JP6289252B2 - Radar equipment - Google Patents

Description

  The present invention relates to a radar apparatus that identifies a target position from a delay time from when a radio wave is emitted until a target reflected wave is received and the arrival direction of the reflected radio wave.

Conventionally, a radar apparatus using MIMO (Multi Input Multi Output) is known (for example, see Non-Patent Document 1).
FIG. 15 is a configuration diagram of a radar apparatus assuming such a conventional MIMO radar.
The illustrated radar apparatus includes linear FM transmitters 101-1 to 101-N, antennas 102-1 to 102-N, circulators 103-1 to 103-N, receivers 104-1 to 104-N, and A / D. Converters 105-1 to 105-N, pulse compression units 106-1 to 106-N, Doppler correction type waveform synthesis units 107-1 to 107-N, a beam generation unit 108, and a target detection unit 109 are provided.

  The linear FM transmitters 101-1 to 101-N are transmitters for transmitting radio waves subjected to linear frequency modulation from the antennas 102-1 to 102-N with a preset time difference. The antennas 102-1 to 102-N are antennas for transmitting and receiving radio waves, and the circulators 103-1 to 103-N are circulators for separating transmission and reception of radio waves. Receivers 104-1 to 104-N are receivers that perform band limitation and phase detection on radio waves received by antennas 102-1 to 102-N. The A / D converters 105-1 to 105-N are processing units that convert analog signals output from the receivers 104-1 to 104-N into digital signals. The pulse compression units 106-1 to 106-N are processing units that perform pulse compression assuming the waveform of the radio wave transmitted from the antennas 102-1 to 102-N. The Doppler correction type waveform synthesis units 107-1 to 107-N are processing units that synthesize a pulse compression signal by correcting a pulse compression signal assuming a Doppler shift of a target reflected wave. The beam generation unit 108 is a processing unit that generates a beam by coherently integrating the Doppler correction type waveform synthesis output signals from the Doppler correction type waveform synthesis units 107-1 to 107-N in the spatial direction. The target detection unit 109 is a processing unit that detects a target signal using a threshold set based on a false alarm probability for erroneously determining noise as a target signal for the beam generation output signal output from the beam generation unit 108.

FIG. 16 is a configuration diagram showing the pulse compression unit 106-n (1 ≦ n ≦ N).
As illustrated, the pulse compression unit 106-n includes a received signal FFT unit 110-n that performs FFT (Fast Fourier Transform) processing on an output signal from the A / D converter 105-n, and a linear FM. Output signals of the reference signal FFT units 111-n1 to 111-nN and the received signal FFT unit 110-n that perform FFT processing on the reference signals # 1 to #N output from the type transmitters 101-1 to 101-N, respectively. IFFT (Inverse) is applied to the output signals of the conventional multiplier circuits 112-n1 to 112-nN and the conventional multiplier circuits 112-n1 to 112-nN that multiply the complex conjugates of the output signals of the reference signal FFT units 111-n1 to 111-nN. IFFT units 113-n1 to 113-n that perform Fast Fourier Transform (Fast Fourier Transform) processing It is equipped with a.

Next, the operation will be described. Target reflected waves transmitted from the linear FM transmitter 101-n and the antenna 102-n and reflected by a target (not shown) are received by the antennas 102-1 to 102-N. FIG. 17 illustrates frequency modulation of radio waves transmitted from the linear FM transmitters 101-1 to 101-N.
The radio wave received by the antenna 102-n is subjected to band limitation and phase detection by the receiver 104-n, and transmitted to the A / D converter 105-n. The A / D converter 105-n converts the output signal of the receiver 104-n into a digital signal and outputs it. The output signal from the A / D converter 105-n is transmitted to the pulse compression unit 106-n. The output signal of the A / D converter 105-n is transmitted to the reception signal FFT unit 110-n. Reception signal FFT section 110-n performs an FFT process on the input reception signal. Here, the output signal of received signal FFT section 110-n represents the frequency spectrum of the output signal of A / D converter 105-n. Reference signal #m (1 ≦ m ≦ N) is transmitted to reference signal FFT sections 111-n1 to 111-nN. In the reference signal FFT unit 111-nm (1 ≦ m ≦ N), the reference signal #m is subjected to FFT processing. The output signal of the reference signal FFT unit 111-nm represents the frequency spectrum of the reference signal #m. The output signal of the reception signal FFT unit 110-n and the output signal of the reference signal FFT unit 111-nm are transmitted to the conventional multiplier circuits 112-n1 to 112-nN. In the conventional multiplication circuits 112-n1 to 112-nN, the complex conjugate of the output signal of the received signal FFT unit 110-n and the output signal of the reference signal FFT units 111-n1 to 111-nN is multiplied. Output signals of conventional multiplier circuits 112-n1 to 112-nN are transmitted to IFFT units 113-n1 to 113-nN. In the IFFT units 113-n1 to 113-nN, IFFT processing is performed on the conventional multiplier circuits 112-n1 to 112-nN to generate waveform # n1 to #nN pulse compression signals. The waveform # n1 to #nN pulse compression signals are transmitted to the Doppler correction type waveform synthesis unit 107-n (1 ≦ n ≦ N).

In the Doppler correction type waveform synthesizer 107-n, the signal component of the k range bin in the waveform #nm pulse compression signal is set to sn _{, m , k} , and the Doppler effect is _{obtained with} respect to sn _{, 1, k} , ..., sn _{, N, k.} FFT for correcting coherent integration by correcting the phase rotation caused is performed. The signals subjected to the FFT are represented by un _{, 1, k} , ..., un _{, M, k} . The output signals un _{, m, k} (1 ≦ m ≦ M) of the Doppler correction type waveform synthesis unit 107-n are transmitted to the beam generation unit 108. The beam generator 108 performs FFT on u1 _{, m, k} ,..., UN _{, m, k} , corrects the phase rotating in the spatial direction depending on the direction of arrival of radio waves, and performs coherent integration. FFT is performed to generate signals x1 _{, m, k} ,..., XN _{, m, k} . A beam is formed by the spatial direction FFT, and a target signal is separated for each direction of arrival with a resolution of the beam width. The output signals _{xn, m, k} of the beam generator 108 are transmitted to the target detector 109. The target detection unit 109 compares the absolute value | x _{n, m, k} | of the output signal of the beam generation unit 108 with a threshold set based on a false alarm probability for erroneously determining noise as a target signal. A signal exceeding the threshold is determined as a target signal.

G. Babur, O.A. Krasnov, A. Yarovoy, P. Aubry, “Nearly Orthogonal Waveforms for MIMO FMCW Radar,” IEEE Trans. On aerospace and electronic systems, vol.49, no.3, July 2013.

  However, in the conventional configuration as described above, the signal input to the beam generation unit 108 is three-dimensional data of the range bin number k, the Doppler bin number m, and the antenna number n, and the beam generation is related to the two-dimensional data of the range and the Doppler. Therefore, there is a problem that the processing load becomes heavy.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a radar apparatus capable of reducing the processing load.

  The radar apparatus according to the present invention cyclically shifts a waveform subjected to linear frequency modulation in the time direction and transmits the uncorrelated radio waves simultaneously from a plurality of antennas, and the transmitted radio waves are reflected on the target. Synthesizing the target reflected wave by performing pulse compression that corrects the effect of the Doppler effect, assuming the waveform of the radio wave transmitted from multiple antennas, for the transmission / reception unit that receives the radio wave and the received signal of the transmission / reception unit A processing unit and a detection processing unit for detecting a target from the output signal of the synthesis processing unit are provided.

  The radar apparatus of the present invention generates uncorrelated waveforms by cyclically shifting a waveform subjected to linear FM modulation, transmits them at the same time, and waveforms of radio waves transmitted from a plurality of antennas. Since the target reflected wave is synthesized by performing pulse compression that corrects the influence of the Doppler effect, the processing load of the radar apparatus can be reduced.

It is a block diagram which shows the radar apparatus by Embodiment 1 of this invention. It is a block diagram which shows the Doppler correction type | mold pulse compression part of the radar apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the modulation | alteration of the waveform transmitted from each antenna of the radar apparatus by Embodiment 1 of this invention. It is explanatory drawing of the process which replaces | exchanges the order of the spectrum of the radar apparatus by Embodiment 1 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 2 of this invention. It is a block diagram which shows the 2nd Doppler correction type | mold pulse compression part of the radar apparatus by Embodiment 2 of this invention. It is explanatory drawing of the process which replaces | exchanges the order of the spectrum of the radar apparatus by Embodiment 2 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 3 of this invention. It is a block diagram which shows the 3rd Doppler correction type | mold pulse compression part of the radar apparatus by Embodiment 3 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 4 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 5 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 6 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 7 of this invention. It is a block diagram which shows the radar apparatus by Embodiment 8 of this invention. It is a block diagram which shows the conventional radar apparatus. It is a block diagram which shows the pulse compression part of the conventional radar apparatus. It is explanatory drawing which shows the frequency modulation of the electromagnetic wave transmitted of the conventional radar apparatus.

Embodiment 1 FIG.
1 is a block diagram showing a radar apparatus according to Embodiment 1 of the present invention.
The radar apparatus shown in FIG. 1 includes FM transmitters 1-1 to 1-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, A / D converters 5-1 to 5-N, Doppler correction type pulse compression units (first Doppler correction type pulse compression units) 6-1 to 6-N, waveform synthesis units 7-1 to 7-N, beam generation units (First beam generation unit) 8 and target detection unit 9 are provided. Here, FM transmitters 1-1 to 1-N to receivers 4-1 to 4-N constitute a transmission / reception unit, and A / D converters 5-1 to 5-N to waveform synthesis unit 7-1. ~ 7-N constitutes a synthesis processing unit. The beam generation unit 8 and the target detection unit 9 constitute a detection processing unit.

  Antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, A / D converters 5-1 to 5-N, beam generation unit 8, and target detection unit 9 Are antennas 102-1 to 102-N, circulators 103-1 to 103-N, receivers 104-1 to 104-N, A / D converters 105-1 to 105-N, beam generation shown in FIG. Since this is the same as the unit 108 and the target detection unit 109, description thereof is omitted here.

  The FM transmitters 1-1 to 1-N make the radio waves transmitted from the antennas 2-1 to 2-N uncorrelated with each other by cyclically shifting the waveform subjected to linear FM modulation in the time direction. It is a transmitter. The Doppler correction type pulse compression units 6-1 to 6-N are processing units that perform pulse compression by correcting the phase rotation of the target reflected wave of each antenna transmission caused by the Doppler effect. For details, see FIG. Will be described later. The waveform synthesis units 7-1 to 7-N are processing units that correct and synthesize different phases for each antenna transmission waveform depending on the target distance.

  FIG. 2 is a configuration diagram showing the Doppler correction type pulse compression unit 6-n (1 ≦ n ≦ N). The illustrated Doppler correction type pulse compression unit 6-n includes a reception signal FFT unit (first reception signal FFT unit) 10-n and a reference signal FFT unit (first reference signal FFT unit) 11-n1 to 11-nN. , Phase correction type multiplication circuits 12-n1 to 12-nN and IFFT units 13-n1 to 13-nN. Here, the received signal FFT unit 10-n, the reference signal FFT units 11-n1 to 11-nN, and the IFFT units 13-n1 to 13-nN are respectively the received signal FFT unit 110-n and the reference signal FFT unit in FIG. 111-n1 to 111-nN and IFFT units 113-n1 to 113-nN are the same as those in FIG. The phase correction type multiplying circuits 12-n1 to 12-nN multiply the output signal of the reception signal FFT unit 10-n by the complex conjugate of the output signals of the reference signal FFT units 11-n1 to 11-nN, and then the spectral order. Is an arithmetic circuit for correcting the phase difference of the target reflected wave of each antenna transmission caused by the target distance.

  Next, the operation of the radar apparatus according to the first embodiment will be described. Radio waves having a waveform obtained by cyclically shifting the waveform subjected to linear FM modulation in the time direction are transmitted from the antennas 2-1 to 2-N from the FM transmitters 1-1 to 1-N. FIG. 3 shows the modulation of the waveform transmitted from the antennas 2-1 to 2-N. A radio wave subjected to FM modulation indicated by a solid line 301 is transmitted from the antenna 2-1. In addition, a radio wave subjected to FM modulation indicated by a dotted line 302 is transmitted from the antenna 2-2. The FM modulation of the dotted line 302 is obtained by cyclically shifting the FM modulation of the solid line by shifting by Tp / N (Tp: pulse width). Similarly, a modulated radio wave indicated by an alternate long and short dash line 303 obtained by cyclically shifting the FM modulation of the solid line 301 by 2Tp / N is transmitted from the antenna 2-3, and the FM modulation of the solid line 301 is transmitted from the antenna 2-N. Is modulated by a wave indicated by a broken line 304 that is cyclically shifted by shifting (N−1) Tp / N.

  Thereafter, the operation is performed in the same manner as the conventional apparatus, and the radio wave from the antenna 2-n is received by the receiver 4-n, A / D converted by the A / D converter 5-n, and the Doppler correction type pulse compression unit 6- n is transmitted to the phase correction type multiplying circuit 12-nm (1 ≦ m ≦ N). In the phase correction type multiplying circuit 12-nm, the output signal of the received signal FFT unit 10-n is multiplied by the complex conjugate of the output signal of the reference signal FFT unit 11-nm, and then the spectrum order as shown in FIG. 4 is exchanged. And output. The phase rotation due to the Doppler effect is corrected by exchanging the spectral order.

そして、次式（２）により波形を合成した信号ｙ_ｎ，ｋ（１≦ｍ≦Ｍ）を生成する。

The waveform #nm pulse compression signal sn _{, m, k} of the phase correction type multiplier circuit 12-nm is transmitted to the waveform synthesizer 7-n. In the waveform synthesizer 7-n, the waveform nm pulse compression signal s _{n, m, k} is multiplied by Δm _{, k} expressed by the following equation to correct the phase rotation depending on the target distance. In the following equation (1), mod (k, N) represents a function that outputs the remainder when k is divided by N.

And the signal yn _{, k} (1 <= m <= M) which synthesize | combined the waveform by following Formula (2) is produced | generated.

The output signal of the waveform synthesizer 7-n is transmitted to the beam generator 8. The beam generating unit 8, a conventional apparatus and in the same _{manner, y 1, k, ...,} y N, FFT alms _k, beam generating signals _x 1, k, _{..., x N,} to produce a _k. The beam generation signals x _{1, k} ,..., X _{N, k} are transmitted to the target detection unit 9 and operate in the same manner as in the conventional apparatus to detect the target.

  As described above, in the first embodiment, it is not necessary to correct the phase rotation caused by the Doppler effect, and the output signal of the waveform synthesis unit 7-n input to the beam generation unit 8 becomes one-dimensional data of the range bin number k. The processing load for beam generation can be reduced.

  In the above example, the radio waves transmitted from the FM transmitters 1-1 to 1-N are uncorrelated with each other. However, an effect is obtained that the phase rotation due to the Doppler effect does not depend on the antenna transmission waveform. If so, a waveform having a small cross-correlation may be generated, and such a process for reducing the cross-correlation is also included in the non-correlation process.

  As described above, according to the radar apparatus of the first embodiment, the waveform subjected to linear FM modulation is cyclically shifted in the time direction and simultaneously transmitted from each antenna to transmit uncorrelated radio waves, Transmitter / receiver that receives the radio waves reflected by the target, and pulse compression that corrects the Doppler effect for the received signals of the transmitter / receiver assuming the waveforms of the radio waves transmitted from multiple antennas. Thus, the processing load of the radar apparatus can be reduced because the synthesis processing unit for synthesizing the target reflected wave and the detection processing unit for detecting the target from the output signal of the synthesis processing unit are provided.

  Further, according to the radar apparatus of the first embodiment, the synthesis processing unit performs a Doppler correction type pulse compression unit that performs pulse compression by exchanging the spectrum order with respect to the received signal of the transmission / reception unit, and a Doppler correction type pulse compression. Since the output signal of the unit is provided with a waveform synthesis unit that corrects and synthesizes the phase of the target reflected wave that differs for each antenna transmission waveform depending on the target distance, the processing load can be reduced.

  Further, according to the radar apparatus of the first embodiment, the detection processing unit erroneously detects noise as a target signal from a beam generation unit that generates a beam by coherent integration in a spatial direction, and a signal generated by the beam generation unit. Since a target detection unit that detects a target using a threshold set based on a false alarm probability to be determined is provided, the processing load can be reduced.

  Further, according to the radar apparatus of the first embodiment, the Doppler correction type pulse compression unit includes the received signal FFT unit that performs the fast Fourier transform process on the input signal, and the fast Fourier transform on the reference signal output from the transmitter of the transmission / reception unit. A reference signal FFT unit that performs conversion processing, a phase correction type multiplication circuit that multiplies the output signal of the reception signal FFT unit by the complex conjugate of the output signal of the reference signal FFT unit, and then exchanges the order of the spectra, and phase correction type multiplication Since an IFFT unit that performs inverse fast Fourier transform processing on the output signal of the circuit is provided, phase rotation caused by the Doppler effect can be corrected.

Embodiment 2. FIG.
5 is a block diagram showing a radar apparatus according to Embodiment 2 of the present invention. The radar apparatus according to the second embodiment includes FM transmitters 1-1 to 1-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, and A. / D converters 5-1 to 5-N, second Doppler correction type pulse compression units 14-1 to 14-N, waveform synthesis units 7-1 to 7-N, beam generation unit 8, and target detection unit 9 Prepare. Here, the configuration other than the second Doppler correction type pulse compression units 14-1 to 14-N is the same as the configuration of the first embodiment shown in FIG. The description is omitted.

  The second Doppler correction type pulse compression units 14-1 to 14 -N are Doppler correction type pulse compression units that use a process (integral loss correction) for correcting a phase advanced due to the influence of the Doppler effect. As shown, the received signal FFT unit 10-n, the reference signal FFT units 11-n1 to 11-nN, the phase advance consideration type multiplier circuits 15-n1 to 15-nN, and the IFFT units 13a-n1 to 13a-nN, 13b- n1-13b-nN. Here, the reception signal FFT unit 10-n and the reference signal FFT units 11-n1 to 11-nN are the same as those in the first embodiment shown in FIG. Phase advance consideration multiplication circuits 15-n1 to 15-nN correct the phase of the output signal of reception signal FFT section 10-n and multiply the complex conjugate of the output signals of reference signal FFT sections 11-n1 to 11-nN. After that, the multiplication circuit considers the phase advance for exchanging the spectrum order. The IFFT units 13a-n1 to 13a-nN and 13b-n1 to 13b-nN respectively include no correction signals # n1 to #nN and phase advance corrections output from the phase advance consideration type multiplier circuits 15-n1 to 15-nN, respectively. An IFFT unit that performs IFFT processing on signals # n1 to #nN and outputs waveform # n1 to #nN pulse compression signals and waveform # n1 to #nN pulse compression signals (phase inversion).

  Next, the operation of the second embodiment will be described. Radio waves having a waveform obtained by cyclically shifting the waveform subjected to linear FM modulation in the time direction are transmitted from the antennas 2-1 to 2-N from the FM transmitters 1-1 to 1-N. Thereafter, the operation is the same as in the first embodiment, and the output signal of the A / D converter 5-n is input to the second Doppler correction type pulse compression unit 14-n. In the second Doppler correction type pulse compression unit 14-n, the output signal of the reception signal FFT unit 10-n and the output signal of the reference signal FFT unit 11-nm are input to the phase advance consideration type multiplication circuit 15-nm. The output signal of the reference signal FFT unit 11-nm is the frequency spectrum of the reference signal #m, and signal components are concentrated in the range of the transmission frequency band B.

In the phase advance consideration multiplication circuit 15-nm, as shown in FIG. 7, the frequency band is divided into an mB / N range and an (N−m) B / N range, and the mB / N range can be anything. First, the complex conjugation of the signal generated by multiplying the range of (N−m) B / N by −1 and the output signal of the received signal FFT unit 10-n are exchanged to replace the spectrum order, and then the integral loss correction is performed. The signal (phase advance correction signal) #nm is output. In addition, the correction no signal #nm generated by operating in the same manner as the phase correction type multiplication circuit 12-nm without being multiplied by -1 is also output. The IFFT section 13a-nm and the IFFT section 13b-nm are subjected to IFFT processing on the non-correction signal #nm and the integral loss correction signal #nm, respectively, and a signal (waveform) that has been subjected to pulse compression by correcting phase advance due to the Doppler effect. The # n1 to #nN pulse compression signals (phase inversion) and the signal (waveforms # n1 to #nN pulse compression signals) compressed without correction are transmitted to the waveform synthesis unit 7-n.
Thereafter, the operation is the same as in the first embodiment, and the target detection process when the phase advance due to the Doppler effect is corrected and the target detection process when the phase advance is not corrected are performed.

  Since the second embodiment is configured as described above, the integral loss that occurs depending on the target distance can be reduced, and the deterioration of the target detection performance can be prevented without lowering the signal-to-noise power ratio.

  As described above, according to the radar apparatus of the second embodiment, the Doppler correction type pulse compression unit uses the processing for correcting the phase advanced due to the influence of the Doppler effect, and thus depends on the target distance. The integral loss that occurs can be reduced.

  In addition, according to the radar apparatus of the second embodiment, the Doppler correction type pulse compression unit includes a received signal FFT unit that performs a fast Fourier transform process on an input signal, and a fast Fourier transform that is applied to a reference signal output from a transmitter of the transmission / reception unit. A phase advance-considering multiplication circuit that corrects the phase of the output signal of the received signal FFT unit by multiplying the complex conjugate of the output signal of the reference signal FFT unit after exchanging the order of the spectrum after performing the conversion process And an IFFT unit that performs inverse fast Fourier transform processing on the output signal of the phase advance-considering multiplication circuit, the integration loss that occurs depending on the target distance can be reduced, and the signal-to-noise power ratio is reduced. Therefore, deterioration of target detection performance can be prevented.

Embodiment 3 FIG.
FIG. 8 is a block diagram showing a radar apparatus according to Embodiment 3 of the present invention. The radar apparatus according to Embodiment 3 includes FM transmitters 1-1 to 1-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, and A. / D converters 5-1 to 5-N, third Doppler correction type pulse compression units 16-1 to 16-N, waveform synthesis units 7-1 to 7-N, beam generation unit 8, and target detection unit 9 Prepare. Here, except for the third Doppler correction type pulse compression units 16-1 to 16-N, the configuration is the same as that of the first embodiment shown in FIG. Description is omitted.

  The third Doppler correction type pulse compression units 16-1 to 16-N perform Doppler that performs high-precision distance measurement by making the target distance setting interval assumed when performing pulse compression smaller than the distance resolution determined by the bandwidth. As shown in FIG. 9, the correction type pulse compression unit includes a second reception signal FFT unit 17-n, second reference signal FFT units 18-n1 to 18-nN, and phase correction type multiplication circuits 12-n1 to 12-n1. 12-nN and IFFT units 13-n1 to 13-nN. The second reception signal FFT unit 17-n performs zero padding interpolation to add a series of 0 to the input signal, and then performs FFT to shorten the interval between adjacent reception signal spectra and to receive the reception signal with high accuracy. An FFT unit for obtaining a spectrum. The second reference signal FFT units 18-n1 to 18-nN are FFT units that obtain a reference signal spectrum with high accuracy by performing zero-padded interpolation on an input signal and performing FFT. Further, the phase correction type multiplying circuits 12-n1 to 12-nN and the IFFT units 13-n1 to 13-nN have the same configuration as that of the first embodiment.

  Next, the operation of the third embodiment will be described. Radio waves having a waveform obtained by cyclically shifting the waveform subjected to linear FM modulation in the time direction are transmitted from the antennas 2-1 to 2-N from the FM transmitters 1-1 to 1-N. Thereafter, the operation is the same as in the first embodiment, and the output signal of the A / D converter 5-n is transmitted to the second received signal FFT unit 17-n of the third Doppler correction type pulse compression unit 16-n. The The second received signal FFT unit 17-n performs zero padding interpolation for adding a 0 series to the output signal of the A / D converter 5-n, and then obtains a received signal spectrum by FFT. Further, the reference signal #m (1 ≦ m ≦ N) is transmitted to the second reference signal FFT unit 18-nm. The second reference signal FFT unit 18-nm obtains the reference signal spectrum with high accuracy by performing zero-padded interpolation on the reference signal #m and performing FFT. Thereafter, the target is detected by operating in the same manner as in the first embodiment.

  Since the third embodiment is configured as described above, the interval between adjacent reception signal spectra in the second reception signal FFT unit 17-n is shortened, and the second reference signal FFT unit 18-nm is used. The target distance can be obtained with high accuracy by pulse compression due to the effect of shortening the interval between adjacent reference signal spectra.

  As described above, according to the radar apparatus of the third embodiment, the Doppler correction type pulse compression unit makes the target distance setting interval assumed when performing pulse compression smaller than the distance resolution determined by the bandwidth. Therefore, the target distance can be obtained with high accuracy.

  Further, according to the radar apparatus of the third embodiment, the Doppler correction type pulse compression unit performs a zero-padded interpolation for adding a sequence of 0 to the input signal, and then performs a fast Fourier transform process on the received signal FFT unit. A reference signal FFT unit that performs zero-padded interpolation on the reference signal output from the transmitter of the transmission / reception unit and performs fast Fourier transform processing, and corrects the phase of the output signal of the reception signal FFT unit to correct the output signal of the reference signal FFT unit After multiplying the complex conjugate, a phase advance consideration type multiplication circuit that exchanges the order of the spectrum and an IFFT unit that performs inverse fast Fourier transform processing on the output signal of the phase advance consideration type multiplication circuit are provided. The accuracy can be obtained.

Embodiment 4 FIG.
FIG. 10 is a block diagram showing a radar apparatus according to Embodiment 4 of the present invention. The radar apparatus according to the fourth embodiment includes FM transmitters 1-1 to 1-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, and A. / D converters 5-1 to 5-N, Doppler correction type pulse compression units 6-1 to 6-N, waveform synthesis units 7-1 to 7-N, second beam generation unit 19, and target detection unit 9 Prepare. Here, since the configuration other than the second beam generation unit 19 is the same as the configuration of the first embodiment shown in FIG. 1, the same reference numerals are given to the corresponding portions, and the description thereof is omitted.

  The second beam generation unit 19 is a high-precision beam generation unit that performs high-precision angle measurement by reducing the interval between adjacent beams when generating a beam.

Next, the operation of the fourth embodiment will be described. Radio waves having a waveform obtained by cyclically shifting the waveform subjected to linear FM modulation in the time direction are transmitted from the antennas 2-1 to 2-N from the FM transmitters 1-1 to 1-N. Thereafter, the operation is performed in the same manner as in the first embodiment, and the second beam generation unit 19 acquires the output signals y _{1, k} ,..., Y _{N, k} of the waveform synthesis unit 7-n (1 ≦ n ≦ N). To do. In the second beam generation unit 19, a zero sequence is added to y _{1, k} ,..., Y _{N, k} to perform zero padding interpolation, and then FFT is performed to obtain signals x _{1, m, k} ,. _{N0, m, k} are generated. Here, N0 represents the number of N + 0 added. Thereafter, the operation is performed in the same manner as in the first embodiment, and the target is detected.

  Since the fourth embodiment is configured as described above, the second beam generation unit 19 can shorten the interval between adjacent beams, and can perform highly accurate angle measurement.

Embodiment 5. FIG.
FIG. 11 is a block diagram showing a radar apparatus according to Embodiment 5 of the present invention. The radar apparatus according to the fifth embodiment includes FM transmitters 1-1 to 1-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, and A. / D converters 5-1 to 5-N, Doppler correction type pulse compression units 6-1 to 6-N, waveform synthesis units 7-1 to 7-N, beam generation unit 8, and search distance limited target detection unit 20 Prepare. Here, since the configuration other than the search distance limited target detection unit 20 is the same as the configuration of the first embodiment, the corresponding parts are denoted by the same reference numerals and the description thereof is omitted. The search distance limited target detection unit 20 is a target detection unit that limits the distance range to be searched.

  Next, the operation of the fifth embodiment will be described. Radio waves having a waveform obtained by cyclically shifting the waveform subjected to linear FM modulation in the time direction are transmitted from the antennas 2-1 to 2-N from the FM transmitters 1-1 to 1-N. Thereafter, the operations up to the beam generator 8 are the same as those in the first embodiment. In the fifth embodiment, the output signal of the beam generator 8 is transmitted to the search distance limited target detector 20. The search distance limited target detection unit 20 is provided with a distance range to search in advance, and performs a target search for the distance range to detect the target.

  As described above, according to the radar apparatus of the fifth embodiment, the target detection unit performs the target detection by limiting the distance range to be searched. Therefore, the processing load is increased by searching only the limited distance range. Can be reduced.

Embodiment 6 FIG.
FIG. 12 is a block diagram showing a radar apparatus according to Embodiment 6 of the present invention. The radar apparatus according to the sixth embodiment includes FM transmitters 1-1 to 1-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, receivers 4-1 to 4-N, and A. / D converters 5-1 to 5-N, Doppler correction type pulse compression units 6-1 to 6-N, waveform synthesis units 7-1 to 7-N, beam generation unit 8, and search angle limited target detection unit 21 Prepare. Here, since the configuration other than the search angle limited target detection unit 21 is the same as the configuration of the first embodiment, the corresponding parts are denoted by the same reference numerals and the description thereof is omitted. The search angle limited target detection unit 21 is a target detection unit that limits the search angle range.

  Next, the operation of the sixth embodiment will be described. Radio waves having a waveform obtained by cyclically shifting the waveform subjected to linear FM modulation in the time direction are transmitted from the antennas 2-1 to 2-N from the FM transmitters 1-1 to 1-N. Thereafter, the operations up to the beam generator 8 are the same as those in the first embodiment. In the sixth embodiment, the output signal of the beam generator 8 is transmitted to the search angle limited target detector 21. The search angle limited target detection unit 21 is provided with an angle range to be searched in advance, and performs a target search for the angle range to detect a target.

  As described above, according to the radar apparatus of the sixth embodiment, the target detection unit performs the target detection by limiting the angle range to be searched. Therefore, the processing load is increased by searching only the limited angle range. Can be reduced.

Embodiment 7 FIG.
13 is a block diagram showing a radar apparatus according to Embodiment 7 of the present invention. The radar apparatus according to the seventh embodiment includes phase control FM transmitters 22-1 to 22-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, and receivers 4-1 to 4-N. A / D converters 5-1 to 5-N, pulse compression units 23-1 to 23-N, waveform synthesis units 7-1 to 7-N, a beam generation unit 8, and a target detection unit 9. Here, since the configuration other than the phase control FM transmitters 22-1 to 22-N and the pulse compression units 23-1 to 23-N is the same as the configuration of the first embodiment, the same reference numerals are used for the corresponding parts. The description is omitted. The phase control FM transmitters 22-1 to 22-N are phase control FM transmitters that adjust the initial phase so that the phase of each antenna transmission waveform at a certain reference time is equal. The pulse compression units 23-1 to 23 -N are pulse compression units having the same configuration as the pulse compression units 106-1 to 106 -N shown in FIG. 15, and the A / D converters 5-1 to 5 -N and A synthesis processing unit is configured together with the waveform synthesis units 7-1 to 7-N.

  Next, the operation of the seventh embodiment will be described. A radio wave having a waveform obtained by cyclically shifting a waveform subjected to linear FM modulation in the time direction by adjusting the initial phase so that the phases at a certain reference time are equal from the phase control FM transmitters 22-1 to 22-N. Are transmitted from the antennas 2-1 to 2-N. For example, since the target speed is known for a tracking target or the like, the initial phase can be adjusted so that the phase at a certain reference time becomes equal by correcting the target speed. Thereafter, the operation is the same as in the first embodiment, and is transmitted to the pulse compression units 23-1 to 23-N. The pulse compression processing in the pulse compression units 23-1 to 23-N operates in the same manner as in the prior art, and a pulse compression signal is output. Thereafter, the operation is performed in the same manner as in the first embodiment, and the target is detected.

  As described above, according to the radar apparatus of the seventh embodiment, the waveform subjected to the linear frequency modulation with the initial phase adjusted so that the phase of the reference time becomes equal is cyclically shifted in the time direction to obtain a plurality of waveforms. Transmitting and receiving radio waves that are uncorrelated with each other by simultaneously transmitting from the antennas, receiving a radio wave reflected by the target, a synthesis processing unit synthesizing the target reflected wave received by the transceiver, and combining Since the detection processing unit for detecting the target from the output signal of the processing unit is provided, the waveform can be synthesized without the influence of the Doppler effect by adjusting the initial phase.

Embodiment 8 FIG.
FIG. 14 is a block diagram showing a radar apparatus according to Embodiment 8 of the present invention. The radar apparatus according to the eighth embodiment includes phase control FM transmitters 22-1 to 22-N, antennas 2-1 to 2-N, circulators 3-1 to 3-N, and receivers 4-1 to 4-N. , A / D converters 5-1 to 5-N, pulse compression units 23-1 to 23-N, second waveform synthesis units 24-1 to 24-N, a beam generation unit 8, and a target detection unit 9. . Here, since the configuration other than the second waveform synthesis units 24-1 to 24-N is the same as the configuration of the seventh embodiment, the corresponding parts are denoted by the same reference numerals and the description thereof is omitted. The second waveform synthesis units 24-1 to 24-N are high-accuracy waveform synthesis units that correct the phase rotation caused by the target distance with high accuracy to reduce the loss of waveform synthesis.

Next, the operation of the eighth embodiment will be described. From the phase control FM transmitters 22-1 to 22 -N, the initial phase is adjusted so that the phases at a certain reference time are equal, and the waveform subjected to linear FM modulation is cyclically shifted in the time direction. Radio waves are transmitted from the antennas 2-1 to 2-N. Thereafter, the operation is the same as in the first embodiment, and is transmitted to the second waveform synthesis units 24-1 to 24-N. In the second waveform synthesis units 24-1 to 24-N, phase correction terms in a predetermined distance unit finer than the range resolution are prepared. Specifically, 'a phase correction for th target distance delta _{m, k, k'} k obtained by dividing the k range bin as, delta _{m, k} instead of delta _{m, k} of the formula _(2), the _{k '} Use to correct. Thereafter, the operation is performed in the same manner as in the first embodiment, and the target is detected.

  As described above, according to the radar apparatus of the eighth embodiment, the waveform synthesizer performs phase correction in units of distance finer than the range resolution, so that phase rotation caused by the target distance can be performed with high accuracy. Correction can reduce the loss of waveform synthesis.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  1-1 to 1-N FM transmitter, 2-1 to 2-N antenna, 3-1 to 3-N circulator, 4-1 to 4-N receiver, 5-1 to 5-N A / D Converter, 6-1 to 6-N Doppler correction type pulse compression unit, 7-1 to 7-N waveform synthesis unit, 8 beam generation unit, 9 target detection unit, 10-n reception signal FFT unit, 11-n1 11-nN reference signal FFT unit, 12-n1 to 12-nN phase correction type multiplier circuit, 13-n1 to 13-nN, 13a-n1 to 13a-nN, 13b-n1 to 13b-nN IFFT unit, 14-1 -14-N second Doppler correction type pulse compression unit, 15-n1 to 15-nN phase advance consideration type multiplication circuit, 16-1 to 16-N third Doppler correction type pulse compression unit, 17-n second Received signal FFT section, 18-n second reference signal FFT section, 9 second beam generation unit, 20 search distance limited target detection unit, 21 search angle limited target detection unit, 222-1 to 22-N phase control FM transmitter, 23-1 to 23-N pulse compression unit, 24 −1 to 24-N Second waveform synthesis unit.

Claims (13)

A transmission / reception unit that cyclically shifts a waveform subjected to linear frequency modulation and transmits uncorrelated radio waves by simultaneously transmitting from a plurality of antennas, and receiving the radio waves reflected by the target to the target; ,
A synthesis processing unit that synthesizes the target reflected wave by performing pulse compression that corrects the influence of the Doppler effect assuming the waveforms of radio waves transmitted from the plurality of antennas with respect to the reception signal of the transmission / reception unit;
A radar apparatus comprising: a detection processing unit that detects the target from an output signal of the synthesis processing unit. The synthesis processing unit
Doppler correction type pulse compression unit that performs pulse compression by exchanging spectrum order for the reception signal of the transmission / reception unit,
And a waveform synthesis unit for correcting and synthesizing a phase of a target reflected wave different for each antenna transmission waveform depending on a target distance with respect to an output signal of the Doppler correction type pulse compression unit. The radar apparatus according to 1. The detection processing unit
A beam generator for generating a beam by coherent integration in the spatial direction;
2. A target detection unit that detects a target using a threshold set based on a false alarm probability that erroneously determines noise as a target signal from the signal generated by the beam generation unit. The radar apparatus described. The Doppler correction type pulse compression unit is
A received signal FFT unit for performing a fast Fourier transform on the input signal;
A reference signal FFT unit that performs fast Fourier transform processing on the reference signal output from the transmitter of the transceiver unit;
A phase correction type multiplication circuit for exchanging the order of spectra after multiplying the output signal of the received signal FFT unit by the complex conjugate of the output signal of the reference signal FFT unit;
The radar apparatus according to claim 2, further comprising an IFFT unit that performs an inverse fast Fourier transform process on an output signal of the phase correction multiplier circuit.   The radar apparatus according to claim 2, wherein the Doppler correction type pulse compression unit also uses a process of correcting a phase advanced due to the influence of the Doppler effect. The Doppler correction type pulse compression unit is
A received signal FFT unit for performing a fast Fourier transform on the input signal;
A reference signal FFT unit that performs fast Fourier transform processing on the reference signal output from the transmitter of the transceiver unit;
A phase-advanced multiplication circuit that corrects the phase of the output signal of the received signal FFT unit and multiplies the complex conjugate of the output signal of the reference signal FFT unit, and then exchanges the order of the spectrum;
6. The radar apparatus according to claim 5, further comprising an IFFT unit that performs an inverse fast Fourier transform process on an output signal of the phase advance consideration type multiplication circuit.   The radar apparatus according to claim 2, wherein the Doppler correction type pulse compression unit makes a target distance setting interval assumed when performing pulse compression smaller than a distance resolution determined by a bandwidth. The Doppler correction type pulse compression unit is
A received signal FFT unit that performs fast Fourier transform processing after performing zero-padded interpolation to add a series of 0 to the input signal;
A reference signal FFT unit which performs fast Fourier transform processing by performing zero padding interpolation on the reference signal output from the transmitter of the transceiver unit;
A phase-advanced multiplication circuit that corrects the phase of the output signal of the received signal FFT unit and multiplies the complex conjugate of the output signal of the reference signal FFT unit, and then exchanges the order of the spectrum;
The radar apparatus according to claim 7, further comprising an IFFT unit that performs an inverse fast Fourier transform process on an output signal of the phase advance consideration type multiplication circuit.   The radar apparatus according to claim 3, wherein the target detection unit performs target detection by limiting a search distance range.   The radar apparatus according to claim 3, wherein the target detection unit performs target detection by limiting a search angle range. Sending uncorrelated radio waves by cyclically shifting the waveform subjected to linear frequency modulation with the initial phase adjusted so that the phase of the reference time is equal and cyclically shifting in the time direction from multiple antennas, A transmission / reception unit that receives the radio wave reflected by the target,
A synthesis processing unit that synthesizes the target reflected wave received by the transmission / reception unit;
A radar apparatus comprising: a detection processing unit that detects the target from an output signal of the synthesis processing unit. The synthesis processing unit
A pulse compression unit that performs pulse compression on a reception signal of the transmission / reception unit;
12. A waveform synthesis unit that corrects and synthesizes a phase of a target reflected wave that differs for each antenna transmission waveform depending on a target distance with respect to an output signal of the pulse compression unit. Radar device. The waveform synthesis section, claim 2, characterized in that the phase correction in finer units of distance than range resolution, a radar device according to any one of claims 8 and claims 1 2 to claim 4 .

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