JP2006017545A - Target detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a downscaled target detection system with enhanced target detection performance by improving the S/N ratio of a reception signal having an amplitude largely time-varying and having a short period during which the amplitude is large. <P>SOLUTION: Target detectors 19-1 to 19-1 and 20-1 to 20-m comprise: a receiver 4 for receiving a reflected wave of a transmitted wave to convert an obtained reception signal into a digital video signal; an unnecessary wave suppressor 9 for suppressing unnecessary components in an output signal of the receiver; convolution calculators 10-1 to 10-n for performing convolution calculation on an output signal of the wave suppressor and on a reference signal being pulse-by-pulse complex-conjugated on a reception signal from a target to be detected and having a pulse-wise length capable of maximizing integration gain; and detectors 8-1 to 8-n for detecting the target on the basis of the result of the convolution calculation. A reference signal control information generator 18 indicates the kind of a reference signal used in the convolution calculation to the convolution calculators of the target detectors. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a target detection system that detects a target whose amplitude changes greatly in time and a received signal having a short period of large amplitude is obtained, such as a rotor blade of a helicopter.

  Conventionally, as one of target detection systems, a radar device that detects a target by emitting a radio wave toward the target, receiving a reflected wave from the target, and performing signal processing is known. When such a conventional radar apparatus is used to detect a helicopter hovering at a low altitude, the reflected wave from the helicopter includes an unnecessary reflected wave called clutter.

  In the case of a reflected wave from a moving target, the reflected wave from the target can be extracted using the Doppler effect. However, when the target is not moving, for example, in the case of a helicopter in a hovering state, the Doppler effect cannot be used, so that the reflected wave from the helicopter fuselage cannot be extracted.

  In order to detect a helicopter in such a hovering state, a method of detecting a target by extracting a reflected wave from a rotor blade or the like that is rotating even in the hovering state is considered.

  For example, the presence / absence of a hit due to CFAR (Constant False Alarm Rate) before and after integration in the frequency direction after frequency analysis of the received signal and the change before and after frequency direction integration of the amplitude where the CFAR hit occurred are extracted, and the presence or absence of the frequency direction integration effect Thus, a radar device that determines helicopter detection is known (see Patent Document 1). This radar device radiates a transmission wave generated by a transmitter from an antenna, sends a received signal to the receiver through a circulator, and converts it into a digital video signal. The received signal is clutter-suppressed by an MTI (Moving Target Indicator) device, coherently integrated by a frequency analyzer, integrated by a frequency direction integrator, and the presence or absence of a CFAR hit before and after frequency direction integration by a CFAR device and a maximum amplitude detector. A change before and after the frequency direction integration of the amplitude in which the CFAR hit occurs is extracted, and it is determined whether or not the target is a helicopter by a detection determination device.

  There is also known a radar apparatus that stably detects a hovering helicopter without being affected by a strong ground clutter (Patent Document 2). The radar apparatus includes a clutter level calculation apparatus that calculates a clutter level from a digital video signal output from a receiver, and a frequency range setting circuit that sets a Doppler frequency range for detecting a hovering helicopter based on the calculated clutter level. In the hovering helicopter detection device, the hovering helicopter is detected based on the Doppler frequency range that changes according to the set clutter size, the preset detection slicer level, and the hovering helicopter determination reference value.

  However, the reflected wave from the rotor blade is a received signal whose amplitude greatly changes with time and whose amplitude is large. For this reason, the FFT (Fast Fourier Transform) often used as an integration means cannot expect a large integration effect for a stationary signal whose amplitude is substantially constant over time. Therefore, in a radar device that extends the detection distance due to the integration effect, for a target such as a rotor blade, where the amplitude changes greatly in time and a received signal with a short period of large amplitude is obtained. The detection distance may be shortened.

  The target detection operation by the conventional radar apparatus as described above will be described with reference to the drawings. FIG. 9 is a block diagram showing an example of the configuration of a conventional radar apparatus. The radar apparatus includes an antenna 1, a transmitter 2, a circulator 3, a receiver 4, an MTI apparatus 5, a frequency analysis apparatus 6, a CFAR apparatus 7, and a detection apparatus 8.

  The antenna 1 converts a transmission signal transmitted from the transmitter 2 via the circulator 3 into a radio wave, and transmits the radio wave as a transmission wave to a space in a specified direction, and receives the reflected wave reflected by the target. The received signal is sent to the receiver 4 via the circulator 3.

  The receiver 4 converts a received signal sent from the antenna 1 via the circulator 3 into a digital video signal. The digital video signal obtained by converting the received signal by the receiver 4 is sent to the MTI device 5.

  The MTI device 5 suppresses clutter components included in the digital video signal sent from the receiver 4. The digital video signal whose clutter component is suppressed by the MTI device 5 is sent to the frequency analysis device 6.

  The frequency analysis device 6 performs coherent integration of the digital video signal in which the clutter component is suppressed in the MTI device 5 for the purpose of improving the signal-to-noise ratio (S / N ratio). Note that FFT is often used for coherent integration in the frequency analyzer 6.

When detecting a target from which a received signal having a substantially constant amplitude in time is detected, an integration effect corresponding to the number of integration pulses can be obtained by the FFT used as the integration means. The relationship between the integration pulse number N and the integration gain G (unit: dB) is shown in the following formula (1).

When detecting a target in which a reception signal whose amplitude changes greatly in time and a period of large amplitude is short is detected, a large integration effect cannot be expected in the FFT used as the integration means. As an example, in the case where the received signal from the target is a rectangular wave having a constant amplitude within the number of pulses M and the amplitude is zero outside the number of pulses M, the number of pulses M and the number of integrated pulses other than zero are the amplitudes. The relationship between N and integral gain G ′ (unit: dB) is shown below.

  When the number M of pulses having an amplitude other than zero is “10”, the integral gain G and the integral gain G ′ are as shown in FIG. As described above, even if the number N of integrated pulses is increased, the integration effect is small when the number of pulses M is not greater than zero, and the integration gain G ′ decreases.

  The CFAR device 7 detects the signal having the amplitude and phase output from the frequency analysis device 6 (converts it into a signal having only amplitude information), calculates the reference amplitude from the signal amplitude around the target range bin, and pays attention to the reference amplitude. An amplitude ratio signal is output as a signal representing the range bin amplitude ratio.

The detection device 8 sets a threshold value for the amplitude ratio signal output from the CFAR device 7 and detects a signal exceeding the threshold value as a target.
Japanese Patent No. 3359586 Patent No. 2991080

  However, in the conventional radar apparatus configured as described above, a predetermined integration effect can be obtained for a target from which a reception signal having a substantially constant amplitude in time is obtained, but the amplitude is large in time. As described above, the desired integration effect cannot be obtained even if the number of integration pulses is increased, and the integration gain decreases. End up. As a result, there is a problem that the signal-to-noise ratio (SN ratio) is lowered and the target detection performance is lowered.

  On the other hand, a network radar system is known in which a plurality of radar devices are connected via a network, and each radar device cooperates to detect a target. In this network radar system, a radar apparatus used as a network node is used by being mounted on a moving body in addition to being installed on the ground. Among such a plurality of radar devices, particularly a radar device mounted on a moving body has many restrictions on shape, size, and mass, and therefore, a reduction in size is desired.

  The present invention has been made in order to solve the above-mentioned problems and to meet the above-mentioned demands. The signal-to-noise ratio (S / N ratio) of a received signal whose amplitude greatly changes over time and whose amplitude is short is short. It is an object of the present invention to provide a target detection system capable of downsizing that can improve target detection performance.

  A target detection system according to a first invention includes a target detection device and a reference signal control information generation device, and the target detection device receives a received signal obtained by receiving a reflected wave of a transmission wave transmitted to space. Receivers that convert digital video signals, unwanted wave suppression devices that suppress unwanted wave components from digital video signals output from receivers, and signals that have unwanted wave components suppressed by unwanted wave suppression devices A convolution operation device that performs a convolution operation with a reference signal having a length in a pulse direction that is a complex conjugate for each pulse of the received signal from the target and that can maximize the integral gain, and is output from the convolution operation device A reference device for detecting a reflected wave signal from the target based on the signal, and the reference signal control information generating device performs a convolution operation on the convolution operation device of the target detection device. Characterized by instructing the kind of the reference signal used.

  A target detection system according to a second aspect of the present invention is a target detection system including a target detection device and a reference signal control information generation device, and the target detection device receives a reflected wave of a transmission wave transmitted to space. A receiver that converts the received signal obtained into the digital video signal, an unnecessary wave suppression device that suppresses unnecessary wave components from the digital video signal output from the receiver, and an unnecessary wave component generated by the unnecessary wave suppression device. The signal obtained by Fourier transforming the signal obtained by Fourier transform of the suppressed signal and the signal having a length in the pulse direction that is a complex conjugate for each pulse of the received signal from the target to be detected and that can maximize the integral gain. A Fourier transform device that performs inverse Fourier transform after multiplying by a reference signal, and a detection device that detects a reflected wave signal from the target based on the signal output from the Fourier transform device With the door, the reference signal control information generator, to Fourier transform device of the target detector, characterized by instructing the kind of the reference signal used for multiplication.

  According to the target detection system of the first aspect of the present invention, the target detection device is obtained by a convolution operation between the received signal and a reference signal having a length that can maximize the integral gain, with the amplitude greatly changing over time. Since the presence / absence of a target is detected based on a large signal, the signal-to-noise ratio (S / N ratio) of a received signal with a short period of large amplitude can be improved. In addition, the reference signal control information generation device is configured to instruct the convolution operation device of the target detection device to specify the type of reference signal used for the convolution operation, so that a large number of convolution operation devices corresponding to the type of reference signal are provided. There is no need to have. As a result, the structure of the target detection device is simplified and the size can be reduced, so that the overall size of the target detection system can be reduced.

  Further, according to the target detection system of the second invention, the target detection device, after multiplying the signal obtained by Fourier transforming the received signal and the reference signal subjected to the Fourier transform having a length capable of maximizing the integral gain, Since the presence / absence of the target is detected based on the large signal obtained by the inverse Fourier transform, the amplitude changes greatly with time even though the calculation amount is smaller than the convolution calculation, and the amplitude is large. The signal-to-noise ratio (S / N ratio) of the received signal with a short period can be improved. In addition, since the reference signal control information generation device is configured to instruct the Fourier transform device of the target detection device to specify the type of reference signal used for multiplication, a large number of Fourier transform devices corresponding to the type of reference signal are provided. It is not necessary to have. As a result, the structure of the target detection device is simplified and the size can be reduced, so that the overall size of the target detection system can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, portions corresponding to the components of the radar apparatus described in the section of the prior art will be described using the same reference numerals as those used in the section of the prior art.

  The target detection system according to the first embodiment of the present invention improves the SN ratio of a received signal using a convolution operation between the received signal and a reference signal.

  FIG. 1 is a block diagram showing a configuration of a target detection system according to Embodiment 1 of the present invention. The target detection system includes a reference signal control information generation device 18, 1 (1 is a positive integer) first target detection devices 19-1 to 19-1 and m (m is a positive integer) second target detection. It is comprised from apparatus 20-1-20-m. The first target detection devices 19-1 to 19-l and the second target detection devices 20-1 to 20-m are constituted by, for example, radar devices.

  The reference signal control information generator 18 generates reference signal control information and sends it to the first target detectors 19-1 to 19-l and the second target detectors 20-1 to 20-m. The reference signal control information is used to indicate the type of reference signal (details will be described later) to be used by the first target detection devices 19-1 to 19-l and the second target detection devices 20-1 to 20-m. Information.

  The first target detection devices 19-1 to 19-l respectively perform convolution operations (details will be described later) on a plurality of types of reference signals in accordance with the reference signal control information from the reference signal control information generation device 18. Then, the target is detected based on the result, and the type of the reference signal from which the maximum S / N ratio is obtained is sent to the reference signal control information generator 18. The reference signal control information generating device 18 generates reference signal control information indicating the type of the reference signal from which the maximum S / N ratio transmitted from the first target detection devices 19-1 to 19-1 is obtained, and the second It sends to the target detection devices 20-1 to 20-m.

  The second target detection devices 20-1 to 20-m perform a convolution operation on the reference signal that provides the maximum S / N ratio according to the reference signal control information from the reference signal control information generation device 18, and A target is detected based on the result.

  FIG. 2 is a block diagram showing the configuration of the first target detection devices 19-1 to 19-l. Each of the first target detection devices 19-1 to 19-1 includes an antenna 1, a transmitter 2, a circulator 3, a receiver 4, an unnecessary wave suppression device 9, a convolution operation device 10-1 to 10 -n, and a CFAR device 7. -1 to 7-n and detection devices 8-1 to 8-n.

  The antenna 1 converts a transmission signal transmitted from the transmitter 2 via the circulator 3 into a radio wave, and transmits the radio wave as a transmission wave to a space in a specified direction, and receives the reflected wave reflected by the target. The received signal is sent to the receiver 4 via the circulator 3.

  The receiver 4 converts a received signal sent from the antenna 1 via the circulator 3 into a digital video signal. The digital video signal obtained by converting the received signal by the receiver 4 is sent to the unwanted wave suppressing device 9.

  The unnecessary wave suppressing device 9 suppresses unnecessary wave components included in the digital video signal transmitted from the receiver 4. The unnecessary wave component includes a component of a reflected wave from the body of the clutter and the helicopter. In order to suppress the reflected wave from the clutter, the MTI apparatus 5 described in the section of the prior art is often used. Although the unnecessary wave suppression device 9 may use the MTI device 5, a higher effect can be obtained by using a band rejection filter that suppresses the frequency of the unnecessary wave signal that does not include the reception signal from the rotor blade. The digital video signal in which the unnecessary wave component is suppressed by the unnecessary wave suppression device 9 is sent to the convolution operation devices 10-1 to 10-n.

  FIG. 3 is a block diagram showing a detailed configuration of each of the convolution operation devices 10-1 to 10-n. In addition, since the configuration of the convolution operation devices 10-2 to 10-n is the same as that of the convolution operation device 10-1, only the convolution operation device 10-1 will be described below. The convolution operation device 10-1 includes a convolution operation unit 12 and a reference signal generation unit 13.

  The reference signal generator 13 generates a reference signal simulating the amplitude and phase of the received signal from the target to be detected, according to the reference signal control information from the reference signal control information generator 18. Here, when the reference signal is represented by h (0) to h (P-1) and the received signal from the target is s (n), the reference signal h (0) to h (P-1) is the signal s. The signal h (n) complex to (−n) is generated by selecting a portion having a length P in the pulse direction that can maximize the integral gain. For example, in the case of a rectangular wave, the integral gain G ′ in the equation (3) is maximized when M = N, and thus the reference signal length P is selected to be M. An example in the case of M = 10 is shown in FIG. The reference signals h (0) to h (P-1) generated by the reference signal generator 13 are sent to the convolution calculator 12.

  The convolution operation unit 12 performs a convolution operation on the signal transmitted from the unwanted wave suppression device 9 and the reference signal generated by the reference signal generation unit 13 and outputs the operation result to the outside. The operation results output from the convolution operation devices 10-1 to 10-n configured as described above are sent to the CFAR devices 7-1 to 7-n, respectively.

  Each of the CFAR devices 7-1 to 7-n detects the signal having the amplitude and phase output from the convolution operation unit 12 (converts it into a signal having only amplitude information), and determines the signal amplitude of the pulses around the target range bin. A reference amplitude is calculated, and an amplitude ratio signal is output as a signal representing the ratio of the target range bin amplitude to the reference amplitude. The amplitude ratio signals generated by the CFAR devices 7-1 to 7-n are sent to the detection devices 8-1 to 8-n, respectively.

  The detection devices 8-1 to 8-n detect signals that exceed the threshold among the amplitude ratio signals from the CFAR devices 7-1 to 7-n, respectively. Here, when the target helicopter is the type j (1 ≦ j ≦ n), the SN ratio of the output signal from the convolution operation device 10-j is maximized.

  Next, the operation of the first target detection devices 19-1 to 19-l configured as described above will be described. Since the operations of the first target detection devices 19-2 to 19-1 are the same as the operation of the first target detection device 19-1, only the operation of the first target detection device 19-1 will be described below. .

  First, the reflected wave received by the antenna 1 is sent to the receiver 4 via the circulator 3 as a received signal. The receiver 4 generates a digital video signal based on the received signal from the circulator 3 and sends it to the unnecessary wave suppressing device 9. The unnecessary wave suppression device 9 suppresses the unnecessary wave component included in the digital video signal from the receiver 4 and sends it to the convolution operation device 10-1.

The convolution operation device 10-1 performs a convolution operation on the signal in which the unnecessary wave component transmitted from the unnecessary wave suppression device 9 is suppressed and the reference signal generated by the reference signal generation unit 13. Now, let x (n) be an input signal of the convolution operation device 10-1, h (0) to h (P-1) as reference signals, and y (n) as an output signal of the convolution operation device 10-1. The output signal y (n) of the arithmetic device 10-1 is obtained by the following equation (4).

  For this reason, in the convolution period, the relationship between the input signals x (n) to x (n−P + 1) and the reference signals h (0) to h (P−1) of the convolution operation device 10-1 is complex conjugate. (Amplitudes only need to have a relative relationship that coincides with each other.) The output y (n) from the convolution operation device 10-1 increases. As a result, the SN ratio of the input signal can be improved.

  The calculation result in the convolution calculation unit 12 is sent to the CFAR device 7-1. The CFAR device 7-1 generates the above-described amplitude ratio signal and sends it to the detection device 8-1. The detection device 8-1 detects a signal exceeding the threshold value among the amplitude ratio signals from the CFAR device 7-1 as a target.

  Each of the first target detection devices 19-1 to 19-1 configured as described above performs a plurality of convolution operations for performing a convolution operation on the output signal of the unwanted wave suppression device 9 with a plurality of reference signals. By providing the devices 10-1 to 10-n, it is possible to obtain a reference signal that maximizes the SN ratio of received signals obtained from a plurality of types of helicopters. However, since the first target detection devices 19-1 to 19-l include a plurality of convolution operation devices 10-1 to 10n, the scale becomes large. Therefore, it is suitable for a radar apparatus installed on the ground of a network radar system.

  FIG. 4 is a block diagram showing the configuration of the second target detection devices 20-1 to 20-m. Each of the second target detection devices 20-1 to 20-m includes an antenna 1, a transmitter 2, a circulator 3, a receiver 4, an unnecessary wave suppression device 9, a convolution operation device 10, a CFAR device 7, and a detection device 8. Has been.

  In the second target detection devices 20-1 to 20-m, the n convolution operation devices 10-1 to 10-n in each of the first target detection devices 19-1 to 19-l are one convolution operation device 10. N CFAR devices 7-1 to 7-n are replaced by one CFAR device 7, and n detection devices 8-1 to 8-n are replaced by one detection device 8. It is configured. The configuration and operation of the convolution operation device 10 are the same as the configuration and operation of each of the n convolution operation devices 10-1 to 10-n. The configuration and operation of the CFAR device 7 are the same as the configuration and operation of each of the n CFAR devices 7-1 to 7-n. The configuration and operation of the detection device 8 are the same as the configuration and operation of each of the n detection devices 8-1 to 8-n.

  In the second target detection devices 20-1 to 20-m configured as described above, reference signal control information for instructing the type of the reference signal that provides the maximum S / N ratio is transmitted from the reference signal control information generating device 18. Therefore, the second target detection devices 20-1 to 20-m detect the target based on the reference signal control information.

  According to this configuration, since the second target detection devices 20-1 to 20-m include only one convolution operation device 10, the scale is larger than that of the first target detection devices 19-1 to 19-l. Can be small. Therefore, it is suitable for a radar apparatus mounted on a moving body of a network radar system.

  In the target detection system configured as described above, when operating with one second target detection device, since the second target detection device does not include a plurality of convolution operation devices, the integration effect may not be maximized. is there. However, the first target detection devices 19-1 to 19-l perform a convolution operation on the reception signals from the plurality of types of helicopters using a plurality of types of reference signals, and maximize the SN ratio of the reception signals. The type of the reference signal that can be transmitted is sent to the reference signal control information generator 18. The reference signal control information generation device 18 instructs the second target detection device to generate a reference signal that provides the maximum S / N ratio with the first target detection device 19.

  The second target detection device 20 generates a reference signal based on the reference signal control information sent from the reference signal control information generation device 18, and performs a convolution operation. As a result, the second target detection device can obtain a reception signal having the maximum S / N ratio even though the second convolution calculation device 10 is not provided.

  For example, in a missile system, the first target detection device 19 is employed in a radar device with a small quantity and a relatively small shape / size / mass restriction, and a radio wave seeker with a large quantity and a large shape / size / mass restriction. By adopting the second target detection device 20 in a missile (guided bullet) equipped with a signal to noise ratio (S / N ratio) can be improved efficiently in the entire target detection system.

  As described above, according to the target detection system according to the first embodiment, the presence / absence of the target is determined based on the large signal obtained by the convolution operation between the received signal and the reference signal having a length that can maximize the integral gain. Since detection is performed, the signal-to-noise ratio (S / N ratio) of the received signal whose amplitude greatly changes with time and whose period of large amplitude is short can be improved. The reference signal control information generating device 18 is configured to instruct the convolution operation device 10 of the second target detection devices 20-1 to 20-m to indicate the type of reference signal used for the convolution operation. There is no need to provide a large number of convolutional operation devices corresponding to the types of signals. As a result, the structure of the second target detection devices 20-1 to 20-m is simplified and the size can be reduced, so that the entire target detection system can be reduced in size.

  Although the second target detection devices 20-1 to 20-m in the target detection system according to the first embodiment described above are configured to include one convolution operation device 10, the second target detection devices 20-1 to 20-m include a plurality of convolution operation devices. It can also be configured as follows. In this case, if the number of convolution operation devices of the second target detection devices 20-1 to 20-m is smaller than the number of convolution operation devices of the first target detection devices 19-1 to 19-l, the above-described effect can be obtained. can get.

  The target detection system according to the second embodiment of the present invention detects a target based on a signal obtained by performing inverse Fourier transform after multiplying a signal obtained by Fourier transforming a received signal and a reference signal subjected to Fourier transform. Is.

  FIG. 5 is a block diagram showing the configuration of the target detection system according to Embodiment 2 of the present invention. The target detection system includes a reference signal control information generation device 18, l (l is a positive integer) third target detection devices 21-1 to 21-l and m (m is a positive integer) fourth target detection. It is comprised from apparatus 22-1-22-m. The third target detection devices 21-1 to 21-l and the fourth target detection devices 22-1 to 22-m are configured by, for example, radar devices.

  The reference signal control information generation device 18 generates reference signal control information and sends it to the third target detection devices 21-1 to 21-l and the fourth target detection devices 22-1 to 22-m. The reference signal control information is information for instructing the types of reference signals to be used by the third target detection devices 21-1 to 21-l and the fourth target detection devices 22-1 to 22-m.

  The third target detection devices 21-1 to 21-l each perform Fourier transform (details will be described later) on a plurality of types of reference signals in accordance with the reference signal control information from the reference signal control information generation device 18. Then, the target is detected based on the result, and the type of the reference signal from which the maximum S / N ratio is obtained is sent to the reference signal control information generator 18. The reference signal control information generating device 18 generates reference signal control information indicating the type of the reference signal from which the maximum S / N ratio sent from the third target detection devices 21-1 to 21-l is obtained, and the fourth It sends to the target detection devices 22-1 to 22-m.

  The fourth target detection devices 22-1 to 22-m perform a Fourier transform on the reference signal from which the maximum S / N ratio is obtained according to the reference signal control information from the reference signal control information generation device 18, A target is detected based on the result.

  FIG. 6 is a block diagram showing a configuration of the third target detection devices 21-1 to 21-l. In the following, the parts corresponding to the constituent parts of the first target detection devices 19-1 to 19-l of the target detection system according to the first embodiment are used in the first target detection devices 19-1 to 19-l. The same reference numerals as those in FIG.

  Each of the third target detection devices 21-1 to 21-l includes an antenna 1, a transmitter 2, a circulator 3, a receiver 4, an unnecessary wave suppression device 9, Fourier transform devices 11-1 to 11-n, and a CFAR device 7. -1 to 7-n and detection devices 8-1 to 8-n.

  FIG. 7 is a block diagram showing a detailed configuration of each of the Fourier transform apparatuses 11-1 to 11-n. In addition, since the structure of the Fourier-transform apparatus 11-2 to 11-n is the same as the structure of the Fourier-transform apparatus 11-1, below, only the Fourier-transform apparatus 11-1 is demonstrated. The Fourier transform device 11-1 includes a Fourier transform unit 14, a Fourier transform reference signal generation unit 15, a multiplication unit 16, and an inverse Fourier transform unit 17.

  The Fourier transform unit 14 performs Fourier transform on the signal sent from the unwanted wave suppression device 9 by FFT. The output of the Fourier transform unit 14 is sent to the multiplication unit 16.

  The Fourier transform reference signal generator 15 generates a signal obtained by Fourier transforming a reference signal simulating the amplitude and phase of a received signal from a target to be detected, according to reference signal control information from the reference signal control information generator 18. . The Fourier-transformed reference signal generated by the Fourier-transform reference signal generator 15 is sent to the multiplier 16.

  The multiplication unit 16 multiplies the Fourier-transformed signal sent from the Fourier transform unit 14 and the Fourier-transformed reference signal sent from the Fourier transform reference signal generation unit 15. The multiplication result in the multiplication unit 16 is sent to the inverse Fourier transform unit 17.

  The inverse Fourier transform unit 17 performs an inverse Fourier transform on the signal transmitted from the multiplication unit 16 by IFFT (Inverse Fast Fourier Transform). The result of the inverse Fourier transform in the inverse Fourier transform unit 17 is output to the outside.

  The operations of the third target detection devices 21-1 to 21-l of the target detection system according to the second embodiment are the same as those of the target detection system according to the first embodiment except that Fourier transform is performed instead of the convolution calculation. The operation is the same as that of the first target detection devices 19-1 to 19-l. That is, the Fourier transform devices 11-1 to 11-n respectively generate signals obtained by Fourier transforming the reference signals corresponding to the n types of helicopters, and multiplying the output signal of the unwanted wave suppression device 9 by the signal obtained by Fourier transform. Inverse Fourier transform is performed. The outputs of the Fourier transform devices 11-1 to 11-n are sent to the CFAR devices 7-1 to 7-n, respectively.

  Each of the third target detection devices 21-1 to 21-1 configured as described above has a plurality of Fourier transform devices 11-1 to 11-n that perform Fourier transform on the output signal of the unnecessary wave suppression device 9. It is possible to obtain a reference signal that maximizes the SN ratio of received signals obtained from a plurality of types of helicopters. However, since the third target detection devices 21-1 to 21-l include a plurality of Fourier transform devices 11-1 to 11n, the scale becomes large. Therefore, it is suitable for a radar apparatus installed on the ground of a network radar system.

  FIG. 8 is a block diagram showing a configuration of the fourth target detection devices 22-1 to 22-m. Each of the fourth target detection devices 22-1 to 22-m includes an antenna 1, a transmitter 2, a circulator 3, a receiver 4, an unnecessary wave suppression device 9, a Fourier transform device 11, a CFAR device 7, and a detection device 8. It is configured.

  In the fourth target detection devices 22-1 to 22-m, the n Fourier transform devices 11-1 to 11-n in the third target detection devices 21-1 to 21-l are replaced with one Fourier transform device 11. N CFAR devices 7-1 to 7-n are replaced with one CFAR device 7, and n detecting devices 8-1 to 8-n are replaced with one detecting device 8. ing. The configuration and operation of the Fourier transform device 11 are the same as the configuration and operation of each of the n Fourier transform devices 11-1 to 11-n. The configuration and operation of the CFAR device 7 are the same as the configuration and operation of each of the n CFAR devices 7-1 to 7-n. The configuration and operation of the detection device 8 are the same as the configuration and operation of each of the n detection devices 8-1 to 8-n.

  In the fourth target detection devices 22-1 to 22-m configured as described above, reference signal control information for instructing the type of the reference signal that provides the maximum S / N ratio is transmitted from the reference signal control information generating device 18. Therefore, the fourth target detection devices 22-1 to 22-m detect the target based on this reference signal control information.

  According to this configuration, since the fourth target detection devices 22-1 to 22-m include only one Fourier transform device 11, the scale is larger than that of the third target detection devices 21-1 to 21-l. Can be small. Therefore, it is suitable for a radar apparatus mounted on a moving body of a network radar system.

  As described above, according to the target detection system according to the second embodiment, the third target detection devices 21-1 to 21-l and the fourth target detection devices 22-1 to 22-m perform Fourier transform on received signals. The presence / absence of the target is detected based on the large signal obtained by performing the inverse Fourier transform after multiplying the obtained signal and the reference signal subjected to the Fourier transform having a length capable of maximizing the integral gain. In addition, processing equivalent to the convolution operation is performed by using IFFT, but when the data length of the reference signal is long, the calculation amount can be reduced as compared with the convolution operation. Further, the reference signal control information generation device 18 instructs the Fourier transform devices 11-1 to 11-n of the fourth target detection devices 22-1 to 22-m to specify the type of reference signal used for multiplication. Since it is configured, it is not necessary to provide a large number of Fourier transform devices corresponding to the types of reference signals. As a result, the structure of the fourth target detection devices 22-1 to 22-m is simplified and can be reduced in size, so that the entire target detection system can be reduced in size.

  In the target detection system according to the second embodiment described above, each of the Fourier transform apparatuses 11-1 to 11-n is configured to Fourier transform the output signal of the unnecessary wave suppression apparatus 9, but the Fourier transform apparatus 11 Any of -1 to 11-n can be configured to Fourier transform the output signal of the unwanted wave suppression device, and the other Fourier transform device can input the output signal. According to this configuration, the calculation load of Fourier transform can be reduced.

  The present invention is applicable to a missile system including a radar device and a radio wave seeker, a network radar system including a plurality of radar devices, and the like.

It is a block diagram which shows the structure of the target detection system which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the 1st target detection apparatus used with the target detection system which concerns on Example 1 of this invention. It is a block diagram which shows the detailed structure of the convolution operation apparatus used with the target detection system which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the 2nd target detection apparatus used with the target detection system which concerns on Example 1 of this invention. It is a block diagram which shows the structure of the target detection system which concerns on Example 2 of this invention. It is a block diagram which shows the detailed structure of the convolution operation apparatus used with the target detection system which concerns on Example 2 of this invention. It is a block diagram which shows the detailed structure of the Fourier-transform apparatus used with the target detection system which concerns on Example 2 of this invention. It is a block diagram which shows the structure of the 2nd target detection apparatus used with the target detection system which concerns on Example 2 of this invention. It is a block diagram which shows the structure of the conventional target detection system. It is a figure which shows the example of calculation of integral gain G and integral gain G '.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Transmitter 3 Circulator 4 Receiver 5 MTI apparatus 6 Frequency analyzer 7, 7-1-7-n CFAR apparatus 8, 8-1-8-n Detector 9 Unwanted wave suppression apparatus 10, 10-1 10-n convolution operation device 11, 11-1 to 11 -n Fourier transform device 12 convolution operation unit 13 reference signal generation unit 14 Fourier transform unit 15 Fourier transformed reference signal generation unit 16 multiplication unit 17 inverse Fourier transform unit 18 Signal control information generators 19-1 to 19-l First target detectors 20-1 to 20-m Second target detectors 21-1 to 21-l Third target detectors 22-1 to 22-m Target detection device

Claims (4)

A target detection system comprising a target detection device and a reference signal control information generation device,
The target detection device includes:
A receiver that converts a received signal obtained by receiving a reflected wave of a transmitted wave transmitted to space into a digital video signal;
An unnecessary wave suppressing device for suppressing unnecessary wave components from the digital video signal output from the receiver;
A reference signal having a length in a pulse direction that is a complex conjugate for each pulse of a received signal from a target to be detected and has a maximum integral gain with respect to the signal in which the unwanted wave component is suppressed by the unwanted wave suppressing device; A convolution operation device that performs a convolution operation between
A detection device that detects a signal of a reflected wave from a target based on a signal output from the convolution operation device;
The reference signal control information generating device instructs a convolution operation device of the target detection device to specify a type of reference signal used for convolution operation. The convolution operation device of the target detection device is:
The target detection system according to claim 1, wherein a convolution operation is performed on a signal whose unnecessary wave component is suppressed by the unnecessary wave suppression device with a plurality of types of reference signals. A target detection system comprising a target detection device and a reference signal control information generation device,
The target detection device includes:
A receiver that converts a received signal obtained by receiving a reflected wave of a transmitted wave transmitted to space into a digital video signal;
An unnecessary wave suppressing device for suppressing unnecessary wave components from the digital video signal output from the receiver;
The signal in which the unwanted wave component is suppressed by the unwanted wave suppression device is Fourier-transformed, and the length of the pulse direction that is a complex conjugate for each pulse of the received signal from the target to be detected and can maximize the integral gain. A Fourier transform device that performs an inverse Fourier transform after multiplying a signal having a signal obtained by performing a Fourier transform on the signal,
A detection device that detects a signal of a reflected wave from a target based on a signal output from the Fourier transform device;
The reference signal control information generation device instructs a Fourier transform device of the target detection device to specify the type of reference signal used for multiplication. The Fourier transform device of the target detection device is
The signal in which the unwanted wave component is suppressed by the unwanted wave suppression device is Fourier-transformed, and the length of the pulse direction that is a complex conjugate for each pulse of the received signal from the target to be detected and can maximize the integral gain. 4. The target detection system according to claim 3, wherein each of the plurality of types of reference signals obtained by performing Fourier transform on the received signal is multiplied, and then inverse Fourier transform is performed.

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