JP2012112874A - Radar device - Google Patents

Abstract

A radar apparatus capable of measuring a target relative velocity using a two-dimensional Fourier transform from a complex multiplication result of signals transmitted and received using ascending and descending frequency sequences.
SOLUTION: A target relative speed information acquisition means 11, a transmission waveform controller 1 for generating transmission waveform specifications, an arbitrary frequency oscillator 2, a 90 degree hybrid device 7, a transmitter 3, and a transmitter 3 An antenna 4 for irradiating a signal to a target and receiving a reflected signal; a distributor 5; phase detectors 6a and 6b; low-pass filters 8a and 8b; and A / D converters 9a and 9b. A video signal storage means 10, a relative speed correction processor 12 that corrects a signal using the target relative speed Vd, a synthesis band processor 13, and a target detection processor 14 that measures a target distance R are provided.
[Selection] Figure 1

Description

  This invention measures a target relative speed (hereinafter referred to as “target relative speed”) based on a received signal (a reflected signal from a target), and performs synthetic band processing on the received signal to achieve high distance and high resolution. The present invention relates to a radar apparatus that measures a distance to a target (hereinafter referred to as “target distance”) and suppresses unnecessary reflected waves other than the target called clutter from a received signal.

In general, distance resolution is one of the main specifications of a radar apparatus, and conventionally, synthetic band processing is known as one of methods for increasing distance resolution.
In the synthesis band processing, transmission is performed by changing the transmission frequency step by step for each pulse, and down-conversion is performed on the received signal within the pulse repetition period (PRI) at the same frequency as the transmission signal. Thus, the video signal is acquired, and the video signal is subjected to inverse Fourier transform to achieve high resolution.

However, in the synthesis band process, an error occurs in the distance measurement result due to the influence of the target relative speed, so it is necessary to measure the target relative speed and correct the relative speed.
Therefore, a relative velocity measurement method using this type of synthetic band radar has been proposed (see, for example, Non-Patent Document 1).

FIG. 9 is an explanatory view showing a conventional relative velocity measuring method described in Non-Patent Document 1.
In FIG. 9, the horizontal axis represents time, the vertical axis represents transmission frequency, one square on the horizontal axis represents PRI (= T _PRI ), one square on the vertical axis represents step frequency Δf, and f ₀ represents the minimum transmission frequency. ing.
Further, black circles and white circles in FIG. 9 indicate transmission frequencies in each PRI, black circles indicate an ascending sequence, and white circles indicate a descending sequence.

  In the prior art shown in FIG. 9, transmission / reception is alternately performed in an ascending sequence and a descending sequence, the signals transmitted and received in the ascending sequence and the descending sequence are complex-multiplied, and the target relative velocity Vd is measured by Fourier transform.

  However, the non-patent document 1 only discloses a relative speed measurement method for a synthetic band radar using a simple ascending sequence and descending sequence. For example, the transmission interval between an ascending sequence and a descending sequence is changed. There is no mention of relative velocity measurement methods for different sequences.

  That is, a technique for measuring the target relative velocity Vd without using a simple ascending frequency sequence and descending frequency sequence in a radar apparatus that performs synthetic band processing has not yet been proposed.

"Highly accurate relative velocity measurement method for synthetic band radar" Kentaro Hamada, Teruyuki Hara, IEICE Technical Report, SANE 2009-134, paragraphs 7-12

  As described in Non-Patent Document 1, a conventional radar apparatus has proposed a target relative velocity measurement technique for a synthetic band radar using a simple ascending sequence and descending sequence. There has been a problem that a technique for measuring a target relative speed for a sequence with a different transmission interval has not been proposed.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain an excellent radar apparatus capable of measuring a target relative speed by synthetic band processing and measuring a target distance with high distance resolution. And

  The radar apparatus according to the present invention generates a transmission waveform specification by generating a transmission frequency sequence in which a predetermined frequency sequence and a frequency sequence different from the predetermined frequency sequence are alternately rearranged at a predetermined interval. A transmission waveform controller, an arbitrary frequency oscillator that oscillates transmission waveform specifications instructed by the transmission waveform controller, a 90-degree hybrid that rotates the phase of the oscillation signal oscillated by the arbitrary frequency oscillator by 90 degrees, and an oscillation signal A transmitter for pulsing the signal, an antenna for irradiating the signal pulsed by the transmitter to receive the signal reflected from the target, a distributor for distributing the signal received by the antenna, and a distributor A phase detector that performs frequency conversion using the oscillation signal and a signal rotated 90 degrees by a 90-degree hybrid device, and a signal that has been frequency-converted by the phase detector. A low-pass filter that cuts off frequency components other than the desired frequency band, an A / D converter that converts the output signal of the low-pass filter from an analog signal to a digital signal, and digitized by the A / D converter A video signal storage means for storing the received video signal, a target relative speed measurement processor for measuring a target relative speed using a two-dimensional Fourier transform from a complex multiplication result of the video signal in the video signal storage means, and a target relative speed Using the target relative speed obtained by the measurement processor, the relative speed correction processor that performs relative speed correction on the video signal in the video signal storage means, and the signal that is corrected by the relative speed correction processor. Synthetic band processor that performs distance high resolution processing and target detection processor that measures the target distance by detecting the target signal from the signal with high distance resolution by the synthetic band processor , It is those with a.

  According to the present invention, the complex relative result of signals transmitted and received using an ascending frequency sequence and a descending frequency sequence is measured for a target relative velocity by a synthesis band process using a two-dimensional Fourier transform, thereby obtaining a high distance resolution. The target distance can be measured.

1 is a block diagram showing a radar apparatus according to Embodiment 1 of the present invention. It is explanatory drawing which shows the transmission frequency sequence at the time of changing the transmission interval of the ascending order sequence and descending order sequence by Embodiment 1 of this invention. It is a block diagram which shows the radar apparatus which concerns on Embodiment 2 of this invention. Transmission frequency sequence F _m of the second embodiment of the present _invention, is an explanatory diagram showing an example of a case of using alternating G _m. It is explanatory drawing which shows the MTI filter characteristic by Embodiment 2 of this invention. FIG. 6 is an explanatory diagram showing an enlargement of the vicinity of 0 [m / s] of the filter characteristics of FIG. 5. It is explanatory drawing which shows the process outline | summary of the target relative speed measurement processor by Embodiment 2 of this invention. It is a block diagram which shows the radar apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows the conventional radar apparatus.

Embodiment 1 FIG.
The first embodiment of the present invention will be described below with reference to FIGS.
1 is a block diagram showing a radar apparatus according to Embodiment 1 of the present invention.
In FIG. 1, a radar apparatus includes a transmission waveform controller 1, an arbitrary frequency oscillator 2, a transmitter 3, an antenna 4, a distributor 5, phase detectors 6a and 6b, a 90-degree hybrid unit 7, Low-pass filters 8a, 8b, A / D converters 9a, 9b, video signal storage means 10, target relative speed measurement processor 11, relative speed correction processor 12, synthesis band processor 13, And a target detection processor 14.

The transmission waveform controller 1 sets a pulse repetition period T _PRI , generates a transmission frequency sequence F _m , and inputs transmission waveform specifications to the arbitrary frequency oscillator 2.
The transmission waveform controller 1 generates, for example, a transmission frequency sequence F _m represented by the following expression (1).

In Equation (1), N _SBR is the number of combined bands, and each variable m and M is an integer that takes the values of m = 0, 1,..., N _SBR −1, and M = 1. ,..., N _SBR / 2-1.
Further, the ascending frequency sequence f _n and the descending frequency sequence g _n include f _n = f ₀ + nΔf, g _n = f ₀ + Δf (N _SBR −1) −nΔf (where n = 0, 1,..., N _SBR / 2-1).

FIG. 2 is an explanatory diagram showing a transmission frequency sequence when the transmission interval between the ascending sequence (see black circle) and the descending sequence (see white circle) is changed, and shows a transmission frequency sequence corresponding to the case of M = 2. .
In FIG. 2, similarly to the above (FIG. 9), the horizontal axis represents time, the vertical axis represents the transmission frequency, one square on the horizontal axis represents PRI (= T _PRI ), and one square on the vertical axis represents the step frequency Δf. F ₀ indicates the minimum transmission frequency.

  Returning to FIG. 1, the arbitrary frequency oscillator 2 oscillates a signal based on the transmission waveform specifications designated by the transmission waveform controller 1, and the oscillated oscillation signal is transmitted to the transmitter 3, the phase detector 6 a and the 90-degree hybrid. Input to the device 7.

The 90-degree hybrid unit 7 rotates the phase of the oscillation signal from the arbitrary frequency oscillator 2 by 90 degrees, and inputs the signal rotated by 90 degrees to the phase detector 6b.
The transmitter 3 pulsates the oscillation signal from the arbitrary frequency oscillator 2 and inputs it to the antenna 4. The antenna 4 irradiates the pulsed oscillation signal to the target, receives the reflected signal from the target, and distributes the signal. Enter 5.

The distributor 5 distributes and inputs the received signal from the antenna 4 to the phase detectors 6a and 6b.
The phase detector 6a performs frequency conversion using the input signal from the distributor 5 and the input signal from the arbitrary frequency oscillator 2, and inputs the frequency-converted signal to the low-pass filter 8a.
The phase detector 6b performs frequency conversion using the input signal from the distributor 5 and the input signal from the 90-degree hybrid unit 7, and inputs the frequency-converted signal to the low-pass filter 8b.

The low-pass filters 8a and 8b input only the low frequency components of the input signals from the phase detectors 6a and 6b to the A / D converters 9a and 9b.
As the low-pass filters 8a and 8b, for example, matched filters that maximize the signal-to-noise ratio are used.

The A / D converters 9a and 9b convert the analog signals from the low-pass filters 8a and 8b into digital signals and input them to the video signal storage means 10.
The video signal storage means 10 stores the video signal converted into a digital signal by the A / D converters 9 a and 9 b and inputs the video signal to the target relative speed measurement processor 11 and the relative speed correction processor 12.

Target relative speed measurement processor 11, a video signal storage means receiving video signals using video signal (ascending frequency sequence f _n stored in 10, and descending frequency column g _n transmitted and received video signal using a ) To measure the target relative speed Vd using a two-dimensional Fourier transform. As a two-dimensional Fourier transform method, for example, FFT (Fast Fourier Transform) can be applied.

Hereinafter, the processing of the target relative speed measurement processor 11 will be described in detail with reference to mathematical expressions.
A video signal transmitted / received using the ascending frequency sequence f _n and the descending frequency sequence g _n , that is, a video signal stored in the video signal storage means 10 is expressed as follows using the light velocity c, the target distance R, and the target relative velocity Vd. (2) and (3).

However, here, in order to simplify the description, the amplitude of the video signal is “1”.
In the equations (2) and (3), the variables k and l take values of k = 0, 1,..., M−1, and l = 0, 1,. The value of _SBR / 2M−1 is taken.
When complex multiplication is performed on the elements (2) and (3) for each element, the following expression (4) is obtained.

However, in the equation (4), P _indicates the sum (f _{k + lM} + g _{k + lM} ) of the frequency sequences f _{k + lM} and g _{k + lM} , and actually P = f _{k + lM} + g _{k + lM} = 2f ₀ + Δf (N _SBR −1) It is represented by
When the equation (4) is summarized for each of the variables k and l, the following equation (5) is obtained.

However, in Equation (5), the phases unrelated to the variables k and l are summarized as θ.
It is possible to measure the target relative speed Vd from the peak value by performing the two-dimensional Fourier transform of the equation (5) in the direction of the variable k and l.
The velocity resolution ΔVd ₁ and the maximum observation velocity ΔVd _{1, max} when the FFT process is performed in the variable k direction are expressed by the following equations (6) and (7), respectively.

Also, the velocity resolution ΔVd ₂ and the maximum observation velocity ΔVd _{2, max} when FFT is performed in the variable l direction are expressed by the following equations (8) and (9), respectively.

  As described above, the target relative speed measurement processor 11 measures the target relative speed Vd and inputs the measurement result to the relative speed correction processor 12.

  Hereinafter, the relative speed correction processor 12 performs relative speed correction on the video signal stored in the video signal storage means 10 using the target relative speed Vd obtained from the target relative speed measurement processor 11, The signal after the relative speed correction is input to the synthesis band processor 13.

The synthetic band processor 13 performs synthetic band processing on the signal after the relative speed correction, and inputs the synthetic band processing result to the target detection processor 14.
The target detection processor 14 detects the target from the combined band processing result and acquires the target distance R. As a target detection method, for example, a detection method based on CFAR (Constant False Alarm Rate) can be applied.

As described above, the radar apparatus according to Embodiment 1 (FIGS. 1 and 2) of the present invention has the predetermined frequency sequence f _n (ascending frequency sequence) and the frequency sequence g different from the predetermined frequency sequence f _n. A transmission waveform controller 1 that generates a transmission waveform specification by generating a transmission frequency sequence F _{m in} which _n (descending order frequency sequence) is alternately rearranged at a predetermined interval MT _PRI , and a transmission waveform controller 1 An arbitrary frequency oscillator 2 that oscillates the instructed transmission waveform specifications, a 90 degree hybrid unit 7 that rotates the phase of the oscillation signal oscillated by the arbitrary frequency oscillator 2 by 90 degrees, and a transmitter 3 that pulses the oscillation signal, And an antenna 4 that irradiates the target with a signal pulsed by the transmitter 3 and receives a signal reflected from the target.

  Further, the radar apparatus according to Embodiment 1 of the present invention distributes a signal received by an antenna 4 to a distributor 5, and an oscillation signal and a 90-degree hybrid for the received signal distributed by the distributor 5. The phase detectors 6a and 6b that perform frequency conversion using the signal rotated by 90 degrees and the low frequency band that blocks the frequency components other than the desired frequency band among the signals frequency-converted by the phase detectors 6a and 6b. Pass filters 8a and 8b, A / D converters 9a and 9b for converting the output signals of the low-pass filters 8a and 8b from analog signals to digital signals, and video digitized by the A / D converters 9a and 9b Video signal storage means 10 for storing signals.

  Furthermore, the radar apparatus according to Embodiment 1 of the present invention is a target relative speed measurement processor that measures the target relative speed Vd using the two-dimensional Fourier transform from the complex multiplication result of the video signal in the video signal storage means 10. 11 and a relative speed correction processor 12 that performs relative speed correction on the video signal in the video signal storage means 10 using the target relative speed Vd obtained by the target relative speed measurement processor 11 and a relative speed correction process. A combined band processor 13 that performs a distance high resolution process on the signal that has been subjected to relative speed correction by the detector 12; and a target signal is detected from the signal that has been subjected to the distance high resolution by the combined band processor 13; And a target detection processor 14 for measuring.

  Thereby, it is possible to measure the target relative speed Vd, increase the resolution of the distance, and measure the target distance R without using a simple ascending sequence and descending sequence.

Embodiment 2. FIG.
In the first embodiment (FIG. 1), the video signal in the video signal storage means 10 is directly input to the relative speed correction processor 12, and the target relative speed Vd (measurement result from the target relative speed measurement processor 11) is measured. ) Is input only to the relative speed correction processor 12, but as shown in FIG. 3, an MTI processor 15 is added and a video signal via the MTI processor 15 is input to the relative speed correction processor 12, and the target The relative speed Vd may be input to the relative speed correction processor 12 and the transmission waveform controller 1A.

FIG. 3 is a block diagram showing a radar apparatus according to Embodiment 2 of the present invention. Components similar to those described above (see FIG. 1) are denoted by the same reference numerals as those described above, or “A” after the reference numerals. The detailed description is omitted.
In FIG. 3, an MTI processor 15 is additionally inserted between the video signal storage means 10 and the relative speed correction processor 12.

In this case, the partial processing of the transmission waveform controller 1A and the target relative speed measurement processor 11A is different from that described above.
Hereinafter, with reference to FIGS. 4 to 7, FIG. 3 will be described with respect to the processing different from the above in the second embodiment of the present invention and the function of the MTI processor 15.

First, the processing of the transmission waveform controller 1A will be described.
Here, in order to simplify the description, description will be made on the premise of MTI processing (single eraser) using two pulses.
In the case of a single eraser, the HIT number N _HIT is N _HIT = 2N _SBR with _respect to the combined band number N _SBR .

Here, the transmission minimum frequency f ₀ is used, and the step frequency Δf is used to change the frequency trains f _n and g _n to f _n = f ₀ + nΔf, g _n = f ₀ + Δf (N _SBR −1) −nΔf (where, If n = 0, 1,..., N _SBR / 2-1), the transmission frequency sequences F _m and G _m are defined by the following equations (10) and (11).

However, in the equations (10) and (11), the variable m takes a value of m = 0, 1,..., N _HIT / 2-1, and the variable M is M = 1, 2,. .., takes a value of N _SBR / 2.
The transmission waveform controller 1A transmits a pulse signal by alternately using the transmission frequency sequences F _m and G _m of Expression (10) and Expression (11) for each PRI.

FIG. 4 is an explanatory diagram showing an example in which transmission frequency sequences F _m (see black circles) and G _m (see white circles) are alternately used.
In FIG. 4, as in the above (FIG. 2), the horizontal axis indicates time, the vertical axis indicates transmission frequency, one square on the horizontal axis indicates PRI, and one square on the vertical axis indicates step frequency Δf.
FIG. 4A shows the case where M = 1, and FIG. 4B shows the case where M = 2.

Since the MTI processing corresponds to taking a difference between signals of the same frequency, if PRI is T _PRI , in the alternating use of the transmission frequency sequences F _m and G _m expressed by the equations (10) and (11), The signal interval of the same frequency is represented by 2MT _PRI .
Therefore, the MTI filter characteristic F _MTI (Vd) is expressed by the following expression (12) using the target relative speed Vd and the light speed c.

However, in Formula (12), _fMM is an intermediate frequency of transmission frequencies.
FIG. 5 is an explanatory diagram showing the MTI filter characteristics according to the second embodiment of the present invention. The horizontal axis represents the target relative speed Vd [m / s] and the vertical axis MTI filter response [dB].
In FIG. 5, the parameters are PRI = 150 μs and f _MM = 1 GHz, the solid line indicates the MTI filter characteristic when M = 1, and the broken line indicates the MTI filter characteristic when M = 2.
As is apparent from FIG. 5, by changing the variable M, the pulse interval for performing the MTI process can be changed, and the MTI filter characteristics change.

The transmission waveform controller 1A determines the variable M so that the MTI filter characteristic F _MTI (Vd) represented by Expression (12) becomes maximum at the target relative speed Vd obtained from the target relative speed information acquisition unit 11A. Thus, the transmission waveform specifications oscillated by the arbitrary frequency oscillator 2 are controlled.
For example, as shown in FIG. 5, when the target relative speed Vd = 125 [m / s], the MTI filter characteristic becomes maximum when M = 2 (broken line). ) Command to transmit the transmission waveform specifications shown in ().

However, if the variable M is set large, the clutter suppression performance deteriorates. Therefore, M that maximizes the MTI filter characteristic F _MTI (Vd) is obtained as follows.
FIG. 6 is an explanatory diagram showing an enlargement of the vicinity of 0 [m / s] of the filter characteristics of FIG.
6, M = 2 (broken line) has a clutter suppression performance of 6 [dB] at a relative speed of 4 [m / s] compared to M = 1 (solid line). Degraded to some extent.

Therefore, the transmission waveform controller 1A obtains the variable M that maximizes the MTI filter characteristic F _MTI (Vd) with respect to the target relative speed Vd while satisfying the desired clutter suppression performance, and the transmission waveform oscillated by the arbitrary frequency oscillator 2 Specifications may be controlled.

For example, if the desired clutter suppression capability is defined as X (> 0) [dB] suppression at a predetermined target relative speed σ _C , the following expression (13) needs to be satisfied in order to satisfy the clutter suppression force. There is.

However, since the MTI filter characteristic is symmetric at the target relative speed σ _C = 0 [m / s], only the positive target relative speed σ _C is considered in the equation (13).
By satisfying the equation (13), M that maximizes the MTI filter characteristic F _MTI (Vd) with respect to the target relative speed Vd is obtained, and by controlling the transmission waveform specifications oscillated by the arbitrary frequency oscillator 2, desired clutter suppression is achieved. The performance can also be satisfied.

In the above description, the PRI is constant. However, if the PRI can be changed within the allowable range of the output rate _TCPI of the target distance measurement result, the degree of freedom of the transmission waveform specification control is increased, and more optimal. Transmission waveform specification control becomes possible.
Here, if a maximum observation distance _{R max} of the radar, PRI must satisfy the following equation (14).

If the output rate _TCPI of the allowable target distance measurement result is used, the PRI needs to satisfy the following formula (15).

M and PRI (= T _PRI ) that satisfy Expression (13), Expression (14), and Expression (15) and maximize the MTI filter characteristic F _MTI (Vd) (Expression (12)) with respect to the target relative speed Vd are obtained. By controlling the transmission waveform specifications oscillated by the arbitrary frequency oscillator 2, the desired clutter suppression performance can also be satisfied.
As described above, the processing by the transmission waveform controller 1A is performed.

  The MTI processor 15 performs MTI processing on the video signals of the same frequency stored in the video signal storage means 10 from the transmission waveform specifications input from the transmission waveform controller 1A, and signals after the MTI processing Is input to the relative speed correction processor 12 and the target relative speed measurement processor 11A.

  The relative speed correction processor 12 performs relative speed correction on the signal from the MTI processor 15 using the target relative speed Vd obtained from the target relative speed measurement processor 11A, and synthesizes the signal after the relative speed correction. Input to the bandwidth processor 13.

Next, processing of the target relative speed measurement processor 11A will be described.
FIG. 7 is an explanatory diagram showing an outline of the processing of the target relative speed measurement processor 11A, and shows the measurement processing when M = 2 and N _SBR = 12.
The target relative velocity measurement processor 11A performs complex multiplication on the signal subjected to MTI processing by the MTI processor 15, and measures the target relative velocity Vd using two-dimensional Fourier transform.

Hereinafter, the measurement process of the target relative speed Vd will be described in detail using mathematical expressions.
A signal obtained by performing MTI processing on video signals having the same frequency by the MTI processor 15 is expressed by the following equations (16) and (17).

Here, Expression (16) shows a case where the transmission frequency string F _m is used, and Expression (17) shows a case where the transmission frequency string G _m is used.
Further, in the equations (9) and (10), the variable k takes the values of k = 0, 1,..., M−1, and the variable l is l = 0, 1,. The value of N _SBR / 2M−1 is taken.
When complex multiplication is performed for each element of Expression (16) and Expression (17), the following Expression (18) is obtained.

However, in the equation (18), P _indicates the sum (f _{k + lM} + g _{k + lM} ) of the frequency sequences f _{k + lM} and g _{k + lM} , and actually P = f _{k + lM} + g _{k + lM} = 2f ₀ + Δf (N _SBR −1) It is represented by
Note that the period of the sine function (sin) in equation (18) is shorter than the exponential function and can be ignored.
Summarizing the exponential function of equation (18) for variables k and l, the following equation (19) is obtained.

However, in the equation (19), the phases unrelated to the variables k and l are summarized as θ.
In the same manner as in the first embodiment described above, the target relative speed Vd can be measured from the peak value by performing the two-dimensional Fourier transform of Equation (19) in the k and l directions.
As the Fourier transform means, for example, FFT (Fast Fourier Transform) can be applied.
The velocity resolution ΔVd ₁ and the maximum observation velocity ΔVd _{1, max} when the FFT process is performed in the variable k direction are expressed by the following equations (20) and (21), respectively.

Further, the velocity resolution ΔVd ₂ and the maximum observation velocity ΔVd _{2, max} when the FFT process is performed in the variable l direction are expressed by the following equations (22) and (23), respectively.

Usually, since the magnitude relationship between the variable M and the number of combined bands N _SBR is M << N _SBR , the variable N _SBR is used rather than the speed resolution ΔVd ₁ of the equation (20) using the variable M. The speed resolution ΔVd _{2 in} the equation (22) is higher.
On the other hand, the maximum observation speeds Vd _{1 and max} of Expression (21) not using the variable M are faster and include ambiguity than the maximum observation speeds Vd _{2 and max of} Expression (23) using the variable M. Therefore, the range that can be measured is wide.

Accordingly, the ambiguity is solved from the expression (21) that is the result of performing the FFT process in the variable k direction, and the relative speed measurement is performed with high accuracy from the expression (22) that is the result of performing the FFT process in the variable l direction. Can do.
However, since there is a relationship of ΔVd ₁ / Vd _{2 and max} = 2, it is necessary to reduce the number of FFT points by “0” to “2M” when performing FFT processing in the variable k direction.

As described above, the radar apparatus according to Embodiment 2 (FIGS. 3 to 7) of the present invention includes the MTI processor 15 inserted on the output side of the video signal storage means 10.
The MTI processor 15 performs clutter suppression processing on the signals transmitted and received at the same frequency in the video signal storage means 10 based on the transmission waveform specifications generated by the transmission waveform controller 1A.

The transmission waveform controller 1A generates transmission frequency sequences F _m and G _{m in} which a predetermined frequency sequence f _{k + 1M} and a frequency sequence g _{k + 1M} different from the predetermined frequency sequence are alternately rearranged at a predetermined interval, Transmission waveform specifications for reducing the clutter suppression processing loss with respect to the target relative speed Vd are generated without changing the PRI (pulse repetition period).
The target relative velocity measurement processor 11A measures the target relative velocity Vd using a two-dimensional Fourier transform from the complex multiplication result of the signal subjected to the clutter suppression processing by the MTI processor 15, and calculates the target relative velocity Vd as the measurement result. Input to the transmission waveform controller 1 </ b> A and the relative speed correction processor 12.

Further, the transmission waveform controller 1A generates transmission frequency sequences F _m and G _{m in} which a predetermined frequency sequence f _{k + 1M} and a frequency sequence g _{k + 1M} different from the predetermined frequency sequence are alternately rearranged at a predetermined interval. Without changing the pulse repetition period, the transmission waveform specifications for reducing the clutter suppression processing loss with respect to the target relative speed Vd and satisfying the desired clutter suppression performance are generated.

Further, the transmission waveform controller 1A generates transmission frequency sequences F _m and G _{m in} which a predetermined frequency sequence f _{k + 1M} and a frequency sequence g _{k + 1M} different from the predetermined frequency sequence are alternately rearranged at a predetermined interval. The loss of clutter suppression processing with respect to the target relative speed Vd is reduced, and the desired distance measurement result output rate T _CPI , the pulse repetition period determined by the maximum observation distance R _max , and the desired clutter suppression performance are satisfied. To generate a transmission waveform specification.

Thereby, it is possible to measure the target relative speed Vd, increase the resolution of the distance, and measure the target distance R without using a simple ascending sequence and descending sequence.
In addition, it can be used in combination with an MTI processor for performing clutter suppression processing, and unnecessary reflected waves can be suppressed.

Embodiment 3 FIG.
In the second embodiment (FIG. 3), the target relative speed Vd from the target relative speed measurement processor 11A is directly input to the transmission waveform controller 1A and the relative speed correction processor 12, but as shown in FIG. The estimated target relative speed Vd ′ via the tracking filter processor 16 may be input to the transmission waveform controller 1A and the relative speed correction processor 12.

Hereinafter, Embodiment 3 of the present invention will be described with reference to FIG.
FIG. 8 is a block diagram showing a radar apparatus according to Embodiment 3 of the present invention. Components similar to those described above (see FIG. 3) are denoted by the same reference numerals as those described above, and detailed description thereof is omitted.
In FIG. 8, the radar apparatus includes a tracking filter processor 16 inserted on the output side of the target relative velocity measurement processor 11A.

The tracking filter processor 16 performs a tracking filter process using the target distance R observed by the target detection processor 14 and the target relative speed Vd measured by the target relative speed measurement processor 11A as input information, and estimates the target. A relative velocity Vd ′ is generated. As the tracking filter, for example, a Kalman filter or the like can be applied.
The estimated target relative speed Vd ′ estimated by the tracking filter processor 16 is input to the transmission waveform controller 1A and the relative speed correction processor 12.

Hereinafter, the transmission waveform controller 1 </ b> A performs transmission waveform control based on the estimated target relative speed Vd ′ input from the tracking filter processor 16.
Further, the relative speed correction processor 12 performs relative speed correction on the signal from the MTI processor 15 using the estimated target relative speed Vd ′ from the tracking filter processor 16, and outputs the signal after the relative speed correction. This is input to the synthesis band processor 13.

  As described above, the radar apparatus according to Embodiment 3 (FIG. 8) of the present invention has the target relative speed Vd measured by the target relative speed measurement processor 11A and the target distance measured by the target detection processor 14. A tracking filter processor 16 that performs tracking filter processing using R as input information is provided, and the tracking filter processor 16 transmits an estimated target relative speed Vd ′ estimated from the target relative speed Vd and the target distance R. Input to the waveform controller 1 </ b> A and the relative speed correction processor 12.

As a result, it is possible to measure the target relative speed Vd, increase the resolution of the distance, and measure the target distance without using a simple ascending sequence and descending sequence.
In addition, it can be used in combination with the MTI processor 15 that performs clutter suppression processing, and unnecessary reflected waves can be suppressed.
Furthermore, transmission waveform control can be performed based on the target specifications accurately estimated by the tracking process.

  The radar device according to the present invention can be used for, for example, a device for tracking a target aircraft, an air traffic control radar, or the like.

  1, 1A Transmission waveform controller, 2 Arbitrary frequency oscillator, 3 Transmitter, 4 Antenna, 5 Divider, 6a, 6b Phase detector, 790 degree hybrid, 8a, 8b Low-pass filter, 9a, 9b A / D converter, 10 video signal storage means, 11, 11A target relative speed measurement processor, 12 relative speed correction processor, 13 synthesis band processor, 14 target detection processor, 15 MTI processor, 16 tracking filter processor, R target distance, Vd target relative speed, Vd ′ estimated target relative speed.

Claims (5)

A transmission waveform controller that generates a transmission waveform specification by generating a transmission frequency sequence in which a predetermined frequency sequence and a frequency sequence different from the predetermined frequency sequence are alternately rearranged at a predetermined interval;
An arbitrary frequency oscillator that oscillates the transmission waveform parameters instructed by the transmission waveform controller;
A 90 degree hybrid that rotates the phase of the oscillation signal oscillated by the arbitrary frequency oscillator by 90 degrees;
A transmitter for pulsing the oscillation signal;
An antenna for irradiating a target with a signal pulsed by the transmitter and receiving a signal reflected from the target;
A distributor for distributing a signal received by the antenna;
A phase detector that performs frequency conversion on the received signal distributed by the distributor using the oscillation signal and a signal rotated 90 degrees by the 90-degree hybrid unit;
Of the signal frequency-converted by the phase detector, a low-pass filter that cuts off frequency components other than the desired frequency band;
An A / D converter that converts an output signal of the low-pass filter from an analog signal to a digital signal;
Video signal storage means for storing the video signal digitized by the A / D converter;
A target relative speed measurement processor for measuring a target relative speed using a two-dimensional Fourier transform from a complex multiplication result of the video signal in the video signal storage means;
A relative speed correction processor for performing relative speed correction on the video signal in the video signal storage means using the target relative speed obtained by the target relative speed measurement processor;
A synthetic band processor for performing a distance high resolution process on the signal subjected to the relative speed correction by the relative speed correction processor;
A target detection processor for measuring a target distance by detecting a target signal from a signal whose distance has been increased in resolution by the synthetic band processor;
A radar apparatus comprising: An MTI processor inserted on the output side of the video signal storage means;
The MTI processor performs clutter suppression processing on signals transmitted and received at the same frequency in the video signal storage means based on the transmission waveform specifications generated by the transmission waveform controller,
The transmission waveform controller is
Generating a transmission frequency sequence in which the predetermined frequency sequence and a frequency sequence different from the predetermined frequency sequence are alternately rearranged at the predetermined interval;
Without changing the pulse repetition period, generate transmission waveform specifications that reduce the clutter suppression processing loss for the target relative speed,
The target relative speed measurement processor measures the target relative speed using a two-dimensional Fourier transform from a complex multiplication result of the signal subjected to clutter suppression processing by the MTI processor, and calculates the target relative speed as a measurement result. Input to the transmission waveform controller and the relative speed correction processor,
The radar apparatus according to claim 1. The transmission waveform controller is
Generating a transmission frequency sequence in which the predetermined frequency sequence and a frequency sequence different from the predetermined frequency sequence are alternately rearranged at the predetermined interval;
Without changing the pulse repetition period, to reduce the loss of clutter suppression processing relative to the target relative speed, and to generate a transmission waveform specification to satisfy the desired clutter suppression performance,
The radar apparatus according to claim 2. The transmission waveform controller is
Generating a transmission frequency sequence in which the predetermined frequency sequence and a frequency sequence different from the predetermined frequency sequence are alternately rearranged at the predetermined interval;
Transmission waveform parameters for reducing the clutter suppression processing loss with respect to the target relative speed, and satisfying the output rate of the desired distance measurement result, the pulse repetition period determined by the maximum observation distance, and the desired clutter suppression performance. Generate the original,
The radar apparatus according to claim 2. A tracking filter processor for performing a tracking filter process with the target relative speed measured by the target relative speed measurement processor and the target distance measured by the target detection processor as input information,
The tracking filter processor inputs an estimated target relative velocity estimated from the target relative velocity and the target distance to the transmission waveform controller and the relative velocity correction processor.
The radar apparatus according to any one of claims 1 to 4, wherein the radar apparatus is characterized in that:

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