Target Detection Device and Target Detection Method

Abstract

A target detection device (2) is configured so as to comprise: a signal division unit (11) that acquires a received signal indicating a reflected wave of a pulse wave every time a pulse wave is emitted into space, and divides the acquired plurality of received signals; a plurality of signal compression units (12-1) to (12-N) that compress the received signals after each division by the signal division unit (11); and a plurality of signal restoration units (13-1) to (13-N) that each restore the delay time of the received signal after compression by any one signal compression unit (12-n) (where n = 1, ..., N) among the plurality of signal compression units (12-1) to (12-N) and the complex amplitude of the received signal after compression, and output a restored signal indicating the delay time and the complex amplitude. The target detection device (2) also comprises: a correlation processing unit (14) that extracts signal components that are correlated with each other from among the restored signals outputted from the plurality of signal restoration units (13-1) to (13-N); and a target detection unit (15) that detects a target on the basis of the signal components extracted by the correlation processing unit (14).

Description

Technical Field

[0001] The present disclosure relates to a target detection device and a target detection method.

Background Art

[0002] There is a target detection device that acquires a reception signal indicating a reflected wave, which is a pulse wave reflected by a target, every time the pulse wave is radiated into space, and detects the target based on the reception signal. As such a target detection device, for example, Non-Patent Document 1 discloses a target detection device including a signal compression unit and a signal processing unit. The signal compression unit compresses the reception signal in order to reduce the processing load of target detection in the signal processing unit. The signal processing unit detects the target based on the reception signal compressed by the signal compression unit.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the target detection device disclosed in Non-Patent Document 1, since the signal processing unit restores the target signal based on the reception signal compressed by the signal compression unit, loss occurs in the process of restoring the target signal. As a result, there is a problem that the target detection performance by the signal processing unit may deteriorate.

[0005] The present disclosure has been made to solve the above-described problems, and an object thereof is to obtain a target detection device that can prevent deterioration of target detection performance even when compression processing of a received signal is performed.

Means for Solving the Problems

[0006] The target detection device according to the present disclosure acquires a received signal indicating a reflected wave of a pulse wave every time the pulse wave is radiated into space, a signal splitting unit that splits the acquired plurality of received signals, and a plurality of signal compression units that compress each of the split received signals by the signal splitting unit. Among the plurality of signal compression units, a plurality of signal restoration units that restore the delay time and the complex amplitude of the compressed received signal by any one of the signal compression units and output a restored signal indicating the delay time and the complex amplitude are provided. Further, the target detection device includes a correlation processing unit that extracts signal components that are correlated with each other from the restored signals output from the plurality of signal restoration units, and a target detection unit that detects a target based on the signal components extracted by the correlation processing unit.

Effects of the Invention

[0007] According to the present disclosure, even when compression processing of a received signal is performed, deterioration of target detection performance can be prevented.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, in order to explain the present disclosure in more detail, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings.

[0010] Embodiment 1. FIG. 1 is a block diagram showing the target detection device 2 according to Embodiment 1. Figure 2 is a hardware configuration diagram showing the hardware of the target detection device 2 according to Embodiment 1. In FIG. 1, every time a pulse wave is radiated into space from a transmitter (not shown), the receiver 1 receives a reflected wave, which is a pulse wave reflected by a target or the like, and outputs a reception signal indicating the reflected wave to the target detection device 2. The target detection device 2 acquires a reception signal indicating a reflected wave from the receiver 1, detects a target based on the reception signal, and outputs the detection result of the target to the display device 3. The display device 3 causes a display (not shown) to display the detection result of the target output from the target detection device 2.

[0011] The target detection device 2 includes a signal splitting unit 11, signal compression units 12-1 to 12-N, signal restoration units 13-1 to 13-N, a correlation processing unit 14, and a target detection unit 15. N is an integer of 2 or more. The signal splitting unit 11 is realized by, for example, a signal splitting circuit 21 shown in FIG. 2. Every time a pulse wave is radiated into space from a transmitter (not shown), the signal splitting unit 11 acquires a reception signal indicating a reflected wave from the receiver 1. The signal splitting unit 11 splits the acquired plurality of reception signals, and outputs each of the split reception signals to the signal compression unit 12-n (n = 1, ···, N).

[0012] The signal compression unit 12-n (n = 1, ···, N) is realized by, for example, a signal compression circuit 22 shown in FIG. 2. The signal compression unit 12-n acquires any one of the plurality of split reception signals by the signal splitting unit 11. The signal compression unit 12-n compresses the split reception signal, and outputs the compressed reception signal to the signal restoration unit 13-n.

[0013] The signal restoration unit 13-n (n = 1, ···, N) is realized by, for example, a signal restoration circuit 23 shown in FIG. 2. The signal restoration unit 13-n acquires the compressed reception signal from any one of the plurality of signal compression units 12-1 to 12-N, i.e., the signal compression unit 12-n. The signal restoration unit 13-n restores the delay time of the compressed received signal and the complex amplitude of the compressed received signal. The signal restoration unit 13-n outputs a restored signal indicating the delay time and the complex amplitude to the correlation processing unit 14.

[0014] The correlation processing unit 14 is realized by, for example, the correlation processing circuit 24 shown in FIG. 2. The correlation processing unit 14 acquires restored signals from each of the signal restoration units 13-1 to 13-N. The correlation processing unit 14 extracts signal components that are correlated with each other from among the N restored signals. The correlation processing unit 14 outputs the signal components that are correlated with each other to the target detection unit 15.

[0015] The target detection unit 15 is realized by, for example, the target detection circuit 25 shown in FIG. 2. The target detection unit 15 acquires the signal components that are correlated with each other from the correlation processing unit 14. The target detection unit 15 detects a target based on the signal components that are correlated with each other. The target detection unit 15 outputs the detection result of the target to the display device 3.

[0016] In FIG. 1, it is assumed that each of the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 14, and the target detection unit 15, which are components of the target detection device 2, is realized by dedicated hardware as shown in FIG. 2. That is, it is assumed that the target detection device 2 is realized by the signal splitting circuit 21, the signal compression circuit 22, the signal restoration circuit 23, the correlation processing circuit 24, and the target detection circuit 25. Each of the signal splitting circuit 21, the signal compression circuit 22, the signal restoration circuit 23, the correlation processing circuit 24, and the target detection circuit 25 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.

[0017] The components of the target detection device 2 are not limited to those realized by dedicated hardware, and the target detection device 2 may be realized by software, firmware, or a combination of software and firmware. Software or firmware is stored in a computer's memory as a program. A computer means the hardware that executes the program, and 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) corresponds thereto.

[0018] FIG. 3 is a hardware configuration diagram of a computer when the target detection device 2 is realized by software, firmware, or the like. When the target detection device 2 is realized by software, firmware, or the like, a program for causing a computer to execute the respective processing procedures in the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 14, and the target detection unit 15 is stored in the memory 31. Then, the processor 32 of the computer executes the program stored in the memory 31.

[0019] Also, FIG. 2 shows an example in which each component of the target detection device 2 is realized by dedicated hardware, and FIG. 3 shows an example in which the target detection device 2 is realized by software, firmware, or the like. However, this is merely an example, and some components in the target detection device 2 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, or the like.

[0020] Next, the operation of the target detection device 2 shown in FIG. 1 will be described. FIG. 4 is a flowchart showing a target detection method that is a processing procedure of the target detection device 2. A transmitter (not shown) repeatedly radiates a pulse wave into space.

[0021] Each time the pulse wave is radiated into space from the transmitter, the receiver 1 receives a reflected wave that is a pulse wave reflected by a target or the like. FIG. 5 is an explanatory diagram showing an example of the reflected wave received by the receiver 1. The receiver 1 is provided with an analog-to-digital converter (hereinafter referred to as an "A / D converter"). The A / D converter converts the received signal of the reflected wave, which is an analog signal, into a digital signal, and outputs the digital received signal to the target detection device 2. In order to prevent the amount of signal information contained in the received signal from being reduced due to the A / D conversion of the A / D converter, the sampling frequency of the A / D converter needs to be at least twice the signal bandwidth. Sampling of an A / D converter with a sampling frequency of at least twice the signal bandwidth is called Nyquist sampling. Therefore, the A / D converter provided in the receiver 1 converts the received signal of the reflected wave into a digital signal by Nyquist sampling.

[0022] In the target detection device 2 shown in FIG. 1, the receiver 1 is provided with an A / D converter. However, this is merely an example, and the A / D converter may be provided at the input stage of the signal splitting unit 11, may be provided at the input stage of the signal compression unit 12-n (n = 1, ···, N), or may be provided at the input stage of the signal restoration unit 13-n.

[0023] Each time a pulse wave is radiated into space from the transmitter, the signal splitting unit 11 of the target detection device 2 acquires a digital reception signal from the receiver 1. The reception signal is a sparse signal. That is, most of the target components included in the reception signal are zero values, and sparsely non-zero target components are included in the reception signal. On the other hand, the noise components included in the reception signal are evenly present in the reception signal. As shown in FIG. 6A, the signal splitting unit 11 time-division multiplexes the acquired plurality of reception signals (step ST1 in FIG. 4). FIG. 6A is an explanatory diagram showing a method (method 1) for splitting a reception signal by the signal splitting unit 11. In the example of FIG. 6A, the reception signal is time-division multiplexed into N blocks #1 to #N. In the example of FIG. 6A, all of the periods of the N blocks #1 to #N are the same length. Specifically, each of the periods of the N blocks #1 to #N is four pulse repetition times. However, this is only an example, and the periods of the N blocks #1 to #N may be different from each other. The signal splitting unit 11 outputs each of the N blocks #1 to #N, which are a plurality of reception signals after time-division multiplexing, to the signal compression unit 12-n (n = 1, ···, N).

[0024] If there is no significant change in the positional relationship between the target detection device 2 and the target from the start of block #1 to the end of block #N, each of the amplitude value of the target component in the signal and the amount of phase change of the target component in the signal hardly changes from the start of block #1 to the end of block #N. On the other hand, each of the amplitude value of the noise component and the amount of phase change of the noise component randomly changes from the start of block #1 to the end of block #N. The noise component is, for example, a white noise component or a colored noise component. Therefore, the correlation between the target components in the signal included in each of the N blocks #1 to #N is high. On the other hand, the correlation between the noise components included in each of the N blocks #1 to #N is low.

[0025] In the target detection device 2 shown in FIG. 1, as shown in FIG. 6A, the signal splitting unit 11 splits the acquired plurality of received signals into N blocks #1 to #N. However, this is merely an example, and the signal splitting unit 11 may split the received signals into N blocks #1 to #N as shown in FIG. 6B. FIG. 6B is an explanatory diagram showing a method (Method 2) for splitting the received signals by the signal splitting unit 11. In the example of FIG. 6B, block #1 includes the received signal related to the (N×(i−1)+1)-th pulse wave. Here, i = 1, ···, N. Also, block #2 includes the received signal related to the (N×(i−1)+2)-th pulse wave, and block #N includes the received signal related to the (N×(i−1)+N)-th pulse wave.

[0026] The signal compression unit 12-n (n = 1, ···, N) acquires block #n from the signal splitting unit 11 as the time-division received signal. The signal compression unit 12-n compresses block #n in order to reduce the processing load at a stage subsequent to the signal compression unit 12-n (step ST2 in FIG. 4). As a method for compressing block #n, for example, a method called compressive sampling or sub-Nyquist sampling is used. Compressive sampling etc. are compression processing methods that assume that the received signal is a sparse signal, and compressive sampling etc. are disclosed in, for example, Non-Patent Document 1. Since the compression processing of block #n itself is a known technique, detailed description thereof is omitted. The signal compression unit 12-n outputs the compressed block #n to the signal restoration unit 13-n.

[0027] The signal restoration unit 13-n (n = 1, ···, N) acquires the compressed block #n from the signal compression unit 12-n. The signal restoration unit 13-n restores the delay time of the compressed block #n and the complex amplitude of the compressed block #n (step ST3 in FIG. 4). The delay time is the time from when the pulse wave is emitted from the transmitter until the reflected wave related to block #n is received by the receiver. As a method for restoring the delay time and the complex amplitude, for example, a convex optimization method or a greedy method is used. Each of the convex optimization method and the greedy method is disclosed in, for example, Non-Patent Document 2. Since the process of restoring the delay time and the complex amplitude itself is a known technique, a detailed description thereof will be omitted. [Non-Patent Document 2] A. Massa et al., "Compressive Sensing in Electromagnetics - A Review", IEEE Antennas and Propagation Magazine, vol. 57, no. 1, Feb. 2015, p. 224-238. The signal restoration unit 13-n outputs a restored signal indicating the delay time and the complex amplitude to the correlation processing unit 14. The restored signal indicating the delay time and the complex amplitude restored by the signal restoration unit 13-n has the characteristic of being sparse. Also, a loss may occur in the complex amplitude value indicated by the restored signal.

[0028] The correlation processing unit 14 acquires the restored signals from each of the signal restoration units 13-1 to 13-N. The restored signals are sparse in time. In other words, the restored signals have the feature that there are a small number of times having non-zero values. The correlation processing unit 14 extracts signal components that are correlated with each other from among the N restored signals (step ST4 in FIG. 4). The signal components that are correlated with each other are likely to be target components with high correlation in the N blocks #1 to #N. Since the noise components have low correlation in the N blocks #1 to #N, the signal components that are correlated with each other are less likely to include noise components. Therefore, even if there is some loss in the complex amplitude value of the target component restored by the signal restoration unit 13-n, the noise components are suppressed more, so that the correlation processing unit 14 can improve the detection performance of the target component. The correlation processing unit 14 outputs the signal components that are correlated with each other to the target detection unit 15.

[0029] Hereinafter, the extraction process of the target component by the correlation processing unit 14 will be specifically described. Among the N restored signals, each of the signals with the same delay time is x 1 , x 2 , ···, x N Let it be so. The correlation processing unit 14 performs a discrete Fourier transform on the signals x 1 , x 2 , ···, x N as shown in the following formula (1).

[0030] TIFF0007686165000001.tif19166

[0031] The correlation processing unit 14 determines the signal Y 1 ~Y Q with the maximum amplitude value Y MAX among them. The correlation processing unit 14 compares the maximum value Y MAX with the threshold Th. The threshold Th may be stored in the internal memory of the correlation processing unit 14 or may be given from outside the target detection device 2. If the maximum value Y MAX is greater than or equal to the threshold Th, the correlation processing unit 14 determines that the signals x 1 , x 2 , ···, x N are signal components that are correlated with each other. If the maximum value Y MAX is less than the threshold Th, the correlation processing unit 14 determines that the signals x 1 , x 2 , ···, x N are not signal components that are correlated with each other.

[0032] Even if a method of inserting a matched filter before the A / D converter of the receiver 1 or a method of calculating a restored signal by the MUSIC (Multiple Signal Classification) method is used, the signal-to-noise ratio can be increased and the degradation of the target detection performance can be reduced. However, when these methods are used, the circuit scale and the processing load are extremely large compared to the case of using the correlation processing unit 14. The reasons are as follows. By inserting a matched filter before the A / D converter, the circuit scale of the target detection device 2 increases. The MUSIC method requires processing with a large amount of calculations such as eigenvalue decomposition, so the circuit scale of the target detection device 2 increases. In comparison with these, since the correlation processing unit 14 performs simple correlation processing only on a small number of signal components, the processing load is small.

[0033] The target detection unit 15 acquires signal components that are correlated with each other from the correlation processing unit 14. The target detection unit 15 detects a target based on the signal components that are correlated with each other (step ST5 in FIG. 4). Specifically, the target detection unit 15 performs amplitude detection of the signal components that are correlated with each other, and compares the detected amplitude with a determination threshold value set so as to obtain a predetermined false alarm probability. The determination threshold value may be stored in the internal memory of the target detection unit 15 or may be given from outside the target detection device 2. If the detected amplitude is equal to or greater than the determination threshold value, the target detection unit 15 detects the presence of a target, and if the detected amplitude is less than the determination threshold value, the target detection unit 15 does not detect the presence of a target. The target detection unit 15 outputs the target detection result to the display device 3 or a target information processing device (not shown).

[0034] The display device 3 causes a display (not shown) to display the target detection result output from the target detection device 2. The target information processing device (not shown) performs, for example, target tracking processing based on the target detection result output from the target detection device 2.

[0035] In the above Embodiment 1, every time a pulse wave is radiated into space, a reception signal indicating the reflected wave of the pulse wave is acquired, and a signal splitting unit 11 that splits the acquired plurality of reception signals, and a plurality of signal compression units 12-1 to 12-N that compress the reception signals after splitting by the signal splitting unit 11. Among the plurality of signal compression units 12-1 to 12-N, a plurality of signal restoration units 13-1 to 13-N that restore the delay time of the reception signal after compression and the complex amplitude of the reception signal after compression by any one signal compression unit 12-n (n = 1, ···, N), and output a restored signal indicating the delay time and the complex amplitude are provided, and the target detection device 2 is configured. Further, the target detection device 2 includes a correlation processing unit 14 that extracts signal components that are correlated with each other from the restored signals output from the plurality of signal restoration units 13-1 to 13-N, and a target detection unit 15 that detects a target based on the signal components extracted by the correlation processing unit 14. Therefore, the target detection device 2 can prevent deterioration of the target detection performance even when performing compression processing on the reception signal.

[0036] Embodiment 2. In Embodiment 2, the target detection device 2 including a signal processing unit 16-n that suppresses noise components included in the reception signal after compression by the signal compression unit 12-n (n = 1, ···, N) will be described.

[0037] FIG. 7 is a configuration diagram showing the target detection device 2 according to Embodiment 2. In FIG. 7, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts, and thus detailed description thereof is omitted. FIG. 8 is a hardware configuration diagram showing the hardware of the target detection device 2 according to Embodiment 2. In FIG. 8, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts, and thus detailed description thereof is omitted. The target detection device 2 shown in FIG. 7 includes a signal splitting unit 11, signal compression units 12-1 to 12-N, signal processing units 16-1 to 16-N, signal restoration units 13-1 to 13-N, a correlation processing unit 14, a signal integration unit 17, and a target detection unit 15.

[0038] The signal processing unit 16-n (n = 1, ···, N) is realized, for example, by the signal processing circuit 26 shown in FIG. 8. The signal processing unit 16-n acquires the compressed received signal from any one of the plurality of signal compression units 12-1 to 12-N, i.e., the signal compression unit 12-n. The signal processing unit 16-n suppresses the noise component included in the compressed received signal and outputs the received signal after the noise component suppression to the signal restoration unit 13-n.

[0039] The signal integration unit 17 is realized, for example, by the signal integration circuit 27 shown in FIG. 8. The signal integration unit 17 acquires the signal components that are correlated with each other from the correlation processing unit 14 and accumulates the acquired signal components. The signal integration unit 17 integrates the plurality of accumulated signal components. The signal integration unit 17 outputs the integrated signal components to the target detection unit 15.

[0040] The target detection device 2 shown in FIG. 7 includes both the signal processing units 16-1 to 16-N and the signal integration unit 17. However, this is merely an example, and the target detection device 2 may include either one of the signal processing units 16-1 to 16-N or the signal integration unit 17.

[0041] In FIG. 7, it is assumed that each of the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 14, the signal integration unit 17, and the target detection unit 15, which are components of the target detection device 2, is realized by dedicated hardware as shown in FIG. 8. That is, it is assumed that the target detection device 2 is realized by a signal splitting circuit 21, a signal compression circuit 22, a signal processing circuit 26, a signal restoration circuit 23, a correlation processing circuit 24, a signal integration circuit 27, and a target detection circuit 25. Each of the signal splitting circuit 21, the signal compression circuit 22, the signal processing circuit 26, the signal restoration circuit 23, the correlation processing circuit 24, the signal integration circuit 27, and the target detection circuit 25 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.

[0042] The components of the target detection device 2 are not limited to being realized by dedicated hardware, and the target detection device 2 may be realized by software, firmware, or a combination of software and firmware. When the target detection device 2 is realized by software or firmware or the like, a program for causing a computer to execute the respective processing procedures in the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 14, the signal integration unit 17, and the target detection unit 15 is stored in the memory 31 shown in FIG. 3. Then, the processor 32 shown in FIG. 3 executes the program stored in the memory 31.

[0043] Also, FIG. 8 shows an example in which each of the components of the target detection device 2 is realized by dedicated hardware, and FIG. 3 shows an example in which the target detection device 2 is realized by software or firmware or the like. However, this is only an example, and some of the components in the target detection device 2 may be realized by dedicated hardware, and the remaining components may be realized by software or firmware or the like.

[0044] Next, the operation of the target detection device 2 shown in FIG. 7 will be described. However, except for the signal processing units 16-1 to 16-N and the signal integration unit 17, it is the same as the target detection device 2 shown in FIG. 1. For this reason, here, mainly, the operations of the signal processing units 16-1 to 16-N and the signal integration unit 17 will be described.

[0045] The target detection device 2 shown in FIG. 7 is provided with signal processing units 16-1 to 16-N and a signal integration unit 17 in order to further suppress noise components and improve the target detection performance compared to the target detection device 2 shown in FIG. 1. The signal processing unit 16-n (n = 1, ···, N) acquires the compressed received signal from the signal compression unit 12-n. The signal processing unit 16-n performs a process of suppressing the noise components included in the compressed received signal. The signal processing unit 16-n outputs the received signal after noise component suppression to the signal restoration unit 13-n. Examples of the process for suppressing noise components by the signal processing unit 16-n include coherent integration processing, clutter suppression processing, beamforming processing, or sidelobe canceller processing.

[0046] The coherent integration processing is the process shown below. However, since the coherent integration processing itself is a known technique, it will be briefly described. The signal processing unit 16-n (n = 1, ···, N) acquires block #n from the signal compression unit 12-n. The signal processing unit 16-n contains K signals in block #n. If the K signals are represented as x n,1 , ···, x n,K , then for each of the K signals x n,1 , x n,2 , ···, x n,K , signals with the same delay time are acquired. K is an integer of 2 or more. The delay time is the time from when the pulse wave is radiated from the transmitter until the reflected wave related to the signal contained in block #n is received by the receiver. The signal processing unit 16-n performs coherent integration shown in the following formula (2) on the K signals x n,1 , x n,2 , ···, x n,K . The signal processing unit 16-n outputs the integration result G h as block #n after noise component suppression to the signal restoration unit 13-n.

[0047] TIFF0007686165000002.tif21166

[0048] The clutter suppression process is a process of suppressing the noise components included in the received signal after compression by utilizing the difference between the Doppler frequency of the target and the Doppler frequency of the noise, such as, for example, a known MTI (Moving Target Indicator) process or a known pulse Doppler process. The MTI process is a process of removing the fixed components having no speed and extracting the speed components by taking the difference between the signals received at a certain time interval.

[0049] The beam forming process is the process shown below. However, since the beam forming process itself is a known technique, it will be briefly described. The signal processing unit 16-n performs the coherent integration shown in the following equation (3) on the received signals x 1 , x 2 , ···, x M ’ received by M antennas arranged at equal intervals in the space coordinates z 1 ’, x 2 ’, ···, x M ’. The signal processing unit 16-n outputs the integration result G to the signal restoration unit 13-n as the received signal after suppressing the noise components.

[0050] TIFF0007686165000003.tif20166 In Equation (3), λ is the wavelength. θ is the direction in which the beam is formed by the beam forming process. Therefore, by the beam forming process, the unwanted signals from directions other than θ are suppressed.

[0051] The side lobe canceller process is a known process of suppressing the interference signals incident from the side lobe direction of the main antenna by performing correlation processing between the received signal by the main antenna and the received signal by the auxiliary antenna when an auxiliary antenna is provided in addition to the main antenna.

[0052] The signal restoration unit 13-n (n = 1, ···, N) acquires the block #n after suppressing the noise components from the signal processing unit 16-n. The signal restoration unit 13-n restores the delay time of block #n after noise component suppression and the complex amplitude of block #n after noise component suppression.

[0053] The signal integration unit 17 acquires the signal components output from the correlation processing unit 14 every time the mutually correlated signal components are output, and accumulates the signal components. The signal components accumulated in the signal integration unit 17 are signal components at a plurality of different times. The signal integration unit 17 integrates the signal components at a plurality of different times, and outputs the integrated signal components to the target detection unit 15. Since the target components at a plurality of different times have high correlation, they are stacked by the signal integration unit 17. On the other hand, since the noise components at a plurality of different times have low correlation, they are hardly stacked by the signal integration unit 17. Therefore, by integrating the signal components at a plurality of different times by the signal integration unit 17, the signal-to-noise ratio is improved.

[0054] The target detection unit 15 acquires the integrated signal components from the signal integration unit 17. The target detection unit 15 detects a target based on the integrated signal components.

[0055] In the above-described Embodiment 2, among the plurality of signal compression units 12-1 to 12-N, a plurality of signal processing units 16-1 to 16-N that suppress noise components included in the received signal after compression by any one of the signal compression units 12-n (n = 1, ···, N) are provided. Each signal restoration unit 13-n restores the delay time of the received signal after noise component suppression by any one of the plurality of signal processing units 16-1 to 16-N and the complex amplitude of the received signal after noise component suppression, and outputs a restored signal indicating the delay time and the complex amplitude to the correlation processing unit 14. Thus, the target detection device 2 shown in FIG. 7, similar to the target detection device 2 shown in FIG. 1, can prevent deterioration of the target detection performance even when performing compression processing on the received signal, and can improve the target detection performance more than the target detection device 2 shown in FIG. 1. Further, since the signal processing units 16-1 to 16-N perform processing on the compressed signal, the processing load of the target detection device 2 is significantly reduced compared to the processing load of a general target detection device that performs signal processing without a signal compression unit.

[0056] Also, in Embodiment 2, a signal integration unit 17 that accumulates the signal components extracted by the correlation processing unit 14 and integrates a plurality of signal components is provided, and the target detection unit 15 detects a target based on the signal components after integration by the signal integration unit 17. Thus, the target detection device 2 shown in FIG. 7, similar to the target detection device 2 shown in FIG. 1, can prevent deterioration of the target detection performance even when performing compression processing on the received signal, and can improve the target detection performance more than the target detection device 2 shown in FIG. 1.

[0057] Embodiment 3. In Embodiment 3, a target detection device 2 in which the correlation processing unit 18 includes a signal switching unit 18a, signal component extraction units 18b-1 to 18b-N, and a signal integration unit 18c will be described.

[0058] FIG. 9 is a configuration diagram showing the target detection device 2 according to Embodiment 3. In FIG. 9, the same reference numerals as those in FIGS. 1 and 7 denote the same or corresponding parts, and thus detailed description thereof is omitted. FIG. 10 is a hardware configuration diagram showing the hardware of the target detection device 2 according to Embodiment 3. In FIG. 10, the same reference numerals as those in FIGS. 2 and 8 denote the same or corresponding parts, and thus detailed description thereof is omitted. The target detection device 2 shown in FIG. 9 includes a signal splitting unit 11, signal compression units 12-1 to 12-N, signal processing units 16-1 to 16-N, signal restoration units 13-1 to 13-N, a correlation processing unit 18, and a target detection unit 15. However, this is merely an example, and the target detection device 2 may or may not include the signal processing units 16-1 to 16-N.

[0059] The correlation processing unit 18 is realized, for example, by the correlation processing circuit 28 shown in FIG. 10. The correlation processing unit 18 includes a signal swapping unit 18a, signal component extraction units 18b-1 to 18b-N, and a signal integration unit 18c. The correlation processing unit 18 shown in FIG. 9 extracts signal components that are correlated with each other in a simpler manner than the correlation processing unit 14 shown in FIG. 1.

[0060] The signal swapping unit 18a acquires restored signals from each of the signal restoration units 13-1 to 13-N. The signal swapping unit 18a swaps a plurality of restored signals. The signal swapping unit 18a outputs each of the swapped restored signals to the signal component extraction unit 18b-n (n = 1, ···, N).

[0061] The signal component extraction unit 18b-n (n = 1, ···, N) acquires the restored signal output from any one of the plurality of signal restoration units 13-1 to 13-N, and acquires one of the plurality of swapped restored signals from the signal swapping unit 18a. The signal component extraction unit 18b-n extracts signal components that are correlated with each other from the restored signal acquired from the signal restoration unit 13-n and the swapped restored signal acquired from the signal swapping unit 18a. The signal component extraction unit 18b-n outputs the signal components that are correlated with each other to the signal integration unit 18c.

[0062] The signal integration unit 18c acquires signal components that are correlated with each other from each of the signal component extraction units 18b-1 to 18b-N. The signal integration unit 18c integrates the acquired plurality of signal components and outputs the integrated signal components to the target detection unit 15.

[0063] In FIG. 9, it is assumed that each of the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 18, and the target detection unit 15, which are components of the target detection device 2, is realized by dedicated hardware as shown in FIG. 10. That is, it is assumed that the target detection device 2 is realized by a signal splitting circuit 21, a signal compression circuit 22, a signal processing circuit 26, a signal restoration circuit 23, a correlation processing circuit 28, and a target detection circuit 25. Each of the signal splitting circuit 21, the signal compression circuit 22, the signal processing circuit 26, the signal restoration circuit 23, the correlation processing circuit 28, and the target detection circuit 25 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.

[0064] The components of the target detection device 2 are not limited to those realized by dedicated hardware, and the target detection device 2 may be realized by software, firmware, or a combination of software and firmware. When the target detection device 2 is realized by software or firmware or the like, a program for causing a computer to execute the respective processing procedures in the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 18, and the target detection unit 15 is stored in the memory 31 shown in FIG. 3. Then, the processor 32 shown in FIG. 3 executes the program stored in the memory 31.

[0065] In addition, FIG. 10 shows an example in which each component of the target detection device 2 is realized by dedicated hardware, and FIG. 3 shows an example in which the target detection device 2 is realized by software, firmware, or the like. However, this is merely an example, and some components in the target detection device 2 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, or the like.

[0066] Next, the operation of the target detection device 2 shown in FIG. 9 will be described. However, except for the correlation processing unit 18, it is the same as the target detection device 2 shown in FIG. 7. Therefore, here, mainly the operation of the correlation processing unit 18 will be described.

[0067] The signal switching unit 18a of the correlation processing unit 18 acquires restoration signals from each of the signal restoration units 13-1 to 13-N and accumulates a plurality of restoration signals. The plurality of restoration signals accumulated by the signal switching unit 18a are the restoration signals of N blocks #1 to #N. The signal switching unit 18a switches the restoration signals of N blocks #1 to #N. Specifically, the signal switching unit 18a switches the restoration signals of N blocks #1 to #N so that the restoration signal of a block different from the restoration signal of block #n output from the signal restoration unit 13-n to the signal component extraction unit 18b-n is output from the signal switching unit 18a to the signal component extraction unit 18b-n. For example, when the restoration signal output from the signal restoration unit 13-n to the signal component extraction unit 18b-n is the restoration signal of the block shown below, the signal switching unit 18a switches the restoration signals of N blocks #1 to #N so that the restoration signal of the block shown below is output from the signal switching unit 18a to the signal component extraction unit 18b-n.

[0068] · Signal restoration unit 13-1 → Signal component extraction unit 18b-1: Restoration signal of block #1 · Signal restoration unit 13-2 → Signal component extraction unit 18b-2: Restoration signal of block #2 : · Signal restoration unit 13-N → Signal component extraction unit 18b-N: Restored signal of block #N

[0069] · Signal swapping unit 18a → Signal component extraction unit 18b-1: Restored signal of block #(N-1) · Signal swapping unit 18a → Signal component extraction unit 18b-2: Restored signal of block #N : · Signal swapping unit 18a → Signal component extraction unit 18b-N: Restored signal of block #2

[0070] FIG. 11 is an explanatory diagram showing an example of the restored signal output from the signal restoration unit 13-n to the signal component extraction unit 18b-n and the restored signal output from the signal swapping unit 18a to the signal component extraction unit 18b-n. These restored signals have sparsity. In the example of FIG. 11, each restored signal contains a target component, and the target components are temporally correlated with each other. Also, in the example of FIG. 11, each restored signal contains a noise component, and the noise components are not temporally correlated with each other. Note that as long as a restored signal of a block different from the restored signal of block #n output from the signal restoration unit 13-n is output from the signal swapping unit 18a to the signal component extraction unit 18b-n, the swapping order of the restored signals of the N blocks #1 to #N by the signal swapping unit 18a is arbitrary. The signal swapping unit 18a outputs the restored signal after swapping to the signal component extraction unit 18b-n.

[0071] The signal component extraction unit 18b-n (n = 1, ···, N) acquires the restored signal of block #n from the signal restoration unit 13-n. The signal component extraction unit 18b-n acquires the restored signal after swapping, which is the restored signal of a block different from block #n, from the signal swapping unit 18a. The signal component extraction unit 18b-n extracts signal components that are temporally correlated with each other from among the restored signal from the signal restoration unit 13-n and the restored signal after swapping. The extraction process of signal components that are temporally correlated with each other by the signal component extraction units 18b-n is the same as the extraction process of signal components by the correlation processing unit 14 shown in FIG. 1 when N = 2. The signal component extraction units 18b-n output the signal components that are correlated with each other to the signal integration unit 18c.

[0072] The signal integration unit 18c acquires signal components that are temporally correlated with each other from each of the signal component extraction units 18b-1 to 18b-N. The signal integration unit 18c integrates the N acquired signal components and outputs the integrated signal components to the target detection unit 15.

[0073] The target detection unit 15 acquires the integrated signal components from the signal integration unit 18c. The target detection unit 15 detects a target based on the integrated signal components.

[0074] In the above Embodiment 3, the correlation processing unit 18 includes a signal replacement unit 18a that acquires restored signals from a plurality of signal restoration units 13-1 to 13-N and replaces the plurality of restored signals, and among the plurality of signal restoration units 13-1 to 13-N, a plurality of signal component extraction units 18b-1 to 18b-N that extract signal components that are correlated with each other from the restored signal output from any one of the signal restoration units 13-n (n = 1, ···, N) and one of the restored signals after replacement of the plurality of restored signals by the signal replacement unit 18a, and a signal integration unit 18c that integrates the signal components extracted by the plurality of signal component extraction units 18b-1 to 18b-N, and configures the target detection device 2 shown in FIG. 9. Further, the target detection unit 15 of the target detection device 2 shown in FIG. 9 detects a target based on the signal components after integration by the signal integration unit 18c. Therefore, similar to the target detection device 2 shown in FIG. 1, the target detection device 2 shown in FIG. 9 can prevent deterioration of the target detection performance even when performing compression processing on the received signal, and can suppress noise components by a simple method.

[0075] Embodiment 4. In Embodiment 4, a target detection device 2 in which a correlation processing unit 19 includes a signal component determination unit 19a and a signal integration unit 19b will be described.

[0076] FIG. 12 is a configuration diagram showing the target detection device 2 according to Embodiment 4. In FIG. 12, the same reference numerals as those in FIGS. 1, 7, and 9 denote the same or corresponding parts, and thus detailed descriptions thereof are omitted. FIG. 13 is a hardware configuration diagram showing the hardware of the target detection device 2 according to Embodiment 4. In FIG. 13, the same reference numerals as those in FIGS. 2, 8, and 10 denote the same or corresponding parts, and thus detailed descriptions thereof are omitted. The target detection device 2 shown in FIG. 12 includes a signal splitting unit 11, signal compression units 12-1 to 12-N, signal processing units 16-1 to 16-N, signal restoration units 13-1 to 13-N, a correlation processing unit 19, and a target detection unit 15. However, this is merely an example, and the target detection device 2 may or may not include the signal processing units 16-1 to 16-N.

[0077] The correlation processing unit 19 is realized, for example, by a correlation processing circuit 29 shown in FIG. 13. The correlation processing unit 19 includes a signal component determination unit 19a and a signal integration unit 19b. The correlation processing unit 19 shown in FIG. 12 extracts signal components that are correlated with each other in a simpler method than the correlation processing unit 14 shown in FIG. 1.

[0078] The signal component determination unit 19a acquires restored signals from each of the signal restoration units 13-1 to 13-N. If the number of restored signals having non-zero signal components among the N restored signals is equal to or greater than a threshold value, the signal component determination unit 19a outputs the N restored signals to the signal integration unit 19b. If the number of restored signals having non-zero signal components among the N restored signals is less than the threshold value, the signal component determination unit 19a outputs, instead of each of the restored signals, a restored signal having only zero-valued signal components to the signal integration unit 19b.

[0079] The signal integration unit 19b acquires the N restored signals from the signal component determination unit 19a. The signal integration unit 19b integrates the N restored signals and outputs the integrated restored signals to the target detection unit 15.

[0080] In FIG. 12, it is assumed that each of the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 19, and the target detection unit 15, which are components of the target detection device 2, is realized by dedicated hardware as shown in FIG. 13. That is, it is assumed that the target detection device 2 is realized by a signal splitting circuit 21, a signal compression circuit 22, a signal processing circuit 26, a signal restoration circuit 23, a correlation processing circuit 29, and a target detection circuit 25. Each of the signal splitting circuit 21, the signal compression circuit 22, the signal processing circuit 26, the signal restoration circuit 23, the correlation processing circuit 29, and the target detection circuit 25 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.

[0081] The components of the target detection device 2 are not limited to those realized by dedicated hardware, and the target detection device 2 may be realized by software, firmware, or a combination of software and firmware. When the target detection device 2 is realized by software or firmware or the like, a program for causing a computer to execute the respective processing procedures in the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 19, and the target detection unit 15 is stored in the memory 31 shown in FIG. 3. Then, the processor 32 shown in FIG. 3 executes the program stored in the memory 31.

[0082] Further, FIG. 13 shows an example in which each component of the target detection device 2 is realized by dedicated hardware, and FIG. 3 shows an example in which the target detection device 2 is realized by software, firmware, or the like. However, this is merely an example, and some components in the target detection device 2 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, or the like.

[0083] Next, the operation of the target detection device 2 shown in FIG. 12 will be described. However, except for the correlation processing unit 19, it is the same as the target detection device 2 shown in FIG. 7. For this reason, here, mainly the operation of the correlation processing unit 19 will be described.

[0084] The signal component determination unit 19a of the correlation processing unit 19 acquires restored signals from each of the signal restoration units 13-1 to 13-N. These restored signals have sparsity. That is, most of the plurality of signal components included in the restored signal are 0 values, and sparsely non-zero signal components are included in the restored signal. The signal component determination unit 19a checks whether each restored signal contains a non-zero signal component. If the number of restored signals having non-zero signal components among the N restored signals is equal to or greater than the threshold Thsv, the signal component determination unit 19a outputs the N restored signals to the signal integration unit 19b. The threshold Thsv may be stored in the internal memory of the signal component determination unit 19a or may be given from outside the target detection device 2. If the number of restored signals having non-zero signal components among the N restored signals is less than the threshold Thsv, the signal component determination unit 19a outputs a restored signal having only 0-valued signal components to the signal integration unit 19b instead of each restored signal.

[0085] The signal integration unit 19b acquires N restored signals from the signal component determination unit 19a. The signal integration unit 19b integrates the N restored signals and outputs the integrated restored signal to the target detection unit 15. Since the target components included in the N restored signals have high correlations in both delay time and complex amplitude, they are accumulated by the signal integrator 19b. On the other hand, since the noise components included in the N restored signals have low correlations in both delay time and complex amplitude, they are hardly accumulated by the signal integrator 19b. Therefore, when the N restored signals are integrated by the signal integrator 19b, the noise components are suppressed. As a result, an improvement effect in target detection performance equivalent to an improvement in signal-to-noise ratio is obtained.

[0086] The target detector 15 acquires the signal components after integration from the signal integrator 19b. The target detector 15 detects a target based on the signal components after integration.

[0087] In the above-described Embodiment 4, in the correlation processing unit 19, if the number of restored signals having non-zero signal components among the restored signals output from the plurality of signal restoration units 13-1 to 13-N is equal to or greater than a threshold value, the plurality of restored signals are output. If the number of restored signals having non-zero signal components is less than the threshold value, a signal component determination unit 19a that outputs a restored signal having only zero-valued signal components as each restored signal, and a signal integrator 19b that integrates the plurality of restored signals output from the signal component determination unit 19a are provided, and the target detection device 2 shown in FIG. 12 is configured. Further, the target detector 15 of the target detection device 2 shown in FIG. 12 detects a target based on the restored signal after integration by the signal integrator 19b. Therefore, similar to the target detection device 2 shown in FIG. 1, the target detection device 2 shown in FIG. 12 can prevent deterioration of target detection performance even when performing compression processing on the received signal, and can suppress noise components by a simple method.

[0088] Embodiment 5. In Embodiment 5, a target detection device 2 in which the correlation processing unit 41 includes a correlation value calculation unit 41a, signal component extraction units 41b-1 to 41b-N, and a signal integrator 41c will be described.

[0089] FIG. 14 is a configuration diagram showing the target detection device 2 according to Embodiment 5. In FIG. 14, the same reference numerals as those in FIGS. 1, 7, 9, and 12 denote the same or corresponding parts, and thus detailed descriptions thereof are omitted. FIG. 15 is a hardware configuration diagram showing the hardware of the target detection device 2 according to Embodiment 5. In FIG. 15, the same reference numerals as those in FIGS. 2, 8, 10, and 13 denote the same or corresponding parts, and thus detailed descriptions thereof are omitted. The target detection device 2 shown in FIG. 14 includes a signal splitting unit 11, signal compression units 12-1 to 12-N, signal processing units 16-1 to 16-N, signal restoration units 13-1 to 13-N, a correlation processing unit 41, and a target detection unit 15. However, this is merely an example, and the target detection device 2 may or may not include the signal processing units 16-1 to 16-N.

[0090] The correlation processing unit 41 is realized, for example, by the correlation processing circuit 51 shown in FIG. 15. The correlation processing unit 41 includes a correlation value calculation unit 41a, signal component extraction units 41b-1 to 41b-N, and a signal integration unit 41c. The correlation processing unit 41 shown in FIG. 14 extracts signal components that are correlated with each other in a simpler method than the correlation processing unit 14 shown in FIG. 1.

[0091] The correlation value calculation unit 41a acquires restored signals from each of the signal restoration units 13-1 to 13-N. The correlation value calculation unit 41a detects the times when non-zero signal components are included in each of the restored signals. The correlation value calculation unit 41a calculates the correlation values between the times detected from each of the N restored signals.

[0092] The signal component extraction unit 41b-n (n = 1, ···, N) acquires a restored signal from the signal restoration unit 13-n. The signal component extraction unit 41b-n extracts the signal components at the times when the correlation values calculated by the correlation value calculation unit 41a are equal to or greater than a threshold value from the restored signal. The signal component extraction unit 41b-n outputs the extracted signal components to the signal integration unit 41c.

[0093] The signal integration unit 41c acquires signal components from each of the signal component extraction units 41b-1 to 41b-N. The signal integration unit 41c integrates a plurality of signal components and outputs the integrated signal components to the target detection unit 15.

[0094] In FIG. 14, it is assumed that each of the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 41, and the target detection unit 15, which are components of the target detection device 2, is realized by dedicated hardware as shown in FIG. 15. That is, it is assumed that the target detection device 2 is realized by a signal splitting circuit 21, a signal compression circuit 22, a signal processing circuit 26, a signal restoration circuit 23, a correlation processing circuit 51, and a target detection circuit 25. Each of the signal splitting circuit 21, the signal compression circuit 22, the signal processing circuit 26, the signal restoration circuit 23, the correlation processing circuit 51, and the target detection circuit 25 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 target detection device 2 are not limited to those realized by dedicated hardware, and the target detection device 2 may be realized by software, firmware, or a combination of software and firmware. When the target detection device 2 is realized by software or firmware or the like, a program for causing a computer to execute the respective processing procedures in the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 41, and the target detection unit 15 is stored in the memory 31 shown in FIG. 3. Then, the processor 32 shown in FIG. 3 executes the program stored in the memory 31.

[0096] Further, FIG. 15 shows an example in which each component of the target detection device 2 is realized by dedicated hardware, and FIG. 3 shows an example in which the target detection device 2 is realized by software, firmware, or the like. However, this is merely an example, and some components of the target detection device 2 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, or the like.

[0097] Next, the operation of the target detection device 2 shown in FIG. 14 will be described. However, except for the correlation processing unit 41, it is the same as the target detection device 2 shown in FIG. 7. Therefore, here, mainly the operation of the correlation processing unit 41 will be described.

[0098] The correlation value calculation unit 41a of the correlation processing unit 41 acquires the restored signal from the signal restoration units 13-n (n = 1, ···, N). The correlation value calculation unit 41a detects the time when a non-zero value signal component is included among the restored signals. The correlation value calculation unit 41a calculates the correlation value C between the times detected from each of the N restored signals. The correlation value calculation unit 41a outputs the correlation value C to each of the signal component extraction units 41b-1 to 41b-N.

[0099] Hereinafter, the calculation process of the correlation value C by the correlation value calculation unit 41a will be specifically described. For example, among the signal restoration units 13-1, the time when a non-zero value signal component is included is t 1,p Among the signal restoration units 13-2, the time when a non-zero value signal component is included is t 2,q Among the signal restoration units 13-N, the time when a non-zero value signal component is included is t N,r Let's assume that each of p, q, and r is an integer greater than or equal to 1. In this case, the correlation value calculation unit 41a calculates the correlation value C between the time t 1,p and the time t 2,q and the time t N,r Since the calculation process of the correlation value C itself is a known technique, a detailed description will be omitted. For example, the correlation value C is the time t 1,p and the time t2,q Time difference with, time t 2,q and time t N,r Time difference with, time t N,r and time t 1,p The smaller each of the time differences is, the larger the value it has.

[0100] The signal component extraction units 41b-n (n = 1, ···, N) acquire the restored signal from the signal restoration unit 13-n and acquire the correlation value C from the correlation value calculation unit 41a. The signal component extraction unit 41b-n extracts the signal component at the time when the correlation value C is equal to or greater than the threshold value Thc from the restored signal. The threshold value Thc may be stored in the internal memory of the signal component extraction unit 41b-n or may be given from outside the target detection device 2. For example, when the times at which the signal component extraction unit 41b-1 includes non-zero signal components are t 1,1 , t 1,2 , ···, if the time when the correlation value C is equal to or greater than the threshold value Thc is time t 1,p then, from the restored signal, the signal component at time t 1,p is extracted. For example, when the times at which the signal component extraction unit 41b-2 includes non-zero signal components are t 2,1 , t 2,2 , ···, if the time when the correlation value C is equal to or greater than the threshold value Thc is time t 2,q then, from the restored signal, the signal component at time t 2,q is extracted. For example, when the times at which the signal component extraction unit 41b-N includes non-zero signal components are time t N,1 , t N,2 , ···, if the time when the correlation value C is equal to or greater than the threshold value Thc is time t N,r then, from the restored signal, the signal component at time t N,r is extracted. The signal component extraction unit 41b-n outputs the extracted signal component to the signal integration unit 41c.

[0101] The signal integration unit 41c acquires signal components from each of the signal component extraction units 41b-1 to 41b-N. The signal integration unit 41c integrates a plurality of signal components and outputs the integrated signal components to the target detection unit 15.

[0102] The target detection unit 15 acquires the integrated signal components from the signal integration unit 41c. The target detection unit 15 detects a target based on the integrated signal components.

[0103] In the above Embodiment 5, the correlation processing unit 41 detects the time when a non-zero signal component is included among the respective restored signals output from the plurality of signal restoration units 13-1 to 13-N, and calculates the correlation value between the times detected from each of the plurality of restored signals. A correlation value calculation unit 41a; among the plurality of signal restoration units 13-1 to 13-N, a plurality of signal component extraction units 41b-1 to 41b-N that extract signal components at times when the correlation value calculated by the correlation value calculation unit 41a is equal to or greater than a threshold value from the restored signals output from any one of the signal restoration units 13-n; and a signal integration unit 41c that integrates the signal components extracted by the plurality of signal component extraction units 41b-1 to 41b-N. The target detection device 2 shown in FIG. 14 is configured. Further, the target detection unit 15 of the target detection device 2 shown in FIG. 14 detects a target based on the signal components after integration by the signal integration unit 41c. Therefore, similar to the target detection device 2 shown in FIG. 1, the target detection device 2 shown in FIG. 14 can prevent deterioration of the target detection performance even when performing compression processing on the received signal, and can suppress noise components by a simple method.

[0104] Embodiment 6. In Embodiment 6, a target detection device 2 in which the correlation processing unit 42 includes a correlation value calculation unit 42a, complex amplitude estimation units 42b-1 to 42b-N, and a signal integration unit 42c will be described.

[0105] FIG. 16 is a configuration diagram showing the target detection device 2 according to Embodiment 6. In FIG. 16, the same reference numerals as those in FIGS. 1, 7, 9, 12, and 14 denote the same or corresponding parts, and thus detailed description thereof is omitted. FIG. 17 is a hardware configuration diagram showing the hardware of the target detection device 2 according to Embodiment 6. In FIG. 17, the same reference numerals as those in FIGS. 2, 8, 10, 13, and 15 denote the same or corresponding parts, and thus detailed descriptions thereof are omitted. The target detection device 2 shown in FIG. 16 includes a signal splitting unit 11, signal compression units 12-1 to 12-N, signal processing units 16-1 to 16-N, signal restoration units 13-1 to 13-N, a correlation processing unit 42, and a target detection unit 15. However, this is merely an example, and the target detection device 2 may or may not include the signal processing units 16-1 to 16-N.

[0106] The correlation processing unit 42 is realized by, for example, the correlation processing circuit 52 shown in FIG. 17. The correlation processing unit 42 includes a correlation value calculation unit 42a, complex amplitude estimation units 42b-1 to 42b-N, and a signal integration unit 42c. The correlation processing unit 42 shown in FIG. 16 extracts signal components that are correlated with each other by a simpler method than the correlation processing unit 14 shown in FIG. 1.

[0107] The correlation value calculation unit 42a acquires restored signals from each of the signal restoration units 13-1 to 13-N. The correlation value calculation unit 42a detects the times when non-zero signal components are included in each of the restored signals. The correlation value calculation unit 42a calculates the correlation values between the times detected from each of the plurality of restored signals.

[0108] The complex amplitude estimation unit 42b-n (n = 1, ···, N) acquires block #n from either the signal processing unit 16-n or the signal compression unit 12-n. The complex amplitude estimation unit 42b-n estimates the complex amplitude of the signal at the time when the correlation value calculated by the correlation value calculation unit 42a is equal to or greater than the threshold value within block #n. The complex amplitude estimation unit 42b-n outputs the estimated complex amplitude to the signal integration unit 42c.

[0109] The signal integration unit 42c acquires complex amplitudes from each of the complex amplitude estimation units 42b-1 to 42b-N. The signal integration unit 42c integrates a plurality of complex amplitudes and outputs the integrated complex amplitudes to the target detection unit 15.

[0110] In FIG. 16, it is assumed that each of the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 42, and the target detection unit 15, which are components of the target detection device 2, is realized by dedicated hardware as shown in FIG. 17. That is, it is assumed that the target detection device 2 is realized by a signal splitting circuit 21, a signal compression circuit 22, a signal processing circuit 26, a signal restoration circuit 23, a correlation processing circuit 52, and a target detection circuit 25. Each of the signal splitting circuit 21, the signal compression circuit 22, the signal processing circuit 26, the signal restoration circuit 23, the correlation processing circuit 52, and the target detection circuit 25 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.

[0111] The components of the target detection device 2 are not limited to those realized by dedicated hardware, and the target detection device 2 may be realized by software, firmware, or a combination of software and firmware. When the target detection device 2 is realized by software or firmware or the like, a program for causing a computer to execute the respective processing procedures in the signal splitting unit 11, the signal compression units 12-1 to 12-N, the signal processing units 16-1 to 16-N, the signal restoration units 13-1 to 13-N, the correlation processing unit 42, and the target detection unit 15 is stored in the memory 31 shown in FIG. 3. Then, the processor 32 shown in FIG. 3 executes the program stored in the memory 31.

[0112] In addition, FIG. 17 shows an example in which each component of the target detection device 2 is realized by dedicated hardware, and FIG. 3 shows an example in which the target detection device 2 is realized by software, firmware, or the like. However, this is merely an example, and some components in the target detection device 2 may be realized by dedicated hardware, and the remaining components may be realized by software, firmware, or the like.

[0113] Next, the operation of the target detection device 2 shown in FIG. 16 will be described. However, except for the correlation processing unit 42, it is the same as the target detection device 2 shown in FIG. 14. Therefore, here, mainly the operation of the correlation processing unit 42 will be described.

[0114] The correlation value calculation unit 42a of the correlation processing unit 42 acquires the restored signal from the signal restoration units 13-n (n = 1, ···, N). The correlation value calculation unit 42a detects the time when the signal component with a non-zero value is included in the restored signal. The correlation value calculation unit 42a calculates the correlation value C between the times detected from each of the N restored signals in the same manner as the correlation value calculation unit 41a shown in FIG. 14. The correlation value calculation unit 42a outputs the correlation value C to each of the complex amplitude estimation units 42b-1 to 42b-N.

[0115] The complex amplitude estimation unit 42b-n (n = 1, ···, N) acquires block #n from either the signal processing unit 16-n or the signal compression unit 12-n, and acquires the correlation value C from the correlation value calculation unit 42a. The complex amplitude estimation unit 42b-n estimates the complex amplitude of the signal at the time when the correlation value C is equal to or greater than the threshold Thc in block #n. The threshold Thc may be stored in the internal memory of the complex amplitude estimation unit 42b-n, or may be given from outside the target detection device 2. The complex amplitude estimation process by the complex amplitude estimation unit 42b-n is the same as the complex amplitude restoration process by the signal restoration unit 13-n. The complex amplitude estimation unit 42b-n outputs the estimated complex amplitude to the signal integration unit 42c.

[0116] The signal integration unit 42c acquires a complex amplitude from each of the complex amplitude estimation units 42b-1 to 42b-N. The signal integration unit 42c integrates a plurality of complex amplitudes and outputs the integrated complex amplitude to the target detection unit 15.

[0117] The target detection unit 15 acquires the integrated complex amplitude from the signal integration unit 42c. The target detection unit 15 detects a target based on the integrated complex amplitude.

[0118] In the above Embodiment 6, the correlation processing unit 41 detects the time when a non-zero signal component is included among the respective restored signals output from the plurality of signal restoration units 13-1 to 13-N, and calculates the correlation value between the times detected from each of the plurality of restored signals. A correlation value calculation unit 42a, and among the received signals compressed by the respective signal compression units 12-n, a plurality of complex amplitude estimation units 42b-1 to 42b-N that estimate the complex amplitude of the signal at the time when the correlation value calculated by the correlation value calculation unit 42a is equal to or greater than a threshold value, and a signal integration unit 42c that integrates the complex amplitudes estimated by the plurality of complex amplitude estimation units 42b-1 to 42b-N. The target detection device 2 shown in FIG. 16 was configured. Further, the target detection unit 15 of the target detection device 2 shown in FIG. 16 detects a target based on the complex amplitude after integration by the signal integration unit 42c. Therefore, similar to the target detection device 2 shown in FIG. 1, the target detection device 2 shown in FIG. 16 can prevent deterioration of the target detection performance even when performing compression processing on the received signal, and can suppress noise components by a simple method.

[0119] Note that in the present disclosure, a free combination of each embodiment, or a modification of any component of each embodiment, or an omission of any component in each embodiment is possible.

Industrial Applicability

[0120] The present disclosure is suitable for a target detection device and a target detection method.

Explanation of Signs

[0121] 1 Receiver, 2 Target detection device, 3 Display device, 11 Signal splitting unit, 12-1 to 12-N Signal compression units, 13-1 to 13-N Signal restoration units, 14 Correlation processing unit, 15 Target detection unit, 16-1 to 16-N Signal processing units, 17 Signal integration unit, 18 Correlation processing unit, 18a Signal swapping unit, 18b-1 to 18b-N Signal component extraction units, 18c Signal integration unit, 19 Correlation processing unit, 19a Signal component determination unit, 19b Signal integration unit, 21 Signal splitting circuit, 22 Signal compression circuit, 23 Signal restoration circuit, 24 Correlation processing circuit, 25 Target detection circuit, 26 Signal processing circuit, 27 Signal integration circuit, 28 Correlation processing circuit, 29 Correlation processing circuit, 31 Memory, 32 Processor, 41 Correlation processing unit, 41a Correlation value calculation unit, 41b-1 to 41b-N Signal component extraction units, 41c Signal integration unit, 42 Correlation processing unit, 42a Correlation value calculation unit, 42b-1 to 42b-N Complex amplitude estimation units, 42c Signal integration unit, 51 Correlation processing circuit, 52 Correlation processing circuit.

Claims

1. A signal splitting unit that acquires a received signal indicating a reflected wave of the pulse wave every time the pulse wave is radiated into space and splits a plurality of acquired received signals; A plurality of signal compression units that compress each of the received signals after splitting by the signal splitting unit; Among the plurality of signal compression units, a plurality of signal restoration units that restore a delay time of the received signal after compression by any one of the signal compression units and a complex amplitude of the received signal after compression, and output a restored signal indicating the delay time and the complex amplitude; A correlation processing unit that extracts signal components that are correlated with each other from the restored signals output from the plurality of signal restoration units; A target detection unit that detects a target based on the signal components extracted by the correlation processing unit A target detection device comprising the same.

2. Among the plurality of signal compression units, a plurality of signal processing units that suppress noise components included in the received signal after compression by any one of the signal compression units are provided, Each signal restoration unit restores a delay time of the received signal after noise component suppression by any one of the plurality of signal processing units and a complex amplitude of the received signal after noise component suppression, and outputs a restored signal indicating the delay time and the complex amplitude to the correlation processing unit. The target detection device according to claim 1, characterized in that

3. A signal integration unit that accumulates the signal components extracted by the correlation processing unit and integrates the plurality of accumulated signal components is provided, The target detection unit detects a target based on the signal components after integration by the signal integration unit. The target detection device according to claim 1, characterized in that

4. The correlation processing unit acquires restored signals from the plurality of signal restoration units, and a signal replacement unit that replaces the plurality of restored signals; Among the plurality of signal restoration units, a plurality of signal component extraction units that extract signal components that are correlated with each other from among the restored signal output from any one of the signal restoration units and one of the restored signals after replacement of the plurality of restored signals by the signal replacement unit; A signal integration unit that integrates the signal components extracted by the plurality of signal component extraction units; The target detection unit detects a target based on the signal components after integration by the signal integration unit. The target detection device according to claim 1, characterized in that

5. The correlation processing unit Among the restored signals output from the plurality of signal restoration units, if the number of restored signals having a non-zero signal component is equal to or greater than a threshold value, a plurality of restored signals are output; if the number of restored signals having a non-zero signal component is less than the threshold value, instead of each restored signal, a restored signal having only a zero-valued signal component is output, which is a signal component determination unit; A signal integration unit that integrates the plurality of restored signals output from the signal component determination unit; The target detection unit The target detection device according to claim 1, wherein the target is detected based on the restored signal after integration by the signal integration unit.

6. The correlation processing unit Among the respective restored signals output from the plurality of signal restoration units, a time when a non-zero signal component is included is detected, and a correlation value between the detected times from each of the plurality of restored signals is calculated, which is a correlation value calculation unit; Among the plurality of signal restoration units, a plurality of signal component extraction units that extract signal components at times when the correlation value calculated by the correlation value calculation unit is equal to or greater than a threshold value from the restored signals output from any one of the signal restoration units; A signal integration unit that integrates the signal components extracted by the plurality of signal component extraction units; The target detection unit The target detection device according to claim 1, wherein the target is detected based on the signal components after integration by the signal integration unit.

7. The correlation processing unit Among the respective restored signals output from the plurality of signal restoration units, a time when a non-zero signal component is included is detected, and a correlation value between the detected times from each of the plurality of restored signals is calculated, which is a correlation value calculation unit; Among the plurality of signal compression units, a plurality of complex amplitude estimation units that estimate the complex amplitude of the signal at a time when the correlation value calculated by the correlation value calculation unit is equal to or greater than a threshold value in the received signal after compression by any one of the signal compression units; A signal integration unit that integrates the complex amplitudes estimated by the plurality of complex amplitude estimation units; The target detection unit The target detection device according to claim 1, wherein the target is detected based on the complex amplitude after integration by the signal integration unit.

8. Every time a pulse wave is radiated into space, the signal splitting unit acquires a received signal indicating the reflected wave of the pulse wave and splits the acquired plurality of received signals. A plurality of signal compression units compress the received signals after splitting by the signal splitting unit. A plurality of signal restoration units restore a delay time of a received signal after compression by any one of the plurality of signal compression units and a complex amplitude of the received signal after compression, and output a restored signal indicating the delay time and the complex amplitude. A correlation processing unit extracts signal components that are correlated with each other from the restored signals output from the plurality of signal restoration units. A target detection unit detects a target based on the signal components extracted by the correlation processing unit. A target detection method.

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