JPS60195471A - Radar signal processing device - Google Patents

Abstract

PURPOSE:To detect exactly the azimuth, elevation angle and a run-length of an interference signal by providing a receiving means by an antenna pencil beam and a clutter eliminating means, and also providing a detecting means of the azimuth, elevation angle and the respective ranges. CONSTITUTION:The intensity of a receiving signal is corrected by an STC (sensitive time control) amplitude correcting circuit 4, and the output video 105 of the STC4 is controlled by a clutter eliminating circuit 5. Also, averaged amplitude value outputs corresponding to three antenna beams being adjacent to an elevation angle are compared by an elevation angle signal extracting circuit 9 and outputted together with antenna scanning beam information, and a value of the azimuth direction of an average amplitude and an azimuth data corresponding to the antenna beam are extracted by an azimuth signal extracting circuit 11, and outputted together with a data of the elevation angle direction. Subsequently, the output of the azimuth signal 11 is selected, and a bearing, an elevation angle and a run-length of a disturbing signal source are calculated by an operating circuit 12. In such a way, the interference signal source can be detected exactly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a radar signal processing device that performs interference signal detection and interference signal data extraction processing in a pencil beam scanning three-dimensional radar device.

(Prior art) In general, radar received signals include unpleasant received signals in addition to target signals, so these unnecessary received signals may make it impossible to detect multiple target signals or There may be cases where a received signal other than the above is erroneously detected. 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, and it becomes difficult to automatically track targets. When the processing is performed by a computer, a large number of 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 signals arrive.

In radar equipment W that is likely to receive such interference signals, the means for suppressing the spinning signal from the received signal, the position data of the interference source, and the range where the interference signal affects the target detection performance of the radar (hereinafter referred to as 2/length) are required. The system has a means for detecting a signal (called "M11") with sufficient accuracy and performing a monthly salary detection process for the reception area affected by the interference signal, and preventing signal detection exceeding the processing capacity of the computer. Examples of such two-dimensional radar devices with anti-jamming measures include the following.

This radar logarithmically amplifies the radar received signal to produce a logarithmic video, integrates this logarithmic video for each radar sweep, and when the (responsibility value) exceeds a preset threshold, the radar equipment & The radar sweep affected by the interference signal is output as a pulse (hereinafter referred to as a strobe response) as a result of the judgment, and the received signal of the radar sweep is input to a circuit that performs target detection processing. On the other hand, the strobe response that is continuously detected in the azimuth direction is processed by Jx+'l/
, the radar sweep (hereinafter referred to as the strobe curve edge) that was determined to be affected by the interference signal for the first time, and the radar sweep (hereinafter referred to as the strobe curve edge) that was determined to be unaffected by the interference signal No. 1N for the first time after the leading edge of this strobe was detected. The center azimuth and run length of the interference signal are calculated from these radar sweep azimuth data (midway between the leading edge and the trailing edge) and output to the outside. In this way, the two-dimensional radar receives the jamming signal from one location over a number of radar sweeps related to the antenna azimuth beam width, so it is possible to detect the center azimuth and run length of the jamming signal.

On the other hand, 3D radar uses a pencil beam scanning method in which a sharp aerial pencil beam is scanned in the azimuth and elevation directions, and the number of transmissions and receptions per scan is usually one. Even if a disturbance signal is received, the next received antenna beam scan in the elevation angle direction (hereinafter referred to as 1113 angle scan) or the antenna beam scan in the azimuth direction will be performed once. Now, in this three-dimensional radar system, if we consider the case where the antenna that runs the beam electronically in the IJIJ angular direction is mechanically rotated, if the rotational speed of the antenna is almost the same as that of the two-dimensional radar (i.e., the data If the rate is approximately the same), the antenna rotation angle during the elevation scan time will be larger than the antenna rotation angle during the pulse repetition time in the two-dimensional radar, and the radar sweep will receive the jamming signal with sufficient strength. The number is smaller than in the case of two-dimensional radar.

Therefore, it is difficult to detect the center direction and run length of the jamming signal using the jamming prevention means used in the two-dimensional radar.

The same reason also applies when an antenna that performs electronic pencil beam scanning in the azimuth direction is mechanically scanned in the elevation direction, or when all pencil beam scanning in the elevation and azimuth directions is performed electronically. This makes it difficult to detect the central azimuth or central elevation angle and run length of the jamming signal using the anti-jamming means.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems and provide a radar signal processing device having a function of detecting the center direction, center strike angle, and run length of a disturbance signal in a three-dimensional radar. It's about doing.

(Structure of the Invention) A radar signal processing apparatus according to the present invention includes a receiving means for receiving a received signal including a disturbance signal by an antenna beam scanned in the azimuth direction and the elevation direction of a search space; clutter removal means for removing a clutter region and extracting the disturbance signal; average amplitude extraction means for extracting an average disturbance intensity for each scanning beam from a plurality of disturbance signals extracted by the clutter removal means; large signal detection means for detecting a first average disturbance signal in a first scanning beam having a maximum intensity among the average disturbance intensities obtained for each scanning beam unit; signal extracting means for extracting second and third average disturbance signals of the scanning beams adjacent in the elevation direction and fourth and fifth average disturbance signals of the scanning beams adjacent in the elevation direction; 3 average jamming signal intensities and a direction detecting means for detecting the center direction from which the jamming signal arrives from the direction of the scanning beam giving each of the average jamming signal intensities; elevation angle detection means for detecting the elevation angle of the center of arrival of the interfering signal from the elevation angle of the scanning beam giving the average interfering signal intensity; the first, second and third average interfering signal intensities, the azimuth of the center of arrival of the interfering signal and the interfering signal; azimuth range detection means for detecting the azimuth range of the jamming signal from a predetermined reference level for determining the jamming signal; and elevation angle range detection means for detecting the elevation angle range of the interference signal.

The configuration of the present invention is to output the position data and run length of the interference signal source in both the azimuth direction and the elevation direction. It is clear that the configuration for detection can be easily made.

(Example of the invention) Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram of a radar signal processing device according to an embodiment of the present invention, and FIG. 3 is an operational waveform diagram of FIG. shall be scanned by (rotation) of the antenna. In this embodiment, a receiving system includes a logarithmic amplifier 2 that receives a radar reception signal 101 from an input terminal 1 and outputs a logarithmic video signal 102, and an A/D converter 3 that converts the logarithmic video signal 102 from analog to digital. Sensitlvi ty Ti
(Me Control) STC amplitude correction circuit 4 for correcting the received signal strength that has undergone negative attenuation, and a clutter area gate 1 for indicating that the area is a ground clutter area.
The clutter area setting circuit 6 generates the clutter area gate 103 and the output bidet 105 of the STC amplitude correction circuit 4 receives the clutter area gate 103 while the clutter area gate is applied.
A clutter removal circuit 5 that prohibits the noise reduction, a receiver noise removal circuit 7 that removes receiver noise from the output 106 of the clutter removal circuit 5, and an output 07 of the noise removal circuit 7.
The average interfering signal amplitude value is extracted and output by integrating between the rudder sweeps and dividing the integral value by the time obtained by subtracting the time corresponding to the clutter region and receiver noise only region in the rudder sweep. An amplitude extraction circuit 8, a sweep memory 13 that delays the output of the average amplitude extraction circuit 8 between two radar sweeps and two radar sweeps, and outputs the output after delaying the output of the average amplitude extraction circuit 8, and the output of the sweep memory 13 and the average amplitude extraction circuit. From the output of 8, compare the average amplitude value output corresponding to three antenna beams adjacent in the elevation direction, and calculate the local maximum value among these and this local maximum value (corresponding to the antenna beam adjacent to the antenna beam giving the local maximum value). an elevation signal extraction circuit 9 that extracts the next largest average amplitude value and outputs it together with information specifying the antenna scanning beam; and an elevation scan memory that stores the output of this elevation signal extraction circuit 9 for two consecutive elevation scans. 10, and from the outputs of the elevation signal extraction circuit 9 and the elevation scan memory 10, the elevation angle output over three consecutive elevation scans and the azimuth signal received from the antenna 20 to the input terminal 15 are received, and the maximum of the average amplitude in the azimuth direction is obtained. (corresponding to the antenna beam adjacent to the antenna beam giving the maximum value)
An azimuth signal extraction circuit 11 that extracts the next largest average amplitude value after the maximum value and azimuth data corresponding to each antenna beam, and outputs it together with data in the elevation angle direction, and an output of this azimuth signal extraction circuit 11 and a disturbance signal 10. − Input terminal 1 to which υ8 is added externally to determine the detection sensitivity
an arithmetic circuit 12 which receives a reference signal from 6, selects the output of the azimuth signal extraction circuit 11 according to this reference signal, calculates the azimuth, elevation angle, and run length of the interference signal source and outputs it from the output terminal 4; It consists of:

FIG. 2 is a schematic diagram of an example of an antenna beam pattern in this embodiment. The antenna 20 is oriented clockwise 30 as shown in the figure.
One antenna beam is formed in the elevation direction in one transmission or reception, and by moving this antenna beam in the elevation direction 32, the radar device of this embodiment
It shall have a dimensional coverage. The antenna beams 41 to 49 in FIG. 1 schematically represent the antenna beams formed continuously in the elevation angle direction over three consecutive elevation angle scans, and it is assumed that the interference signal is radiated from the arrow direction 31.

FIG. 3 is a waveform diagram illustrating the operation of FIG. 1.

In FIG. 2, a signal received by an antenna beam is converted into a logarithmic video signal 102 (FIG. 3) by a logarithmic amplifier 2, and then its amplitude is converted into a digital code by an A/D converter 3. This logarithmic bidet No. 102 contains ground clutter etc. in addition to interference signals, and since attenuation is added to signals received from a short distance by STC,
The A/D converted logarithmic video is then subjected to amplitude correction of the STC inverse characteristic by the STC amplitude correction circuit 4, and this amplitude correction output 105 (FIG. 3) is sent to the clutter removal circuit 5.

This clutter removal circuit 5 uses a logarithmic bidet 105 whose amplitude has been corrected and a clutter area gate 103 (a third Figure)
The period STC specified in this clutter area game) 103
After cutting off the logarithmic video from the amplitude correction circuit 4, this logarithmic video 106 (FIG. 3) is sent to the receiver noise removal circuit 7. Comparing the logarithmic video sent from the receiver noise removal circuit 7F'i clutter removal circuit 5 with a preset threshold value corresponding to the receiver noise level,
Of the outputs 106 of the clutter removal circuit 5, only the logarithmic video amplitude signal exceeding this threshold value is outputted to the average amplitude extraction circuit 8 (signal 107 (Fig. 3)), and at the same time the rudder sweep signal is outputted to this circuit 8. The number of data per unit (hereinafter referred to as the number of samples) is # [forgive. This average amplitude extraction circuit 8 integrates its output during the rudder sweep, and divides this integrated value by the number of samples per rudder sweep sent from the noise removal circuit 7, which is the average amplitude value 108 ( 3) and sends it to the elevation angle signal extraction circuit 9 and sweep memory 13.

This sweep memory 13 uses a signal obtained by delaying the average amplitude value 108 from the flat amplitude extraction circuit 8 by the rudder trigger interval as a signal for extracting the local maximum value of the average amplitude value in the elevation direction, etc. The signal delayed by the da trigger interval is output to the elevation angle signal extraction circuit 9. This elevation signal extraction circuit 9
is one of the three types of average amplitude values sent from the average amplitude extraction circuit 8 and the sweep memory 13.
3- Determine whether or not it is a local maximum value, and if it is a local maximum value, the amplitude value, information specifying the antenna beam, and the average amplitude value corresponding to the antenna beam adjacent to the antenna beam giving this maximum value. , the one that gives the next largest value after the local maximum value K
The value and information specifying the antenna beam are extracted and sent to the elevation scan memory 10 and the azimuth signal extraction circuit 11.

This situation will be explained using figure 42. In this diagram,
Assuming that the currently formed antenna beam is beam 43, antenna beam 41.
The average amplitude value corresponding to the antenna beam 42 is outputted from the average amplitude extraction circuit 8, and the average amplitude value corresponding to the antenna beam 43 is outputted from the average amplitude extraction circuit 8. First, it is determined whether the elevation angle signal is distorted. That is, as a result of comparing the antenna beam 42 with the antenna beams 41 and 43, if the average amplitude value is larger than both, it is determined that the antenna beam 42 has the maximum value. When it is determined that this antenna beam 42 has a local maximum value, the average amplitude value of the antenna beam 42 and information specifying the antenna beam 42 (eg, beam number) are extracted. At the same time, the antenna beams 41 and 43 are compared, and the larger value behind these and the corresponding antenna beam designation information are also extracted.

On the other hand, the elevation scan memory 10 stores the output of the elevation signal extraction circuit 9 over two consecutive elevation scans 1 to 1.
Compared to the output of this circuit 9, the outputs before the elevation angle scan and before the elevation angle scan are sent to the azimuth signal extraction circuit 11. Similar to the operation of the elevation signal extraction circuit 9, the azimuth signal extraction circuit 11 compares the outputs of the elevation signal extraction circuit 9 and the elevation scan memory 10, and determines the maximum value and maximum value of the average amplitude in the azimuth direction. The next largest average amplitude value after the maximum value corresponding to the antenna beam adjacent to the given antenna beam and the corresponding azimuth data are extracted.

Now, in the model of Figure 2, each antenna beam is 42.45
．． Assuming that the received power of the 48 jamming signals is the maximum in each elevation scan, the jamming signal reception (St level) in each antenna beam is shown as shown in FIG. 4. In this figure, 42A, 45A.

48A shows the pattern in the azimuth direction of the antenna beams 42, 45.48, and the antenna gain of each antenna beam with respect to the interference signal arriving from the direction 31 is the reception level 51, 52.53 in the interference arrival direction 31, respectively. The antenna gain corresponds to

In this model, the antenna gain (52) of the aerial 4til pattern 45A is the largest, followed by the antenna gain (53) of the antenna pattern 48A and the antenna gain (I4) of the antenna pattern 42A. Therefore, the thick value output of the average amplitude value from the elevation angle signal extraction circuit 9 in FIG. 1 is the output 54, 55 .
56, and the direction signal extraction circuit 11 outputs the output 55.
The amplitude values of 56 are extracted as the maximum value and the average amplitude value next to the maximum value, respectively, and the azimuth angles (θ2, θ3) of the noses of the antenna beams 42 and 45 are extracted as the azimuth data corresponding to the output 55.56. .

The two-dimensional maximum value and the value next to the maximum value of the average amplitude value of the interference signal obtained by the elevation data extraction circuit 9 and the azimuth data extraction circuit 11 in this way, the antenna beam elevation angle information and the azimuth angle corresponding thereto. The information is sent to the arithmetic circuit 12, and the arithmetic circuit 12 calculates the center azimuth, center elevation angle azimuth direction run length, and elevation angle direction run length of the interfering signal source from each data and reference No. 18/, 1! However, since the processing algorithm is the same for both the azimuth and elevation directions, here we will use the run lengths in the center azimuth and azimuth directions.
il: Explain about appearance.

Now, in FIG. 4, the azimuth angle of the beam nose direction of the antenna beams 42, 45° 48 is set to 01. θ7. When θ is assumed, the outputs 54, 55, and 56 have values proportional to the antenna pattern characteristics, as shown in FIG. 5(a). Here, if the local maximum value of the average amplitude is At, and the value A1 is the next largest value after the maximum amplitude, then the central direction of the interfering signal is calculated by the order of magnitude θ1.

Here, the correction angle Δθ is the correction amount related to the maximum value A2 and the next largest value A after the maximum value, and as shown in Fig. 5), it has a linear relationship with the values of A and -A. Yes, -17 = its slope is determined by the antenna pattern.

Therefore, the vJIJ direction θ1 can be determined by calculating Δθ from the actually measured values A, , A, and A.

- As for the run length θR, the antenna beam pattern characteristics of a strong reception interference signal are estimated from the local maximum value rAa, and the estimated pattern characteristics are calculated from the angle range in which the estimated pattern characteristics exceed the reference signal value set from the outside. That is,
57 is the pattern characteristic estimated from outputs 55 and 56, 5
8 is the reference signal level, the angular range θ8 exceeding this reference signal level 58 becomes the run length.

Regarding the center elevation angle and the run length in the elevation direction, it is necessary to calculate the elevation angle of the antenna beam from the information specifying the antenna beam instead of the angle data, but the subsequent processing is based on the center azimuth and the run length in the azimuth direction. This is the same process as obtaining the run length.

Note that in this example, the local maximum value in the elevation direction is first extracted,
After that, the maximum value in the azimuth direction was detected, but this order can be reversed, and it is also easily possible to process the azimuth direction and the elevation direction simultaneously. It is also possible to form multiple antenna beams with one transmission.

(Effects of the Invention) As explained above, according to the present invention, even in a pencil beam scanning three-dimensional radar device in which the number of transmissions and receptions per beam scan is normally one, the direction of the interference signal source can be , elevation angle and run length can be detected reliably.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of an antenna beam pattern in this embodiment, FIG. 3 is a signal waveform diagram of the block in FIG. 1, and FIG. 4 2 is an explanatory diagram of a method for calculating the direction of the interference signal source from the nominal antenna value in FIG. 2. FIG. In the figure, 1... Radar reception signal input terminal, 2...
・Logarithmic amplifier, 3...A/D converter, 4...
... S T C amplitude correction circuit, 5 ... clutter removal circuit, 6 ... clutter area setting circuit, 7
...Receiver noise removal 1 River road, 8 ... Average amplitude extraction circuit, 9 ... Elevation angle signal extraction circuit, 1
0... Elevation scan memo 1c 11...
・Azimuth signal extraction circuit, 12... Arithmetic circuit, 13
...Sweep memo 1c 14...Disturbance signal output terminal, 1.....Azimuth input terminal, 16.
...Reference signal input terminal, 20...Antenna, 30...Antenna rotation direction, 31...
Interfering signal arrival direction, 32... Elevation angle scanning direction, 4
1-49・・・Aerial pencil beam, 42A,
45A. 48A... Each of the antenna beams 42, 45.48 (rL pattern, 51, 52.53... Reception level of the interference signal, 54, 55.56... each Amplitude output of antenna beam 42, 45, 48, 57...
... Specified pattern characteristics, 58 ... Reference 1d level, 101 ... Radar reception signal, 1
02... Logarithmic video, 103... Clutter region gate, 104... Sample number signal,
105...STC amplitude correction circuit output, 10
6...Clutter removal circuit output, 107...
. . . Receiver noise removal circuit output, 108 . . . Average amplitude value, 109 . . . Interfering signal. Agent Patent Attorney Susumu Uchihara Gu-N'i2゜Chamita!
:' 21- -431- Figure ■)

Claims (1)

[Claims] receiving means for receiving a received signal including a disturbance signal by an antenna pencil beam scanned in the azimuth and elevation directions of a search space; and clutter removal means for removing a clutter region from the received signal to extract the disturbance signal. , average amplitude extraction means for extracting an average disturbance intensity for each scanning beam unit from among the plurality of disturbance signals extracted by the clutter removal means; maximum signal detection means for detecting a first average disturbance signal in a first scanning beam having a maximum intensity; second and third average disturbances in scanning beams adjacent in the azimuthal direction to the first scanning beam; signal extraction means for extracting the signal and fourth and fifth average jamming signals of adjacent scanning beams in the elevation direction, and providing said first, second and third average jamming signal strengths and respective average jamming signal strengths; azimuth detecting means for detecting the center azimuth from which the interfering signal arrives from the azimuth of the scanning beam; elevation angle detection means for detecting an arrival center elevation angle; m1, second and third average interfering signal intensities;
azimuth range detection means for detecting the azimuth range of the jamming signal from the arrival center azimuth of the jamming signal and a predetermined reference level for determining the jamming signal; A radar signal processing device comprising an elevation angle range detection means for detecting an elevation angle range of a disturbance signal from an arrival center elevation angle and the reference level.