Radar signal processing device and radar signal processing method

Abstract

A radar signal processing device (11) is configured to comprise a reception signal acquisition unit (12) that acquires a reception signal related to a reflected wave of a signal reflected from a target after the signal has been transmitted, the signal having a plurality of transmission channels in which data are modulated differently between hits, the plurality of transmission channels including an offset transmission channel in which a phase offset is applied to the data starting partway through a hit. The radar signal processing device (11) further comprises: a map calculation unit (13) that calculates, from the reception signal acquired by the reception signal acquisition unit (12), a range-Doppler map before the phase offset is applied to the data and a range-Doppler map after the phase offset has been applied to the data; and a Doppler velocity calculation unit (15) that calculates a target Doppler velocity on the basis of the range-Doppler maps calculated by the map calculation unit (13).

Description

[Technical Field]

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

[0002] There is a radar signal processing device that calculates the target Doppler velocity. As an example of such a radar signal processing device, Patent Document 1 discloses a radar device that includes a receiving unit that calculates the Doppler velocity of a target based on a received signal relating to the reflected wave of the signal reflected from the target, after a signal having multiple transmission channels in which the data is modulated differently between hits has been transmitted from a transmitting unit. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-204603 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The radar device disclosed in Patent Document 1 had the problem that the range of Doppler speeds that could be determined without ambiguity decreased as the number of transmission channels increased.

[0005] This disclosure was made to solve the above-mentioned problems, and aims to provide a radar signal processing device that can suppress the reduction in the range of Doppler speeds that can be determined without ambiguity, even when the number of transmission channels increases. [Means for solving the problem]

[0006] The radar signal processing device according to this disclosure has multiple transmission channels in which data is modulated differently between hits, and among the multiple transmission channels, there is an offset transmission channel in which a phase offset is added to the data midway through the hit. After a signal is transmitted, the device includes a received signal acquisition unit that acquires a received signal relating to the reflected wave of the signal reflected from the target. The radar signal processing device also includes a map calculation unit that calculates a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data from the received signal acquired by the received signal acquisition unit. Range Doppler map before phase offset is added to data and range Doppler map after phase offset is added to data It includes a Doppler velocity calculation unit that calculates the target Doppler velocity based on [the specified value]. [Effects of the Invention]

[0007] According to this disclosure, even if the number of transmission channels increases, the reduction in the range of Doppler speeds that can be determined without ambiguity can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This is a configuration diagram showing a transmitting device applied to the radar signal processing device 11 according to Embodiment 1. [Figure 2] This is a configuration diagram showing a radar system including a radar signal processing device 11 according to Embodiment 1. [Figure 3] This is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to Embodiment 1. [Figure 4] This is a hardware configuration diagram of a computer when the radar signal processing device 11 is implemented by software or firmware, etc. [Figure 5] This is a flowchart showing the radar signal processing method, which is the processing procedure of the radar signal processing device 11. [Figure 6] This is an explanatory diagram showing an example of the phases of multiple data contained in a conventional DDMA transmission channel and the phases of multiple data contained in a DDMA transmission channel used by the transmission device shown in Figure 1. [Figure 7] It is an explanatory diagram showing a range-Doppler map before addition and a range-Doppler map after addition. [Figure 8] It is an explanatory diagram showing the calculation processing of the element-wise product of a first bin and a second bin. [Figure 9] It is a configuration diagram showing a transmission device applied to the radar signal processing device 11 according to the second embodiment. [Figure 10] It is a configuration diagram showing a radar device including the radar signal processing device 11 according to the second embodiment. [Figure 11] It is a hardware configuration diagram showing hardware of the radar signal processing device 11 according to the second embodiment. [Figure 12] It is an explanatory diagram showing an example of phases of a plurality of pieces of data included in a transmission channel based on DDMA used by the transmission device shown in FIG. 9. [Figure 13] It is an explanatory diagram showing a range-Doppler map based on data from the 1st hit to the (H-1)-th hit, and a range-Doppler map based on data from the 2nd hit to the H-th hit. [Figure 14] It is an explanatory diagram showing the calculation processing of the element-wise product of a first bin and a second bin. [Figure 15] It is a configuration diagram showing a transmission device applied to the radar signal processing device 11 according to the third embodiment. [Figure 16] It is a configuration diagram showing a radar device including the radar signal processing device 11 according to the third embodiment. [Figure 17] It is a hardware configuration diagram showing hardware of the radar signal processing device 11 according to the third embodiment. [Figure 18] It is an explanatory diagram showing an example of phases of a plurality of pieces of data included in a conventional CDMA transmission channel, and phases of a plurality of pieces of data included in a CDMA transmission channel used by the transmission device shown in FIG. 15. [Figure 19] It is an explanatory diagram showing a range-Doppler map before addition and a range-Doppler map after addition. [Figure 20] It is an explanatory diagram showing the calculation processing of the element-wise product of a first bin and a second bin. [Figure 21] This is a configuration diagram showing a transmitting device applied to the radar signal processing device 11 according to Embodiment 4. [Figure 22] This is a configuration diagram showing a radar system including a radar signal processing device 11 according to Embodiment 4. [Figure 23] This is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to Embodiment 4. [Figure 24] Figure 21 is an explanatory diagram showing an example of the phases of multiple data contained in the CDMA transmission channel used by the transmitting device shown. [Figure 25] This is an explanatory diagram showing a range Doppler map based on the data from the 1st hit to the (H-1)th hit, and a range Doppler map based on the data from the 2nd hit to the Hth hit. [Figure 26] This is an explanatory diagram illustrating the process of calculating the elemental product between the first bin and the second bin. [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 transmitting device applied to the radar signal processing device 11 according to Embodiment 1. Figure 2 is a configuration diagram showing a radar system including a radar signal processing device 11 according to Embodiment 1. Figure 3 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to Embodiment 1.

[0011] The transmitting device shown in Figure 1 comprises a signal source 1, a modulation unit 2, and transmitting antennas 3a, 3b, and 3c. The modulation unit 2 includes modulators 2a, 2b, and 2c. In the transmitting device shown in Figure 1, the modulation unit 2 is equipped with three modulators 2a, 2b, and 2c, and the transmitting device is equipped with three transmitting antennas 3a, 3b, and 3c. However, this is merely an example, and the modulation unit 2 may be equipped with two modulators, or four or more modulators, and the transmitting device may be equipped with two transmitting antennas, or four or more transmitting antennas.

[0012] The transmitting device shown in Figure 1 is a device that transmits signals with three transmission channels: ch1, ch2, and ch3. Signal source 1 oscillates a transmission signal and outputs the transmission signal to modulation unit 2. In the transmitting device shown in Figure 1, the transmission signal output by signal source 1 to modulator 2a is the transmission signal for transmission channel ch1, the transmission signal output by signal source 1 to modulator 2b is the transmission signal for transmission channel ch2, and the transmission signal output by signal source 1 to modulator 2c is the transmission signal for transmission channel ch3.

[0013] Modulator 2a acquires the transmission signal for transmission channel ch1 from signal source 1. Modulator 2a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a. Modulator 2b acquires the transmission signal for transmission channel ch2 from signal source 1. Modulator 2b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. When modulator 2b applies different modulations to multiple data points, it adds a phase offset to the data midway through the hit. Therefore, transmit channel ch2 is a transmit channel with an offset. Modulator 2c acquires the transmission signal for transmission channel ch3 from signal source 1. Modulator 2c modulates multiple data points in the hit direction contained in the transmission signal of transmission channel ch3 with different modulations, and outputs the modulated transmission signal of transmission channel ch3 to transmission antenna 3c.

[0014] The transmitting antenna 3a radiates the modulated transmission signal of the transmission channel ch1 output from the modulator 2a into space. The transmitting antenna 3b radiates the modulated transmission signal of the transmission channel ch2 output from the modulator 2b into space. The transmitting antenna 3c radiates the modulated transmission signal of the transmitting channel ch3 output from the modulator 2c into space. This causes a signal with three transmission channels, ch1, ch2, and ch3, to be radiated into space.

[0015] The radar system shown in Figure 2 includes receiving antennas 10a, 10b, 10c, and 10d, and a radar signal processing device 11. Each of the receiving antennas 10a, 10b, 10c, and 10d receives the reflected signal from the target after a signal with three transmission channels, ch1, ch2, and ch3, has been transmitted from the transmitting device shown in Figure 1, and outputs the received signal related to the reflected signal to the radar signal processing device 11. In Figure 2, no receivers are shown between each of the receiving antennas 10a, 10b, 10c, and 10d and the radar signal processing device 11. However, receivers may be provided between each of the receiving antennas 10a, 10b, 10c, and 10d and the radar signal processing device 11. The radar system shown in Figure 2 is equipped with four receiving antennas 10a, 10b, 10c, and 10d. However, this is merely an example, and the radar system may be equipped with two to three receiving antennas, or five or more receiving antennas.

[0016] The radar signal processing device 11 includes a received signal acquisition unit 12, a map calculation unit 13, a target detection unit 14, a Doppler velocity calculation unit 15, and an angle measurement unit 16. The received signal acquisition unit 12 is implemented, for example, by the received signal acquisition circuit 22 shown in Figure 3. The received signal acquisition unit 12 includes signal acquisition processing units 12a, 12b, 12c, and 12d. The received signal acquisition unit 12 acquires the received signal related to the reflected wave of the signal reflected by the target after a signal having three transmission channels ch1, ch2, and ch3 has been transmitted from the transmitting device shown in Figure 1.

[0017] The signal acquisition processing unit 12a acquires the received signal from the receiving antenna 10a and outputs the received signal to the Fourier transform unit 13a, which will be described later. The signal acquisition processing unit 12b acquires the received signal from the receiving antenna 10b and outputs the received signal to the Fourier transform unit 13b, which will be described later. The signal acquisition processing unit 12c acquires the received signal from the receiving antenna 10c and outputs the received signal to the Fourier transform unit 13c, which will be described later. The signal acquisition processing unit 12d acquires the received signal from the receiving antenna 10d and outputs the received signal to the Fourier transform unit 13d, which will be described later.

[0018] The map calculation unit 13 is implemented, for example, by the map calculation circuit 23 shown in Figure 3. The map calculation unit 13 includes Fourier transform units 13a, 13b, 13c, 13d and an integration processing unit 13e. The map calculation unit 13 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 13 calculates a range Doppler map from the received signal, before the phase offset is added to the data, and a range Doppler map after the phase offset is added to the data. The map calculation unit 13 outputs the range Doppler map before the phase offset is added to the data and the range Doppler map after the phase offset is added to the data to the Doppler velocity calculation unit 15.

[0019] The Fourier transform unit 13a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 13a performs a Fast Fourier Transform (FFT) in the range direction on data that does not have a phase offset added to it, among the multiple data in the hit direction contained in the received signal of the transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range Doppler map before the phase offset is added to the data. The Fourier transform unit 13a performs an FFT in the range direction on the data with the phase offset added, among the multiple data in the hit direction contained in the received signal of the transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range Doppler map after the phase offset has been added to the data. The Fourier transform unit 13a outputs each range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 13a calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 13a outputs the range Doppler maps of transmission channels ch1 and ch3 to the integration unit 13e.

[0020] The Fourier transform unit 13b acquires the received signal from the signal acquisition processing unit 12b. The Fourier transform unit 13b calculates a range Doppler map before the phase offset is added to the data by performing an FFT in the range direction on the data that does not have a phase offset added to it, among the multiple data in the hit direction included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 13b calculates a range Doppler map after the phase offset has been added to the data by performing an FFT in the range direction on the data with the phase offset added, and then performing an FFT in the Doppler direction on the data with the phase offset added, among the multiple data in the hit direction included in the received signal of the transmission channel ch2. The Fourier transform unit 13b outputs each range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 13b calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 13b outputs the range Doppler maps of transmission channels ch1 and ch3 to the integration unit 13e.

[0021] The Fourier transform unit 13c acquires the received signal from the signal acquisition processing unit 12c. The Fourier transform unit 13c performs an FFT in the range direction on the data that does not have a phase offset added to it, among the multiple data in the hit direction contained in the received signal of the transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range Doppler map before the phase offset is added to the data. The Fourier transform unit 13c performs an FFT in the range direction on the data with the phase offset added, among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range Doppler map after the phase offset has been added to the data. The Fourier transform unit 13c outputs each range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 13c calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 13c outputs the range Doppler maps of the transmission channels ch1 and ch3 to the integration processing unit 13e.

[0022] The Fourier transform unit 13d acquires the received signal from the signal acquisition processing unit 12d. The Fourier transform unit 13d performs an FFT in the range direction on the data that does not have a phase offset added to it, among the multiple data in the hit direction contained in the received signal of the transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range Doppler map before the phase offset is added to the data. The Fourier transform unit 13d performs an FFT in the range direction on the data with the phase offset added, among the multiple data in the hit direction contained in the received signal of the transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range Doppler map after the phase offset has been added to the data. The Fourier transform unit 13d outputs each range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 13d calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 13d outputs the range Doppler maps of transmission channels ch1 and ch3 to the integration unit 13e.

[0023] The integration processing unit 13e obtains range Doppler maps of transmission channels ch1 and ch3 from the Fourier transform units 13a, 13b, 13c, and 13d, respectively. The integration processing unit 13e integrates the range Doppler maps of the transmission channels ch1 and ch3 output from the Fourier transform units 13a, 13b, 13c, and 13d. The integration processing unit 13e outputs the integrated range Doppler map to the target detection unit 14.

[0024] The target detection unit 14 is implemented, for example, by the target detection circuit 24 shown in Figure 3. The target detection unit 14 obtains the integrated range Doppler map from the integration processing unit 13e. The target detection unit 14 detects targets by performing CFAR (Constant False Alarm Rate) processing on the integrated range Doppler map. The target detection unit 14 outputs the target detection result to the Doppler velocity calculation unit 15.

[0025] The Doppler velocity calculation unit 15 is implemented, for example, by the Doppler velocity calculation circuit 25 shown in Figure 3. The Doppler velocity calculation unit 15 obtains from the map calculation unit 13 a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data. The Doppler velocity calculation unit 15 calculates the target Doppler velocity based on those range Doppler maps. Specifically, the Doppler velocity calculation unit 15 calculates the number of Doppler aliasing for the target from the range Doppler map before the phase offset is added to the data and the range Doppler map after the phase offset is added to the data, and calculates the target Doppler velocity based on the number of Doppler aliasing. More specifically, the Doppler velocity calculation unit 15 extracts a first bin, which is the bin where the target exists, from the range Doppler map before the phase offset is added to the data, based on the target detection result by the target detection unit 14, and also extracts a second bin, which is the bin where the target exists, from the range Doppler map after the phase offset has been added to the data. Then, the Doppler velocity calculation unit 15 calculates the number of Doppler aliasing for the target based on the element product of the first bin and the second bin. The Doppler velocity calculation unit 15 calculates the Doppler velocity of the target based on the number of Doppler aliasing. The Doppler velocity calculation unit 15 outputs information indicating the target Doppler velocity to the angle measurement unit 16.

[0026] The angle measuring unit 16 is implemented, for example, by the angle measuring circuit 26 shown in Figure 3. The angle measuring unit 16 acquires information indicating the target Doppler velocity from the Doppler velocity calculation unit 15. The angle measuring unit 16 measures the angle of the target based on the target's Doppler velocity. The angle measuring unit 16 outputs the angle measurement result of the target to a display device (not shown), for example.

[0027] In Figure 2, it is assumed that the components of the radar signal processing device 11—the received signal acquisition unit 12, the map calculation unit 13, the target detection unit 14, the Doppler velocity calculation unit 15, and the angle measurement unit 16—are each implemented by dedicated hardware as shown in Figure 3. Specifically, the radar signal processing device 11 is assumed to be implemented by the received signal acquisition circuit 22, the map calculation circuit 23, the target detection circuit 24, the Doppler velocity calculation circuit 25, and the angle measurement circuit 26. Each of the receiving signal acquisition circuit 22, map calculation circuit 23, target detection circuit 24, Doppler velocity calculation circuit 25, and angle measurement circuit 26 can 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.

[0028] The components of the radar signal processing device 11 are not limited to those implemented by dedicated hardware; the radar signal processing device 11 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).

[0029] Figure 4 is a hardware configuration diagram of a computer when the radar signal processing unit 11 is implemented by software or firmware, etc. If the radar signal processing device 11 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 12, map calculation unit 13, target detection unit 14, Doppler velocity calculation unit 15, and angle measurement unit 16. The computer's processor 32 then executes the program stored in the memory 31.

[0030] Furthermore, Figure 3 shows an example in which each component of the radar signal processing unit 11 is implemented by dedicated hardware, and Figure 4 shows an example in which the radar signal processing unit 11 is implemented by software or firmware, etc. However, this is only one example, and some components of the radar signal processing unit 11 may be implemented by dedicated hardware, while the remaining components may be implemented by software or firmware, etc.

[0031] Next, we will explain the operation of the transmitting device shown in Figure 1 and the radar signal processing device 11 shown in Figure 2. Figure 5 is a flowchart showing the radar signal processing method, which is the processing procedure of the radar signal processing device 11. The transmitting device shown in Figure 1 transmits a signal having three transmission channels ch1, ch2, and ch3 using the DDMA (Doppler Division Multiple Access) method, as shown in the right-hand diagram of Figure 6, in order to enable the radar signal processing device 11 to separate the three transmission channels ch1, ch2, and ch3. Figure 6 is an explanatory diagram showing an example of the phases of multiple data contained in a conventional DDMA transmission channel and the phases of multiple data contained in a DDMA transmission channel used by the transmission device shown in Figure 1. DDMA is a method that applies different modulations to multiple data points in the hit direction contained in the transmitted signal.

[0032] Conventional DDMA does not add a phase offset to each data when applying different modulations to multiple data in the hit direction. The phases of the multiple data contained in the conventional DDMA transmission channels ch1, ch2, and ch3 are as follows, for example, as shown in Figure 6. ch1→φ1=[0° 0° 0° 0°···] ch2→φ2=[0° 180° 0° 180°···] ch3→φ3=[0° 90° 180° 270°···]

[0033] The DDMA used by the transmitting device shown in Figure 1 applies different modulations to multiple data in the hit direction. For example, for transmission channel ch2, a phase offset is added to the data midway through the hit. The phases of the multiple data contained in the DDMA transmission channels ch1, ch2, and ch3 used by the transmitting device shown in Figure 1 are, for example, as shown in Figure 6, as follows: ch1→φ1 =[0° 0° 0° 0°···],[0° 0° 0° 0°···] ch2→φ2 =[0° 180° 0° 180°···],[180° 0° 180° 0°···] ch3→φ3 =[0° 90° 180° 270°···],[0° 90° 180° 270°···]

[0034] Signal source 1 generates transmission signals for transmission channels ch1, ch2, and ch3. Signal source 1 outputs the transmission signal for transmission channel ch1 to modulator 2a, the transmission signal for transmission channel ch2 to modulator 2b, and the transmission signal for transmission channel ch3 to modulator 2c. Modulator 2a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a.

[0035] Modulator 2b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. When modulator 2b applies different modulations to multiple data points, it adds a phase offset to the data midway through the hit, as shown in the right-hand diagram of Figure 6. Therefore, transmission channel ch2 is a transmission channel with an offset. Modulator 2c modulates multiple data points in the hit direction contained in the transmission signal of transmission channel ch3 with different modulations, and outputs the modulated transmission signal of transmission channel ch3 to transmission antenna 3c.

[0036] The transmitting antenna 3a radiates the modulated transmission signal of the transmission channel ch1 output from the modulator 2a into space. The transmitting antenna 3b radiates the modulated transmission signal of the transmission channel ch2 output from the modulator 2b into space. The transmitting antenna 3c radiates the modulated transmission signal of the transmitting channel ch3 output from the modulator 2c into space. As a result, the transmitter shown in Figure 1 transmits a signal having three transmission channels: ch1, ch2, and ch3.

[0037] Each of the receiving antennas 10a, 10b, 10c, and 10d receives the reflected wave of the signal that has been reflected off the target after a signal with three transmission channels, ch1, ch2, and ch3, has been transmitted from the transmitting device shown in Figure 1. The receiving antenna 10a outputs the received signal related to the reflected wave to the signal acquisition processing unit 12a of the receiving signal acquisition unit 12. The receiving antenna 10b outputs the received signal related to the reflected wave to the signal acquisition processing unit 12b of the receiving signal acquisition unit 12. The receiving antenna 10c outputs the received signal related to the reflected wave to the signal acquisition processing unit 12c of the receiving signal acquisition unit 12. The receiving antenna 10d outputs the received signal related to the reflected wave to the signal acquisition processing unit 12d of the receiving signal acquisition unit 12.

[0038] The received signal acquisition unit 12 acquires the received signal relating to the reflected wave of the signal reflected from the target (step ST1 in Figure 5). In other words, the signal acquisition processing unit 12a acquires the received signal from the receiving antenna 10a and outputs the received signal to the Fourier transform unit 13a of the map calculation unit 13. The signal acquisition processing unit 12b acquires the received signal from the receiving antenna 10b and outputs the received signal to the Fourier transform unit 13b of the map calculation unit 13. The signal acquisition processing unit 12c acquires the received signal from the receiving antenna 10c and outputs the received signal to the Fourier transform unit 13c of the map calculation unit 13. The signal acquisition processing unit 12d acquires the received signal from the receiving antenna 10d and outputs the received signal to the Fourier transform unit 13d of the map calculation unit 13.

[0039] The map calculation unit 13 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 13 calculates a range Doppler map from the received signal before the phase offset is added to the data (hereinafter referred to as the "pre-addition range Doppler map") and a range Doppler map after the phase offset is added to the data (hereinafter referred to as the "post-addition range Doppler map") (step ST2 in Figure 5). Figure 7 is an explanatory diagram showing the range Doppler map before and after addition. The map calculation unit 13 outputs the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. The following describes in detail the calculation process of the range Doppler map by the map calculation unit 13.

[0040] The Fourier transform unit 13a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 13a calculates a pre-addition range Doppler map by performing an FFT in the range direction on data that does not have a phase offset added, among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 13a calculates a post-added range Doppler map by performing an FFT in the range direction on the data with a phase offset added from among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 13a outputs the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. Furthermore, the Fourier transform unit 13a calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 13a outputs the range Doppler maps of transmission channels ch1 and ch3 to the integration unit 13e.

[0041] The Fourier transform units 13b, 13c, and 13d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 13b, 13c, and 13d calculate the pre-addition range Doppler map and the post-addition range Doppler map, respectively, in the same manner as the Fourier transform unit 13a, and output the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform units 13b, 13c, and 13d calculate range Doppler maps for transmission channels ch1 and ch3, similar to the Fourier transform unit 13a, and output the range Doppler maps for transmission channels ch1 and ch3 to the integration unit 13e.

[0042] The integration processing unit 13e obtains range Doppler maps of transmission channels ch1 and ch3 from the Fourier transform units 13a, 13b, 13c, and 13d, respectively. The integration processing unit 13e integrates the range Doppler maps of the transmission channels ch1 and ch3 output from the Fourier transform units 13a, 13b, 13c, and 13d. The integration processing unit 13e outputs the integrated range Doppler map to the target detection unit 14.

[0043] The target detection unit 14 obtains the integrated range Doppler map from the integration processing unit 13e. The target detection unit 14 detects the target by performing CFAR processing on the integrated range Doppler map (step ST3 in Figure 5). The target detection unit 14 outputs the target detection result to the Doppler velocity calculation unit 15. The target detection result indicates the Doppler bin in which the target exists and the distance bin in which the target exists.

[0044] The Doppler velocity calculation unit 15 obtains the pre-addition range Doppler map and the post-addition range Doppler map from the map calculation unit 13. The Doppler velocity calculation unit 15 calculates the target Doppler velocity based on the pre-addition range Doppler map and the post-addition range Doppler map (step ST4 in Figure 5). The Doppler velocity calculation unit 15 outputs information indicating the target Doppler velocity to the angle measurement unit 16. The following describes in detail the process of calculating the Doppler velocity by the Doppler velocity calculation unit 15.

[0045] The Doppler velocity calculation unit 15 extracts a first bin from the pre-addition range Doppler map, which is the bin in which the target exists, based on the target detection result by the target detection unit 14. Furthermore, the Doppler velocity calculation unit 15 extracts a second bin from the added range Doppler map, which is the bin in which the target exists, based on the target detection result by the target detection unit 14. As shown in Figure 8, the Doppler velocity calculation unit 15 calculates the Doppler folding number DC for the target based on the element product of the first bin and the second bin. Figure 8 is an explanatory diagram illustrating the process of calculating the element product between the first bin and the second bin.

[0046] The following describes in detail the process by which the Doppler velocity calculation unit 15 calculates the number of Doppler reflections. In Figure 8, for the sake of explanation, the bottle on the left in the first bottle is designated as s1, the bottle in the center of the first bottle is designated as s2, and the bottle on the right in the first bottle is designated as s3. Furthermore, assume that the bin on the left in the second bin is s1*exp(jφ), the bin in the center of the second bin is s2*exp(jφ)*exp(jπ), and the bin on the right in the second bin is s3×exp(jφ). φ is the phase offset amount, as shown in Figure 8. offset,1 , φ offset,2 , φ offset,3 It corresponds to this.

[0047] In this case, the Doppler velocity calculation unit 15 calculates the element product x1 of the bin s1 on the left side of the figure and the bin s1*exp(jφ) on the left side of the figure, as shown in equation (1) below. x1 = s1 * (s1 * exp(jφ))^* =|s1| 2 *exp(-jφ) (1) The Doppler velocity calculation unit 15 calculates the element product x2 of the central bin s2 in the figure and the central bin s2*exp(jφ)*exp(jπ) as shown in equation (2) below. x2=s2*(s2*exp(jφ)*exp(jπ))^* =|s2| 2 *exp(-jφ)*exp(jπ) (2) The Doppler velocity calculation unit 15 calculates the element product x3 of the bin s3 on the right side of the figure and the bin s3*exp(jφ) on the right side of the figure, as shown in equation (3) below. x3 = s3 * (s1 * exp(jφ))^* =|s3| 2 *exp(-jφ) (3)

[0048] The Doppler velocity calculation unit 15 focuses on the phases of the element products x1, x2, and x3, and determines that the Doppler folding number DC is 0 if the phase of element product x1 and the phase of element product x3 are in phase, and the phase of element product x2 is rotated by 180 degrees relative to the phases of element products x1 and x3. The Doppler velocity calculation unit 15 focuses on the phases of the element products x1, x2, and x3, and determines that the Doppler folding number DC is 1 if the phase of element product x1 and the phase of element product x2 are in phase, and the phase of element product x3 is rotated by 180 degrees relative to the phases of element products x1 and x2. The Doppler velocity calculation unit 15 focuses on the phases of the element products x1, x2, and x3, and determines that the Doppler folding number DC is 2 if the phase of element product x2 and the phase of element product x3 are in phase, and the phase of element product x1 is rotated by 180 degrees relative to the phases of element products x2 and x3.

[0049] The Doppler velocity calculation unit 15 calculates the target Doppler velocity vd based on the Doppler folding number DC, as shown in equation (4) below. vd=vd s1 +(PRF / M)×DC (4) In equation (4), vd s1 is the Doppler velocity of bin s1 on the left side of the figure, PRF is the pulse repetition frequency, and M is a constant.

[0050] The angle measuring unit 16 acquires information indicating the target Doppler velocity vd from the Doppler velocity calculation unit 15. The angle measuring unit 16 measures the angle of the target based on the target's Doppler velocity vd (step ST5 in Figure 5). The angle measuring process of the target based on the Doppler velocity vd is a well-known technique, so a detailed explanation is omitted. The angle measuring unit 16 outputs the angle measurement result of the target to a display device (not shown), for example.

[0051] In the above embodiment 1, the radar signal processing device 11 is configured to have a plurality of transmission channels in which the data is modulated differently between hits, and among the plurality of transmission channels, there is an offset transmission channel in which a phase offset is added to the data midway through the hit. After a signal is transmitted, the radar signal processing device 11 is configured to have a received signal acquisition unit 12 that acquires a received signal relating to the reflected wave of the signal reflected from the target. The radar signal processing device 11 also includes a map calculation unit 13 that calculates a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data from the received signal acquired by the received signal acquisition unit 12, and a Doppler velocity calculation unit 15 that calculates the target's Doppler velocity based on the range Doppler map calculated by the map calculation unit 13. Therefore, even if the number of transmission channels increases, the radar signal processing device 11 can suppress a decrease in the range of Doppler velocities that can be determined without ambiguity.

[0052] Embodiment 2. Embodiment 2 describes a radar signal processing device 11 applied to a transmitting device that transmits a signal having multiple transmission channels in which the data is modulated differently from each other between hits.

[0053] Figure 9 is a configuration diagram showing a transmitting device applied to the radar signal processing device 11 according to Embodiment 2. In Figure 9, the same reference numerals as in Figure 1 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 10 is a configuration diagram showing a radar system including a radar signal processing device 11 according to Embodiment 2. In Figure 10, the same reference numerals as in Figure 2 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 11 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to Embodiment 2. In Figure 11, the same reference numerals as in Figure 3 indicate the same or corresponding parts, so a detailed explanation is omitted.

[0054] The transmitting device shown in Figure 9 comprises a signal source 1, a modulation unit 4, and transmitting antennas 3a, 3b, and 3c. The modulation unit 4 includes modulators 4a, 4b, and 4c. In the transmitting device shown in Figure 9, the modulation unit 4 is equipped with three modulators 4a, 4b, and 4c, and the transmitting device is equipped with three transmitting antennas 3a, 3b, and 3c. However, this is merely an example, and the modulation unit 4 may be equipped with two modulators, or four or more modulators, and the transmitting device may be equipped with two transmitting antennas, or four or more transmitting antennas.

[0055] The transmitting device shown in Figure 9 is a device that transmits signals having three transmission channels: ch1, ch2, and ch3. Modulator 4a acquires the transmission signal for transmission channel ch1 from signal source 1. Modulator 4a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a. Modulator 4b acquires the transmission signal for transmission channel ch2 from signal source 1. Modulator 4b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. Modulator 4c acquires the transmission signal for transmission channel ch3 from signal source 1. Modulator 4c modulates multiple data points in the hit direction contained in the transmit signal of transmit channel ch3 with different modulations, and outputs the modulated transmit signal of transmit channel ch3 to transmit antenna 3c.

[0056] The radar signal processing device 11 includes a received signal acquisition unit 12, a map calculation unit 17, a target detection unit 14, a Doppler velocity calculation unit 18, and an angle measurement unit 16. The received signal acquisition unit 12 acquires the received signal related to the reflected wave of the signal reflected from the target after a signal having multiple transmission channels ch1, ch2, and ch3, in which the data is modulated differently between hits, has been transmitted.

[0057] The map calculation unit 17 is implemented, for example, by the map calculation circuit 27 shown in Figure 11. The map calculation unit 17 includes Fourier transform units 17a, 17b, 17c, 17d and an integration processing unit 17e. The map calculation unit 17 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 17 calculates a range Doppler map based on the data of the (H-1)th hit from the first hit data to the Hth hit data (where H is an integer greater than or equal to 2) among the data of the first hit data included in the received signal, and a range Doppler map based on the data of the second hit data to the Hth hit data. The map calculation unit 17 outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18.

[0058] The Fourier transform unit 17a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 17a performs an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform unit 17a performs an FFT in the range direction on the data from the second hit to the Hth hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform unit 17a outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform unit 17a calculates a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform unit 17a outputs a range Doppler map to the integration unit 17e.

[0059] The Fourier transform units 17b, 17c, and 17d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 17b, 17c, and 17d, similar to the Fourier transform unit 17a, perform an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform units 17b, 17c, and 17d, similar to the Fourier transform unit 17a, perform an FFT in the range direction on the data from the second hit to the Hth hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform units 17b, 17c, and 17d output a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform units 17b, 17c, and 17d, similar to the Fourier transform unit 17a, calculate a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform units 17b, 17c, and 17d output a range Doppler map to the integration unit 17e.

[0060] The integration processing unit 17e obtains range Doppler maps from each of the Fourier transform units 17a, 17b, 17c, and 17d. The integration unit 17e integrates the range Doppler maps output from the Fourier transform units 17a, 17b, 17c, and 17d. The integration processing unit 17e outputs the integrated range Doppler map to the target detection unit 14.

[0061] The Doppler velocity calculation unit 18 is implemented, for example, by the Doppler velocity calculation circuit 28 shown in Figure 11. The Doppler velocity calculation unit 18 obtains a range Doppler map from the map calculation unit 17 based on the data from the first hit to the data of the (H-1)th hit, and a range Doppler map based on the data from the second hit to the data of the Hth hit. The Doppler velocity calculation unit 18 calculates the target Doppler velocity based on those range Doppler maps. Specifically, the Doppler velocity calculation unit 18 calculates the number of Doppler reflections for the target from a range Doppler map based on the data from the first hit to the (H-1)th hit and a range Doppler map based on the data from the second hit to the Hth hit, and calculates the target's Doppler velocity based on the number of Doppler reflections. More specifically, the Doppler velocity calculation unit 18 extracts a first bin, which is the bin where the target exists, from a range Doppler map based on the data of the (H-1)th hit, starting from the data of the first hit, and also extracts a second bin, which is the bin where the target exists, from a range Doppler map based on the data of the Hth hit, starting from the data of the second hit. Then, the Doppler velocity calculation unit 18 calculates the number of Doppler reflections for the target based on the element product of the first bin and the second bin. The Doppler velocity calculation unit 18 calculates the Doppler velocity of the target based on the number of Doppler reflections. The Doppler velocity calculation unit 18 outputs information indicating the target Doppler velocity to the angle measurement unit 16.

[0062] In Figure 10, it is assumed that the components of the radar signal processing device 11—the received signal acquisition unit 12, the map calculation unit 17, the target detection unit 14, the Doppler velocity calculation unit 18, and the angle measurement unit 16—are each implemented by dedicated hardware as shown in Figure 11. Specifically, the radar signal processing device 11 is assumed to be implemented by the received signal acquisition circuit 22, the map calculation circuit 27, the target detection circuit 24, the Doppler velocity calculation circuit 28, and the angle measurement circuit 26. Each of the receiving signal acquisition circuit 22, map calculation circuit 27, target detection circuit 24, Doppler velocity calculation circuit 28, and angle measurement circuit 26 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.

[0063] The components of the radar signal processing device 11 are not limited to those implemented by dedicated hardware; the radar signal processing device 11 may also be implemented by software, firmware, or a combination of software and firmware. If the radar signal processing device 11 is implemented by software or firmware, a program that causes the computer to execute the respective processing procedures in the received signal acquisition unit 12, map calculation unit 17, target detection unit 14, Doppler velocity calculation unit 18, and angle measurement unit 16 is stored in the memory 31 shown in Figure 4. Then, the processor 32 shown in Figure 4 executes the program stored in the memory 31.

[0064] Furthermore, Figure 11 shows an example in which each component of the radar signal processing unit 11 is implemented by dedicated hardware, and Figure 4 shows an example in which the radar signal processing unit 11 is implemented by software or firmware, etc. However, this is only one example, and some components of the radar signal processing unit 11 may be implemented by dedicated hardware, while the remaining components may be implemented by software or firmware, etc.

[0065] Next, the operation of the transmitting device shown in Figure 9 and the radar signal processing device 11 shown in Figure 10 will be explained. The transmitting device shown in Figure 9 transmits a signal having three transmission channels ch1, ch2, and ch3 using the DDMA method, as shown in Figure 12, in order to enable the radar signal processing device 11 to separate the three transmission channels ch1, ch2, and ch3. Figure 12 is an explanatory diagram showing an example of the phases of multiple data contained in the DDMA transmission channel used by the transmitting device shown in Figure 9. DDMA is a method that applies different modulations to multiple data points in the hit direction contained in the transmitted signal.

[0066] The DDMA used by the transmitting device shown in Figure 9, like conventional DDMA, does not add a phase offset to each data when applying different modulations to multiple data in the hit direction. The phases of the multiple data contained in the DDMA transmission channels ch1, ch2, and ch3 used by the transmitting device shown in Figure 9 are, for example, as shown in Figure 12, as follows: ch1→φ1=[0° 0° 0° 0°···] ch2→φ2=[0° 180° 0° 180°···] ch3→φ3=[0° 90° 180° 270°···]

[0067] Signal source 1 generates transmission signals for transmission channels ch1, ch2, and ch3. Signal source 1 outputs the transmission signal for transmission channel ch1 to modulator 2a, the transmission signal for transmission channel ch2 to modulator 2b, and the transmission signal for transmission channel ch3 to modulator 2c. Modulator 2a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a.

[0068] Modulator 2b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. Modulator 2c modulates multiple data points in the hit direction contained in the transmission signal of transmission channel ch3 with different modulations, and outputs the modulated transmission signal of transmission channel ch3 to transmission antenna 3c.

[0069] The transmitting antenna 3a radiates the modulated transmission signal of the transmission channel ch1 output from the modulator 2a into space. The transmitting antenna 3b radiates the modulated transmission signal of the transmission channel ch2 output from the modulator 2b into space. The transmitting antenna 3c radiates the modulated transmission signal of the transmitting channel ch3 output from the modulator 2c into space. As a result, the transmitter shown in Figure 9 transmits a signal having three transmission channels: ch1, ch2, and ch3.

[0070] Each of the receiving antennas 10a, 10b, 10c, and 10d receives the reflected wave of the signal that has been reflected off the target after a signal with three transmission channels, ch1, ch2, and ch3, has been transmitted from the transmitting device shown in Figure 9. The receiving antenna 10a outputs the received signal related to the reflected wave to the signal acquisition processing unit 12a of the receiving signal acquisition unit 12. The receiving antenna 10b outputs the received signal related to the reflected wave to the signal acquisition processing unit 12b of the receiving signal acquisition unit 12. The receiving antenna 10c outputs the received signal related to the reflected wave to the signal acquisition processing unit 12c of the receiving signal acquisition unit 12. The receiving antenna 10d outputs the received signal related to the reflected wave to the signal acquisition processing unit 12d of the receiving signal acquisition unit 12.

[0071] The received signal acquisition unit 12 acquires the received signal relating to the reflected wave of the signal reflected from the target. In other words, the signal acquisition processing unit 12a acquires the received signal from the receiving antenna 10a and outputs the received signal to the Fourier transform unit 17a of the map calculation unit 17. The signal acquisition processing unit 12b acquires the received signal from the receiving antenna 10b and outputs the received signal to the Fourier transform unit 17b of the map calculation unit 17. The signal acquisition processing unit 12c acquires the received signal from the receiving antenna 10c and outputs the received signal to the Fourier transform unit 17c of the map calculation unit 17. The signal acquisition processing unit 12d acquires the received signal from the receiving antenna 10d and outputs the received signal to the Fourier transform unit 17d of the map calculation unit 17.

[0072] The map calculation unit 17 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 17 calculates a range Doppler map based on the data from the first hit to the (H-1)th hit among the data from the first hit to the Hth hit included in the received signal. Furthermore, the map calculation unit 17 calculates a range Doppler map based on the data of the Hth hit, starting from the data of the second hit. Figure 13 is an explanatory diagram showing range Doppler maps based on the data from the first hit to the (H-1)th hit, and range Doppler maps based on the data from the second hit to the Hth hit. The map calculation unit 13 outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. The following describes in detail the calculation process of the range Doppler map by the map calculation unit 13.

[0073] The Fourier transform unit 17a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 17a performs an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform unit 17a performs an FFT in the range direction on the data from the second hit to the Hth hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform unit 17a outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform unit 17a calculates a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform unit 17a outputs a range Doppler map to the integration unit 17e.

[0074] The Fourier transform units 17b, 17c, and 17d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 17b, 17c, and 17d, similar to the Fourier transform unit 17a, perform an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform units 17b, 17c, and 17d, similar to the Fourier transform unit 17a, perform an FFT in the range direction on the data from the second hit to the Hth hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform units 17b, 17c, and 17d output a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform units 17b, 17c, and 17d, similar to the Fourier transform unit 17a, calculate a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform units 17b, 17c, and 17d output a range Doppler map to the integration unit 17e.

[0075] The integration processing unit 17e obtains range Doppler maps from each of the Fourier transform units 17a, 17b, 17c, and 17d. The integration unit 17e integrates the range Doppler maps output from the Fourier transform units 17a, 17b, 17c, and 17d. The integration processing unit 17e outputs the integrated range Doppler map to the target detection unit 14.

[0076] The target detection unit 14 obtains the integrated range Doppler map from the integration processing unit 17e. The target detection unit 14 detects targets by performing CFAR processing on the integrated range Doppler map. The target detection unit 14 outputs the target detection result to the Doppler velocity calculation unit 18. The target detection result indicates the Doppler bin in which the target exists and the distance bin in which the target exists.

[0077] The Doppler velocity calculation unit 18 obtains a range Doppler map from the map calculation unit 17 based on the data from the first hit to the data of the (H-1)th hit, and a range Doppler map based on the data from the second hit to the data of the Hth hit. The Doppler velocity calculation unit 18 calculates the target Doppler velocity based on a range Doppler map based on the data from the first hit to the (H-1)th hit and a range Doppler map based on the data from the second hit to the Hth hit. The Doppler velocity calculation unit 18 outputs information indicating the target Doppler velocity to the angle measurement unit 16. Hereinafter, the Doppler velocity calculation process performed by the Doppler velocity calculation unit 18 will be specifically described.

[0078] The Doppler velocity calculation unit 18 extracts a first bin, which is a bin in which a target exists, from a range-Doppler map based on data from the 1st hit to the (H-1)th hit, based on the target detection result obtained by the target detection unit 14. Further, the Doppler velocity calculation unit 18 extracts a second bin, which is a bin in which a target exists, from a range-Doppler map based on data from the 2nd hit to the H-th hit, based on the target detection result obtained by the target detection unit 14. As shown in FIG. 14, the Doppler velocity calculation unit 18 calculates the Doppler folding number for the target based on the element-wise product of the first bin and the second bin. FIG. 14 is an explanatory diagram showing the calculation process of the element-wise product of the first bin and the second bin.

[0079] In FIG. 14, for convenience of explanation, it is assumed that the left bin in the drawing of the first bin is s1, the center bin in the drawing of the first bin is s2, and the right bin in the drawing of the first bin is s3. Further, it is assumed that the left bin in the drawing of the second bin is s1*exp(jφ1), the center bin in the drawing of the second bin is s2*exp(jφ2), and the right bin in the drawing of the second bin is s3*exp(jφ3). φ1 is the amount of phase rotation that changes for each PRI in a signal transmitted from the 1st transmission channel, and is φ shown in FIG. 8 offset,1 corresponds to. φ2 is the amount of phase rotation that changes for each PRI in a signal transmitted from the 2nd transmission channel, and is φ shown in FIG. 8 offset,2 corresponds to. φ3 is the amount of phase rotation that changes for each PRI in a signal transmitted from the 3rd transmission channel, and is φ shown in FIG. 8 offset,3 corresponds to.

[0080] In this case, as shown in the following formula (5), the Doppler velocity calculation unit 18 calculates the element-wise product x1 of the left bin s1 in the drawing and the left bin s1*exp(jφ) in the drawing. x1 = s1 * (s1 * exp(jφ1))^* =|s1| 2 *exp(-jφ1) (5) The Doppler velocity calculation unit 18 calculates the element product x2 of the central bin s2 in the figure and the central bin s2*exp(jφ) as shown in equation (6) below. x² = s² * (s² * exp(jφ²))^* =|s2| 2 *exp(-jφ2) (6) The Doppler velocity calculation unit 18 calculates the element product x3 of the bin s3 on the right side of the figure and the bin s3*exp(jφ) on the right side of the figure, as shown in equation (7) below. x3 = s3 * (s1 * exp(jφ3))^* =|s3| 2 *exp(-jφ3) (7)

[0081] Here, we assume that phase rotation amounts φ1, φ2, and φ3 change at equal intervals. For example, transmit channel ch1 rotates by 0 degrees with each hit, transmit channel ch2 rotates by 90 degrees with each hit, and transmit channel ch3 rotates by 180 degrees with each hit. In this case, if we focus on the phase of the element products x1, x2, and x3, if the Doppler folding number DC is 0, the phase difference between element product x1 and element product x2 (1-2) will be the same as the phase difference between element product x2 and element product x3 (2-3), but it will be different from the phase difference between element product x3 and element product x1 (3-1). If the Doppler aliasing number DC is 1, the phase difference (2-3) will be the same value as the phase difference (3-1), but different from the phase difference (1-2). If the Doppler aliasing number DC is 2, the phase difference (1-2) will be the same value as the phase difference (3-1), but different from the phase difference (2-3).

[0082] The Doppler velocity calculation unit 18 determines that the Doppler aliasing number DC is 0 if the phase difference (1-2) and the phase difference (2-3) are the same value, and the phase difference (1-2) and the phase difference (3-1) are different values. The Doppler velocity calculation unit 18 determines that the Doppler aliasing number DC is 1 if the phase difference (2-3) and the phase difference (3-1) are the same value, and the phase difference (2-3) and the phase difference (1-2) are different values. The Doppler velocity calculation unit 18 determines that the Doppler aliasing number DC is 2 if the phase difference (1-2) and the phase difference (3-1) are the same value, and the phase difference (1-2) and the phase difference (2-3) are different values.

[0083] The Doppler velocity calculation unit 18 calculates the target Doppler velocity vd based on the Doppler folding number DC, as shown in equation (4). The angle measuring unit 16 acquires information indicating the target Doppler velocity vd from the Doppler velocity calculation unit 18. The angle measuring unit 16 measures the angle of the target based on the target's Doppler velocity vd. The angle measuring unit 16 outputs the angle measurement result of the target to a display device (not shown), for example.

[0084] In the above embodiment 2, the radar signal processing device 11 is configured to include a received signal acquisition unit 12 that acquires a received signal relating to the reflected wave of the signal reflected from the target after a signal having multiple transmission channels in which the data is modulated differently between hits has been transmitted. The radar signal processing device 11 also includes a map calculation unit 17 that calculates a range Doppler map based on the data of the (H-1)th hit from the data of the first hit to the data of the Hth hit (where H is an integer of 2 or more) included in the received signal acquired by the received signal acquisition unit 12, and a range Doppler map based on the data of the second hit to the data of the Hth hit, and a Doppler velocity calculation unit 18 that calculates the Doppler velocity of the target based on the range Doppler map calculated by the map calculation unit 17.Therefore, even if the number of transmission channels increases, the radar signal processing device 11 can suppress the decrease in the range of Doppler velocities that can be determined without ambiguity.

[0085] Embodiment 3. Embodiment 1 describes a radar signal processing device 11 that is applied to a transmitting device that transmits a signal having multiple transmission channels using the DDMA method. Embodiment 3 describes a radar signal processing device 11 that is applied to a transmitting device that transmits signals having multiple transmission channels using the CDMA (Code Division Multiple Access) method.

[0086] Figure 15 is a configuration diagram showing a transmitting device applied to the radar signal processing device 11 according to Embodiment 3. In Figure 15, the same reference numerals as in Figure 1 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 16 is a configuration diagram showing a radar system including a radar signal processing device 11 according to Embodiment 3. In Figure 16, the same reference numerals as in Figure 2 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 17 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to Embodiment 3. In Figure 17, the same reference numerals as in Figure 3 indicate the same or corresponding parts, so a detailed explanation is omitted.

[0087] The transmitting device shown in Figure 15 comprises a signal source 1, a modulation unit 5, and transmitting antennas 3a, 3b, and 3c. The modulation unit 5 includes modulators 5a, 5b, and 5c. In the transmitting device shown in Figure 15, the modulation unit 5 is equipped with three modulators 5a, 5b, and 5c, and the transmitting device is equipped with three transmitting antennas 3a, 3b, and 3c. However, this is merely an example, and the modulation unit 5 may be equipped with two modulators, or four or more modulators, and the transmitting device may be equipped with two transmitting antennas, or four or more transmitting antennas.

[0088] The transmitting device shown in Figure 15 is a device that transmits signals having three transmission channels: ch1, ch2, and ch3. Signal source 1 oscillates a transmission signal and outputs the transmission signal to modulation unit 2. In the transmitting device shown in Figure 15, the transmission signal output by signal source 1 to modulator 5a is the transmission signal for transmission channel ch1, the transmission signal output by signal source 1 to modulator 5b is the transmission signal for transmission channel ch2, and the transmission signal output by signal source 1 to modulator 5c is the transmission signal for transmission channel ch3.

[0089] Modulator 5a acquires the transmission signal for transmission channel ch1 from signal source 1. Modulator 5a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a. Modulator 5b acquires the transmission signal for transmission channel ch2 from signal source 1. Modulator 5b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. When modulator 5b applies different modulations to multiple data points, it adds a phase offset to the data midway through the hit. Therefore, transmission channel ch2 is a transmission channel with an offset. Modulator 5c acquires the transmission signal for transmission channel ch3 from signal source 1. Modulator 5c modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch3 with different modulations, and outputs the modulated transmission signal of transmission channel ch3 to transmission antenna 3c.

[0090] The radar signal processing device 11 includes a received signal acquisition unit 12, a map calculation unit 19, a target detection unit 14, a Doppler velocity calculation unit 15, and an angle measurement unit 16. The map calculation unit 19 is implemented, for example, by the map calculation circuit 29 shown in Figure 17. The map calculation unit 19 includes Fourier transform units 19a, 19b, 19c, 19d and an integration processing unit 19e. The map calculation unit 19 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 19 calculates a range Doppler map from the received signal, in the case of a transmission channel with an offset, before the phase offset is added to the data, as the pre-addition range Doppler map. The map calculation unit 19 calculates the range Doppler map after the phase offset has been added to the data, as a post-added range Doppler map. The map calculation unit 19 outputs the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15.

[0091] The Fourier transform unit 19a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 19a calculates a pre-addition range Doppler map by performing an FFT in the range direction on data that does not have a phase offset added, among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 19a calculates a post-added range Doppler map by performing an FFT in the range direction on the data with a phase offset added from among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 19a outputs the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 19a calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 19a outputs the range Doppler maps of the transmission channels ch1 and ch3 to the integration unit 19e.

[0092] The Fourier transform units 19b, 19c, and 19d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 19b, 19c, and 19d calculate the pre-addition range Doppler map and the post-addition range Doppler map, respectively, in the same manner as the Fourier transform unit 19a, and output the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform units 19b, 19c, and 19d calculate range Doppler maps for transmission channels ch1 and ch3, similar to the Fourier transform unit 19a, and output the range Doppler maps for transmission channels ch1 and ch3 to the integration unit 19e.

[0093] The integration processing unit 19e obtains range Doppler maps of transmission channels ch1 and ch3 from the Fourier transform units 19a, 19b, 19c, and 19d, respectively. The integration processing unit 19e integrates the range Doppler maps of the transmission channels ch1 and ch3 output from the Fourier transform units 19a, 19b, 19c, and 19d. The integration processing unit 19e outputs the integrated range Doppler map to the target detection unit 14.

[0094] In Figure 16, it is assumed that the components of the radar signal processing device 11—the received signal acquisition unit 12, the map calculation unit 19, the target detection unit 14, the Doppler velocity calculation unit 15, and the angle measurement unit 16—are each implemented by dedicated hardware as shown in Figure 17. Specifically, the radar signal processing device 11 is assumed to be implemented by the received signal acquisition circuit 22, the map calculation circuit 29, the target detection circuit 24, the Doppler velocity calculation circuit 25, and the angle measurement circuit 26. Each of the receiving signal acquisition circuit 22, map calculation circuit 29, target detection circuit 24, Doppler velocity calculation circuit 25, and angle measurement circuit 26 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.

[0095] The components of the radar signal processing device 11 are not limited to those implemented by dedicated hardware; the radar signal processing device 11 may also be implemented by software, firmware, or a combination of software and firmware. If the radar signal processing unit 11 is implemented by software or firmware, a program that causes the computer to execute the respective processing procedures in the received signal acquisition unit 12, map calculation unit 19, target detection unit 14, Doppler velocity calculation unit 15, and angle measurement unit 16 is stored in the memory 31 shown in Figure 4. Then, the processor 32 shown in Figure 4 executes the program stored in the memory 31.

[0096] Furthermore, Figure 17 shows an example in which each component of the radar signal processing unit 11 is implemented by dedicated hardware, while Figure 4 shows an example in which the radar signal processing unit 11 is implemented by software or firmware. However, this is merely one example, and some components of the radar signal processing unit 11 may be implemented by dedicated hardware, while the remaining components may be implemented by software or firmware.

[0097] Next, the operation of the transmitting device shown in Figure 15 and the radar signal processing device 11 shown in Figure 16 will be explained. The transmitting device shown in Figure 15 transmits a signal having three transmission channels ch1, ch2, and ch3 using the CDMA method, as shown in Figure 18, in order to enable the radar signal processing device 11 to separate the three transmission channels ch1, ch2, and ch3. Figure 18 is an explanatory diagram showing an example of the phases of multiple data contained in a conventional CDMA transmission channel and the phases of multiple data contained in a CDMA transmission channel used by the transmission device shown in Figure 15. CDMA is a method that applies different modulations to multiple data points in the hit direction contained in the transmitted signal.

[0098] Conventional CDMA does not add a phase offset to each data when applying different modulations to multiple data in the hit direction. The phases of the multiple data contained in the conventional DDMA transmission channels ch1, ch2, and ch3 are as shown in Figure 18, for example, the following data. ch1→φ1=[0° 0° 0° 0°···] ch2→φ2=[0° 180° 0° 180°···] ch3→φ3=[0° 0° 180° 180°···]

[0099] The CDMA used by the transmitter shown in Figure 15 applies different modulations to multiple data points in the hit direction, adding a phase offset to the data midway through the hit. The phases of the multiple data contained in the CDMA transmission channels ch1, ch2, and ch3 used by the transmitting device shown in Figure 15 are, for example, as shown in Figure 18, as follows: ch1→φ1 =[0° 0° 0° 0°···],[0° 0° 0° 0°···] ch2→φ2 =[0° 180° 0° 180°···],[180° 0° 180° 0°···] ch3→φ3 =[0° 0° 180° 180°···],[0° 0° 180° 180°···]

[0100] Signal source 1 generates transmission signals for transmission channels ch1, ch2, and ch3. Signal source 1 outputs the transmission signal for transmission channel ch1 to modulator 5a, the transmission signal for transmission channel ch2 to modulator 5b, and the transmission signal for transmission channel ch3 to modulator 5c. Modulator 5a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a.

[0101] Modulator 5b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. When modulator 5b applies different modulations to multiple data points, it adds a phase offset to the data midway through the hit, as shown in Figure 18. Therefore, transmission channel ch2 is a transmission channel with an offset. Modulator 5c modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch3 with different modulations, and outputs the modulated transmission signal of transmission channel ch3 to transmission antenna 3c.

[0102] The transmitting antenna 3a radiates the modulated transmission signal of the transmission channel ch1 output from the modulator 5a into space. The transmitting antenna 3b radiates the modulated transmission signal of the transmitting channel ch2 output from the modulator 5b into space. The transmitting antenna 3c radiates the modulated transmission signal of the transmitting channel ch3, output from the modulator 5c, into space. As a result, the transmitter shown in Figure 15 transmits a signal having three transmission channels: ch1, ch2, and ch3.

[0103] Each of the receiving antennas 10a, 10b, 10c, and 10d receives the reflected wave of the signal that has been reflected off the target after a signal with three transmission channels, ch1, ch2, and ch3, has been transmitted from the transmitting device shown in Figure 15. The receiving antenna 10a outputs the received signal related to the reflected wave to the signal acquisition processing unit 12a of the receiving signal acquisition unit 12. The receiving antenna 10b outputs the received signal related to the reflected wave to the signal acquisition processing unit 12b of the receiving signal acquisition unit 12. The receiving antenna 10c outputs the received signal related to the reflected wave to the signal acquisition processing unit 12c of the receiving signal acquisition unit 12. The receiving antenna 10d outputs the received signal related to the reflected wave to the signal acquisition processing unit 12d of the receiving signal acquisition unit 12.

[0104] The received signal acquisition unit 12 acquires the received signal relating to the reflected wave of the signal reflected from the target. In other words, the signal acquisition processing unit 12a acquires the received signal from the receiving antenna 10a and outputs the received signal to the Fourier transform unit 19a of the map calculation unit 19. The signal acquisition processing unit 12b acquires the received signal from the receiving antenna 10b and outputs the received signal to the Fourier transform unit 19b of the map calculation unit 19. The signal acquisition processing unit 12c acquires the received signal from the receiving antenna 10c and outputs the received signal to the Fourier transform unit 19c of the map calculation unit 19. The signal acquisition processing unit 12d acquires the received signal from the receiving antenna 10d and outputs the received signal to the Fourier transform unit 19d of the map calculation unit 19.

[0105] The map calculation unit 19 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 19 calculates a range Doppler map from the received signal, in the case of a transmission channel with an offset, before the phase offset is added to the data, as the pre-addition range Doppler map. The map calculation unit 19 calculates the range Doppler map after the phase offset has been added to the data, as a post-added range Doppler map. Figure 19 is an explanatory diagram showing the range Doppler map before and after addition. The map calculation unit 19 outputs the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. The following describes in detail the calculation process of the range Doppler map by the map calculation unit 19.

[0106] The Fourier transform unit 19a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 19a calculates a pre-addition range Doppler map by performing an FFT in the range direction on data that does not have a phase offset added, among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 19a calculates a post-added range Doppler map by performing an FFT in the range direction on the data with a phase offset added from among the multiple hit direction data included in the received signal of the transmission channel ch2, and then performing an FFT in the Doppler direction. The Fourier transform unit 19a outputs the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. Furthermore, the Fourier transform unit 19a calculates a range Doppler map by performing an FFT in the range direction on multiple data points in the hit direction contained in the received signals of transmission channels ch1 and ch3, and then performing an FFT in the Doppler direction. The Fourier transform unit 19a outputs the range Doppler maps of transmission channels ch1 and ch3 to the integration unit 13e.

[0107] The Fourier transform units 19b, 19c, and 19d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 19b, 19c, and 19d calculate the pre-addition range Doppler map and the post-addition range Doppler map, respectively, in the same manner as the Fourier transform unit 19a, and output the pre-addition range Doppler map and the post-addition range Doppler map to the Doppler velocity calculation unit 15. The Fourier transform units 19b, 19c, and 19d calculate range Doppler maps for transmission channels ch1 and ch3, similar to the Fourier transform unit 19a, and output the range Doppler maps for transmission channels ch1 and ch3 to the integration unit 19e.

[0108] The integration processing unit 19e obtains range Doppler maps of transmission channels ch1 and ch3 from the Fourier transform units 19a, 19b, 19c, and 19d, respectively. The integration processing unit 19e integrates the range Doppler maps of the transmission channels ch1 and ch3 output from the Fourier transform units 19a, 19b, 19c, and 19d. The integration processing unit 19e outputs the integrated range Doppler map to the target detection unit 14.

[0109] The operations of the target detection unit 14, the Doppler velocity calculation unit 15, and the angle measurement unit 16 are the same as those of the radar signal processing device 11 shown in Figure 2, so a detailed explanation is omitted. Figure 20 is an explanatory diagram illustrating the process of calculating the element product between the first bin and the second bin.

[0110] Based on the above, when a transmitting device transmits a signal having multiple transmission channels using the CDMA method, the radar signal processing device 11 can suppress the reduction in the range of Doppler speeds that can be determined without ambiguity, even when the number of transmission channels increases.

[0111] Embodiment 4. Embodiment 2 describes a radar signal processing device 11 that is applied to a transmitting device that transmits a signal having multiple transmission channels using the DDMA method. Embodiment 4 describes a radar signal processing device 11 that is applied to a transmitting device that transmits a signal having multiple transmission channels using the CDMA method.

[0112] Figure 21 is a configuration diagram showing a transmitting device applied to the radar signal processing device 11 according to Embodiment 4. In Figure 21, the same reference numerals as in Figure 9 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 22 is a configuration diagram showing a radar system including a radar signal processing device 11 according to Embodiment 4. In Figure 22, the same reference numerals as in Figure 10 indicate the same or corresponding parts, so a detailed explanation is omitted. Figure 23 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to Embodiment 4. In Figure 23, the same reference numerals as in Figure 11 indicate the same or corresponding parts, so a detailed explanation is omitted.

[0113] The transmitting device shown in Figure 21 comprises a signal source 1, a modulation unit 6, and transmitting antennas 3a, 3b, and 3c. The modulation unit 6 includes modulators 6a, 6b, and 6c. In the transmitting device shown in Figure 21, the modulation unit 6 is equipped with three modulators 6a, 6b, and 6c, and the transmitting device is equipped with three transmitting antennas 3a, 3b, and 3c. However, this is merely an example, and the modulation unit 6 may be equipped with two modulators, or four or more modulators, and the transmitting device may be equipped with two transmitting antennas, or four or more transmitting antennas.

[0114] The transmitting device shown in Figure 21 is a device that transmits signals having three transmission channels: ch1, ch2, and ch3. Signal source 1 oscillates a transmission signal and outputs the transmission signal to modulation unit 2. In the transmitting device shown in Figure 21, the transmission signal output by signal source 1 to modulator 6a is the transmission signal for transmission channel ch1, the transmission signal output by signal source 1 to modulator 6b is the transmission signal for transmission channel ch2, and the transmission signal output by signal source 1 to modulator 6c is the transmission signal for transmission channel ch3.

[0115] Modulator 6a acquires the transmission signal for transmission channel ch1 from signal source 1. Modulator 6a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a. Modulator 6b acquires the transmission signal for transmission channel ch2 from signal source 1. Modulator 6b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. Modulator 6c acquires the transmission signal for transmission channel ch3 from signal source 1. Modulator 6c modulates multiple data points in the hit direction contained in the transmit signal of transmit channel ch3 with different modulations, and outputs the modulated transmit signal of transmit channel ch3 to transmit antenna 3c.

[0116] The radar signal processing device 11 includes a received signal acquisition unit 12, a map calculation unit 20, a target detection unit 14, a Doppler velocity calculation unit 18, and an angle measurement unit 16. The received signal acquisition unit 12 acquires the received signal related to the reflected wave of the signal reflected from the target after a signal having multiple transmission channels ch1, ch2, and ch3, in which the data is modulated differently between hits, has been transmitted.

[0117] The map calculation unit 20 is implemented, for example, by the map calculation circuit 30 shown in Figure 23. The map calculation unit 20 includes Fourier transform units 20a, 20b, 20c, 20d and an integration processing unit 20e. The map calculation unit 20 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 20 calculates a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, from the data of the Hth hit (where H is an integer greater than or equal to 2) included in the received signal. The map calculation unit 20 outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hthth hit, to the Doppler velocity calculation unit 18.

[0118] The Fourier transform unit 20a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 20a performs an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform unit 20a performs an FFT in the range direction on the data from the second hit to the Hth hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform unit 20a outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform unit 20a calculates a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform unit 20a outputs a range Doppler map to the integration unit 20e.

[0119] The Fourier transform units 20b, 20c, and 20d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 20b, 20c, and 20d, similar to the Fourier transform unit 20a, perform an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform units 20b, 20c, and 20d, similar to the Fourier transform unit 20a, perform an FFT in the range direction on the data from the second hit to the Hth hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform units 20b, 20c, and 20d output a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform units 20b, 20c, and 20d, similar to the Fourier transform unit 20a, calculate a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform units 20b, 20c, and 20d output a range Doppler map to the integration unit 17e.

[0120] The integration processing unit 20e obtains range Doppler maps from each of the Fourier transform units 20a, 20b, 20c, and 20d. The integration processing unit 20e integrates the range Doppler maps output from the Fourier transform units 20a, 20b, 20c, and 20d. The integration processing unit 20e outputs the integrated range Doppler map to the target detection unit 14.

[0121] In Figure 22, it is assumed that the components of the radar signal processing device 11—the received signal acquisition unit 12, the map calculation unit 20, the target detection unit 14, the Doppler velocity calculation unit 18, and the angle measurement unit 16—are each implemented by dedicated hardware as shown in Figure 23. Specifically, the radar signal processing device 11 is assumed to be implemented by the received signal acquisition circuit 22, the map calculation circuit 30, the target detection circuit 24, the Doppler velocity calculation circuit 28, and the angle measurement circuit 26. Each of the receiving signal acquisition circuit 22, map calculation circuit 30, target detection circuit 24, Doppler velocity calculation circuit 28, and angle measurement circuit 26 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.

[0122] The components of the radar signal processing device 11 are not limited to those implemented by dedicated hardware; the radar signal processing device 11 may also be implemented by software, firmware, or a combination of software and firmware. If the radar signal processing device 11 is implemented by software or firmware, a program that causes the computer to execute the respective processing procedures in the received signal acquisition unit 12, map calculation unit 20, target detection unit 14, Doppler velocity calculation unit 18, and angle measurement unit 16 is stored in the memory 31 shown in Figure 4. Then, the processor 32 shown in Figure 4 executes the program stored in the memory 31.

[0123] Furthermore, Figure 23 shows an example in which each component of the radar signal processing unit 11 is implemented by dedicated hardware, and Figure 4 shows an example in which the radar signal processing unit 11 is implemented by software or firmware, etc. However, this is only one example, and some components of the radar signal processing unit 11 may be implemented by dedicated hardware, while the remaining components may be implemented by software or firmware, etc.

[0124] Next, the operation of the transmitting device shown in Figure 21 and the radar signal processing device 11 shown in Figure 22 will be explained. The transmitting device shown in Figure 21 transmits a signal having three transmission channels ch1, ch2, and ch3 using the CDMA method, as shown in Figure 24, in order to enable the radar signal processing device 11 to separate the three transmission channels ch1, ch2, and ch3. Figure 24 is an explanatory diagram showing an example of the phases of multiple data contained in the CDMA transmission channel used by the transmitting device shown in Figure 21.

[0125] The CDMA used by the transmitter shown in Figure 21 does not add a phase offset to each data when applying different modulations to multiple data in the hit direction. The phases of the multiple data contained in the CDMA transmission channels ch1, ch2, and ch3 used by the transmitting device shown in Figure 21 are, for example, as shown in Figure 24, as follows: ch1→φ1=[0° 0° 0° 0°···] ch2→φ2=[0° 180° 0° 180°···] ch3→φ3=[0° 0° 180° 180°···]

[0126] Signal source 1 generates transmission signals for transmission channels ch1, ch2, and ch3. Signal source 1 outputs the transmission signal for transmission channel ch1 to modulator 2a, the transmission signal for transmission channel ch2 to modulator 2b, and the transmission signal for transmission channel ch3 to modulator 2c.

[0127] Modulator 6a modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch1 with different modulations, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a. Modulator 6b modulates multiple data points in the hit direction included in the transmission signal of transmission channel ch2 with different modulations, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. Modulator 6c modulates multiple data points in the hit direction contained in the transmit signal of transmit channel ch3 with different modulations, and outputs the modulated transmit signal of transmit channel ch3 to transmit antenna 3c.

[0128] The transmitting antenna 3a radiates the modulated transmission signal of the transmission channel ch1 output from the modulator 6a into space. The transmitting antenna 3b radiates the modulated transmit signal of the transmit channel ch2 output from the modulator 6b into space. The transmitting antenna 3c radiates the modulated transmit signal of the transmit channel ch3 output from the modulator 6c into space. As a result, the transmitter shown in Figure 21 transmits a signal having three transmission channels: ch1, ch2, and ch3.

[0129] Each of the receiving antennas 10a, 10b, 10c, and 10d receives the reflected wave of the signal that has been reflected off the target after a signal with three transmission channels, ch1, ch2, and ch3, has been transmitted from the transmitting device shown in Figure 21. The receiving antenna 10a outputs the received signal related to the reflected wave to the signal acquisition processing unit 12a of the receiving signal acquisition unit 12. The receiving antenna 10b outputs the received signal related to the reflected wave to the signal acquisition processing unit 12b of the receiving signal acquisition unit 12. The receiving antenna 10c outputs the received signal related to the reflected wave to the signal acquisition processing unit 12c of the receiving signal acquisition unit 12. The receiving antenna 10d outputs the received signal related to the reflected wave to the signal acquisition processing unit 12d of the receiving signal acquisition unit 12.

[0130] The received signal acquisition unit 12 acquires the received signal relating to the reflected wave of the signal reflected from the target. In other words, the signal acquisition processing unit 12a acquires the received signal from the receiving antenna 10a and outputs the received signal to the Fourier transform unit 20a of the map calculation unit 20. The signal acquisition processing unit 12b acquires the received signal from the receiving antenna 10b and outputs the received signal to the Fourier transform unit 20b of the map calculation unit 20. The signal acquisition processing unit 12c acquires the received signal from the receiving antenna 10c and outputs the received signal to the Fourier transform unit 20c of the map calculation unit 20. The signal acquisition processing unit 12d acquires the received signal from the receiving antenna 10d and outputs the received signal to the Fourier transform unit 20d of the map calculation unit 20.

[0131] The map calculation unit 20 acquires the received signal from the received signal acquisition unit 12. The map calculation unit 20 calculates a range Doppler map based on the data from the first hit to the (H-1)th hit among the data from the first hit to the Hth hit included in the received signal. The map calculation unit 20 calculates a range Doppler map based on the data of the Hth hit, starting from the data of the second hit. Figure 25 is an explanatory diagram showing range Doppler maps based on the data from the first hit to the (H-1)th hit, and range Doppler maps based on the data from the second hit to the Hth hit. The map calculation unit 20 outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. The following describes in detail the calculation process of the range Doppler map by the map calculation unit 20.

[0132] The Fourier transform unit 20a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 20a performs an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform unit 20a performs an FFT in the range direction on the data from the second hit to the Hth hit, and then performs an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit as an added range Doppler map. The Fourier transform unit 20a outputs a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform unit 20a calculates a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform unit 20a outputs a range Doppler map to the integration unit 20e.

[0133] The Fourier transform units 20b, 20c, and 20d acquire the received signal from the signal acquisition processing units 12b, 12c, and 12d. The Fourier transform units 20b, 20c, and 20d, similar to the Fourier transform unit 20a, perform an FFT in the range direction on the data from the first hit to the (H-1)th hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the first hit to the (H-1)th hit. The Fourier transform units 20b, 20c, and 20d, similar to the Fourier transform unit 20a, perform an FFT in the range direction on the data from the second hit to the Hth hit, and then perform an FFT in the Doppler direction to calculate a range Doppler map based on the data from the second hit to the Hth hit. The Fourier transform units 20b, 20c, and 20d output a range Doppler map based on the data from the first hit to the (H-1)th hit, and a range Doppler map based on the data from the second hit to the Hth hit, to the Doppler velocity calculation unit 18. Furthermore, the Fourier transform units 20b, 20c, and 20d, similar to the Fourier transform unit 20a, calculate a range Doppler map by performing an FFT in the range direction on the data from the first hit to the Hth hit, and then performing an FFT in the Doppler direction. The Fourier transform units 20b, 20c, and 20d output a range Doppler map to the integration unit 20e.

[0134] The integration processing unit 20e obtains range Doppler maps from each of the Fourier transform units 20a, 20b, 20c, and 20d. The integration processing unit 20e integrates the range Doppler maps output from the Fourier transform units 20a, 20b, 20c, and 20d. The integration processing unit 20e outputs the integrated range Doppler map to the target detection unit 14.

[0135] The operations of the target detection unit 14, the Doppler velocity calculation unit 18, and the angle measurement unit 16 are the same as those of the radar signal processing device 11 shown in Figure 9, so a detailed explanation is omitted. Figure 26 is an explanatory diagram illustrating the process of calculating the element product between the first bin and the second bin.

[0136] Based on the above, when a transmitting device transmits a signal having multiple transmission channels using the CDMA method, the radar signal processing device 11 can suppress the reduction in the range of Doppler speeds that can be determined without ambiguity, even when the number of transmission channels increases.

[0137] 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]

[0138] This disclosure can suppress the reduction in the range of Doppler speeds that can be determined without ambiguity, even when the number of transmission channels increases, and can be used in radar signal processing equipment and radar signal processing methods. [Explanation of Symbols]

[0139] 1 Signal source, 2 Modulation unit, 2a, 2b, 2c Modulators, 3a, 3b, 3c Transmitting antenna, 4 Modulation unit, 4a, 4b, 4c Modulators, 5 Modulation unit, 5a, 5b, 5c Modulators, 6 Modulation unit, 6a, 6b, 6c Modulators, 10a, 10b, 10c, 10d Receiving antenna, 11 Radar signal processing unit, 12 Received signal acquisition unit, 12a, 12b, 12c, 12d Signal acquisition processing unit, 13 Map calculation unit, 13a, 13b, 13c, 13d Fourier transform unit, 13e Integration processing unit, 14 Target detection unit, 15, 18 Doppler velocity calculation unit, 16 Angle measurement unit, 17 Map calculation unit, 17a, 17b, 17c, 17d Fourier transform unit, 17e Integration processing unit, 19 Map calculation unit, 19a, 19b, 19c, 19d Fourier transform unit, 19e Integration processing unit, 20 Map calculation unit, 20a, 20b, 20c, 20d Fourier transform unit, 20e Integration processing unit, 22 Received signal acquisition circuit, 23, 27, 29, 30 Map calculation circuit, 24 Target detection circuit, 25, 28 Doppler velocity calculation circuit, 26 Angle measurement circuit, 31 Memory, 32 Processor.

Claims

1. A signal is transmitted having multiple transmission channels in which the data is modulated differently between hits, and among the multiple transmission channels, there is an offset transmission channel in which a phase offset is added to the data from the middle of the hit. After this signal is transmitted, a received signal acquisition unit acquires a received signal relating to the reflected wave of the signal reflected from the target. A map calculation unit calculates a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data from the received signal acquired by the received signal acquisition unit, A Doppler velocity calculation unit calculates the target Doppler velocity based on a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data. A radar signal processing device equipped with [a specific feature / feature].

2. The Doppler velocity calculation unit is The radar signal processing device according to claim 1, characterized in that it calculates the number of Doppler aliasing for the target from a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data, and calculates the Doppler velocity of the target based on the number of Doppler aliasing.

3. The Doppler velocity calculation unit is The radar signal processing device according to claim 2, characterized in that it extracts a first bin, which is the bin in which the target exists, from a range Doppler map before the phase offset is added to the data, and extracts a second bin, which is the bin in which the target exists, from a range Doppler map after the phase offset is added to the data, and calculates the number of Doppler aliasing for the target based on the element product of the first bin and the second bin.

4. A signal having multiple transmission channels in which data is modulated differently between hits is transmitted, and a received signal acquisition unit acquires a received signal relating to the reflected wave of the signal reflected from the target. A map calculation unit calculates a range Doppler map based on the data of the (H-1)th hit from the data of the first hit to the data of the Hth hit, which are included in the received signal acquired by the received signal acquisition unit, and a range Doppler map based on the data of the second hit to the data of the Hth hit. A Doppler velocity calculation unit calculates the target Doppler velocity based on a range Doppler map derived from the data of the (H-1)th hit and a range Doppler map derived from the data of the second hit and the data of the Hth hit. A radar signal processing device equipped with [a specific feature / feature].

5. The Doppler velocity calculation unit is The radar signal processing device according to claim 4, characterized in that it calculates the number of Doppler aliasing for the target from a range Doppler map based on the data of the (H-1)th hit from the data of the first hit and a range Doppler map based on the data of the Hth hit from the data of the second hit, and calculates the Doppler velocity of the target based on the number of Doppler aliasing.

6. The Doppler velocity calculation unit is The radar signal processing device according to claim 5, characterized in that it extracts a first bin, which is the bin in which the target exists, from a range Doppler map based on the data of the (H-1)th hit, from the data of the first hit, and extracts a second bin, which is the bin in which the target exists, from a range Doppler map based on the data of the Hth hit, from the data of the second hit, and calculates the number of Doppler aliasing for the target based on the element product of the first bin and the second bin.

7. The received signal acquisition unit has multiple transmission channels in which the data is modulated differently between hits, and among the multiple transmission channels, there is an offset transmission channel in which a phase offset is added to the data from the middle of the hit. After a signal is transmitted, the unit acquires a received signal relating to the reflected wave of the signal reflected from the target. The map calculation unit calculates a range Doppler map before the phase offset is added to the data and a range Doppler map after the phase offset is added to the data from the received signal acquired by the received signal acquisition unit. The Doppler velocity calculation unit calculates the target Doppler velocity based on the range Doppler map before the phase offset is added to the data and the range Doppler map after the phase offset is added to the data. Radar signal processing method.

8. The received signal acquisition unit acquires a received signal relating to the reflected wave of the signal reflected from the target after a signal having multiple transmission channels, in which the data is modulated differently between hits, has been transmitted. The map calculation unit calculates a range Doppler map based on the data of the (H-1)th hit from the data of the first hit to the data of the Hth hit, which is included in the received signal acquired by the received signal acquisition unit, and a range Doppler map based on the data of the second hit to the data of the Hth hit. The Doppler velocity calculation unit calculates the target Doppler velocity based on a range Doppler map derived from the data of the first hit to the data of the (H-1)th hit and a range Doppler map derived from the data of the second hit to the data of the Hth hit. Radar signal processing method.

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