates a positive return, the speed of the target obtained by the target detection unit is set to a value obtained by adding a value twice the maximum speed value of a speed measurement range for the speed of the target obtained by the target detection unit, When the result of the determination by the speed estimation unit as to whether or not there is a wraparound indicates a negative wraparound, a value obtained by subtracting twice the maximum speed value of a speed measurement range for the speed of the target obtained by the target detection unit from the speed of the target obtained by the target detection unit is set as the value; If the result of the determination of the presence or absence of aliasing by the velocity estimation unit indicates that there is no positive or negative aliasing, the velocity is set to the velocity of the target obtained by the target detection unit. The radar signal processing device according to any one of claims 1 to 4.

6. 5. The radar signal processing device according to claim 1, wherein a phase element dependent on the velocity of the target, which is not affected by a phase element due to an azimuth angle with respect to the target, for a spatial signal obtained by a combination of the plurality of transmitting antennas and the plurality of receiving antennas by the target detection unit in the velocity compensation processing unit, is an estimated velocity of the target obtained by the velocity estimation unit.

7. A radar signal processing device as described in any one of claims 1 to 4, further comprising a target number detection unit that performs spatial averaging of a receiving correlation matrix obtained using spatial signals obtained by the combination of the multiple transmitting antennas and the multiple receiving antennas, determines the number of targets based on eigenvalues ​​obtained using the spatially averaged receiving correlation matrix, and executes subsequent processing if the number of targets is one, and interrupts subsequent processing if the number of targets is two or more.

8. a target signal detection step in which a target detection unit acquires a distance to the target, an angle of arrival, and a speed of the target using received signals corresponding to incoming waves from the plurality of receiving antennas that receive the reflected waves from the target, and transmitted signals corresponding to the transmitted waves from the plurality of transmitting antennas; an angle-of-arrival compensation step in which an angle measurement compensation processing unit acquires an angle-compensated signal in which the distance / azimuth angle phase elements are cancelled from a signal having a distance / azimuth angle phase element and a velocity phase element obtained by a combination of the plurality of transmitting antennas and the plurality of receiving antennas; a velocity estimation step in which a velocity estimation unit performs a fast Fourier transform process on the angle-compensated signal, determines whether or not the acquired velocity of the target is aliased using a processing result obtained by the fast Fourier transform process, and obtains an estimated velocity of the target from the acquired velocity of the target based on the determination result; a velocity compensation step in which a velocity compensation processing unit obtains a velocity-compensated signal in which the velocity phase element is cancelled from a signal having a distance / azimuth phase element and a velocity phase element obtained by a combination of the plurality of transmitting antennas and the plurality of receiving antennas; an angle measurement step in which an angle measurement unit performs signal processing on the velocity-compensated signal to measure an angle, thereby obtaining an azimuth angle with respect to the target; Equipped with Radar signal processing method.

9. a target signal detection step in which transmission waves transmitted in a time-division manner from a plurality of transmission antennas are reflected by a target, and the distance and angle of arrival of the target and the velocity of the target are acquired using reception signals corresponding to the arrival waves from a plurality of reception antennas that receive the reflected waves from the target and transmission signals corresponding to the transmission waves from the plurality of transmission antennas; an angle-of-arrival compensation step for obtaining an angle-compensated signal in which the range-azimuth phase elements are cancelled from a signal having a range-azimuth phase element and a velocity phase element obtained by combining the plurality of transmitting antennas and the plurality of receiving antennas; a velocity acquisition step of performing a fast Fourier transform process on the angle-compensated signal, determining whether or not the acquired velocity of the target is aliased using a processing result obtained by the fast Fourier transform process, and obtaining an estimated velocity of the target from the acquired velocity of the target based on the determination result; a velocity compensation step of obtaining a velocity-compensated signal in which the velocity phase elements are cancelled from a signal having a distance / azimuth phase element and a velocity phase element obtained by combining the plurality of transmitting antennas and the plurality of receiving antennas; an angle measurement step for performing signal processing of the velocity compensated signal to obtain an azimuth angle relative to the target; A radar signal processing program that causes a computer to execute the above.

10. a target signal detection step in which transmission waves transmitted in a time-division manner from a plurality of transmission antennas are reflected by a target, and the distance and angle of arrival of the target and the velocity of the target are acquired using reception signals corresponding to the arrival waves from a plurality of reception antennas that receive the reflected waves from the target and transmission signals corresponding to the transmission waves from the plurality of transmission antennas; an angle-of-arrival compensation step for obtaining an angle-compensated signal in which the range-azimuth phase elements are cancelled from a signal having a range-azimuth phase element and a velocity phase element obtained by combining the plurality of transmitting antennas and the plurality of receiving antennas; a velocity acquisition step of performing a fast Fourier transform process on the angle-compensated signal, determining whether or not the acquired velocity of the target is aliased using a processing result obtained by the fast Fourier transform process, and obtaining an estimated velocity of the target from the acquired velocity of the target based on the determination result; a velocity compensation step of obtaining a velocity-compensated signal in which the velocity phase elements are cancelled from a signal having a distance / azimuth phase element and a velocity phase element obtained by combining the plurality of transmitting antennas and the plurality of receiving antennas; an angle measurement step for performing signal processing of the velocity compensated signal to obtain an azimuth angle relative to the target; A recording medium storing a program that causes a computer to execute the above.

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