JPH07294633A - Radar signal processing device - Google Patents

Abstract

PURPOSE:To obtain a radar signal processing device for improving the detection rate of a target by effectively utilizing a filter where the number is limited in terms of the relationship with the number of bits. CONSTITUTION:An MTI map is set by an MTI (Moving Target Indicator) map generator 1, an automatic clutter map is set by an automatic clutter map generator 2, a trigger pulse for stagger synchronization is generated by a synchronizer 4, and a specific filter coefficient which is different for each trigger pulse is output from a filter coefficient controller 3. By this filter coefficient, the filter characteristics of filters 8-11 are switched over and by a selection switch 5 and a switch 7 the transfer path of an input video signal is switched over. By switching over the filter characteristics of the filters 8-11 for each trigger pulse, filter characteristics are set to be compensated each other and the maximum signal of each filter is detected by a maximum value detector 16 as an output video signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar signal processing device, and more particularly to a signal processing device for a radar device adopting a group stagger system.

[0002]

2. Description of the Related Art Conventionally, a signal processing device in a radar device extracts only a target signal from an input video signal composed of various reflected signals. For this extraction, a canceller is used to suppress the fixed clutter signal, which is the first unnecessary signal due to the reflection of fixed objects such as buildings and ground, from the input video signal. Further, the second unnecessary signal, ie, the moving clutter signal due to the reflection of moving objects such as clouds and rain, is suppressed.

A filter is used to separate and suppress each unnecessary signal according to the Doppler frequency, and as a result, only the target signal that is not suppressed is extracted. FIG. 4 shows a circuit configuration example of a radar signal processing device provided with four filters for this suppression.

In FIG. 4, an MTI (Moving Target In
dicator / moving target indicating device) The map generator 1 is an MT that indicates the distribution status of the fixed clutter region in the fixed clutter region.
The I-map is generated, and the automatic clutter map generator 2 automatically detects the distribution situation of the moving clutter region from the input video signal and generates the automatic clutter map in the moving clutter region. The filter coefficient controller 3b inputs the MTI map output by the MTI map generator 1 and the automatic clutter map output by the automatic clutter map generator 2 and outputs the fixed clutter region, the moving clutter region and the clear region. The filter coefficients are output to the four filters 8, 9, 10, 11 via the signal line 18. Also, the fixed clutter region or the other region is output to the changeover switch 5 via the signal line 19 as a changeover control signal.

On the basis of the switching control signal input from the signal line 19, the changeover switch 5 inputs the video signal input via the signal line 17 to the eraser 6 via the signal line 20 in the fixed clutter region, In other areas, the signal is output to the output terminal side of the eraser 6 via the signal line 21.

To the output terminal of the eraser 6, three filters 8, 9, 10 are connected, and the remaining one filter 11 is connected via a switch 7. Switch 7
It opens and closes in conjunction with the changeover switch 5 via the control line 22, and opens in the fixed clutter region and closes in the exceptional region. That is, the eraser 6 is also a filter, and the switch 7 is arranged so that there are always the same number of filters (4 in the example of FIG. 4) in the fixed clutter region and other regions.

In the fixed clutter region, the input video signal is input to the canceller 6 via the signal line 20, and the fixed clutter signal contained therein is suppressed, and is input to the three filters 8, 9 and 10.

In regions other than the above, the signals are input to the four filters 8, 9, 10, 11 via the signal line 21. The filters 8, 9, 10 and 11 form the filter characteristics for the fixed clutter region, the moving clutter region and the clear region shown in FIG. 5 according to the filter coefficient input through the signal line 18, and extract the filter characteristics from the input video signal. Remaining fixed clutter signal, moving clutter signal and target signal are separated according to Doppler frequency. The four clutter suppressors 12, 13, 14, 15 are filters 8, 9, 1
The clutter signal of the output video signal corresponding to each connection of 0 and 11 is suppressed. The maximum value selector 16 compares the output video signals of each of the four clutter suppressors 12, 13, 14, 15 and selects the maximum value, combines them and outputs them as an output video signal.

[0009]

However, in this conventional radar signal processing device, since the number of filters is limited due to the relationship with the number of hits of the radar device, the target signal, fixed clutter signal remaining unerased and moving clutter. Even if the target signal can be separated from the video signal in which the signal is present according to the Doppler frequency, the maximum power level (A) of the filter and the power level (B) at the intersection of the filters on both sides are displayed as shown in FIG. Since the power level difference (C) is generated, the detection rate of the target signal is reduced.

An object of the present invention is to provide a radar signal processing device which can effectively utilize a filter whose number is limited in relation to the number of hits and can improve the detection rate of a target.

[0011]

In order to achieve the above object, the radar signal processing apparatus of the present invention comprises MTI map generating means for setting an MTI map in a fixed clutter area,
An automatic clutter map generating means for setting an automatic clutter map in the moving clutter area from an input video signal, a synchronizer for outputting a trigger pulse for a stagger cycle, an MTI map, an automatic clutter map and a trigger pulse are inputted, and a trigger pulse is inputted. Filter coefficient control means for outputting a different predetermined filter coefficient for each, a plurality of filters whose filter characteristics are set based on the predetermined filter coefficient output from the filter coefficient control means, and outputs of the plurality of filters A clutter suppressor for performing clutter suppression processing, and a maximum value selecting means for selecting the maximum value of the outputs of the plurality of clutter suppressors, and a plurality of different filter characteristics are set for each trigger pulse. Input the output signal of the filter, select the maximum output signal, and It is characterized by combining signals.

[0012]

Therefore, according to the radar signal processing apparatus of the present invention, the filter coefficient control means is provided with M in the fixed clutter area.
The TI map, the automatic clutter map of the moving clutter region of the input video signal, and the trigger pulse for the stagger period are input, and the filter coefficient is changed based on a predetermined filter coefficient that is different for each trigger pulse output from the filter coefficient control means. The filter characteristics are set. For example, in FIG.
As shown in (A) and (B), the center frequencies of the plurality of filter characteristics in one stagger cycle are set to the intersection points of the plurality of filter characteristics in the other stagger cycle. It goes without saying that FIG. 2 shows the best case. In this way, the decrease in detection sensitivity in one stagger cycle can be compensated for in the other stagger cycle, and the difference in detection sensitivity can be reduced.Therefore, by selecting a large signal in each stagger cycle, high detection can be achieved. The target signal can be obtained at a rate.

[0013]

Embodiments of the radar signal processing apparatus according to the present invention will now be described in detail with reference to the accompanying drawings. 1 to 3
Referring to FIG. 3, there is shown an embodiment of the radar signal processing device of the present invention. FIG. 1 is a block diagram of a circuit configuration showing an embodiment, FIG. 2 is a principle invention diagram of a target signal detection method of the present invention, (A) is a filter characteristic diagram of one stagger cycle, and (B) is another stagger. It is a filter characteristic figure of a period.
FIG. 3 is a sampling example of a trigger pulse for explaining the operation of the synchronizer constituting the radar signal processing device of the embodiment, (A) is a frame trigger, (C) is a stagger radar trigger, and (B) is It is a trigger pulse that switches every stagger cycle.

The radar signal processing apparatus of this embodiment separates the input signal into the target signal and the clutter signal according to the Doppler frequency, and changes the characteristics of the filter at regular intervals.

A radar signal processing device having this function is an MT which corresponds to a fixed clutter region of an input video signal.
An MTI map generator 1 for generating an I map, an automatic clutter map generator 2 for automatically detecting a moving clutter region from an input video signal and generating an automatic clutter map,
A filter coefficient controller 3a for outputting a filter coefficient, a synchronizer 4 for outputting a trigger pulse for a timing for changing the filter coefficient, a changeover switch 5 and a switch 7 for switching a signal line, an eraser 6 for erasing fixed clutter by MTI processing, Filters 8, 9, 10, 1
1, a clutter suppressor 12, 13, 14, 15 for suppressing a clutter signal in the input video signal, and the largest signal among the video signals output from these clutter suppressors is selected and combined as an output video signal And a maximum value detector 16 for outputting.

The MTI map generator 1 generates an MTI map in the fixed clutter area and outputs the generated MTI map to the filter coefficient controller 3a. Further, the automatic clutter map generator 2 automatically detects a moving clutter region from the input video signal, generates an automatic clutter map, and outputs it to the filter coefficient controller 3a.

The filter coefficient controller 3a discriminates between the fixed clutter region and other regions from the MTI map output from the MTI map generator 1 and the automatic clutter map output from the automatic clutter map generator 2. It is a control circuit unit that outputs the changeover signal based on this identification to the changeover switch 5 through the signal line 19. The filter coefficient controller 3a further uses the trigger pulse output from the synchronizer 4 as an input signal, and filters each filter for a predetermined fixed clutter region, a moving clutter region, and a clear region, which is different for each sampling of this trigger pulse. Output the coefficient.

An example of sampling of trigger pulses output from the synchronizer 4 with different pulse intervals is shown in FIG.
It is shown in (B). As described above, the filter characteristics of the filters 8 to 11 are switched and changed based on the sampling of the trigger pulse. The sampling interval of the trigger pulse output from the synchronizer 4 is arbitrary, and the sampling speed is determined based on the Doppler characteristic of the target, the number of hits, and the like.

The filter coefficient controller 3a outputs different filter coefficients to the signal line 18 based on the trigger pulse input from the synchronizer 4. Each filter 8 ~
11, the filter characteristic is changed by the filter coefficient output from the filter coefficient controller 3a, and the changed filter characteristic is held until a new filter coefficient is input.

An example of the characteristics of the filters 8 to 11 is shown in FIG.
It is shown in (B). Each of the filter characteristics shown in FIGS. 2A and 2B has four filters 8-11.
Is formed by the four curves 28a and 29.
a, 30a, 31a and 28b, 29b, 30b, 3
1b is a filter characteristic of each filter 8-11.
The two types of filter characteristics (A) and (B) are characteristics set by the filter coefficient output from the filter coefficient controller 3a based on the trigger pulse output from the synchronizer 4. In the two types of filter characteristics (A) and (B) of this embodiment, the peaks / valleys of the characteristics of the output voltage level G with respect to the Doppler frequency f are set to complement each other.

The changeover switches 5 and 7 are changers for changing the processing system based on the type of clutter area during processing of the input video signal. In this embodiment,
Switching is changed depending on whether or not the signal being processed is in the fixed clutter area.

If the information output from the filter coefficient controller 3a via the signal line 19 is in the fixed clutter area, the changeover switch 5 connects the signal line 17 and the signal line 20 to erase the input video. Lead to vessel 6. The eraser 6 erases the fixed clutter of the input video signal guided to the signal line 20 by the changeover switch 5 by MTI processing. The video signal output from the eraser 6 is input to the filters 8, 9 and 10.

The switch 7 is connected to the changeover switch 5 by the changeover control line 22, and if the information output from the filter coefficient controller 3a via the signal line 19 is the fixed clutter area, the switch 7 is opened. The video signal output from the eraser 6 is not sent to the filter 11. If the information output from the filter coefficient controller 3a via the signal line 19 is in a region other than the fixed clutter region, the changeover switch 5 connects the signal line 17 and the signal line 21 to each other, and inputs the input video signal. Is the filter 8, 9,
Sent to 10, 11.

The filters 8, 9, 10 and 11 receive the filter coefficients controlled by the filter coefficient controller 3a via the signal line 18, and respectively receive the fixed clutter area, the moving clutter area and the clear area. A filter characteristic is formed to frequency-separate the target signal, the remaining fixed clutter signal and the moving clutter signal from the video signal output from the canceller 6 or the video signal transmitted via the signal line 21.

The clutter suppressors 12 to 15 are circuit parts for suppressing clutter signals. The clutter suppressor 12 is a circuit unit that suppresses the clutter signal of the video signal output from the filter 8 and outputs it to the maximum selector 16. The other clutter suppressors 13, 14 and 15 also have the same circuit configuration unit as the clutter suppressor 12, and suppress the moving clutter signals of the video signals output from the filters 9, 10 and 11, and each have a maximum value selector. Output to 16.

The maximum value selector 16 compares the video signals output from the four clutter suppressors 12, 13, 14, 15 and selects the signal having the maximum value, and selects the selected video signal. This is a circuit unit that synthesizes and outputs a video signal.

Although the above-described embodiment is a preferred embodiment of the present invention, the present invention is not limited to this and various modifications can be made without departing from the gist of the present invention. For example, the type of filter characteristics to switch is
The present invention is not limited to the two types of the embodiment, and may be a multi-type of three or more types.

[0028]

As described above, according to the present invention, two filters having different characteristics are prepared in the fixed clutter area, the moving clutter area and the clear area, and each time the group stagger ratio changes, the Change the type of filter characteristics over time. With this configuration, using a limited number of filters from the relationship with the number of hits,
There is an effect that the detection rate of the target signal can be further improved.

[Brief description of drawings]

FIG. 1 is a circuit configuration block diagram showing an embodiment of a radar signal processing device of the present invention.

FIG. 2 is a diagram showing an example of filter characteristics of the radar signal processing device shown in FIG. 1, and FIGS. 2A and 2B are example characteristics when switching to two stages.

FIG. 3 is a diagram showing an example of trigger pulses output from a synchronizer constituting the radar signal processing device of FIG. 1, (A) is a frame trigger, (B) is a trigger pulse that is switched for each stagger cycle, (C). Is a staggered radar trigger.

FIG. 4 is a block diagram showing a circuit configuration example of a conventional radar signal processing device.

5A and 5B are diagrams showing a characteristic example of a plurality of filters in a conventional radar signal processing device, FIG. 5A is a filter characteristic diagram in a fixed clutter region, FIG. 5B is a filter characteristic diagram in a moving clutter region, and FIG. FIG. 3C is a filter characteristic diagram of the clear area.

6 is a diagram showing an example of filter characteristics of the radar signal processing device of FIG.

[Description of Reference Signs] 1 MTI map generator 2 Automatic clutter map generator 3a Filter coefficient controller 4 Synchronizer 5 Changeover switch 6 Eraser 7 Switch 8, 9, 10, 11 Filter 12, 13, 14, 15 Clutter suppressor 16 Maximum value detector

Claims (2)

[Claims] 1. An MTI map generating means for setting an MTI map in a fixed clutter area, an automatic clutter map generating means for setting an automatic clutter map in a moving clutter area from an input video signal, and a trigger pulse for a stagger period are output. Synchronizer, filter coefficient control means for inputting the MTI map, the automatic clutter map, and the trigger pulse, and outputting a different predetermined filter coefficient for each trigger pulse, and the filter coefficient control means for outputting the filter coefficient control means. A plurality of filters whose filter characteristics are set based on predetermined filter coefficients, a plurality of clutter suppressors for performing clutter suppression processing on each output of the plurality of filters, and each output of the plurality of clutter suppressors The maximum value selecting means for selecting the maximum value of the Value selection means receives the output signal of a different predetermined filter for each of the trigger pulse, selects the output signal having the maximum radar signal processing apparatus characterized by synthesizing the radar signal. 2. The radar according to claim 1, wherein the different predetermined filter coefficients are set such that peaks / valleys of the filter characteristics of the filters set by the filter coefficients complement each other. Signal processing device.