JP2636770B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar device, and more particularly to a radar device capable of removing a target-like unnecessary signal.

[0002]

2. Description of the Related Art An example of a conventional radar device will be described with reference to a block diagram of FIG. A signal input to a reception signal input 200 from a radar receiver is converted into a digital signal by an A / D converter 210, and N (N is an integer of 1 or more) Doppler filters 221 to 22N connected in parallel. By utilizing the difference in Doppler frequency, the target and clutter
Unnecessary signals such as jams are separated.

The outputs of the Doppler filters 221 to 22N are input to CFAR (constant false alarm probability) processors 231 to 23N, and by subtracting the average value of the amplitude of a certain section in the distance direction of the input signal from the input signal, Unnecessary signals such as clutter and jam that spread in the distance direction are suppressed to a noise level. At this time, the target signal that does not spread in the distance direction is hardly affected. As a result, unnecessary signals are separated and suppressed from the outputs of the CFAR processors 231 to 23N.

[0004] Then, these N signal MDF (multi Doppler filter) by the video selector 250 1 distance direction processing unit (hereinafter, referred to as range bins) for each, from among the N amplitude maximum Is selected as one video output and input to the stagger video selector 260. The staggered video selector 260 is an MDF video selector 2 that is output for each of M different PRFs (pulse repetition frequencies).
The output of 50 is stored, and the output having the largest amplitude is selected from among these M outputs for each range bin, and the processed video output 2 is selected.
70.

In the staggered video selector 260, the Doppler frequency of the unwanted signal coincides with the target in one of the M types of PRFs, and the Doppler filters 221 to 2
Even if the target and the unnecessary signal cannot be separated in 2N, it has a function of being separable in another PRF.

[0006] As described above, unnecessary signals are suppressed in the processed video output 270, and signals can be supplied to the target detection device and the video display device to operate as a radar.

[0007]

In the conventional radar apparatus, the amplitude characteristics of the unnecessary signals are not equal to those of the CFAR processors 231 to 23.
If N differs from what is assumed in the design, CFAR is not performed and a target-like unnecessary signal remains. This target-like unnecessary signal is MDF
Since it is not removed by the video selector 250 and the staggered video selector 260, it is output from the processing video output 270,
This was causing a false impact on radar operation.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a radar apparatus capable of eliminating a target-like unnecessary signal and eliminating a false signal even when the amplitude characteristic of the unnecessary signal is different from the expected one. Is to do.

[0009]

The radar apparatus according to the present invention comprises:
N Doppler filters to which the received signal from the radar receiver is input, and connected to the output terminal of each Doppler filter. Based on the amplitude and spread in the distance direction, clutter, jam, etc. are unnecessary for each distance processing unit. N clutter detectors for judging the presence or absence of a signal, N CFAR processors for CFAR processing the output of each Doppler filter, and each CFAR
An MDF video selector for selecting and outputting one of the outputs of the CFAR processor corresponding to the Doppler filter determined to have no unnecessary signal by the clutter detector from the outputs of the processors for each distance direction processing unit And a staggered video selector for selecting and outputting one of the outputs of the MDF video selector from the M types of pulse repetition frequencies for each processing unit in one distance direction.

[0010] Here, the clutter detector for each distance direction processing unit, the center distance direction processing unit in question
Includes the lever direction processing unit and the target distance direction
Large enough than the number of processing units in the distance direction corresponding to the spread
Calculate the average value of the amplitudes of the number
It is configured to compare with a predetermined value and determine that there is an unnecessary signal when the average value is large.

The staggered video selector stores the output of the MDF video selector for each of M types of pulse repetition frequencies, and selects one of the M types having the largest amplitude for each processing unit in one distance direction. It is configured to select and output.

[0012]

The presence or absence of an unnecessary signal is determined by the clutter detector for each output of the Doppler filter. Based on the determination result, the MDF video selector determines the output of the CFAR processor corresponding to the output of the Doppler filter including the unnecessary signal. Since the signal is excluded from the selection targets, it is possible to remove a target-like unnecessary signal resulting from the CFAR processing of the unnecessary signal from the output of the Doppler filter.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. An A / D converter 110 is connected to a reception signal input terminal 100 from the radar receiver. N (N is an integer of 1 or more) Doppler filters 12 are connected to an output terminal of the A / D converter 110.
1 to 12N are connected in parallel. Further, each of the Doppler filters 121 to 12N has a CFAR processor 131, respectively.
To 13N are connected, and these CFAR processors 131 to
13N is connected to the MDF video selector 150. The MDF video selector 150 includes a staggered video selector 16
0 is connected, and the output is output to a target detection device or a video display device (not shown) via an output terminal 170.

Here, clutter detectors 141 to 14N for detecting the presence or absence of unnecessary signals such as clutter and jam are connected to the output terminals of the N Doppler filters 121 to 12N, respectively. The detection of the presence / absence of an unnecessary signal such as clutter, jam, or the like is performed for each range bin, including the range bin of interest.
Range bin equivalent to the target range
Calculate the average value of the range bins whose number is sufficiently larger than
This is compared with a predetermined value, and when the average value is large, it is determined based on the principle of determining that there is an unnecessary signal.

In the radar apparatus having such a configuration, a signal input to a reception signal input terminal 100 from a radar receiver is converted into a digital signal by an A / D converter 110, and N Doppler filters 121 to 121 are provided. With 12N, a target is separated from unnecessary signals such as clutter and jam using the difference in Doppler frequency.

The N Doppler filters 121 to 12
Each output of N is input to clutter detectors 141 to 14N, respectively. These N clutter detectors 141 to 14N
Then, for each range bin, this range bin is included around the range bin of interest , and a target distance direction
Number of records that is sufficiently larger than the number of range bins
Calculate the average value of the amplitude of
If the average value is larger than the average value, it is determined that there is an unnecessary signal such as clutter or jam. This determination result is MD
It is sent to the F video selector 150.

The outputs of the Doppler filters 121 to 12N are input to CFAR processors 131 to 13N, respectively.
By subtracting the average value of the amplitude of the input signal in a certain section in the distance direction from the input signal, unnecessary signals such as clutter and jam that spread in the distance direction are suppressed to a noise level. At this time, targets that are not spread in the distance direction are hardly affected.

However, as described above, when the amplitude characteristics of the unnecessary signals are different from those assumed in the design by the CFAR processors 131 to 13N, the signals are not effectively CFAR-converted and the target signal remains. It is input to the MDF video selector 150 in a state where it is mixed with the true target. The MDF video selector 150 selects one output having the largest amplitude value from the N outputs of the CFAR processors 131 to 13N for each range bin, and outputs the selected output to the staggered video selector 160.

However, in this case, the clutter detectors 141 to 141
14N, the CFA corresponding to the outputs of the Doppler filters 121 to 12N for which it has been determined that there is an unnecessary signal in the range bin.
The outputs of the R processors 131 to 13N are excluded from selection targets. By this operation, the outputs of the Doppler filters 121 to 12N including the unnecessary signal are removed by the MDF video selector 150, and the signal causing the target-like false is also removed.

The output of the MDF video selector 150 is input to the stagger video selector 160. The stagger video selector 160 outputs the M output for each of the M different PRFs.
The output results of the DF video selector 150 are stored in M (M is an integer of 1 or more), and the one having the largest amplitude is selected from the M and output to the processing video output 170 for each range bin.

In this radar apparatus, the outputs of the Doppler filters 121 to 12N determined to have an unnecessary signal by the clutter detectors 141 to 14N are finally removed by the MDF video selector 150. In the case where the Doppler frequencies of the target and the unwanted signal coincide with each other and the target signal is sufficiently stronger than the unwanted signal, the target can be detected by the conventional radar apparatus, whereas the target is detected by the radar apparatus of the present invention. May not be detected.
However, here, a method is employed in which the maximum amplitude of these M results is detected using M kinds of PRFs, so that even if a certain PRF has an adverse effect, it can be avoided by another PRF. In practice, this is not a problem.

[0022]

As described above, according to the present invention, the output terminals of the N Doppler filters to which the received signals from the radar receivers are input are provided for each distance direction processing unit based on the amplitude and the spread in the distance direction. Is connected to N clutter detectors that determine the presence or absence of unnecessary signals such as clutter and jam, and the output of each Doppler filter is processed by CFAR processing. Since one of the outputs of the corresponding CFAR processor is selected and output for each distance direction processing unit, unnecessary signals are output from the output of the Doppler filter to the CFAR.
Effect that to be able to remove the target-like unwanted signals caused by treated is obtained.

In the staggered video selector, the output of the MDF video selector is stored for each of M types of pulse repetition frequencies, and one of the M types having the largest amplitude is stored for each one processing unit in one distance direction. In the case where the Doppler frequency of the target and the unwanted signal coincides by chance and the target signal is sufficiently stronger than the unwanted signal, the target may not be detected by a certain PRF. This can be avoided with other PRFs, so this is not really a problem.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a radar apparatus according to the present invention.

FIG. 2 is a block diagram of an example of a conventional radar device.

[Explanation of symbols]

 110 A / D converter 121-12N Doppler filter 131-13N CFAR processor 141-14N Clutter detector 150 MDF video selector 160 Stagger video selector

Claims (3)

(57) [Claims] An N-number (N is an integer greater than 1) Doppler filter to which a reception signal from a radar receiver is input;
It is connected to the output end of each Doppler filter, and based on its amplitude and spread in the distance direction, clutter,
N clutter detectors that determine the presence or absence of unnecessary signals such as jams, N CFAR processors that perform CFAR processing on the output of each Doppler filter, and the clutter detector among the outputs of each CFAR processor One of the outputs of the CFAR processor corresponding to the Doppler filter determined to be none
An MDF video selector that selects and outputs one for each distance direction processing unit, and outputs M types (M
A staggered video selector for selecting and outputting one for each processing unit in the distance direction from a pulse repetition frequency of (1 is an integer greater than 1). 2. A clutter detector for each distance direction processing unit, this about a distance direction processing unit in question
Includes the distance direction processing unit and the target distance direction spread
Number of distances sufficiently larger than the number of processing units in the distance direction corresponding to
Calculate the average value of the amplitude of the unit in the direction of separation and set this value in advance.
2. The radar apparatus according to claim 1, wherein the radar apparatus determines that there is an unnecessary signal when the average value is larger than the determined value. 3. The staggered video selector stores the output of the MDF video selector for each of M types of pulse repetition frequencies, and selects one of the M types having the largest amplitude for each one distance direction processing unit. Claim 1 for selecting and outputting
Or 2 radar devices.