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

Abstract

A radar signal processing device (5) is configured to comprise: a reception signal acquisition unit (11) for acquiring respective reception signals in a plurality of reception antennas (3-1) to (3-NRx); a spectrum calculation unit (12) for calculating an initial value of a two-dimensional spectrum indicating the direction in which a target is present and the speed of the target on the basis of the reception signals acquired by the reception signal acquisition unit (11); and a spectrum update unit (13) for updating the two-dimensional spectrum on the basis of a nonlinear component included in the spectrum of the speed in the two-dimensional spectrum and the position error of the reception antenna included in the spectrum of an angle in the two-dimensional spectrum.

Description

[Technical Field]

[0001] This disclosure relates to a radar signal processing device, a radar signal processing method, and a radar device. [Background technology]

[0002] There is a radar signal processing device that calculates the direction in which a target is located based on the received signals from multiple receiving antennas. As an example of such a radar signal processing device, Non-Patent Document 1 discloses a radar signal processing device that can accurately estimate the direction in which a target is located, even when there is an unknown positional error at the installation location of the receiving antenna. This radar signal processing device uses the RISR (ReIterative Super Resolution) method as a method for estimating the direction in which a target is located. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] CC Jones et al., “Development & Experimental Assessment of Robust Direction Finding and Self-Calibration,” in Proc. IEEE Radar Conf., Mar. 2022. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The radar signal processing device disclosed in Non-Patent Document 1 has the problem that, although it has the technology to calculate the direction in which a target is located when there is an unknown positional error at the installation location of the receiving antenna, it does not have the technology to calculate the speed of the target.

[0005] This disclosure was made to solve the above-mentioned problems, and aims to provide a radar signal processing device that can calculate not only the direction in which the target is located, but also the speed of the target, when there is an unknown positional error at the installation location of the receiving antenna. [Means for solving the problem]

[0006] The radar signal processing device according to this disclosure includes a received signal acquisition unit that acquires received signals from each of a plurality of receiving antennas, a spectrum calculation unit that calculates initial values ​​of a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target based on the received signals acquired by the received signal acquisition unit, and a spectrum update unit that updates the two-dimensional spectrum based on the nonlinear component included in the velocity spectrum in the two-dimensional spectrum and the position error of the receiving antenna included in the angle spectrum in the two-dimensional spectrum. [Effects of the Invention]

[0007] According to this disclosure, when there is an unknown positional error at the installation location of the receiving antenna, it is possible to calculate not only the direction in which the target is located, but also the speed of the target. [Brief explanation of the drawing]

[0008] [Figure 1] This is a configuration diagram showing a radar system including a radar signal processing device 5 according to Embodiment 1. [Figure 2] This is a hardware configuration diagram showing the hardware of the radar signal processing device 5 according to Embodiment 1. [Figure 3] This is a hardware configuration diagram of a computer when the radar signal processing device 5 is implemented by software or firmware, etc. [Figure 4] This is an explanatory diagram showing the relationship between a vehicle equipped with radar and its target, and the position error Δdj of the receiving antenna 3-j (j=1,···,NRx). [Figure 5] This is an explanatory diagram showing the position error Δdi of the transmitting antenna 2-i (i=1,2,3). [Figure 6] This is an explanatory diagram showing the timing of the pulses output from transmitter 1 to each of the three transmitting antennas 2-1 to 2-3. [Figure 7] This is a flowchart showing the radar signal processing method, which is the processing procedure of the radar signal processing device 5. [Figure 8] This is a configuration diagram showing a radar system including a radar signal processing device 5 according to Embodiment 2. [Figure 9] This is a hardware configuration diagram showing the hardware of the radar signal processing device 5 according to Embodiment 2. [Figure 10] This is an explanatory diagram showing the relationship between a vehicle equipped with radar and its target, and the position error Δdj of the receiving antenna 3-j (j=1,···,NRx). [Figure 11] This is an explanatory diagram showing the relationship between a vehicle equipped with radar and its target, and the position error Δdj of the receiving antenna 3-j (j=1,···,NRx). [Figure 12] This is an explanatory diagram showing the relationship between a vehicle equipped with radar and its target, and the position error Δdj of the receiving antenna 3-j (j=1,···,NRx). [Figure 13] This is an explanatory diagram showing an example of displaying a 2D spectrum with xm and n hats. [Modes for carrying out the invention]

[0009] To provide a more detailed explanation of this disclosure, the forms for implementing this disclosure will be described below with reference to the attached drawings.

[0010] Embodiment 1. Figure 1 is a configuration diagram showing a radar system including a radar signal processing device 5 according to Embodiment 1. Figure 2 is a hardware configuration diagram showing the hardware of the radar signal processing device 5 according to Embodiment 1. The radar system shown in Figure 1 consists of transmitter 1 and transmitting antennas 2-1 to 2-N. Tx , receiving antenna 3-1~3-N Rx, and includes a receiver 4, a radar signal processing device 5, and a display device 6. N Tx is an integer of 1 or more, and N Rx is an integer of 2 or more.

[0011] The transmitter 1 outputs, as a transmission signal, for example, pulses to each of the transmission antennas 2-1 to 2-N Tx The timings at which pulses are output from the transmitter 1 to the transmission antennas 2-1 to 2-N Tx are different from each other. The transmission antenna 2-i (i = 1, ···, N Tx ) radiates, as a transmission signal, for example, pulses toward the target. The transmission timings of the pulses in the transmission antennas 2-1 to 2-N Tx are different from each other.

[0012] The reception antenna 3-j (j = 1, ···, N Rx ) receives the reception signal, which is the transmission signal after being reflected by the target. The reception antenna 3-j outputs the reception signal to the receiver 4. The receiver 4 demodulates the reception signal output from the reception antenna 3-j, and converts the demodulated reception signal from an analog signal to a digital signal. The receiver 4 outputs a digital signal to the radar signal processing device 5 as the reception signal of the reception antenna 3-j.

[0013] The radar signal processing device 5 includes a reception signal acquisition unit 11, a spectrum calculation unit 12, and a spectrum update unit 13. The display device 6 displays the two-dimensional spectrum calculated by the radar signal processing device 5. The two-dimensional spectrum indicates the direction in which the target exists and the speed of the target. In the radar device shown in FIG. 1, the radar signal processing device 5 outputs the two-dimensional spectrum to the display device 6, and the display device 6 displays the two-dimensional spectrum. However, this is only an example, and the radar signal processing device 5 may output the two-dimensional spectrum to, for example, a tracking device not shown in the figure, and the tracking device may track the target based on the two-dimensional spectrum.

[0014] The received signal acquisition unit 11 is implemented, for example, by the received signal acquisition circuit 21 shown in Figure 2. The received signal acquisition unit 11 receives the signal from the receiver 4 to the receiving antenna 3-j (j=1,···,N Rx ) Obtain the received signal. The received signal acquisition unit 11 outputs the received signal to the spectrum calculation unit 12.

[0015] The spectrum calculation unit 12 is implemented, for example, by the spectrum calculation circuit 22 shown in Figure 2. The spectrum calculation unit 12 acquires the received signal from the received signal acquisition unit 11. The spectrum calculation unit 12 calculates initial values ​​for a two-dimensional spectrum that indicates the direction in which the target is located and the velocity of the target, based on the received signal. The target is a moving object such as a vehicle, airplane, or animal. If the radar device shown in Figure 1 is installed on a vehicle, for example, the target's speed shown in the 2D spectrum is the target's relative speed to the vehicle on which the radar device is installed. If the radar device shown in Figure 1 is installed, for example, on a road structure, the target's velocity shown in the 2D spectrum is the target's absolute velocity. The spectrum calculation unit 12 outputs the initial values ​​of the two-dimensional spectrum to the spectrum update unit 13.

[0016] The spectrum update unit 13 is implemented, for example, by the spectrum update circuit 23 shown in Figure 2. The spectrum update unit 13 includes a first update processing unit 13a, a second update processing unit 13b, and a third update processing unit 13c. The spectrum update unit 13 obtains the initial values ​​of the two-dimensional spectrum from the spectrum calculation unit 12. The spectrum update unit 13 processes the nonlinear components contained in the velocity spectrum in the two-dimensional spectrum (hereinafter referred to as the "velocity spectrum") and the receiving antennas 3-1 to 3-N contained in the angle spectrum in the two-dimensional spectrum (hereinafter referred to as the "angle spectrum"). RxThe 2D spectrum is updated based on the positional error. Once the spectrum update unit 13 has completed the two-dimensional spectrum update process, it outputs the updated two-dimensional spectrum to, for example, the display device 6.

[0017] The first update processing unit 13a obtains the initial values ​​of the two-dimensional spectrum from the spectrum calculation unit 12. The first update processing unit 13a updates the two-dimensional spectrum based on the nonlinear components included in the velocity spectrum. Specifically, the first update processing unit 13a updates the two-dimensional spectrum based on the nonlinear component in the velocity spectrum that is caused by the target acceleration. Furthermore, the first update processing unit 13a analyzes the nonlinear components included in the velocity spectrum, specifically the transmitting antennas 2-1 to 2-N Tx The two-dimensional spectrum is updated based on the nonlinear components resulting from variations in the transmission intervals of the pulses sent from each of them. The first update processing unit 13a outputs the updated two-dimensional spectrum to the second update processing unit 13b.

[0018] The second update processing unit 13b acquires the updated two-dimensional spectrum from the first update processing unit 13a. The second update processing unit 13b processes the receiving antennas 3-1 to 3-N included in the angular spectrum. Rx Based on the positional error, the updated 2D spectrum is updated by the first update processing unit 13a. The second update processing unit 13b outputs the updated two-dimensional spectrum to the third update processing unit 13c.

[0019] The third update processing unit 13c acquires the updated two-dimensional spectrum from the second update processing unit 13b. The third update processing unit 13c processes the nonlinear components included in the velocity spectrum and the receiving antennas 3-1 to 3-N Nx Based on the coupling error with the position error, the updated 2D spectrum is updated by the second update processing unit 13b. The third update processing unit 13c outputs the updated two-dimensional spectrum to, for example, the display device 6.

[0020] In Figure 1, the radar signal processing device 5 is assumed to be implemented by dedicated hardware as shown in Figure 2, with each of its components—the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 13—being implemented by dedicated hardware. Specifically, the radar signal processing device 5 is assumed to be implemented by a received signal acquisition circuit 21, a spectrum calculation circuit 22, and a spectrum update circuit 23. The received signal acquisition circuit 21, the spectrum calculation circuit 22, and the spectrum update circuit 23 can each be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0021] The components of the radar signal processing unit 5 are not limited to those implemented by dedicated hardware; the radar signal processing unit 5 may also be implemented by software, firmware, or a combination of software and firmware. Software or firmware is stored as a program in the computer's memory. A computer refers to the hardware that executes programs, and includes, for example, a CPU (Central Processing Unit), GPU (Graphics Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP (Digital Signal Processor).

[0022] Figure 3 is a hardware configuration diagram of a computer when the radar signal processing unit 5 is implemented by software or firmware, etc. If the radar signal processing device 5 is implemented by software or firmware, a program is stored in the memory 31 that causes the computer to execute the respective processing procedures in the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 13. The computer's processor 32 then executes the program stored in the memory 31.

[0023] Furthermore, Figure 2 shows an example in which each component of the radar signal processing unit 5 is implemented by dedicated hardware, and Figure 3 shows an example in which the radar signal processing unit 5 is implemented by software or firmware, etc. However, this is only one example, and some components of the radar signal processing unit 5 may be implemented by dedicated hardware, while the remaining components may be implemented by software or firmware, etc.

[0024] The radar device shown in Figure 1 is installed near the front of the vehicle, for example, as shown in Figure 4, and its target is, for example, another vehicle traveling to the right front of the vehicle. In the example in Figure 4, the intervals of the transmitted signal pulses are set to λ / 2, which is half the wavelength of the pulses. Rx Individual receiving antennas 3-1~3-N Rx They are installed in a single row. In the example in Figure 4, transmitting antennas 2-1 to 2-N Tx The description has been omitted. In the example in Figure 4, receiving antennas 3-1 to 3-N Rx In the direction in which they are aligned, the receiving antenna 3-j (j=1,···,N Rx ) Position error Δd j These occur randomly. Furthermore, in the example shown in Figure 4, the vehicle equipped with the radar device is traveling at a constant speed, while the target vehicle is traveling with an unknown acceleration. Figure 4 shows the relationship between the vehicle equipped with the radar device and the target, and the position error Δd of the receiving antenna 3-j. j This is an explanatory diagram illustrating the above.

[0025] Figure 4 shows the position error Δd of the receiving antenna 3-j. j This shows an example where the error occurs randomly. The position error Δd of the receiving antenna 3-j. j Even if this does not occur, as shown in Figure 5, the transmitting antenna 2-i(i=1,···,N Tx ) position error Δd i If this occurs, the position error Δd of the receiving antenna 3-j is as shown in Figure 4. j It can be treated as something that has occurred. Figure 5 shows the position error Δd of the transmitting antenna 2-i (i=1,2,3). i This is an explanatory diagram illustrating the concept. N Tx Individual transmitting antennas 2-1~2-N Tx They are arranged in a line so that they are spaced at intervals of two wavelengths 2λ of the transmitted signal pulses. However, in the example in Figure 5, the position error Δd of the transmitting antenna 2-i is i These occur randomly.

[0026] Next, we will explain the operation of the radar device shown in Figure 1. Transmitter 1 repeatedly generates pulses as a transmission signal, and transmits the pulses to the transmitting antennas 2-1 to 2-N. Tx Output to each of them. Transmitter 1 to transmitting antenna 2-i (i=1,···,N) Tx The period at which pulses are output is an interval of time T, as shown in Figure 6. Figure 6 is an explanatory diagram showing the timing of pulses output from transmitter 1 to each of the three transmitting antennas 2-1 to 2-3. In the example shown in Figure 6, the timing at which a pulse is output from transmitter 1 to transmitting antenna 2-1 and the timing at which a pulse is output from transmitter 1 to transmitting antenna 2-2 are staggered by time τ. Furthermore, the timing at which a pulse is output from transmitter 1 to transmitting antenna 2-2 and the timing at which a pulse is output from transmitter 1 to transmitting antenna 2-3 are staggered by time τ. The transmitting antenna 2-i radiates the pulse output from transmitter 1 toward the target.

[0027] Transmitting antenna 2-i (i=1,···,N) Tx A portion of the pulse emitted from ) is reflected by the target. The pulse after reflection by the target is received by the receiving antenna 3-j(j=1,···,N Rx ) will return. The receiving antenna 3-j receives the pulse after it has been reflected by the target and outputs the received pulse signal to the receiver 4. Receiver 4 demodulates the received signal output from receiving antenna 3-j and converts the demodulated received signal from an analog signal to a digital signal. The receiver 4 outputs a received signal s(i,j,h), which is a digital signal, to the radar signal processing device 5, as shown in equation (1) below.

[0028] TIFF0007840497000001.tif34166

[0029] In equation (1), h is the hit number of the pulse radiated from the transmitting antenna 2-i. For the sake of explanation, let's assume that h = 0, 1, ..., H-1. H is an integer greater than or equal to 2. i is a variable that represents the transmitting antenna 2-i that emitted the pulse. For the sake of explanation, here i = 0, 1, ..., N TX Let's assume it's -1. However, this is just one example, i=1,...,N TX That's fine. j is a variable that indicates the receiving antenna 3-j that received the pulse. For the sake of explanation, here we have j = 0, 1, ..., N RX Let's assume it's -1. However, this is just one example, and j=1,...,N RX That's fine. v0 is the initial velocity of the target in the line of sight, β is the acceleration of the target in the line of sight, and θ is the direction in which the target is located, as measured from the boresight. k c This is the central wavenumber.

[0030] In equation (1), k c·βhT·hT is the phase disturbance term of the received signal s(i,j,h) caused by the acceleration β in the line of sight direction of the target. k c ·sinθ·Δd i This is the position error Δd of the transmitting antenna 2-i. i This is the phase distortion term of the received signal s(i,j,h) that results from the following: k c ·(2v0+βiτ)·iτ is the phase disturbance term of the received signal s(i,j,h) caused by the acceleration β in the line of sight direction of the target. k c ·2β·hT·iτ is the phase disturbance term of the received signal s(i,j,h) caused by the acceleration β in the line of sight direction of the target.

[0031] The four phase disturbance terms are errors ΔT that follow different Gaussian distributions. h ,ΔD i ,Δτ i ,Δe hi Using this, we can approximate it as shown in equations (2) to (5) below, where the error ΔT h ,ΔD i ,Δτ i ,Δe hi is ΔT h ~N(0,σ T 2 ), ΔD i ~N(0,σ D 2 ), Δe hi ~N(0,σ e 2 ) shall be followed.

[0032] TIFF0007840497000002.tif47166

[0033] By substituting equations (2) to (5) into equation (1), the received signal s(i,j,h) can be approximated as shown in equation (6) below.

[0034] TIFF0007840497000003.tif22166

[0035] In a two-dimensional RISR (Reiterative Super Resolution) that includes multiple error models, if we can ignore the dynamic error component of the receiving antenna 3-j, the two-dimensional RISR can be modeled as shown in equations (7) to (16) below.

[0036] TIFF0007840497000004.tif51166

[0037] y∈C (in bold) NRx×1 is, N Rx 3-j (j=0,1,···,N) receiving antennas RX The received signal vector of an array antenna having (-1) (s(i,0,h),···,s(i,N Rx -1, h)) A∈C (in bold) Nv×Ma This is a steering vector a corresponding to Ma (where Ma is an integer greater than or equal to 2) angle grids. m,n This is an array manifold matrix with the elements arranged in the column direction. Steering vector a m,n This refers to receiving antennas 3-1 to 3-N in a certain direction. Rx This indicates the amplitude ratio or phase difference between the two signals, and is a known value in the radar signal processing device 5. Bold x = [x 1,1 ,···,x m,n ,···,x Ma,Nv ] is an angle grid of m (m=1,···,M a ), the velocity grid is n (n=1,···,N v This is the signal amplitude vector, which shows the signal amplitude of the grid. The bolded n is the complex noise vector. Q (1) ∈C Nv×Ma This is a static array error matrix that lists the steering vector errors caused by the target acceleration. Q (2) ∈C Nv×Ma This is the position error Δd of the receiving antenna 3-j. j This is a static array error matrix consisting of steering vector errors resulting from the following: Q(3) ∈C Nv×Ma is a static array error matrix arranging steering vector errors caused by coupling errors. M a is the number of angle grids in the two-dimensional spectrum including the angle spectrum indicating the direction where the target exists and the velocity spectrum indicating the velocity of the target, and N v is the number of velocity grids in the two-dimensional spectrum.

[0038] TIFF0007840497000005.tif125166

[0039] TIFF0007840497000006.tif195166

[0040] FIG. 7 is a flowchart showing a radar signal processing method which is a processing procedure of the radar signal processing apparatus 5. The reception signal acquisition unit 11 of the radar signal processing apparatus 5 acquires reception signals s(i, j, h) from the receiver 4 for reception antennas 3-j (j = 0, ···, N Rx -1) (step ST1 in FIG. 7). In FIG. 1, for the N Rx reception antennas, signs 3-1 to 3-N Rx are attached, but here, for convenience of explanation, it is assumed that j = 0, ···, N Rx -l. The reception signal acquisition unit 11 outputs the reception signal s(i, j, h) to the spectrum calculation unit 12.

[0041] The spectrum calculation unit 12 acquires the reception signal s(i, j, h) from the reception signal acquisition unit 11. The spectrum calculation unit 12 calculates an initial value of a two-dimensional spectrum x m,n hat indicating the direction where the target exists and the velocity of the target (step ST2 in FIG. 7). Due to the relationship of electronic applications, in the text of the specification, the symbol "^" cannot be attached above the character "x m,n ", so it is expressed as "x m,n hat". Specifically, as shown in the following equation (17), the spectrum calculation unit 12 uses the received signal vector y = (s(i,0,h), ···, s(i,N Rx -1,h)) of the array antenna and the steering vector a m,n shown in equation (13) to calculate the initial value of the two-dimensional spectrum x m,n with a hat. The spectrum calculation unit 12 outputs the initial value of the two-dimensional spectrum x m,n with a hat to the spectrum update unit 13.

[0042] TIFF0007840497000007.tif14166

[0043] The spectrum update unit 13 obtains the initial value of the two-dimensional spectrum x m,n with a hat from the spectrum calculation unit 12. The spectrum update unit 13 updates the two-dimensional spectrum x Rx with a hat based on the non-linear component included in the velocity spectrum of the two-dimensional spectrum and the position error of the receiving antennas 3-1 to 3-N m,n included in the angle spectrum of the two-dimensional spectrum. When the update process of the two-dimensional spectrum x m,n with a hat by the spectrum update unit 13 is completed, the updated two-dimensional spectrum x m,n with a hat is output to, for example, the display device 6.

[0044] Hereinafter, the update process of the two-dimensional spectrum x m,n with a hat by the spectrum update unit 13 will be specifically described. First, the first update processing unit 13a of the spectrum update unit 13 calculates the expected value E[q m,n (1) q m,n (1)H of the error covariance matrix in the two-dimensional RISR according to either of the following equations (18) or (19). m = 1, ···, M a where n = 1, ···, N v where.

[0045] In formulas (18) to (19) of TIFF0007840497000008.tif43166, 1 K×L This is a K×L matrix where all elements are 1, and I K This is the K×K identity matrix.

[0046] The second update processing unit 13b of the spectrum update unit 13 calculates the expected value E[q] of the error covariance matrix in 2D RRISR using either equation (20) or equation (21) below. m,n (2) q m,n (2)H [As described in ].

[0047] TIFF0007840497000009.tif44166

[0048] The third update processing unit 13c of the first update processing unit 13a calculates the expected value E[q] of the error covariance matrix in 2D RRISR using either equation (22) or equation (23) below. m,n (3) q m,n (3)H [As described in ].

[0049] TIFF0007840497000010.tif40166

[0050] Next, the first update processing unit 13a calculates the expected value E[q] of the error covariance matrix, as shown in equations (24) to (28) below. m,n (1) q m,n (1)H Using the approximate analytical solution of ], the array error matrix Q (1) Approximate analytical solution E[yx] when only the error component is included in the RRISR model. m,n * ] and the approximate analytical solution E[yy H Calculate ]. Specifically, the first update processing unit 13a processes the two-dimensional spectrum x calculated by the spectrum calculation unit 12. m,nThe initial value of the hat is p m,n By substituting this into equation (24), we obtain the approximate analytical solution E[yx m,n * [As described in ]. Furthermore, the first update processing unit 13a processes the 2D spectrum x m,n The initial value of the hat is p m,n By substituting this into equation (27), the correlation matrix R xx Calculate. Then, the first update processing unit 13a processes the correlation matrix R xx By substituting this into equation (25), we obtain the approximate analytical solution E[yy H [As described in ].

[0051] TIFF0007840497000011.tif68166

[0052] The second update processing unit 13b calculates the expected value E[q] of the error covariance matrix, as shown in equations (29) to (31) below. m,n (2) q m,n (2)H Using the approximate analytical solution of ], the array error matrix Q (2) Approximate analytical solution E[yx] when only the error component is included in the RRISR model. m,n * ] and the approximate analytical solution E[yy H Calculate ]. Specifically, the second update processing unit 13b processes the two-dimensional spectrum x calculated by the spectrum calculation unit 12. m,n The initial value of the hat is p m,n By substituting this into equation (29), we obtain the approximate analytical solution E[yx m,n * [As described in ]. Furthermore, the second update processing unit 13b processes the correlation matrix R calculated by the first update processing unit 13a. xx By substituting this into equation (30), we obtain the approximate analytical solution E[yy H [As described in ].

[0053] TIFF0007840497000012.tif44166

[0054] The third update processing unit 13c calculates the expected value E[q] of the error covariance matrix, as shown in equations (32) to (34) below. m,n (3) q m,n (3)H Using the approximate analytical solution of ], the array error matrix Q (3) Approximate analytical solution E[yx] when only the error component is included in the RRISR model. m,n * ] and the approximate analytical solution E[yy H Calculate ]. Specifically, the third update processing unit 13c processes the two-dimensional spectrum x calculated by the spectrum calculation unit 12. m,n The initial value of the hat is p m,n By substituting this into equation (32), we obtain the approximate analytical solution E[yx m,n * [As described in ]. Furthermore, the third update processing unit 13c processes the correlation matrix R calculated by the first update processing unit 13a. xx By substituting this into equation (33), we obtain the approximate analytical solution E[yy H [As described in ].

[0055] TIFF0007840497000013.tif39166

[0056] Here, the approximate analytical solution E[yy] shown in equation (25) H ] and the approximate analytical solution E[yy shown in equation (30) H ] and the approximate analytical solution E[yy shown in equation (33) H Comparing them, we can see that their block matrix structures are different. Because the block matrix structures are different, the array error matrix Q (1) Error components and array error matrix Q (2) Error components and array error matrix Q (3) The optimal weights for RISR when all error components are included in the RISR model. m,n (1) Hat, w m,n (2) Hat, wm,n (3) Calculating hats is not easy.

[0057] Therefore, the first update processing unit 13a calculates the array error matrix Q for the RISR model, as shown in equations (35) to (36) below. (1) By including the error component, the optimal weight of RRISR w m,n (1) Calculate the hat. Specifically, the optimal weight w by the first update processing unit 13a m,n (1) If the hat calculation is the first calculation, the first update processing unit 13a calculates the already calculated correlation matrix R xx By substituting into equation (36), the optimal weight w m,n (1) Calculate the hat. Optimal weight w by the first update processing unit 13a m,n (1) If the hat calculation is the second or subsequent calculation, the first update processing unit 13a, in step ST5 described later, uses the 2D spectrum x that was previously updated by the third update processing unit 13c. m,n hat p m,n By substituting this into equation (27), the correlation matrix R xx The 2D spectrum x is calculated by the third update processing unit 13c. m,n The update of the hat will be discussed later. The first update processing unit 13a calculates the correlation matrix R xx By substituting into equation (36), the optimal weight w m,n (1) Calculate the hat. The first update processing unit 13a uses the optimal weight w as shown in equation (37) below. m,n (1) Using a hat, the 2D spectrum x m,n Update the hat (step ST3 in Figure 7).

[0058] In equation (35) of TIFF0007840497000014.tif49166, α is a partial constraint coefficient that takes values ​​between 0 and 1.

[0059] Next, the second update processing unit 13b calculates the array error matrix Q for the RRISR model, as shown in equations (38) to (39) below. (2) By including the error component, the optimal weight of RRISR w m,n (2) Calculate the hat. Specifically, the second update processing unit 13b processes the two-dimensional spectrum x after it has been updated by the first update processing unit 13a. m,n hat p m,n By substituting this into equation (27), the correlation matrix R xx Calculate. The second update processing unit 13b calculates the correlation matrix R xx By substituting this into equation (39), the optimal weight w m,n (2) Calculate the hat. The second update processing unit 13b uses the optimal weight w as shown in equation (40) below. m,n (2) Using a hat, the updated 2D spectrum x by the first update processing unit 13a is obtained. m,n Further update the hat (step ST4 in Figure 7).

[0060] TIFF0007840497000015.tif49166

[0061] Next, the third update processing unit 13c calculates the array error matrix Q for the RRISR model, as shown in equations (41) to (42) below. (3) By including the error component, the optimal weight of RRISR w m,n (3) Calculate the hat. Specifically, the third update processing unit 13c processes the two-dimensional spectrum x after it has been updated by the second update processing unit 13b. m,n hat p m,n By substituting this into equation (27), the correlation matrix R xxCalculate. The third update processing unit 13c calculates the correlation matrix R xx By substituting into equation (42), the optimal weight w m,n (3) Calculate the hat. The third update processing unit 13c uses the optimal weight w as shown in equation (43) below. m,n (3) Using a hat, the updated 2D spectrum x by the second update processing unit 13b is obtained. m,n Further update the hat (step ST5 in Figure 7).

[0062] TIFF0007840497000016.tif44166

[0063] The spectrum update unit 13 displays the updated 2D spectrum x by the third update processing unit 13c. m,n If the hats have not converged (step ST6: NO in Figure 7), the update process in steps ST3 to ST5 is repeated. Each time the update process in steps ST3 to ST5 is repeated, the 2D spectrum x m,n The accuracy of the hat markers will improve. The spectrum update unit 13 updates the 2D spectrum x m,n If the hats have converged (step ST6: YES in Figure 7), the updated 2D spectrum x by the third update processing unit 13c m,n The hat is output to, for example, the display device 6. 2D spectrum x m,n The convergence conditions for the hat are not particularly limited, but for example, the 2D spectrum x before and after the update m,n If the difference in hats is below the threshold, the updated 2D spectrum x m,n We can conclude that the hats have converged. On the other hand, the 2D spectrum x before and after the update m,n If the difference in hats is greater than the threshold, the updated 2D spectrum x m,n It can be determined that the hats have not converged.

[0064] The display device 6 receives the updated 2D spectrum x from the radar signal processing device 5. m,n Get a hat. As shown in Figure 13, the display device 6 displays the updated 2D spectrum x m,n Display the hat on a display that is not shown. Figure 13 shows the 2D spectrum x m,n This is an explanatory diagram showing an example of how to display a hat symbol. In Figure 13, the horizontal axis represents angle, and the vertical axis represents velocity. The grid in the diagram, which indicates the direction in which the target is located and the target's speed, is shown in black.

[0065] In the above embodiment 1, multiple receiving antennas 3-1 to 3-N Rx The radar signal processing device 5 is configured to include a received signal acquisition unit 11 that acquires each received signal at the receiving signal acquisition unit 11, a spectrum calculation unit 12 that calculates initial values ​​of a two-dimensional spectrum indicating the direction in which the target is located and the speed of the target based on the received signals acquired by the received signal acquisition unit 11, and a spectrum update unit 13 that updates the two-dimensional spectrum based on the nonlinear component included in the speed spectrum and the position error of the receiving antenna included in the angle spectrum of the two-dimensional spectrum. Therefore, the radar signal processing device 5 can calculate not only the direction in which the target is located but also the speed of the target when there is an unknown position error at the installation position of the receiving antenna 3-j.

[0066] Embodiment 2. In Embodiment 2, the spectrum update unit 14 adjusts the optimal weight w for the first number of updates. m,n (1) Using a hat, the 2D spectrum x m,n The process of updating the hat is performed, and the optimal weight is applied only for the second update. m,n (2) Using a hat, the 2D spectrum x m,n The process of updating the hat is performed, and the optimal weight is applied only for the third update. m,n (3)Using a hat, the 2D spectrum x m,n The radar signal processing device 5, which performs the process of updating the hat, will now be described.

[0067] Figure 8 is a configuration diagram showing a radar system including a radar signal processing device 5 according to Embodiment 2. In Figure 8, the same reference numerals as in Figure 1 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 9 is a hardware configuration diagram showing the hardware of the radar signal processing device 5 according to Embodiment 2. In Figure 9, the same reference numerals as in Figure 2 indicate the same or corresponding parts, so a detailed explanation is omitted. The radar signal processing device 5 shown in Figure 8 includes a received signal acquisition unit 11, a spectrum calculation unit 12, and a spectrum update unit 14.

[0068] The spectrum update unit 14 is implemented, for example, by the spectrum update circuit 24 shown in Figure 9. The spectrum update unit 14 includes a first update processing unit 14a, a second update processing unit 14b, and a third update processing unit 14c. The spectrum update unit 14 obtains the initial values ​​of the two-dimensional spectrum from the spectrum calculation unit 12. The spectrum update unit 14 calculates a first update count, which is the number of update processes for the two-dimensional spectrum based on the nonlinear components included in the velocity spectrum of the two-dimensional spectrum. The spectrum update unit 14 repeatedly performs the update process of the two-dimensional spectrum based on the nonlinear component for a first number of update cycles.

[0069] The spectrum update unit 14 is connected to the receiving antennas 3-1 to 3-N. Rx Based on the positional error, receiving antennas 3-1 to 3-N Rx The second update count, which is the number of times the 2D spectrum is updated based on the position error, is calculated. The spectrum update unit 14 repeatedly performs the update process of the 2D spectrum based on the position error for a second number of update cycles. The spectrum update unit 14 calculates a third update count, which is the number of times the two-dimensional spectrum is updated based on the coupling error. The spectrum update unit 14 repeatedly performs the two-dimensional spectrum update process based on the coupling error for a third update cycle. The spectrum update unit 14 generates a 2D spectrum x m,n Once the hat update process is complete, the updated 2D spectrum x m,n The hat is output to, for example, the display device 6.

[0070] The first update processing unit 14a obtains the initial values ​​of the two-dimensional spectrum from the spectrum calculation unit 12. The first update processing unit 14a calculates the first update count based on the magnitude of the nonlinear component caused by the target acceleration and the magnitude of the nonlinear component caused by the variation in the pulse transmission interval. The first update processing unit 14a repeatedly performs the update process of the two-dimensional spectrum based on the nonlinear component for a first number of update cycles. The two-dimensional spectrum update process performed by the first update processing unit 14a is the same as the two-dimensional spectrum update process performed by the first update processing unit 13a shown in Figure 1. The first update processing unit 14a outputs the updated two-dimensional spectrum to the second update processing unit 14b.

[0071] The second update processing unit 14b acquires the updated two-dimensional spectrum from the first update processing unit 14a. The second update processing unit 14b processes the receiving antennas 3-1 to 3-N included in the angular spectrum. Rx Based on the positional error, the second update count is calculated. The second update processing unit 14b repeatedly performs the update process of the 2D spectrum based on the position error for a second number of update cycles. The two-dimensional spectrum update process by the second update processing unit 14b is the same as the two-dimensional spectrum update process by the second update processing unit 13b shown in Figure 1. The second update processing unit 14b outputs the updated two-dimensional spectrum to the third update processing unit 14c.

[0072] The third update processing unit 14c acquires the updated two-dimensional spectrum from the second update processing unit 14b. The third update processing unit 14c calculates the third update count based on the coupling error. The third update processing unit 14c repeatedly performs the update process of the two-dimensional spectrum based on the coupling error for a third number of update cycles. The two-dimensional spectrum update process by the third update processing unit 14c is the same as the two-dimensional spectrum update process by the third update processing unit 13c shown in Figure 1. The third update processing unit 14c outputs the updated two-dimensional spectrum to, for example, the display device 6.

[0073] In Figure 8, the radar signal processing device 5 is assumed to be implemented by dedicated hardware as shown in Figure 9, with each of its components—the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 14—being implemented by dedicated hardware. Specifically, the radar signal processing device 5 is assumed to be implemented by the received signal acquisition circuit 21, the spectrum calculation circuit 22, and the spectrum update circuit 24. Each of the receiving signal acquisition circuit 21, spectrum calculation circuit 22, and spectrum update circuit 24 can be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0074] The components of the radar signal processing unit 5 are not limited to those implemented by dedicated hardware; the radar signal processing unit 5 may also be implemented by software, firmware, or a combination of software and firmware. When the radar signal processing unit 5 is implemented by software or firmware, a program that causes a computer to execute the respective processing procedures in the received signal acquisition unit 11, the spectrum calculation unit 12, and the spectrum update unit 14 is stored in the memory 31 shown in Figure 3. Then, the processor 32 shown in Figure 3 executes the program stored in the memory 31.

[0075] Furthermore, Figure 9 shows an example in which each component of the radar signal processing unit 5 is implemented by dedicated hardware, while Figure 3 shows an example in which the radar signal processing unit 5 is implemented by software or firmware. However, this is merely one example, and some components of the radar signal processing unit 5 may be implemented by dedicated hardware, while the remaining components may be implemented by software or firmware.

[0076] Next, the operation of the radar system shown in Figure 8 will be explained. However, it is the same as the radar system shown in Figure 1, except for the spectrum update unit 14 of the radar signal processing device 5. Therefore, only the operation of the spectrum update unit 14 will be explained here.

[0077] The first update processing unit 14a calculates the first update count UPC1 based on the magnitude of the nonlinear component NC1 caused by the target line-of-sight acceleration β and the magnitude of the nonlinear component NC2 caused by the variation in the pulse transmission interval, for example, as shown in equation (44) below.

[0078] In formula (44) of TIFF0007840497000017.tif15166, PC1 and PC2 are proportionality constants, which may be stored in the internal memory of the first update processing unit 14a, for example, or may be provided from outside the radar signal processing unit 5.

[0079] The second update processing unit 14b processes the receiving antenna 3-j (j=1,···,N) included in the angular spectrum, for example, as shown in equation (45) or equation (46) below. Rx) position error Δd j Based on this, the second update count, UPC2, is calculated.

[0080] In equations (45) and (46) of TIFF0007840497000018.tif42166, PC3 is a proportionality constant, which may be stored in the internal memory of the second update processing unit 14b, or it may be provided from outside the radar signal processing unit 5.

[0081] The third update processing unit 14c calculates the third update count UPC3 based on the coupling error CE, for example, as shown in equation (47) below.

[0082] In formula (47) of TIFF0007840497000019.tif11166, PC4 is a proportionality constant, which may be stored in the internal memory of the third update processing unit 14c, for example, or it may be provided from outside the radar signal processing unit 5.

[0083] The first update processing unit 14a, the second update processing unit 14b, and the third update processing unit 14c, respectively, perform the same two-dimensional spectral x as the first update processing unit 13a, the second update processing unit 13b, and the third update processing unit 13c shown in Figure 1. m,n The hat update process is performed sequentially. However, while the number of update operations in the first update processing unit 13a, the second update processing unit 13b, and the third update processing unit 13c shown in Figure 1 are the same, the number of update operations in the first update processing unit 14a, the second update processing unit 14b, and the third update processing unit 14c are different from each other. In other words, the first update processing unit 14a calculates the 2D spectrum x based on the nonlinear component for the first update cycle UPC1. m,n Perform the hat update process. The second update processing unit 14b adjusts the position error Δd by the second update cycle UPC2. j 2D spectrum x based on m,n Perform the hat update process. The third update processing unit 14c generates a 2D spectrum x based on the coupling error CE for the third update cycle UPC3. m,n Perform the hat update process.

[0084] In the above embodiment 2, the spectrum update unit 14 calculates a first update count, which is the number of update processes for the two-dimensional spectrum based on the nonlinear components, based on the nonlinear components included in the velocity spectrum, and the receiving antenna 3-j(j=1,···,N Rx Based on the position error of the receiving antenna 3-j, a second update count is calculated, which is the number of update processes for the 2D spectrum based on the position error of the receiving antenna 3-j. Based on the coupling error, a third update count is calculated, which is the number of update processes for the 2D spectrum based on the coupling error. The radar signal processing device 5 shown in Figure 8 is configured such that the spectrum update unit 14 repeatedly performs the 2D spectrum update process based on the nonlinear component for the first update count, repeatedly performs the 2D spectrum update process based on the position error of the receiving antenna 3-j for the second update count, and repeatedly performs the 2D spectrum update process based on the coupling error for the third update count. Therefore, the radar signal processing device 5 shown in Figure 8, like the radar signal processing device 5 shown in Figure 1, can calculate not only the direction in which the target is located but also the speed of the target when there is an unknown position error at the installation position of the receiving antenna 3-j, and can optimize the number of update processes.

[0085] Embodiment 3. In Embodiments 1 and 2, as an example of the application of the radar signal processing device 5, Figure 4 shows a scenario in which a vehicle equipped with a radar device is traveling at a constant speed, and a target vehicle is traveling with an unknown acceleration. However, this is just one example, and as an example of the application of the radar signal processing device 5, as shown in Figure 10, the vehicle on which the radar device is installed may be traveling with acceleration, while the target vehicle is traveling at a constant speed. In the example in Figure 10, the intervals of the transmitted signal pulses are set to λ / 2, which is half the wavelength of the pulses. RxIndividual receiving antennas 3-1~3-N Rx They are installed in a row. In the example in Figure 10, transmitting antennas 2-1 to 2-N Tx The description has been omitted. In the example in Figure 10, the receiving antenna 3-j (j=1,···,N) Rx ) Position error Δd j These occur randomly. Figure 10 shows the relationship between the vehicle equipped with the radar device and the target, and the position error Δd of the receiving antenna 3-j. j This is an explanatory diagram illustrating the above. Even if the application example of the radar signal processing device 5 is as shown in Figure 10, the radar signal processing device 5 can calculate a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target, when there is an unknown positional error at the installation position of the receiving antenna 3-j, similar to embodiments 1 and 2.

[0086] Furthermore, as an example of the application of the radar signal processing device 5, as shown in Figure 11, both the vehicle on which the radar device is installed and the target vehicle may be traveling at a constant speed. However, in the example in Figure 11, the transmitting antennas 2-1 to 2-N Tx There is variation in the transmission interval of the pulses sent from the device. Figure 11 shows the relationship between the vehicle equipped with the radar device and the target, and the position error Δd of the receiving antenna 3-j. j This is an explanatory diagram illustrating the above. Even if the application example of the radar signal processing device 5 is as shown in Figure 11, the radar signal processing device 5 can calculate a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target, when there is an unknown positional error at the installation position of the receiving antenna 3-j, similar to embodiments 1 and 2.

[0087] Furthermore, as an example of the application of the radar signal processing device 5, as shown in Figure 12, the vehicle on which the radar device is installed may be traveling with acceleration, while the target vehicle is traveling with an unknown acceleration. In the example in Figure 12, the intervals of the transmitted signal pulses are set to λ / 2, which is half the wavelength of the pulses. Rx Individual receiving antennas 3-1~3-N Rx They are installed in a row. In the example in Figure 12, transmitting antennas 2-1 to 2-N Tx The description has been omitted. In the example in Figure 12, the receiving antenna 3-j (j=1,···,N) Rx ) Position error Δd j These occur randomly. Figure 12 shows the relationship between the vehicle equipped with the radar device and the target, and the position error Δd of the receiving antenna 3-j. j This is an explanatory diagram illustrating the above. Even if the application example of the radar signal processing device 5 is as shown in Figure 12, the radar signal processing device 5 can calculate a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target, when there is an unknown positional error at the installation position of the receiving antenna 3-j, similar to embodiments 1 and 2.

[0088] Furthermore, this disclosure allows for free combination of each embodiment, modification of any component in each embodiment, or omission of any component in each embodiment. [Industrial applicability]

[0089] This disclosure is suitable for radar signal processing equipment, radar signal processing methods, and radar equipment. [Explanation of symbols]

[0090] 1 Transmitter, 2-1~2-N Tx Transmitting antenna, 3-1~3-N Rx 4 Receiving antenna, 5 Receiver, 5 Radar signal processing unit, 6 Display device, 11 Received signal acquisition unit, 12 Spectrum calculation unit, 13,14 Spectrum update unit, 13a,14a First update processing unit, 13b,14b Second update processing unit, 13c,14c Third update processing unit, 21 Received signal acquisition circuit, 22 Spectrum calculation circuit, 23 Spectrum update circuit, 31 Memory, 32 Processor.

Claims

1. A receiving signal acquisition unit that acquires the received signals from each of multiple receiving antennas, A spectrum calculation unit calculates initial values ​​of a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target, based on the received signal acquired by the received signal acquisition unit. A spectrum update unit updates the two-dimensional spectrum based on the nonlinear component included in the velocity spectrum in the two-dimensional spectrum and the position error of the receiving antenna included in the angle spectrum in the two-dimensional spectrum. A radar signal processing device equipped with [a specific feature / feature].

2. The spectral update unit is, A first update processing unit updates the two-dimensional spectrum calculated by the spectrum calculation unit based on the nonlinear components included in the velocity spectrum, A second update processing unit updates the updated two-dimensional spectrum based on the position error of the receiving antenna included in the spectrum of the angle, A third update processing unit updates the updated two-dimensional spectrum based on the coupling error between the nonlinear component and the position error, and the second update processing unit updates the two-dimensional spectrum after updating. The radar signal processing device according to claim 1, characterized by comprising the following:

3. The first update processing unit is: The radar signal processing apparatus according to claim 2, characterized in that the two-dimensional spectrum calculated by the spectrum calculation unit is updated based on the nonlinear component attributable to the acceleration of the target among the nonlinear components included in the velocity spectrum.

4. The first update processing unit is: The radar signal processing apparatus according to claim 2, characterized in that the two-dimensional spectrum calculated by the spectrum calculation unit is updated based on the nonlinear component among the nonlinear components included in the speed spectrum that is caused by variations in the transmission interval of pulses transmitted from the transmitting antenna.

5. The spectral update unit is, The radar signal processing apparatus according to claim 1, characterized in that the updating process of the two-dimensional spectrum is repeatedly performed until the two-dimensional spectrum converges.

6. The spectral update unit is, Based on the nonlinear components included in the velocity spectrum, a first update count is calculated, which is the number of update processes for the two-dimensional spectrum based on the nonlinear components. Based on the position error of the receiving antenna, a second update count is calculated, which is the number of update processes for the two-dimensional spectrum based on the position error of the receiving antenna. Based on the nonlinear components included in the velocity spectrum, the position error of the receiving antenna, and the coupling error caused by the mutual coupling between the receiving antennas, a third update count is calculated, which is the number of update processes for the two-dimensional spectrum based on the coupling error. The update process for the two-dimensional spectrum based on the nonlinear component is repeatedly performed for the first number of updates, the update process for the two-dimensional spectrum based on the position error of the receiving antenna is repeatedly performed for the second number of updates, and the update process for the two-dimensional spectrum based on the coupling error is repeatedly performed for the third number of updates. The radar signal processing device according to feature 1.

7. The received signal acquisition unit acquires the received signals from each of the multiple receiving antennas. The spectrum calculation unit calculates initial values ​​of a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target, based on the received signal acquired by the received signal acquisition unit. The spectrum update unit updates the two-dimensional spectrum based on the nonlinear component included in the velocity spectrum of the two-dimensional spectrum and the position error of the receiving antenna included in the angle spectrum of the two-dimensional spectrum. Radar signal processing method.

8. A transmitting antenna that radiates a transmission signal toward the target, Multiple receiving antennas that receive the received signal, which is the transmitted signal after reflection by the aforementioned target, A receiving signal acquisition unit that acquires the received signals from each of the multiple receiving antennas, A spectrum calculation unit calculates initial values ​​of a two-dimensional spectrum indicating the direction in which the target is located and the velocity of the target, based on the received signal acquired by the received signal acquisition unit. A spectrum update unit updates the two-dimensional spectrum based on the nonlinear component included in the velocity spectrum in the two-dimensional spectrum and the position error of the receiving antenna included in the angle spectrum in the two-dimensional spectrum. A radar device equipped with [a specific feature / feature].

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