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

Radar signal processing device and radar signal processing method

[0001] The present disclosure relates to a radar signal processing device and a radar signal processing method.

[0002] There is a radar signal processing device that calculates the Doppler velocity of a target. For example, Patent Document 1 discloses a radar signal processing device that includes a receiver that calculates the Doppler velocity of a target based on a received signal related to a wave reflected by the target after a transmitter transmits a signal having a plurality of transmission channels in which data is modulated differently between hits.

[0003] Japanese Patent Application Laid-Open No. 2020-204603

[0004] The radar device disclosed in Patent Document 1 has a problem in that the range of Doppler velocities that can be determined without ambiguity decreases as the number of transmission channels increases.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a radar signal processing device that can suppress a decrease in the range of Doppler velocities that can be determined unambiguously, even if the number of transmission channels increases.

[0006] A radar signal processing device according to the present disclosure includes a plurality of transmission channels in which data is modulated differently between hits, and includes a received signal acquisition unit that acquires received signals relating to reflected waves of the signals reflected by a target after the transmission of signals including a transmission channel with an offset in which a phase offset is added to the data midway through the hit.The radar signal processing device also includes a map calculation unit that calculates, from the received signals acquired by the received signal acquisition unit, 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 a Doppler velocity calculation unit that calculates the Doppler velocity of the target based on the range-Doppler map calculated by the map calculation unit.

[0007] According to the present disclosure, even if the number of transmission channels increases, it is possible to suppress a decrease in the range of Doppler velocities that can be determined without ambiguity.

[0008] 9 is a configuration diagram showing a transmission device applied to the radar signal processing device 11 according to a first embodiment. FIG. 9 is a configuration diagram showing a radar device including the radar signal processing device 11 according to the first embodiment. FIG. 9 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to the first embodiment. FIG. 9 is a hardware configuration diagram of a computer in the case where the radar signal processing device 11 is realized by software, firmware, or the like. FIG. 9 is a flowchart showing a radar signal processing method, which is a processing procedure of the radar signal processing device 11. FIG. 9 is an explanatory diagram showing an example of the phases of multiple data included in a transmission channel using conventional DDMA and the phases of multiple data included in a transmission channel using DDMA used by the transmission device shown in FIG. 1. FIG. 9 is an explanatory diagram showing a pre-addition range Doppler map and a post-addition range Doppler map. FIG. 9 is an explanatory diagram showing a calculation process of an element product of a first bin and a second bin. FIG. 9 is a configuration diagram showing a transmission device applied to the radar signal processing device 11 according to a second embodiment. FIG. 9 is a configuration diagram showing a radar device including the radar signal processing device 11 according to the second embodiment. FIG. 9 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to the second embodiment. FIG. 9 is an explanatory diagram showing an example of the phases of multiple data included in a transmission channel using DDMA used by the transmission device shown in FIG. 15A and 15B are explanatory diagrams showing a range Doppler map based on data from the first hit to the (H-1)th hit and a range Doppler map based on data from the second hit to the Hth hit.

[0033] FIG. 16 is an explanatory diagram showing a calculation process of an element product of a first bin and a second bin.

[0034] FIG. 17 is a configuration diagram showing a transmission device applied to a radar signal processing device 11 according to a third embodiment.

[0035] FIG. 18 is a configuration diagram showing a radar device including a radar signal processing device 11 according to the third embodiment.

[0036] FIG. 19 is a hardware configuration diagram showing hardware of the radar signal processing device 11 according to the third embodiment.

[0037] FIG. 19 is an explanatory diagram showing an example of the phases of multiple data included in a conventional CDMA transmission channel and the phases of multiple data included in a CDMA transmission channel used by the transmission device shown in FIG. 15.

[0038] FIG. 19 is an explanatory diagram showing a pre-addition range Doppler map and a post-addition range Doppler map.

[0039] FIG. 20 is an explanatory diagram showing a calculation process of an element product of a first bin and a second bin.

[0039] FIG. 21 is a configuration diagram showing a transmission device applied to a radar signal processing device 11 according to a fourth embodiment.22 is a configuration diagram showing a radar device including a radar signal processing device 11 according to embodiment 4. FIG. 23 is a hardware configuration diagram showing hardware of the radar signal processing device 11 according to embodiment 4. FIG. 24 is an explanatory diagram showing an example of the phases of multiple data included in the CDMA transmission channel used by the transmission device shown in FIG. 21. FIG. 25 is an explanatory diagram showing a range-Doppler map based on data from the first hit to the (H-1)th hit and a range-Doppler map based on data from the second hit to the Hth hit. FIG. 26 is an explanatory diagram showing a calculation process of an element product of a first bin and a second bin.

[0009] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] Embodiment 1 Fig. 1 is a configuration diagram showing a transmission device applied to a radar signal processing device 11 according to embodiment 1. Fig. 2 is a configuration diagram showing a radar device including the radar signal processing device 11 according to embodiment 1. Fig. 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 Fig. 1 includes a signal source 1, a modulating unit 2, and transmitting antennas 3a, 3b, and 3c. The modulating unit 2 includes modulators 2a, 2b, and 2c. In the transmitting device shown in Fig. 1, the modulating unit 2 includes three modulators 2a, 2b, and 2c, and the transmitting device includes three transmitting antennas 3a, 3b, and 3c. However, this is merely an example, and the modulating unit 2 may include two modulators or four or more modulators, and the transmitting device may include two or four or more transmitting antennas.

[0012] The transmitting device shown in Fig. 1 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 Fig. 1, the transmission signal that signal source 1 outputs to modulator 2a is the transmission signal of transmission channel ch1, the transmission signal that signal source 1 outputs to modulator 2b is the transmission signal of transmission channel ch2, and the transmission signal that signal source 1 outputs to modulator 2c is the transmission signal of transmission channel ch3.

[0013] The modulator 2a acquires a transmission signal for transmission channel ch1 from the signal source 1. The modulator 2a performs different modulations on multiple pieces of data for the hit direction included in the transmission signal for transmission channel ch1, and outputs the modulated transmission signal for transmission channel ch1 to the transmission antenna 3a. The modulator 2b acquires a transmission signal for transmission channel ch2 from the signal source 1. The modulator 2b performs different modulations on multiple pieces of data for the hit direction included in the transmission signal for transmission channel ch2, and outputs the modulated transmission signal for transmission channel ch2 to the transmission antenna 3b. When performing different modulations on multiple pieces of data, the modulator 2b adds a phase offset to the data from the middle of the hit. Therefore, the transmission channel ch2 is a transmission channel with an offset. The modulator 2c acquires a transmission signal for transmission channel ch3 from the signal source 1. The modulator 2c performs different modulations on multiple pieces of data for the hit direction included in the transmission signal for transmission channel ch3, and outputs the modulated transmission signal for transmission channel ch3 to the transmission antenna 3c.

[0014] The transmitting antenna 3a radiates into space the modulated transmission signal of transmission channel ch1 output from the modulator 2a. The transmitting antenna 3b radiates into space the modulated transmission signal of transmission channel ch2 output from the modulator 2b. The transmitting antenna 3c radiates into space the modulated transmission signal of transmission channel ch3 output from the modulator 2c. As a result, signals having three transmission channels ch1, ch2, and ch3 are radiated into space.

[0015] The radar device shown in FIG. 2 includes receiving antennas 10a, 10b, 10c, and 10d and a radar signal processing device 11. After signals having three transmission channels ch1, ch2, and ch3 are transmitted from the transmitting device shown in FIG. 1 , the receiving antennas 10a, 10b, 10c, and 10d each receive a reflected wave of the signal reflected by a target and output a received signal related to the reflected wave to the radar signal processing device 11. Although FIG. 2 does not illustrate a receiver between each of the receiving antennas 10a, 10b, 10c, and 10d and the radar signal processing device 11, a receiver may be provided between each of the receiving antennas 10a, 10b, 10c, and 10d and the radar signal processing device 11. The radar device shown in FIG. 2 includes four receiving antennas 10a, 10b, 10c, and 10d. However, this is merely an example, and the radar device may include 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 realized, for example, by a received signal acquisition circuit 22 shown in Fig. 3. The received signal acquisition unit 12 includes signal acquisition processing units 12a, 12b, 12c, and 12d. After signals having three transmission channels ch1, ch2, and ch3 are transmitted from the transmitting device shown in Fig. 1, the received signal acquisition unit 12 acquires received signals related to reflected waves of the signals reflected by targets.

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

[0018] The map calculation unit 13 is realized by, for example, the map calculation circuit 23 shown in FIG. 3 . The map calculation unit 13 includes Fourier transform units 13a, 13b, 13c, and 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, from the received signal, a range-Doppler map before a 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 a 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 an FFT (Fast Fourier Transform) in the range direction on data to which no phase offset has been added among multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range-Doppler map before the phase offset has been added to the data. The Fourier transform unit 13a performs an FFT in the range direction on data to which a phase offset has been added among multiple pieces of data in the hit direction included in the received signal of 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 performs an FFT in the range direction on multiple pieces of data in the hit direction included in the received signals of the transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 13a outputs the range-Doppler maps of the transmission channels ch1 and ch3 to the integration processing unit 13e.

[0020] The Fourier transform unit 13b acquires the received signal from the signal acquisition processing unit 12b. The Fourier transform unit 13b performs an FFT in the range direction on data to which no phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range-Doppler map before the phase offset has been added to the data. The Fourier transform unit 13b performs an FFT in the range direction on data to which a phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of 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 13b outputs each range-Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 13b performs an FFT in the range direction on multiple pieces of data in the hit direction included in the received signals of transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 13b outputs the range-Doppler maps of the transmission channels ch1 and ch3 to the integration processing 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 data to which no phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range-Doppler map before the phase offset has been added to the data. The Fourier transform unit 13c performs an FFT in the range direction on data to which a phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of 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 performs an FFT in the range direction on multiple pieces of data in the hit direction included in the received signals of transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. 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 data to which no phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a range-Doppler map before the phase offset has been added to the data. The Fourier transform unit 13d performs an FFT in the range direction on data to which a phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of 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 performs an FFT in the range direction on multiple pieces of data in the hit direction included in the received signals of transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 13d outputs the range-Doppler maps of the transmission channels ch1 and ch3 to the integration processing unit 13e.

[0023] The integration processing unit 13e acquires range-Doppler maps of the 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 range-Doppler maps after integration to the target detection unit 14.

[0024] The target detection unit 14 is realized by, for example, the target detection circuit 24 shown in FIG. 3. The target detection unit 14 acquires 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 realized by, for example, the Doppler velocity calculation circuit 25 shown in FIG. 3. The Doppler velocity calculation unit 15 acquires from the map calculation unit 13 a range-Doppler map before a phase offset is added to the data and a range-Doppler map after a phase offset is added to the data. The Doppler velocity calculation unit 15 calculates the Doppler velocity of the target based on these range-Doppler maps. Specifically, the Doppler velocity calculation unit 15 calculates the Doppler aliasing number for the target from the range-Doppler map before a phase offset is added to the data and the range-Doppler map after a phase offset is added to the data, and calculates the Doppler velocity of the target based on the Doppler aliasing number. More specifically, based on the target detection result by the target detection unit 14, the Doppler velocity calculation unit 15 extracts a first bin, which is a bin in which the target exists, from the range-Doppler map before the phase offset is added to the data, and extracts a second bin, which is a bin in which the target exists, from the range-Doppler map after the phase offset is added to the data.The Doppler velocity calculation unit 15 then calculates the Doppler aliasing number for the target based on the product of the elements of the first bin and the second bin.The Doppler velocity calculation unit 15 calculates the Doppler velocity of the target based on the Doppler aliasing number.The Doppler velocity calculation unit 15 outputs information indicating the Doppler velocity of the target to the angle measurement unit 16.

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

[0027] 2, it is assumed that each of the components of the radar signal processing device 11, namely, 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, is realized by dedicated hardware as shown in Fig. 3. That is, it is assumed that the radar signal processing device 11 is realized by a received signal acquisition circuit 22, a map calculation circuit 23, a target detection circuit 24, a Doppler velocity calculation circuit 25, and an angle measurement circuit 26. Each of 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 corresponds to, 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 realized by dedicated hardware, and the radar signal processing device 11 may be realized by software, firmware, or a combination of software and firmware. Software or firmware is stored as a program in the memory of a computer. The computer refers to hardware that executes a program, and includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0029] 4 is a hardware configuration diagram of a computer when the radar signal processing device 11 is realized by software, firmware, etc. When the radar signal processing device 11 is realized by software, firmware, etc., a program for causing the computer to execute the respective processing procedures of 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 is stored in a memory 31. A processor 32 of the computer then executes the program stored in the memory 31.

[0030] 3 shows an example in which each of the components of the radar signal processing device 11 is realized by dedicated hardware, while Fig. 4 shows an example in which the radar signal processing device 11 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar signal processing device 11 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

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

[0032] In conventional DDMA, when different modulations are applied to multiple data in the hit direction, no phase offset is added to each data. The phases of multiple data included in transmission channels ch1, ch2, and ch3 in conventional DDMA are, for example, as shown in Figure 6: ch1 → φ １ = [0° 0° 0° 0° ...] ch2 → φ ２ = [0° 180° 0° 180° ...] ch3 → φ ３ = [0° 90° 180° 270° ...]

[0033] In the DDMA used by the transmitting device shown in Fig. 1, when different modulations are applied to multiple data in the hit direction, for example, for transmission channel ch2, a phase offset is added to the data from the middle of the hit. The phases of multiple data contained in transmission channels ch1, ch2, and ch3 by the DDMA used by the transmitting device shown in Fig. 1 are, for example, as shown in Fig. 6, as follows: ch1 → φ １ = [0° 0° 0° 0° ...], [0° 0° 0° 0° ...] ch2 → φ ２ = [0° 180° 0° 180° ...], [180° 0° 180° 0° ...] ch3 → φ ３ = [0° 90° 180° 270°...], [0° 90° 180° 270°...]

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

[0035] The modulator 2b performs different modulations on the multiple data in the hit direction included in the transmission signal of the transmission channel ch2, and outputs the modulated transmission signal of the transmission channel ch2 to the transmission antenna 3b. When performing different modulations on the multiple data, the modulator 2b adds a phase offset to the data from the middle of the hit, as shown in the right diagram of Figure 6. Therefore, the transmission channel ch2 is a transmission channel with an offset. The modulator 2c performs different modulations on the multiple data in the hit direction included in the transmission signal of the transmission channel ch3, and outputs the modulated transmission signal of the transmission channel ch3 to the transmission antenna 3c.

[0036] The transmitting antenna 3a radiates into space the modulated transmission signal of transmission channel ch1 output from the modulator 2a. The transmitting antenna 3b radiates into space the modulated transmission signal of transmission channel ch2 output from the modulator 2b. The transmitting antenna 3c radiates into space the modulated transmission signal of transmission channel ch3 output from the modulator 2c. As a result, signals having three transmission channels ch1, ch2, and ch3 are transmitted from the transmitting device shown in FIG.

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

[0038] The received signal acquisition unit 12 acquires received signals related to reflected waves of signals reflected by a target (step ST1 in FIG. 5 ). That is, the signal acquisition processing unit 12a acquires received signals from the receiving antenna 10a and outputs the received signals to the Fourier transform unit 13a of the map calculation unit 13. The signal acquisition processing unit 12b acquires received signals from the receiving antenna 10b and outputs the received signals to the Fourier transform unit 13b of the map calculation unit 13. The signal acquisition processing unit 12c acquires received signals from the receiving antenna 10c and outputs the received signals to the Fourier transform unit 13c of the map calculation unit 13. The signal acquisition processing unit 12d acquires received signals from the receiving antenna 10d and outputs the received signals 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. From the received signal, the map calculation unit 13 calculates a range-Doppler map before a phase offset is added to the data (hereinafter referred to as the "pre-addition range-Doppler map") and a range-Doppler map after a phase offset is added to the data (hereinafter referred to as the "post-addition range-Doppler map") (step ST2 in FIG. 5). FIG. 7 is an explanatory diagram showing the pre-addition range-Doppler map and the post-addition range-Doppler map. 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 calculation process of the range-Doppler map by the map calculation unit 13 will be described in detail below.

[0040] The Fourier transform unit 13a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 13a performs an FFT in the range direction on data to which no phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a pre-addition range-Doppler map. The Fourier transform unit 13a performs an FFT in the range direction on data to which a phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a post-addition range-Doppler map. The Fourier transform unit 13a outputs each of the pre-addition range-Doppler map and the post-addition range-Doppler map to the Doppler velocity calculation unit 15. The Fourier transform unit 13a also performs an FFT in the range direction on multiple pieces of data in the hit direction included in the received signals of transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 13a outputs the range-Doppler maps of the transmission channels ch1 and ch3 to the integration processing unit 13e.

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

[0042] The integration processing unit 13e acquires range-Doppler maps of the 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 range-Doppler maps after integration to the target detection unit 14.

[0043] The target detection unit 14 acquires the integrated range-Doppler map from the integration processing unit 13e. The target detection unit 14 detects targets by performing CFAR processing on the integrated range-Doppler map (step ST3 in FIG. 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 range bin in which the target exists.

[0044] The Doppler velocity calculation unit 15 acquires 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 Doppler velocity of the target based on the pre-addition range-Doppler map and the post-addition range-Doppler map (step ST4 in FIG. 5). The Doppler velocity calculation unit 15 outputs information indicating the Doppler velocity of the target to the angle measurement unit 16. The calculation process of the Doppler velocity by the Doppler velocity calculation unit 15 will be specifically described below.

[0045] The Doppler velocity calculation unit 15 extracts a first bin, which is a bin in which a target exists, from the pre-addition range-Doppler map based on the target detection result by the target detection unit 14. The Doppler velocity calculation unit 15 also extracts a second bin, which is a bin in which a target exists, from the post-addition range-Doppler map based on the target detection result by the target detection unit 14. As shown in Fig. 8, the Doppler velocity calculation unit 15 calculates the Doppler aliasing number DC for the target based on the product of the elements of the first bin and the second bin. Fig. 8 is an explanatory diagram showing the calculation process of the product of the elements of the first bin and the second bin.

[0046] Hereinafter, a specific description will be given of the calculation process of the Doppler aliasing number by the Doppler velocity calculation unit 15. In FIG. 8, for the sake of convenience, the left bin in the first bin is s １ , the central bin in the first bin is s ２ , the bin on the right side of the figure in the first bin is s ３ In addition, the left bin in the second bin is s １ *exp(jφ), the center bin in the second bin is s ２ *exp(jφ) *exp(jπ), the bin on the right side of the figure in the second bin is s ３ ×exp(jφ), where φ is the phase offset amount, and is shown in FIG. ｏｆｆｓｅｔ，１ , φ ｏｆｆｓｅｔ，２ , φ ｏｆｆｓｅｔ，３ is equivalent to

[0047] In this case, the Doppler velocity calculation unit 15 calculates the Doppler velocity by calculating the velocity of the bin s on the left side of the figure as shown in the following equation (1). １ and the bin s on the left side of the figure １ * exp(jφ) and element product x １ Calculate x １ =s １ *(s １ *exp(jφ))^* =|s １ | ２ *exp(-jφ) (1) The Doppler velocity calculation unit 15 calculates the Doppler velocity using the central bin s in the figure as shown in the following equation (2). ２ and the central bin s ２ *exp(jφ)*exp(jπ) and element product x ２ Calculate x ２ =s ２ *(s ２ *exp(jφ)*exp(jπ))^* = |s ２ | ２ *exp(-jφ)*exp(jπ) (2) The Doppler velocity calculation unit 15 calculates the Doppler velocity using the bin s on the right side of the figure as shown in the following equation (3). ３ and the bin s on the right side of the figure ３ * exp(jφ) and element product x ３ Calculate x ３ =s ３ *(s１ *exp(jφ))^* =|s ３ | ２ *exp(-jφ) (3)

[0048] The Doppler velocity calculation unit 15 calculates the element product x １ , x ２ , x ３ Focusing on the topology of １ Topology and element product x ３ The topology of x is the same as that of x ２ The topology of the element product x １ , x ３ If the phase of the Doppler signal is rotated by 180 degrees, the Doppler aliasing number DC is determined to be 0. １ , x ２ , x ３ Focusing on the topology of １ Topology and element product x ２ The topology of x is the same as that of x ３ The topology of the element product x １ , x ２ If the phase of the Doppler signal is rotated by 180 degrees, the Doppler aliasing number DC is determined to be 1. １ , x ２ , x ３ Focusing on the topology of ２ Topology and element product x ３ The topology of x is the same as that of x １ The topology of the element product x ２ , x ３ If the phase is rotated by 180 degrees, the Doppler aliasing number DC is determined to be 2.

[0049] The Doppler velocity calculation unit 15 calculates the Doppler velocity vd of the target based on the Doppler aliasing number DC as shown in the following equation (4): vd=vd ｓ１ + (PRF / M) × DC (4) In equation (4), vd ｓ１ is the bin s on the left side of the figure １ is the Doppler velocity, PRF is the pulse repetition frequency, and M is a constant.

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

[0051] In the first embodiment described above, the radar signal processing device 11 is configured to include a plurality of transmission channels in which data is modulated differently between hits, including a transmission channel with an offset in which a phase offset is added to data midway through a hit, and a received signal acquisition unit 12 that acquires a received signal related to a reflected wave of the signal reflected by a target after the transmission of the signal. The radar signal processing device 11 also includes a map calculation unit 13 that calculates, from the received signal acquired by the received signal acquisition unit 12, 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 a Doppler velocity calculation unit 15 that calculates the Doppler velocity of the target 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 prevent a decrease in the range of Doppler velocities that can be determined without ambiguity.

[0052] Second Embodiment In a second embodiment, a radar signal processing device 11 will be described which is applied to a transmitting device that transmits a signal having a plurality of transmission channels in which data is modulated differently between hits.

[0053] Fig. 9 is a configuration diagram showing a transmission device applied to a radar signal processing device 11 according to embodiment 2. In Fig. 9, the same reference numerals as in Fig. 1 indicate the same or corresponding parts, and detailed descriptions thereof will be omitted. Fig. 10 is a configuration diagram showing a radar device including the radar signal processing device 11 according to embodiment 2. In Fig. 10, the same reference numerals as in Fig. 2 indicate the same or corresponding parts, and detailed descriptions thereof will be omitted. Fig. 11 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to embodiment 2. In Fig. 11, the same reference numerals as in Fig. 3 indicate the same or corresponding parts, and detailed descriptions thereof will be omitted.

[0054] The transmitting device shown in Fig. 9 includes a signal source 1, a modulating unit 4, and transmitting antennas 3a, 3b, and 3c. The modulating unit 4 includes modulators 4a, 4b, and 4c. In the transmitting device shown in Fig. 9, the modulating unit 4 includes three modulators 4a, 4b, and 4c, and the transmitting device includes three transmitting antennas 3a, 3b, and 3c. However, this is merely an example, and the modulating unit 4 may include two modulators or four or more modulators, and the transmitting device may include two 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 of transmission channel ch1 from signal source 1. Modulator 4a performs different modulations on multiple hit direction data included in the transmission signal of transmission channel ch1, and outputs the modulated transmission signal of transmission channel ch1 to transmission antenna 3a. Modulator 4b acquires the transmission signal of transmission channel ch2 from signal source 1. Modulator 4b performs different modulations on multiple hit direction data included in the transmission signal of transmission channel ch2, and outputs the modulated transmission signal of transmission channel ch2 to transmission antenna 3b. Modulator 4c acquires the transmission signal of transmission channel ch3 from signal source 1. Modulator 4c performs different modulations on multiple hit direction data included in the transmission signal of transmission channel ch3, and outputs the modulated transmission signal of transmission channel ch3 to transmission 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. After a signal having a plurality of transmission channels ch1, ch2, and ch3, in which data hits are modulated differently from one another, is transmitted, the received signal acquisition unit 12 acquires a received signal related to a reflected wave of the signal reflected by a target.

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

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

[0060] The integration processing unit 17e acquires the range-Doppler maps from each of the Fourier transform units 17a, 17b, 17c, and 17d. The integration processing 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 range-Doppler maps after integration to the target detection unit 14.

[0061] The Doppler velocity calculation unit 18 is realized, for example, by a Doppler velocity calculation circuit 28 shown in FIG. 11 . The Doppler velocity calculation unit 18 acquires from the map calculation unit 17 a range-Doppler map based on data from the first hit to the (H−1)th hit and a range-Doppler map based on data from the second hit to the Hth hit. The Doppler velocity calculation unit 18 calculates the Doppler velocity of the target based on these range-Doppler maps. Specifically, the Doppler velocity calculation unit 18 calculates the Doppler aliasing number for the target from the range-Doppler map based on data from the first hit to the (H−1)th hit and the range-Doppler map based on data from the second hit to the Hth hit, and calculates the Doppler velocity of the target based on the Doppler aliasing number. More specifically, based on the target detection result by the target detection unit 14, the Doppler velocity calculation unit 18 extracts a first bin, where the target exists, from a range-Doppler map based on data from the first hit to the (H-1)th hit, and extracts a second bin, where the target exists, from a range-Doppler map based on data from the second hit to the Hth hit.The Doppler velocity calculation unit 18 then calculates the Doppler aliasing number for the target based on the product of the elements of the first bin and the second bin.The Doppler velocity calculation unit 18 calculates the Doppler velocity of the target based on the Doppler aliasing number.The Doppler velocity calculation unit 18 outputs information indicating the Doppler velocity of the target to the angle measurement unit 16.

[0062] 10 assumes that the received signal acquisition unit 12, map calculation unit 17, target detection unit 14, Doppler velocity calculation unit 18, and angle measurement unit 16, which are components of the radar signal processing device 11, are each realized by dedicated hardware as shown in Fig. 11. That is, it is assumed that the radar signal processing device 11 is realized by a received signal acquisition circuit 22, map calculation circuit 27, target detection circuit 24, Doppler velocity calculation circuit 28, and angle measurement circuit 26. Each of the received signal acquisition circuit 22, map calculation circuit 27, target detection circuit 24, Doppler velocity calculation circuit 28, and angle measurement circuit 26 corresponds to, 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 realized by dedicated hardware, and the radar signal processing device 11 may be realized by software, firmware, or a combination of software and firmware. When the radar signal processing device 11 is realized by software, firmware, or the like, a program for causing a computer to execute the respective processing procedures of 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 is stored in a memory 31 shown in Fig. 4. Then, a processor 32 shown in Fig. 4 executes the program stored in the memory 31.

[0064] 11 shows an example in which each of the components of the radar signal processing device 11 is realized by dedicated hardware, while Fig. 4 shows an example in which the radar signal processing device 11 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar signal processing device 11 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

[0065] Next, the operation of the transmitting device shown in Fig. 9 and the radar signal processing device 11 shown in Fig. 10 will be described. The transmitting device shown in Fig. 9 transmits a signal having three transmission channels ch1, ch2, and ch3 using the DDMA method as shown in Fig. 12 so that the three transmission channels ch1, ch2, and ch3 can be separated in the radar signal processing device 11. Fig. 12 is an explanatory diagram showing an example of the phases of multiple data included in the transmission channels by DDMA used by the transmitting device shown in Fig. 9. DDMA is a method of applying different modulations to multiple hit-direction data included in a transmission signal.

[0066] The DDMA used by the transmitter shown in Fig. 9 does not add a phase offset to each data when performing different modulations on multiple data in the hit direction, as in the conventional DDMA. The phases of multiple data included in the transmission channels ch1, ch2, and ch3 by the DDMA used by the transmitter shown in Fig. 9 are, for example, as shown in Fig. 12: ch1 → φ １ = [0° 0° 0° 0° ...] ch2 → φ ２ = [0° 180° 0° 180° ...] ch3 → φ ３ = [0° 90° 180° 270° ...]

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

[0068] The modulator 2b performs different modulations on the multiple hit direction data included in the transmission signal of the transmission channel ch2, and outputs the modulated transmission signal of the transmission channel ch2 to the transmission antenna 3b. The modulator 2c performs different modulations on the multiple hit direction data included in the transmission signal of the transmission channel ch3, and outputs the modulated transmission signal of the transmission channel ch3 to the transmission antenna 3c.

[0069] The transmitting antenna 3a radiates into space the modulated transmission signal of transmission channel ch1 output from the modulator 2a. The transmitting antenna 3b radiates into space the modulated transmission signal of transmission channel ch2 output from the modulator 2b. The transmitting antenna 3c radiates into space the modulated transmission signal of transmission channel ch3 output from the modulator 2c. As a result, signals having three transmission channels ch1, ch2, and ch3 are transmitted from the transmitting device shown in FIG.

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

[0071] The received signal acquisition unit 12 acquires received signals related to reflected waves of signals reflected by targets. That is, the signal acquisition processing unit 12a acquires received signals from the receiving antenna 10a and outputs the received signals to the Fourier transform unit 17a of the map calculation unit 17. The signal acquisition processing unit 12b acquires received signals from the receiving antenna 10b and outputs the received signals to the Fourier transform unit 17b of the map calculation unit 17. The signal acquisition processing unit 12c acquires received signals from the receiving antenna 10c and outputs the received signals to the Fourier transform unit 17c of the map calculation unit 17. The signal acquisition processing unit 12d acquires received signals from the receiving antenna 10d and outputs the received signals 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 of the first hit to the (H-1)th hit among the data of the first hit to the Hth hit included in the received signal. The map calculation unit 17 also calculates a range-Doppler map based on the data of the second hit to the Hth hit. FIG. 13 is an explanatory diagram showing a range-Doppler map based on the data of the first hit to the (H-1)th hit and a range-Doppler map based on the data of the second hit to the Hth hit. The map calculation unit 13 outputs the range-Doppler map based on the data of the first hit to the (H-1)th hit and the range-Doppler map based on the data of the second hit to the Hth hit to the Doppler velocity calculation unit 18. The calculation process of the range-Doppler map by the map calculation unit 13 will be specifically described below.

[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 on the data from the first hit to the (H-1)th hit in the range direction, and then performs an FFT in the Doppler direction, thereby calculating 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 on the data from the second hit to the Hth hit in the range direction, and then performs an FFT in the Doppler direction, thereby calculating a range-Doppler map based on the data from the second hit to the Hth hit. The Fourier transform unit 17a outputs the range-Doppler map based on the data from the first hit to the (H-1)th hit and the range-Doppler map based on the data from the second hit to the Hth hit to the Doppler velocity calculation unit 18. The Fourier transform unit 17a also performs an FFT on the data from the first hit to the Hth hit in the range direction, and then performs an FFT in the Doppler direction, thereby calculating a range-Doppler map. The Fourier transform unit 17a outputs the range-Doppler map to the integration processing unit 17e.

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

[0075] The integration processing unit 17e acquires the range-Doppler maps from each of the Fourier transform units 17a, 17b, 17c, and 17d. The integration processing 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 range-Doppler maps after integration to the target detection unit 14.

[0076] The target detection unit 14 acquires 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 range bin in which the target exists.

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

[0078] The Doppler velocity calculation unit 18 extracts a first bin, in which the target exists, from a range-Doppler map based on data from the first hit to the (H-1)th hit, based on the target detection result by the target detection unit 14. The Doppler velocity calculation unit 18 also extracts a second bin, in which the target exists, from a range-Doppler map based on data from the second hit to the Hth hit, based on the target detection result by the target detection unit 14. The Doppler velocity calculation unit 18 calculates the Doppler aliasing number for the target based on the product of the elements of the first bin and the second bin, as shown in FIG. 14 . FIG. 14 is an explanatory diagram showing the process of calculating the product of the elements of the first bin and the second bin.

[0079] In FIG. 14, for convenience of explanation, the bin on the left side of the first bin is s １ , the central bin in the first bin is s ２ , the bin on the right side of the figure in the first bin is s３ In addition, the left bin in the second bin is s １ *exp(jφ １ ), the central bin in the figure in the second bin is s ２ *exp(jφ ２ ), the bin on the right side of the figure in the second bin is s ３ ×exp(jφ ３ ) φ １ is the amount of phase rotation that the signal transmitted from the first transmission channel changes for each PRI, and is represented by φ ｏｆｆｓｅｔ，１ Equivalent to φ ２ is the amount of phase rotation that the signal transmitted from the second transmission channel changes for each PRI, and is represented by φ ｏｆｆｓｅｔ，２ Equivalent to φ ３ is the amount of phase rotation that the signal transmitted from the third transmission channel changes for each PRI, and is represented by φ ｏｆｆｓｅｔ，３ is equivalent to

[0080] In this case, the Doppler velocity calculation unit 18 calculates the Doppler velocity by calculating the velocity of the bin s on the left side of the figure as shown in the following equation (5). １ and the bin s on the left side of the figure １ * exp(jφ) and element product x １ Calculate x １ =s １ *(s １ *exp(jφ １ ))^* = |s １ | ２ *exp(-jφ １ ) (5) The Doppler velocity calculation unit 18 calculates the Doppler velocity of the central bin s in the figure as shown in the following equation (6). ２ and the central bin s ２ * exp(jφ) and element product x ２ Calculate x ２ =s ２ *(s ２ *exp(jφ ２ ))^* = |s ２ | ２ *exp(-jφ ２ ) (6) The Doppler velocity calculation unit 18 calculates the Doppler velocity for the bin s on the right side of the figure as shown in the following equation (7). ３and the bin s on the right side of the figure ３ * exp(jφ) and element product x ３ Calculate x ３ =s ３ *(s １ *exp(jφ ３ ))^* = |s ３ | ２ *exp(-jφ ３ ) (7)

[0081] Here, the phase rotation amount φ １ and the phase rotation amount φ ２ and the phase rotation amount φ ３ and are changed at equal intervals. For example, the phase of transmission channel ch1 is rotated by 0 degrees for each hit, the phase of transmission channel ch2 is rotated by 90 degrees for each hit, and the phase of transmission channel ch3 is rotated by 180 degrees for each hit. In this case, the element product x １ , x ２ , x ３ If the Doppler aliasing number DC is 0, then the element product x １ and the element product x ２ The phase difference (1-2) is the element product x ２ and the element product x ３ The phase difference (2-3) is the same as the element product x ３ and the element product x １ If the Doppler aliasing number DC is 1, the phase difference (2-3) will be the same as the phase difference (3-1), but will be a different value from the phase difference (1-2). If the Doppler aliasing number DC is 2, the phase difference (1-2) will be the same as the phase difference (3-1), but will be a different value from the phase difference (2-3).

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

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

[0084] In the second embodiment described above, the radar signal processing device 11 is configured to include a received signal acquisition unit 12 that acquires received signals related to the reflected waves of the signals reflected by a target after transmitting a signal having multiple transmission channels in which data hits are modulated differently from one another. 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 first to (H-1)th hits and a range-Doppler map based on the data of the second to Hth hits, among the data of the first to Hth hits (H is an integer equal to or greater than 2) included in the received signal acquired by the received signal acquisition unit 12, and a Doppler velocity calculation unit 18 that calculates the Doppler velocity of the target based on the range-Doppler maps calculated by the map calculation unit 17. Therefore, the radar signal processing device 11 can prevent a decrease in the range of Doppler velocities that can be determined without ambiguity, even if the number of transmission channels increases.

[0085] Embodiment 3. In the first embodiment, a radar signal processing device 11 is described that is applied to a transmitter that transmits a signal having multiple transmission channels using the DDMA system. In the third embodiment, a radar signal processing device 11 is described that is applied to a transmitter that transmits a signal having multiple transmission channels using the CDMA (Code Division Multiple Access) system.

[0086] Fig. 15 is a configuration diagram showing a transmission device applied to a radar signal processing device 11 according to embodiment 3. In Fig. 15, the same reference numerals as in Fig. 1 indicate the same or corresponding parts, and detailed description thereof will be omitted. Fig. 16 is a configuration diagram showing a radar device including the radar signal processing device 11 according to embodiment 3. In Fig. 16, the same reference numerals as in Fig. 2 indicate the same or corresponding parts, and detailed description thereof will be omitted. Fig. 17 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to embodiment 3. In Fig. 17, the same reference numerals as in Fig. 3 indicate the same or corresponding parts, and detailed description thereof will be omitted.

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

[0088] The transmitting device shown in Fig. 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 Fig. 15, the transmission signal that signal source 1 outputs to modulator 5a is the transmission signal of transmission channel ch1, the transmission signal that signal source 1 outputs to modulator 5b is the transmission signal of transmission channel ch2, and the transmission signal that signal source 1 outputs to modulator 5c is the transmission signal of transmission channel ch3.

[0089] The modulator 5a acquires the transmission signal of transmission channel ch1 from the signal source 1. The modulator 5a performs different modulations on multiple pieces of data for the hit direction included in the transmission signal of transmission channel ch1, and outputs the modulated transmission signal of transmission channel ch1 to the transmission antenna 3a. The modulator 5b acquires the transmission signal of transmission channel ch2 from the signal source 1. The modulator 5b performs different modulations on multiple pieces of data for the hit direction included in the transmission signal of transmission channel ch2, and outputs the modulated transmission signal of transmission channel ch2 to the transmission antenna 3b. When performing different modulations on multiple pieces of data, the modulator 5b adds a phase offset to the data from the middle of the hit. Therefore, the transmission channel ch2 is a transmission channel with an offset. The modulator 5c acquires the transmission signal of transmission channel ch3 from the signal source 1. The modulator 5c performs different modulations on multiple pieces of data for the hit direction included in the transmission signal of transmission channel ch3, and outputs the modulated transmission signal of transmission channel ch3 to the 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 realized by, for example, a map calculation circuit 29 shown in FIG. 17 . The map calculation unit 19 includes Fourier transform units 19a, 19b, 19c, and 19d and an integration processing unit 19e. The map calculation unit 19 acquires a received signal from the received signal acquisition unit 12. From the received signal, the map calculation unit 19 calculates a range-Doppler map before a phase offset is added to data in an offset-attached transmission channel as a pre-adjustment range-Doppler map. The map calculation unit 19 calculates a range-Doppler map after a phase offset is added to data as a post-adjustment range-Doppler map. The map calculation unit 19 outputs the pre-adjustment range-Doppler map and the post-adjustment 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 performs an FFT in the range direction on data to which no phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a pre-addition range-Doppler map. The Fourier transform unit 19a performs an FFT in the range direction on data to which a phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a post-addition range-Doppler map. 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 performs an FFT in the range direction on data in the hit direction included in the received signals of transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 19a outputs the range-Doppler maps of the transmission channels ch1 and ch3 to the integration processing unit 19e.

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

[0093] The integration processing unit 19e acquires range-Doppler maps of the 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 range-Doppler maps after integration to the target detection unit 14.

[0094] 16, it is assumed that each of the components of the radar signal processing device 11, namely 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, is realized by dedicated hardware as shown in Fig. 17. That is, it is assumed that the radar signal processing device 11 is realized by a received signal acquisition circuit 22, a map calculation circuit 29, a target detection circuit 24, a Doppler velocity calculation circuit 25, and an angle measurement circuit 26. Each of 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 corresponds to, 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 realized by dedicated hardware, and the radar signal processing device 11 may be realized by software, firmware, or a combination of software and firmware. When the radar signal processing device 11 is realized by software, firmware, or the like, a program for causing a computer to execute the respective processing procedures of 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 is stored in a memory 31 shown in Fig. 4. Then, a processor 32 shown in Fig. 4 executes the program stored in the memory 31.

[0096] 17 shows an example in which each of the components of the radar signal processing device 11 is realized by dedicated hardware, while Fig. 4 shows an example in which the radar signal processing device 11 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar signal processing device 11 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

[0097] Next, the operation of the transmitting device shown in Fig. 15 and the radar signal processing device 11 shown in Fig. 16 will be described. The transmitting device shown in Fig. 15 transmits a signal having three transmission channels ch1, ch2, and ch3 using the CDMA method as shown in Fig. 18 so that the three transmission channels ch1, ch2, and ch3 can be separated in the radar signal processing device 11. Fig. 18 is an explanatory diagram showing an example of the phases of multiple data contained in a transmission channel using conventional CDMA and the phases of multiple data contained in a transmission channel using CDMA used by the transmitting device shown in Fig. 15. CDMA is a method of applying different modulations to multiple hit-direction data contained in a transmission signal.

[0098] In conventional CDMA, when different modulations are applied to multiple data in the hit direction, no phase offset is added to each data. The phases of multiple data included in transmission channels ch1, ch2, and ch3 in conventional DDMA are, for example, as shown in Figure 18: ch1 → φ １ = [0° 0° 0° 0° ...] ch2 → φ ２ = [0° 180° 0° 180° ...] ch3 → φ ３ = [0° 0° 180° 180°...]

[0099] In the CDMA used by the transmitter shown in Fig. 15, when different modulations are applied to multiple data in the hit direction, a phase offset is added to the data from the middle of the hit. The phases of multiple data included in the transmission channels ch1, ch2, and ch3 by the CDMA used by the transmitter shown in Fig. 15 are, for example, as shown in Fig. 18: ch1 → φ １ = [0° 0° 0° 0° ...], [0° 0° 0° 0° ...] ch2 → φ ２ = [0° 180° 0° 180° ...], [180° 0° 180° 0° ...] ch3 → φ ３ = [0° 0° 180° 180°...], [0° 0° 180° 180°...]

[0100] Signal source 1 oscillates 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 performs different modulations on multiple hit direction data included in the transmission signal for transmission channel ch1, and outputs the modulated transmission signal for transmission channel ch1 to transmitting antenna 3a.

[0101] The modulator 5b performs different modulations on the multiple data in the hit direction included in the transmission signal of transmission channel ch2, and outputs the modulated transmission signal of transmission channel ch2 to the transmission antenna 3b. When performing different modulations on the multiple data, the modulator 5b adds a phase offset to the data from the middle of the hit, as shown in Figure 18. Therefore, transmission channel ch2 is a transmission channel with an offset. The modulator 5c performs different modulations on the multiple data in the hit direction included in the transmission signal of transmission channel ch3, and outputs the modulated transmission signal of transmission channel ch3 to the transmission antenna 3c.

[0102] The transmitting antenna 3a radiates into space the modulated transmission signal of transmission channel ch1 output from the modulator 5a. The transmitting antenna 3b radiates into space the modulated transmission signal of transmission channel ch2 output from the modulator 5b. The transmitting antenna 3c radiates into space the modulated transmission signal of transmission channel ch3 output from the modulator 5c. As a result, signals having three transmission channels ch1, ch2, and ch3 are transmitted from the transmitting device shown in FIG.

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

[0104] The received signal acquisition unit 12 acquires received signals related to reflected waves of signals reflected by targets. That is, the signal acquisition processing unit 12a acquires received signals from the receiving antenna 10a and outputs the received signals to a Fourier transform unit 19a of the map calculation unit 19. The signal acquisition processing unit 12b acquires received signals from the receiving antenna 10b and outputs the received signals to a Fourier transform unit 19b of the map calculation unit 19. The signal acquisition processing unit 12c acquires received signals from the receiving antenna 10c and outputs the received signals to a Fourier transform unit 19c of the map calculation unit 19. The signal acquisition processing unit 12d acquires received signals from the receiving antenna 10d and outputs the received signals to a 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. From the received signal, the map calculation unit 19 calculates, as a pre-addition range-Doppler map, a range-Doppler map before a phase offset is added to data in an offset-attached transmission channel. The map calculation unit 19 calculates, as a post-addition range-Doppler map, a range-Doppler map after a phase offset is added to data. FIG. 19 is an explanatory diagram showing the pre-addition range-Doppler map and the post-addition 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. The calculation process of the range-Doppler map by the map calculation unit 19 will be described in detail below.

[0106] The Fourier transform unit 19a acquires the received signal from the signal acquisition processing unit 12a. The Fourier transform unit 19a performs an FFT in the range direction on data to which no phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a pre-addition range-Doppler map. The Fourier transform unit 19a performs an FFT in the range direction on data to which a phase offset has been added, among the multiple pieces of data in the hit direction included in the received signal of transmission channel ch2, and then performs an FFT in the Doppler direction to calculate a post-addition range-Doppler map. The Fourier transform unit 19a outputs each of 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 also performs an FFT in the range direction on multiple pieces of data in the hit direction included in the received signals of transmission channels ch1 and ch3, and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 19a outputs the range-Doppler maps of the transmission channels ch1 and ch3 to the integration processing unit 13e.

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

[0108] The integration processing unit 19e acquires range-Doppler maps of the 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 range-Doppler maps after integration 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 Fig. 2, and therefore detailed explanations will be omitted. Fig. 20 is an explanatory diagram showing the calculation process of the element product of the first bin and the second bin.

[0110] As described above, when a transmitter transmits a signal having multiple transmission channels using the CDMA system, the radar signal processing device 11 can suppress a decrease in the range of Doppler velocities that can be determined without ambiguity, even if the number of transmission channels increases.

[0111] Embodiment 4. In embodiment 2, a radar signal processing device 11 is described that is applied to a transmitter that transmits a signal having multiple transmission channels using the DDMA system. In embodiment 4, a radar signal processing device 11 is described that is applied to a transmitter that transmits a signal having multiple transmission channels using the CDMA system.

[0112] FIG. 21 is a configuration diagram showing a transmission device applied to a radar signal processing device 11 according to embodiment 4. In FIG. 21, the same reference numerals as in FIG. 9 indicate the same or corresponding parts, and detailed description thereof will be omitted. FIG. 22 is a configuration diagram showing a radar device including the radar signal processing device 11 according to embodiment 4. In FIG. 22, the same reference numerals as in FIG. 10 indicate the same or corresponding parts, and detailed description thereof will be omitted. FIG. 23 is a hardware configuration diagram showing the hardware of the radar signal processing device 11 according to embodiment 4. In FIG. 23, the same reference numerals as in FIG. 11 indicate the same or corresponding parts, and detailed description thereof will be omitted.

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

[0114] The transmitting device shown in Fig. 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 Fig. 21, the transmission signal that signal source 1 outputs to modulator 6a is the transmission signal of transmission channel ch1, the transmission signal that signal source 1 outputs to modulator 6b is the transmission signal of transmission channel ch2, and the transmission signal that signal source 1 outputs to modulator 6c is the transmission signal of transmission channel ch3.

[0115] The modulator 6a acquires a transmission signal of transmission channel ch1 from the signal source 1. The modulator 6a performs different modulations on multiple pieces of hit direction data included in the transmission signal of transmission channel ch1, and outputs the modulated transmission signal of transmission channel ch1 to the transmission antenna 3a. The modulator 6b acquires a transmission signal of transmission channel ch2 from the signal source 1. The modulator 6b performs different modulations on multiple pieces of hit direction data included in the transmission signal of transmission channel ch2, and outputs the modulated transmission signal of transmission channel ch2 to the transmission antenna 3b. The modulator 6c acquires a transmission signal of transmission channel ch3 from the signal source 1. The modulator 6c performs different modulations on multiple pieces of hit direction data included in the transmission signal of transmission channel ch3, and outputs the modulated transmission signal of transmission channel ch3 to the transmission 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. After a signal having a plurality of transmission channels ch1, ch2, and ch3, in which data hits are modulated differently from one another, is transmitted, the received signal acquisition unit 12 acquires a received signal related to a reflected wave of the signal reflected by a target.

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

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

[0120] The integration processing unit 20e acquires the 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 range-Doppler maps after integration to the target detection unit 14.

[0121] 22 assumes that the received signal acquisition unit 12, map calculation unit 20, target detection unit 14, Doppler velocity calculation unit 18, and angle measurement unit 16, which are components of the radar signal processing device 11, are each realized by dedicated hardware such as that shown in Fig. 23. That is, it is assumed that the radar signal processing device 11 is realized by a received signal acquisition circuit 22, map calculation circuit 30, target detection circuit 24, Doppler velocity calculation circuit 28, and angle measurement circuit 26. Each of the received signal acquisition circuit 22, map calculation circuit 30, target detection circuit 24, Doppler velocity calculation circuit 28, and angle measurement circuit 26 corresponds to, 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 realized by dedicated hardware, and the radar signal processing device 11 may be realized by software, firmware, or a combination of software and firmware. When the radar signal processing device 11 is realized by software, firmware, or the like, a program for causing a computer to execute the respective processing procedures of 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 is stored in a memory 31 shown in Fig. 4. Then, a processor 32 shown in Fig. 4 executes the program stored in the memory 31.

[0123] 23 shows an example in which each of the components of the radar signal processing device 11 is realized by dedicated hardware, while Fig. 4 shows an example in which the radar signal processing device 11 is realized by software, firmware, etc. However, this is merely an example, and some of the components in the radar signal processing device 11 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, etc.

[0124] Next, the operation of the transmitting device shown in Fig. 21 and the radar signal processing device 11 shown in Fig. 22 will be described. The transmitting device shown in Fig. 21 transmits a signal having three transmission channels ch1, ch2, and ch3 using the CDMA system as shown in Fig. 24 so that the three transmission channels ch1, ch2, and ch3 can be separated in the radar signal processing device 11. Fig. 24 is an explanatory diagram showing an example of the phases of multiple data included in the CDMA transmission channels used by the transmitting device shown in Fig. 21.

[0125] In the CDMA used by the transmitter shown in Fig. 21, when different modulations are applied to multiple data in the hit direction, no phase offset is added to each data. The phases of multiple data included in the transmission channels ch1, ch2, and ch3 by the CDMA used by the transmitter shown in Fig. 21 are, for example, as shown in Fig. 24, as follows: ch1 → φ １ = [0° 0° 0° 0° ...] ch2 → φ ２ = [0° 180° 0° 180° ...] ch3 → φ ３ = [0° 0° 180° 180°...]

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

[0127] The modulator 6a performs different modulations on the multiple hit direction data included in the transmission signal of transmission channel ch1, and outputs the modulated transmission signal of transmission channel ch1 to the transmission antenna 3a. The modulator 6b performs different modulations on the multiple hit direction data included in the transmission signal of transmission channel ch2, and outputs the modulated transmission signal of transmission channel ch2 to the transmission antenna 3b. The modulator 6c performs different modulations on the multiple hit direction data included in the transmission signal of transmission channel ch3, and outputs the modulated transmission signal of transmission channel ch3 to the transmission antenna 3c.

[0128] The transmitting antenna 3a radiates into space the modulated transmission signal of transmission channel ch1 output from the modulator 6a. The transmitting antenna 3b radiates into space the modulated transmission signal of transmission channel ch2 output from the modulator 6b. The transmitting antenna 3c radiates into space the modulated transmission signal of transmission channel ch3 output from the modulator 6c. As a result, signals having three transmission channels ch1, ch2, and ch3 are transmitted from the transmitting device shown in FIG.

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

[0130] The received signal acquisition unit 12 acquires received signals related to reflected waves of signals reflected by targets. That is, the signal acquisition processing unit 12a acquires received signals from the receiving antenna 10a and outputs the received signals to the Fourier transform unit 20a of the map calculation unit 20. The signal acquisition processing unit 12b acquires received signals from the receiving antenna 10b and outputs the received signals to the Fourier transform unit 20b of the map calculation unit 20. The signal acquisition processing unit 12c acquires received signals from the receiving antenna 10c and outputs the received signals to the Fourier transform unit 20c of the map calculation unit 20. The signal acquisition processing unit 12d acquires received signals from the receiving antenna 10d and outputs the received signals 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 of the first hit to the (H-1)th hit among the data of 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 second hit to the Hth hit. FIG. 25 is an explanatory diagram showing a range-Doppler map based on the data of the first hit to the (H-1)th hit and a range-Doppler map based on the data of the second hit to the Hth hit. The map calculation unit 20 outputs the range-Doppler map based on the data of the first hit to the (H-1)th hit and the range-Doppler map based on the data of the second hit to the Hth hit to the Doppler velocity calculation unit 18. The calculation process of the range-Doppler map by the map calculation unit 20 will be described in detail below.

[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 on the data from the first hit to the (H-1)th hit in the range direction, 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 on the data from the second hit to the Hth hit in the range direction, 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 the range-Doppler map based on the data from the first hit to the (H-1)th hit and the range-Doppler map based on the data from the second hit to the Hth hit to the Doppler velocity calculation unit 18. The Fourier transform unit 20a performs an FFT on the data from the first hit to the Hth hit in the range direction and then performs an FFT in the Doppler direction to calculate a range-Doppler map. The Fourier transform unit 20a outputs the range-Doppler map to the integration processing unit 20e.

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

[0134] The integration processing unit 20e acquires the 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 range-Doppler maps after integration 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 Fig. 9, and therefore detailed explanations will be omitted. Fig. 26 is an explanatory diagram showing the calculation process of the element product of the first bin and the second bin.

[0136] As described above, when a transmitter transmits a signal having multiple transmission channels using the CDMA system, the radar signal processing device 11 can suppress a decrease in the range of Doppler velocities that can be determined without ambiguity, even if the number of transmission channels increases.

[0137] In addition, the present disclosure allows for free combination of the respective embodiments, modification of any of the components of the respective embodiments, or omission of any of the components of the respective embodiments.

[0138] The present disclosure can suppress a decrease in the range of Doppler velocities that can be determined without ambiguity even when the number of transmission channels increases, and can be used in radar signal processing devices and radar signal processing methods.

[0139] 1 signal source, 2 modulation unit, 2a, 2b, 2c modulator, 3a, 3b, 3c transmitting antenna, 4 modulation unit, 4a, 4b, 4c modulator, 5 modulation unit, 5a, 5b, 5c modulator, 6 modulation unit, 6a, 6b, 6c modulator, 10a, 10b, 10c, 10d receiving antenna, 11 radar signal processing device, 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 radar signal processing device comprising: a received signal acquisition unit that acquires received signals relating to reflected waves of the signals reflected by a target after a signal is transmitted, the received signals having a plurality of transmission channels in which data is modulated differently between hits, the plurality of transmission channels including an offset transmission channel in which a phase offset is added to the data midway through the hit; a map calculation unit that calculates, from the received signals acquired by the received signal acquisition unit, 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 a Doppler velocity calculation unit that calculates the Doppler velocity of the target based on the range-Doppler map calculated by the map calculation unit.

2. The radar signal processing device according to claim 1, characterized in that the Doppler velocity calculation unit calculates the number of Doppler folds 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 folds.

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

4. A radar signal processing device comprising: a received signal acquisition unit that acquires received signals relating to the reflected waves of the signals reflected by a target after a signal having a plurality of transmission channels in which data is modulated differently between hits is transmitted; a map calculation unit that calculates a range-Doppler map based on data from the first hit to the (H-1)th hit (H is an integer of 2 or more) hits included in the received signals acquired by the received signal acquisition unit, and a range-Doppler map based on data from the second hit to the Hth hit; and a Doppler velocity calculation unit that calculates the Doppler velocity of the target based on the range-Doppler map calculated by the map calculation unit.

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

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

7. A radar signal processing method, in which a received signal acquisition unit has a plurality of transmission channels in which data is modulated differently between hits, and the plurality of transmission channels include an offset transmission channel in which a phase offset is added to data midway through a hit, and then acquires a received signal related to a reflected wave of the signal reflected by a target, a map calculation unit calculates, from the received signal acquired by the received signal acquisition unit, 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 a Doppler velocity calculation unit calculates the Doppler velocity of the target based on the range-Doppler map calculated by the map calculation unit.

8. A radar signal processing method, in which a received signal acquisition unit acquires a received signal relating to a wave reflected from a target after transmitting a signal having a plurality of transmission channels in which data is modulated differently between hits, and a map calculation unit calculates a range-Doppler map based on data from the first hit to the (H-1)th hit (H is an integer of 2 or more) hit included in the received signal acquired by the received signal acquisition unit, and a range-Doppler map based on data from the second hit to the Hth hit, and a Doppler velocity calculation unit calculates the Doppler velocity of the target based on the range-Doppler map calculated by the map calculation unit.