JPH01223376A - Radar signal processor - Google Patents

Abstract

PURPOSE:To eliminate the saturation of even a jamming signal of a high intensity, by detecting the jamming signal and a received signal containing a solar radio wave after a logarithmic amplification thereof to output a logarithmic video signal. CONSTITUTION:This apparatus is provided with a logarithmic amplifier 102 and an A/D converter 103 as logarithmic detection means, an amplitude detector 109 and an A/D converter 110 as amplitude detecting means, clutter removers 104 and 111 and a clutter area setter 105 as clutter removing means, average- amplitude extractors 106 and 112 and amplitude/display distance converters 107 and 113 as average amplitude extracting means, video generators 108 and 114 as video generating means, an amplitude decider 115 as amplitude deciding means and a video selector 116 as video selecting means. Then, outputs of the generators 108 and 114 and a video selection signal 118 from the decider 115 are sent to the selector 116. The selector 116 selects the output of the generator 108 when the signal 118 gives a logical value '1' (or '0'). Otherwise, the selector 116 does that of the generator 114 to produce outputs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar signal processing device, and more particularly to a radar signal processing device that detects jamming radio waves and the like and extracts direction of arrival data of the interference waves in a pulse radar device.

[Conventional technology]

In general, the radar received signal contains unnecessary received signals in addition to the target signal, so these unnecessary received signals may make it impossible to detect the target signal or cause received signals other than the target signal to be mistakenly detected. There may be cases where the detection occurs.

In particular, when strong electromagnetic waves within the radar reception band (hereinafter referred to as jamming signals) are artificially mixed in from the outside, it becomes difficult to detect targets in the direction of arrival of the jamming signals.
Furthermore, when automatic target tracking processing or the like is processed by a computer, many interference signals are erroneously detected, so that automatic target tracking processing may become impossible even in areas other than the direction in which the interference signal arrives.

Radar devices that are likely to receive such interference signals have means for suppressing interference signals included in received signals, as well as means for detecting the presence or absence of interference signals and accurately detecting the position data of the interference source. ing.

The above-mentioned means are usually semi-automatic and use AVA (Amplitude Tude) where pulses are output at a distance proportional to the average amplitude value every nine radar repetition periods of the logarithmic video signal.
vs. Azimuth) The arrival of the jamming signal is visually confirmed using a PPI scope using video, and then converted to distance.
By manually setting the same threshold (video displayed on the PPI) and supplying the value to the interference signal detection circuit, the detection of the interference signal and the location data of the interference source are extracted.

This situation is shown in FIG.

FIG. 3 301 shows the PPI scope tube surface, and when an interfering signal is received, the AVA video is displayed as 302. In other words, the shape is determined by the direction of arrival of the jamming signal, the strength of the jamming signal, and the azimuth pattern of the antenna of the radar device. 303 shows the thread, shield, and field (hereinafter referred to as thread, field, and field video) converted into distance and displayed on the PPI, and FIG. 3 shows the threshold video display distance 305.
This shows a state in which the AVA video maximum display distance is set to be less than or equal to the AVA video maximum display distance 304.

Since the present invention relates to AVA video generation among the above processes, the AVA video generation process will be described below. A typical example of a conventional AV human video generation circuit is shown in FIG.

In FIG. 2, a radar reception signal 201 is logarithmically amplified and detected by a logarithmic amplifier 202, and a logarithmic video signal 203 is detected.
Output as . Logarithmic video signal 203 has a higher dynamic range than normal amplitude detected video and is suitable for processing strong interfering signals.

Since the logarithmic video signal 203 is digitally processed,
After the signal is converted into a pn bit digital signal by the A/D converter 204, the clutter component is first removed by the clutter remover 205.

The clutter remover 205 receives the clutter gate signal 207 output from the clutter area setter 206, and when this signal is at the 2^ logical value l (or O), the A/D converter 20
4 output is set to O level.

The clutter area setter 206 stores the 92-dimensional information set in advance as a clutter area, and outputs a clutter and tagging signal 207 for this area in accordance with the radar timing. The clutter removed logarithmic video signal 208 from which 2 ivy has been removed by the clutter remover 205 is used by an average amplitude extractor 209 to calculate the average amplitude for each sweep.

The average amplitude extractor 209 uses preset threads,
- Accumulates amplitude take exceeding the shield and 1 of the radar
The average amplitude data 210 is output by removing this cumulative value by the cumulative data number in units of sweeps. The average amplitude take 210 is sent to the next amplitude/display distance converter 211. Average amplitude take 2 with amplitude/display distance conversion 9211
10 is linearly transformed to the display distance of the AV person video.

FIG. 4 shows an example of the conversion characteristics of the nine-linear conversion described above. Fourth
401 on the horizontal axis of the figure indicates the average amplitude value of the logarithmic video signal, and 402 on the vertical axis indicates the surface water distance with the PPI scope. Although the average amplitude value of a logarithmic video signal is a discrete value due to digital processing, the characteristics shown in FIG. 4 are shown as a continuous quantity for ease of understanding. 403 is the maximum value of the average amplitude value of the logarithmic video signal, 404 is the maximum value of the display distance, 40
5 indicates the average amplitude value for receiver noise. That is, in the conversion shown in FIG. 4, the range from the average amplitude value 405 for receiver noise in the logarithmic video signal to RMAX, which is the maximum value 403 of the average amplitude level of the logarithmic video signal, is proportional to the display distance.

Distance data 2 which is the output of the amplitude/display distance converter 211
12, a video generator 213 generates a pulse at a timing corresponding to the distance, converts it to a level that can be displayed on a PPI scope, and outputs it as an AVA video signal 214. Up to this amplitude/display distance converter 211, processing is performed at the timing of the transmitter trigger.
The video generator 213 performs timing conversion processing, and the AVA video signal 214 is output at the timing of the PPI display trigger.

[Problem to be solved by the invention]

The conventional radar signal processing device described above generates an AVA video whose display distance is proportional to the average amplitude of the logarithmic video, so a wide dynamo can process clutter interference signals, but the signal is low level, close to the receiver noise level. When receiving interfering signals, solar radio waves, etc., a sufficient display distance for AVA video cannot be obtained due to logarithmic characteristics, and it is difficult to distinguish from AVA video due to receiver noise.

That is, in FIG. 4, if the fluctuation width of the average amplitude for receiver noise is 406 and the fluctuation width of the average amplitude for low-level interference signals etc. is 407, then the average width of the AVA display distance for these fluctuation widths is 408. , 409, but the fluctuation widths of these two AVA display distances are close and the PPI
It becomes difficult to distinguish between the two on the display.

[Means to solve the problem]

The device of the present invention is a pulse radar device whose purpose is to send a high-frequency pulse into a search space and detect a target in the search space from the reflected signal of the high-frequency pulse. (called town)
logarithmic detection means for logarithmically amplifying and detecting a received signal containing the signal and outputting a logarithmic video signal, amplitude detection means for amplitude detecting the received signal and outputting a normal video signal, and corresponding to a predetermined clutter area. a clutter removing means for removing the logarithmic video signal and the normal video signal and outputting the logarithmic video signal and the normal video signal containing no clutter; an average amplitude extraction means for calculating an average value and outputting it as an average signal strength; an amplitude/distance conversion means for converting the average signal strength into independent distance data; and a video generating means for independently generating , and when the output of the average amplitude extraction means for the logarithmic video signal or the output of the average amplitude extraction means for the normal video signal exceeds a predetermined value, a logical value l( or 0), and selects and outputs the output of the video generating means regarding the logarithmic video signal, which is the output of the video generating means regarding the logarithmic video signal and the output of the video generating means regarding the normal video signal. At other times, the video selecting means selects and outputs the output of the video generating means relating to the normal video signal.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the present invention, in which a logarithmic amplifier 102° A/D converter 1 is used as a logarithmic detection means.
03. Amplitude detector 109 as amplitude detection means. A/D
Transducer 110. Clutter removers 104, 111 and clutter area setter 105 as clutter removal means, average amplitude extractors 106, 112 as average amplitude extraction means
．． It is configured to include amplitude/display distance converters 107 and 113, video generators 108 and 114 as video generation means, amplitude determiner l15 as amplitude determination means, and video selector 116 as video selection means.

In the configuration of the embodiment shown in FIG.
D converter 103. Clutter remover 104. Clutter area setter 105. Average amplitude extractor 106° amplitude/display distance converter 107. For video generator 108, the amplitude/
Symbol numbers 202 and 204 in the conventional example in FIG. 2 except for the average amplitude and display distance conversion characteristics of the display distance converter 107.
．． 205, 206, 209, 211, and 213 have the same functions as those with the same names, and therefore their operations are the same as described above. Note that the conversion characteristics of the amplitude/display distance converter 107 will be described later.

Amplitude detector 109. A/l) converter 110. Clutter remover Ill, average amplitude extractor 112. Amplitude/display distance converter 113. Video generator 114° amplitude determiner 115.
The video selector 116 is a new function added to the conventional radar signal processing device shown in FIG.
L) The converter 110 has exactly the same functions as the A/D converter 103, the clutter remover 111 as the clutter remover 104, the average amplitude extractor 112 as the average amplitude extractor 106, and the video generator 114 as the video generator 108. It has the following. Therefore, in the following, the amplitude detector 109° amplitude/display distance converter 107, 113 . The operation of video selector 108 will be described.

The amplitude detector 109 performs amplitude detection on the received signal 101 and outputs a normal video signal 117, but the dynamic range of the received signal that can normally be processed by the amplitude detector is smaller than that of the logarithmic amplifier 102. Moreover, the logarithmic amplifier 102
The maximum amplitude of the output of the amplitude detector 109 and the output of the amplitude detector 109 are usually the same.Ninth, when each video signal is quantized by the A/D converter 103 and 110, the received signal corresponding to the -quantization unit The intensity width is smaller than in the case of a logarithmic amplifier. This situation is shown in FIG. In Figure 5, 5 on the horizontal axis
01 indicates the received signal level in logarithmic form, and 5 on the vertical axis
02 indicates the video level (voltage) after detection. Also, 5
o3 indicates the detection characteristics of logarithmic video, and the logarithmic detection range is 50
Outputs a voltage proportional to 5.

On the other hand, 504 indicates a normal video characteristic as a detection characteristic of the amplitude detector, and is a voltage proportional to the inverse log value of the received signal level (logarithm representation) in the amplitude detection range 506.

Assuming that the number of bits of the A/D converters 103 and 110 is n bits, the A/D converters 103 and 110 have a range of 2f from 0 on the vertical axis to the maximum video level 507 shown in amplitude.
Divide into l and quantize. If the video level difference corresponding to one quantization unit at this time is 508, the corresponding received signal strength width is 5091. In the case of normal video, it is 510, and the received signal strength width for the normal video signal is smaller. That is,
In the range indicated by the amplitude detection range 506, the A/D converter 11
When the output is 0, the received signal is quantized thinner.

This embodiment uses the above characteristics to select the AVA video generated based on the normal video signal when the received signal level is within the amplitude detection range 506 or a predetermined range thereof, and selects the AVA video generated based on the normal video signal, and As for the level, by selecting AVA video generated based on logarithmic video as before, it does not saturate even with high-strength interference signals, and can withstand low-level interference signals near receiver noise. The aim is to generate AVA video that is easily distinguishable from receiver noise.

In the amplitude/display distance converters 107 and 113, when switching videos with the video selector 116 described below, A
Display distance characteristics with respect to the average amplitude value of the logarithmic video and the average value of the normal video are determined so that the display of the VA video is not discontinuous.

The output of the average amplitude extractor 106 is also sent to the amplitude determiner 115, where it is compared with a predetermined threshold, and if it exceeds the threshold, it is output as the video selection signal 118.
Outputs the logical value 11'' (or 'θ) of the value.

Outputs of video generators 108 and 114, video selection signal 1
18 is sent to video selector 116.

The video selector 116 selects the output of the video generator 108 when the video selection signal 118 has a logical value of "1" (or v'0"), and selects and outputs the video generator 114 at other times. .

FIG. 6 shows an example of the characteristics of the average amplitude value and AVA display distance with respect to the received signal level according to this embodiment.

In FIG. 6, 601 on the horizontal axis is the average amplitude value of the received signal converted to the average amplitude of logarithmic video, and 602 on the vertical axis is A
VA display distance, 603 is maximum average amplitude value, 604 is AV
The maximum display distance for A video, 605, indicates the average value for receiver noise. In FIG. 6, a variation width 606 of the average amplitude value for receiver noise corresponds to the variation width 406 of the average amplitude value for receiver noise in FIG. 4, and a variation width 407 for the average amplitude value for interference signals, etc. The AVA Piteo display distance for the fluctuation width 607 of the average amplitude @ value for low-level interference signals etc. is 608.609, respectively, and the difference in display distance is remarkable compared to the case of Fig. 4.
It becomes much easier to identify low-level interference signals and the like with respect to receiver noise.

〔Effect of the invention〕

As explained above, the present invention selects the AVA video generated from the normal video for low-intensity interference signals close to the receiver noise level up to a predetermined value, and For the signal, by selecting and outputting AVA video generated from conventional logarithmic video, it does not saturate even in the face of high-strength interference signals, and can suppress low-strength interference signals near receiver noise. An advantage of this method is that it is possible to generate AVA video that is highly distinguishable from receiver noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a typical configuration example of a conventional radar signal processing device, and FIG. 3 shows AYA video and threshold on PPI,
4 is a characteristic diagram showing the relationship between the average amplitude value and display distance of a conventional radar signal processing device, and FIG. A characteristic diagram showing the comparison with logarithmic detection characteristics, Figure 6 is
FIG. 3 is a characteristic diagram comparing and showing the relationship between the received signal level and the AVA display distance in the illustrated embodiment. 101... Received signal, 102... Logarithmic amplifier, 103... A/D converter, 104...
...Clutter remover, 105...Clutter area setter, 106... ... Average amplitude extractor, 107 ... Amplitude/display distance converter, 108 ... Video generator, 109
...°°° amplitude detector, 110... A/D converter, 111... clutter remover, 112...
... Average amplitude extractor, 113 ... Amplitude/display distance converter, 114 ... Video generator, 11
5...Amplitude determiner, 116...Video selector, 117...°...Normal video signal, 20
1... Received signal, 202... Logarithmic amplifier, 203... Logarithmic video signal, 204...
... A/D converter, 205 ... clutter remover, 206 ... clutter area setter, 207.
...Clutter gate signal, 20B...Clutter removed logarithmic video signal, 209...Average amplitude extractor, 210...Average amplitude data, 211
...fam/display distance converter, 212...
...Distance data, 213...Video generator, 2
14...AVA video, 301...P
PI scope tube surface, 302...AVA video,
303...Threshold video, 304...
...AVA video maximum display distance, 305...
...Thread, short video display distance, 401...
...Average amplitude value of logarithmic video signal, 402...
AVA display distance, 403... Maximum value of average amplitude value of logarithmic video signal, 404... Maximum value of AVA display distance, 405... Average amplitude value with respect to receiver noise. , 406... Fluctuation width of average amplitude with respect to receiver noise, 407... Fluctuation width of average amplitude with respect to interfering signal, 408... Fluctuation width of average amplitude with respect to receiver noise AVA display distance for 4
09... AVA display distance with respect to the variation range of average amplitude with respect to the interference signal ring, 501... Received signal level, 502.°°°.° Video level after detection, 5
03... Logarithmic video detection characteristics, 504° old °°
Normal video characteristics, giant 05...logarithmic detection range, 506...amplitude detection range, 507...
- Maximum video level, 508...Video level difference corresponding to one quantization rate of the A/D converter, 509...
. . . Reception level difference with respect to video level difference 508 corresponding to 1 quantization rate of A/D converter in logarithmic video, 51O . . . A/D in normal video
Video level difference 508 corresponding to one quantization rate position of the converter
601...Average amplitude value of received signal, 602...AVA video display distance, 603 PA°...Maximum average amplitude value, 604...
・AVA video maximum display distance, 605... Average amplitude value relative to receiver noise, 606... °° Fluctuation range of average amplitude value relative to receiver noise, 607...
... Fluctuation range of average amplitude value for interference signals, etc., 608.
... AVA display distance for the fluctuation range 606 of the average amplitude #A value against receiver noise, 609 ... A for the fluctuation range 607 of the average amplitude value for interference signals, etc.
VA display distance. Agent Patent Attorney Uchihara Den 1N\N 304-1--△VA Video Maximum Display Distance 305--
- Threshold 3 - Rudo Hiteo Display Distance Figure 6

Claims (1)

[Claims] In a pulse radar device whose purpose is to send a high-frequency pulse into a search space and detect a target in the search space from the reflected signal of this high-frequency pulse, it includes interference signals and solar radio waves (hereinafter referred to as interference signals, etc.). logarithmic detection means for logarithmically amplifying and detecting a received signal and outputting a logarithmic video signal; amplitude detection means for amplitude detecting the received signal and outputting a normal video signal; Clutter removing means for removing a logarithmic video signal and a normal video signal and outputting the logarithmic video signal and normal video signal that do not include clutter; an average amplitude extracting means that calculates and outputs it as an average signal strength; an amplitude distance converting means that converts the average signal strength into independent distance data; and an amplitude distance converter that converts the average signal strength into independent distance data; a logical value of 1 (or 0) when the output of the average amplitude extraction means for the logarithmic video signal or the output of the average amplitude extraction means for the normal video signal exceeds a predetermined value; An output of the amplitude determining means receives the output of the video generating means regarding the logarithmic video signal, the output of the video generating means regarding the normal video signal, and the output of the amplitude determining means, so that the output of the amplitude determining means has a logical value of 1. (or 0), selects and outputs the output of the video generation means related to the logarithmic video signal, and otherwise selects and outputs the output of the video generation means related to the normal video signal; A radar signal processing device comprising: