JP5980636B2 - Target detection device - Google Patents

Description

  The present invention relates to a radar device or a sonar device that improves a signal-to-noise ratio.

  A MIMO (Multiple-Input Multiple-Output) type radar device or sonar device is known. The MIMO scheme is a technique in which a plurality of antennas are arranged in a transmitter, a plurality of antennas are arranged in a receiver, and an antenna beam of a virtual array synthesized by each transmission / reception data is scanned at a high speed and spatial resolution is improved. is there. Hereinafter, the radar apparatus will be described, but the same applies to the sonar apparatus.

  The radar transmission signals from each antenna of the transmitter need to be orthogonal to each other so as not to interfere with each other. In the prior art, as signals orthogonal to each other, a frequency hopping signal whose frequency is randomly changed and a phase modulation signal whose phase is randomly changed are known. In Non-Patent Document 1, signals that are orthogonal to each other are generated using a mapping function that is sensitive to the initial value and behaves like a chaos.

Shen Dong, Zhang Lin-rang, Liu Nan, and Liu Xin, “Increasing the Mainlobe-to-Sidelobe Ratio of Processing in MIMO Radar with Catch.” 11, no. 10, 2011.

  In the prior art and Non-Patent Document 1, signals that are orthogonal to each other are generated in order to perform MIMO measurement, but in order to perform a sweep integration process for each sweep and a scan correlation process for a scan around the entire circumference. It does not generate signals that are orthogonal to each other.

  Therefore, in order to solve the above-described problems, an object of the present invention is to improve the performance of sweep integration processing and scan correlation processing by using signals orthogonal to each other.

  In order to achieve the above object, the performance of the sweep integration process is improved by making the pseudo-noise codes generated for each sweep of target detection orthogonal to each other.

  The present invention includes a first pseudo-noise code generation unit that generates a different first pseudo-noise code by changing an initial value of a linear feedback shift register for each sweep of target detection, and an entire circumference of target detection. In the single scan period, the initial value of the linear feedback shift register is fixed to fix the second pseudo noise code generation unit that generates the same second pseudo noise code, and the first pseudo noise having the same period. A third pseudo noise code generation unit that generates a third pseudo noise code by calculating an exclusive OR of the code and the second pseudo noise code; and a transmission signal modulated using the third pseudo noise code. A matched transmitter that generates a matched filter signal by correlating the received signal and the transmission signal for each sweep of the radar, and a receiving unit that receives a received signal that is a reflection signal of the transmitted signal. A filter processing unit, a plurality of sweeps of the target detection is a target detection device which is characterized in that it comprises a sweep integrator for performing integration processing of the matched filter signal.

  According to this configuration, by using signals orthogonal to each other, the performance of the sweep integration process can be improved for each sweep of target detection.

  In order to achieve the above object, by making the pseudo-noise codes generated for each sweep of target detection orthogonal to each other, the performance of the sweep integration process is improved, and at the entire circumference of the target detection. The performance of scan correlation processing is improved by making the sets of pseudo-noise codes generated for each scan different from each other.

  In the present invention, the second pseudo-noise code generation unit generates different second pseudo-noise codes by changing an initial value of a linear feedback shift register for each scan of the entire target detection. The target detection apparatus further includes a scan correlation unit that executes correlation processing of integration results of the sweep integration unit for a plurality of scans of target detection.

  According to this configuration, by using signals orthogonal to each other, the performance of the sweep integration process is improved for each sweep of the target detection, and the scan correlation process is performed for the scan around the entire circumference of the target detection. Performance can be improved.

  The present invention further includes a plurality of transmitting antennas and an array combining processing unit that generates an array combined signal by array combining the matched filter signals, and the transmitting unit performs radar transmission for each transmitting antenna. Modulation is performed using pseudo-noise signals orthogonal to each other for each of the transmission antennas so that the signals are orthogonal to each other, and the sweep integration unit integrates the array composite signal for a plurality of sweeps for target detection A target detection apparatus characterized by executing processing.

  According to this configuration, the radar apparatus of the present invention can be applied to a MIMO system or a MISO (Multiple-Input Single-Output) system. Here, in the MISO system, a plurality of antennas are arranged in the transmitter, a single antenna is arranged in the receiver, and the antenna beam of the virtual array synthesized by each transmission / reception data is scanned at a high speed and the spatial resolution is increased. It is a technology to improve.

  The present invention can improve the performance of sweep integration processing and scan correlation processing by using signals orthogonal to each other.

It is a figure which shows the structure of the radar apparatus of this invention. It is a figure which shows the structure of the pseudo noise signal generation part of this invention.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments.

  The configuration of the radar apparatus of the present invention is shown in FIG. The radar apparatus R includes a pseudo noise signal generation unit 1, a radar transmission unit 2, a radar transmission antenna 3, a radar reception antenna 4, a radar reception unit 5, a matched filter processing unit 6, an array synthesis processing unit 7, a sweep integration unit 8, and It comprises a scan correlation unit 9. Hereinafter, a radar apparatus using electromagnetic waves will be described, but the same applies to a sonar apparatus using ultrasonic waves.

  The pseudo noise signal generation unit 1 generates a pseudo noise signal as described in detail with reference to FIG. The radar transmitter 2 transmits a radar transmission signal modulated using a pseudo noise code.

  The radar transmission antenna 3 includes a plurality of antennas (four antennas in FIG. 1). The radar receiving antenna 4 is composed of a plurality (four in FIG. 1) of antennas. The signal transmitted from the radar transmitting antenna 3 is reflected by the target T and received by the radar receiving antenna 4.

  The radar receiver 5 receives a radar reception signal that is a reflection signal of the radar transmission signal. The matched filter processing unit 6 generates a matched filter signal by correlating the radar reception signal and the radar transmission signal for each sweep of the radar. The array synthesis processing unit 7 performs array synthesis of the matched filter signals, thereby scanning the virtual array beam and generating a signal in the observation direction. The sweep integration unit 8 executes an integration process of the array composite signal for a plurality of radar sweeps. The scan correlator 9 performs correlation processing of the integration result of the sweep integrator 8 for a plurality of radar scans.

  The configuration of the pseudo noise signal generation unit of the present invention is shown in FIG. The pseudo noise signal generation unit 1 includes a first M sequence code generation unit 11, a second M sequence code generation unit 12, an XOR (eXclusive OR) circuit 13, and an XOR selector 14.

  The first M-sequence code generator 11 corresponds to the first pseudo noise code generator and is a linear feedback shift register. A different first M-sequence code is generated by changing the initial value of the linear feedback shift register for each sweep of the radar.

  The second M-sequence code generation unit 12 corresponds to the second pseudo noise code generation unit and is a linear feedback shift register. In the single scan period around the entire circumference of the radar, the same second M-sequence code is generated by fixing the initial value of the linear feedback shift register. That is, for each sweep of the radar, the initial value of the linear feedback shift register is not changed, but a different second M-sequence code is not generated. However, a different second M-sequence code is generated by changing the initial value of the linear feedback shift register for every scan of the entire circumference of the radar.

Here, as long as the first M-sequence code and the second M-sequence code have the same period, they may be the same code or different codes. The period is equal to the number of sweeps per scan. That is, when all sweeps for one scan are completed, the first M-sequence code is cycled. In FIG. 2, the period is 2 ⁸ −1 = 255.

  The XOR circuit 13 corresponds to the third pseudo noise code generation unit, and generates a Gold code by calculating an exclusive OR of the first M sequence code and the second M sequence code. The radar transmitter 2 transmits a radar transmission signal modulated using a Gold code.

  The XOR selector 14 receives the second M-sequence code from the second M-sequence code generator 12 and generates a plurality (four in FIG. 2) of mutually orthogonal M-sequence codes based on the input second M-sequence code. Then, the generated M-sequence signals orthogonal to each other are output to each XOR circuit 13 (four in FIG. 2). Thereby, the radar apparatus R can be applied to the MIMO system and the MISO system in which the radar transmission antenna 3 is composed of a plurality of antennas.

  The processing flow of the radar sweep and scan will be described. In the n-th sweep (n = 1 to 255 in FIG. 2) of one scan, the first M-sequence code generation unit 11 receives the n-th initial value and outputs the n-th first M-sequence code. The second M-sequence code generation unit 12 receives a fixed initial value and outputs a fixed second M-sequence code.

  In the n-th sweep of one scan, the XOR circuit 13 generates a Gold code by calculating an exclusive OR of the n-th first M-sequence code and the fixed second M-sequence code. The radar transmission unit 2 and the radar reception unit 5 perform MIMO measurement via the radar transmission antenna 3, the radar reception antenna 4, and radar reflection at the target T.

  The above processing is executed for each scan. However, in different scans, the second M-sequence code generation unit 12 receives a different initial value and outputs a different second M-sequence code.

  The matched filter processing unit 6 generates a matched filter signal by correlating the radar reception signal and the radar transmission signal for each sweep of the radar. The array synthesis processing unit 7 performs array synthesis of the matched filter signals, thereby scanning the virtual array beam and generating a signal in the observation direction.

  The sweep integration unit 8 executes an integration process of the array composite signal for a plurality of radar sweeps. By performing sweep integration, side lobes that are not correlated between different sweeps can be reduced. By utilizing different Gold codes between different sweeps, uncorrelated side lobes between different sweeps can be made smaller.

  The scan correlator 9 performs correlation processing of the integration result of the sweep integrator 8 for a plurality of radar scans. By performing scan correlation, the uncorrelated sidelobe waveforms differ between different scans, so that the target T and sidelobe can be easily identified. By utilizing different sets of Gold codes between different scans, the target T and side lobes can be more easily identified because the uncorrelated sidelobe waveforms are different between different scans.

  In the embodiment, both the sweep integration and the scan correlation are executed. As a modification, only sweep integration may be performed. In this modification, the scan correlation unit 9 is unnecessary, and the second M-sequence code generation unit 12 only needs to receive a fixed initial value.

  In the embodiment, the XOR selector 14 is arranged on the output side of the second M-sequence code generation unit 12. As a modification, the XOR selector 14 may be arranged on the output side of the first M-sequence code generation unit 11. In either case, the MIMO system or the MISO system can be supported.

  In the embodiment, the radar apparatus R is applied to a MIMO system or a MISO system in which the radar transmission antenna 3 is configured by a plurality of antennas. As a modification, the radar apparatus R may be applied to a single-input multiple-output (SIMO) system or a single-input single-output (SISO) system in which the radar transmission antenna 3 is configured by a single antenna. .

  Here, the SIMO method is a technique in which a single antenna is arranged in a transmitter and a plurality of antennas are arranged in a receiver, and a beam of a receiving array is scanned at high speed. The SISO system is a technique of a normal system in which a single antenna is arranged at the transmitter and a single antenna is arranged at the receiver. In this modification, the XOR selector 14 is unnecessary, and only one radar transmission antenna 3 and one XOR circuit 13 are required.

  Further, in the modified example of the SISO system, the array synthesis processing unit 7 is not necessary, and the sweep integration unit 8 executes integration processing of the matched filter signal for a plurality of sweeps of the radar.

  The target detection apparatus according to the present invention can be applied to a MIMO system, a MISO system, a SIMO system, or a SISO system, and can be applied to a radar, a sonar, or the like of a ship or aviation.

R: Radar apparatus T: Target 1: Pseudo noise signal generation unit 2: Radar transmission unit 3: Radar transmission antenna 4: Radar reception antenna 5: Radar reception unit 6: Matched filter processing unit 7: Array synthesis processing unit 8: Sweep integration unit 9: scan correlation unit 11: first M sequence code generation unit 12: second M sequence code generation unit 13: XOR circuit 14: XOR selector

Claims (3)

A first pseudo-noise code generator that generates a different first pseudo-noise code by changing the initial value of the linear feedback shift register for each sweep of target detection;
In a single scan period around the entire target detection, a second pseudo-noise code generation unit that generates the same second pseudo-noise code by fixing the initial value of the linear feedback shift register;
A third pseudo-noise code generator for generating a third pseudo-noise code by calculating an exclusive OR of the first pseudo-noise code and the second pseudo-noise code having the same period;
A transmission unit for transmitting a transmission signal modulated using the third pseudo-noise code;
A reception unit that receives a reception signal that is a reflection signal of the transmission signal;
A matched filter processing unit that generates a matched filter signal by correlating the received signal and the transmission signal for each sweep of the radar;
For a plurality of sweeps of target detection, a sweep integration unit that performs integration processing of the matched filter signal;
A target detection apparatus comprising: The second pseudo noise code generation unit generates a different second pseudo noise code by changing an initial value of a linear feedback shift register for each scan in the entire circumference of target detection,
The target detection apparatus according to claim 1, further comprising: a scan correlation unit that executes correlation processing of integration results of the sweep integration unit for a plurality of scans of target detection. Multiple transmit antennas,
An array synthesis processing unit that generates an array synthesis signal by performing array synthesis of the matched filter signal;
The transmission unit performs modulation using pseudo-noise signals orthogonal to each other for each transmission antenna so that radar transmission signals are orthogonal to each other for each transmission antenna;
The target detection apparatus according to claim 1, wherein the sweep integration unit executes an integration process of the array composite signal for a plurality of sweeps for target detection.

Images