JPH0479546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an improvement in a radar search device that eliminates clutter such as mountains and buildings and detects point targets such as aircraft.

[Conventional technology]

Conventional radar search equipment displays the received video signal of the search radar on a PPI display, and the operator places a marker on the target on the PPI display with a track ball, etc.
The position was sent out as a target position (R, θ) signal.

FIG. 6 is a diagram showing an example of the configuration of a conventional device of this kind, in which 1 is a search radar, 2 is a transmitted pulse signal, 3 is a received video signal, 4 is a bearing antenna angle signal, and 5 is a PPI display. , 6 is a track ball, 7A is a target position (R, θ) signal, and 7B is a machining signal.

In FIG. 6, the search radar 1 is constantly rotating in the bearing direction, and while transmitting the rotation angle as a bearing antenna angle signal 4, emits electromagnetic waves and simultaneously transmits a transmission pulse signal 2.

The reflected electromagnetic waves from the target are transmitted from the search radar 1 as a received video signal 3 and displayed on the PPI display 5. The investigator identifies the target and the clutter on the CRT screen of the PPI display 5, indicates the target with the track ball 6, and uses the output of the track ball as the target position (R, θ) signal 7A and indicates that the target has been indicated. A signal from a relay contact or the like that is used as an acquisition signal 7B is sent to other equipment such as a tracking radar.

FIG. 7 shows an example of the relationship between the transmitted pulse signal 2 and the received video signal 3, where 8 is the target echo 1 and 9 is the clutter echo 1.

In FIG. 7, electromagnetic waves are emitted from the search radar 1 at the timing of the transmission pulse signal 2. The electromagnetic waves reflected by a point target such as an aircraft are obtained as a target echo 18 having approximately the same pulse width as the transmitted pulse signal 2. Furthermore, electromagnetic waves reflected by mountains, large buildings, etc. are obtained as clutter echoes 19 with a pulse width larger than that of the transmitted pulse signal 2.

FIG. 8 is a diagram showing an example of one display on the PPI display 5 of the conventional radar search device shown in FIG.
10 is a PPI display example, 11 is a target echo 2, 12 is a clutter echo 2, and 13 is a target indicating marker.

In FIG. 8, a point target such as an aircraft is displayed as a target echo 18 and a target echo 211 having approximately the same pulse width as the pulse width of the transmitted pulse signal 2. In addition, clutter from mountains etc. is a clutter echo 1 with a pulse width larger than the pulse width of the transmission pulse signal 2.
9, displayed as Kuratsuta Echo 212. Furthermore, since the reflection area of clutter is generally larger than that of a point target, the amplitude of clutter is also larger.
The operator operates the trackball 6 to place the target indication marker 13 on the target echo 18, and transfers the output of the trackball 6 at that position to the target position (R,
θ) Send as signal 7A.

At the same time, an acquisition signal 7B indicating that the target has been designated is sent out.

[Problem that the invention seeks to solve]

In this way, in conventional equipment, the operator
Detecting a point target such as an aircraft on the CRT screen of a PPI display and transmitting target position (R, θ) signals requires the operator's skill and complicated operations. Also,
There was a problem that if the area around the search radar was complex, there would be a lot of clutter, making it difficult to target quickly.

This invention measures the area of a received video signal,
The purpose of this system is to eliminate received video signals with large areas such as clutter, detect only received video signals with small areas such as aircraft, and automatically detect their positions.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention
A means for treating the received video signal as a two-dimensional image and assigning an area number to a block of the same received video signal, a means for measuring the area for each area number, and a means for measuring the target position (angle and angle) for each area. This method uses means for measuring distance) and means for detecting a target position in a small area.

[Effect]

In the apparatus according to the present invention, a received video signal is binarized to generate a binary video signal, an area number is assigned to the two-dimensional array of the binary video signal, and the area and position ( angle, distance)
Measure. Depending on the area of each area number measured, the target position (angle, distance) with a large area is disabled, the target position (angle, distance) with a small area is enabled, and the target position (angle, distance) is valid. Point targets such as aircraft are automatically detected by detecting.

〔Example〕

FIG. 2 is a diagram for explaining an example of a video arrangement when the display example shown in FIG. 8 is binarized.
4 is an example of a binary video array, and 15 is a pixel.

In FIG. 2, the horizontal size of the pixel 15 corresponds to one range bin, and the vertical size corresponds to a radar transmission cycle. When the display example shown in FIG. 8 is binarized, it becomes a pixel arrangement as shown in FIG. 2.

3 is a diagram for explaining the outline of the operation of the area number assigning circuit 25 shown in FIG. 1, FIG. 3a is a diagram for explaining the area detection window, and FIG. 3b is a diagram for explaining the area number This is a diagram for explaining a storage register array, where 16 is an area detection window and 17 is an area number storage register array.

In the area detection window 16, A is located at the position of a pixel to which an area number is assigned, and B, C,
There are D and E. Further, assuming that the pixel width in the distance direction is m pixels, the area numbers of pixels to which area numbers have already been assigned are stored in the area number storage register array 17 for the past m+1 pixels.
Let the values of the binary video at positions A, B, C, D, and E be F(A), F(B), F(C), F(D), and F(E), respectively.
The contents of the area storage register array 17 indicating the area numbers of the pixels at positions B, C, D, and E are written as R(1) and R, respectively.
(m-1), R(m), R(m+1), and A
Assuming that the area number of the pixel at the position is N, the theory of area numbering is expressed by the following equations (1) to (9).

F(A)=0→N=0 ...(1) F(A)=1, F(B)=F(C)=F(D)=F(E) =0→N=k ...( 2) However, k is the smallest natural number among the area numbers not stored in the area number storage register column 17.

F(A)=F(B)=1, F(C)=F(D)=F(E) =0→N=R(1)...(3) F(A)=F(E)= 1, F(C)=F(D) =0→N=R(m+1) ...(4) F(A)=F(D)=1, F(C)=0→N=R(m) ……(5) F(A)=F(C)=1, F(B)=F(D)=F(E) =0→N=R(m−1) ……(6) F(A )=F(C)=F(D)=1, →N=R(m-1)...(7) F(A)=F(C)=F(E)=1, F(D)= 0→N = R(m-1), R(m+1) = R(m-1)
...(8) F(A)=F(B)=F(C)=1, F(D)=R(E)=0→N =R(m-1), R(1)=R( m-1)...(9) Therefore, by scanning with the area detection window 16, the same area number is assigned to the parts where the binary videos are connected.

FIG. 4 is a diagram for explaining the outline of the output of the area number assignment circuit 25 shown in FIG. 1 when the binary video array string 14 of FIG. is area number 1, 20 is area number 2, 21 is area number 3, and 22 is area number 4. The binary video signal 24 shown in FIG. 1 corresponds to the binary video array example 14 shown in FIG. According to the formula, the target echo 18 has area number 220, and the Kuratsuta echo 19 has area number 11.
9. The target echo 211 is output as the area number 422, and the clutter echo 212 is output as the area number 321. In addition, Kuratsuta Echo 212 at the upper and lower ends
Since the search radar 1 shown in FIG. 6 rotates endlessly in the bearing direction, the search radar 1 shown in FIG. 6 is inputted with the combined video signal, so the same area number 321 is given as shown in FIG.

FIG. 1 shows one embodiment of the present invention, in which 23 is a binarization circuit, 23A is a threshold value, and 24 is a binarization circuit.
25 is an area number assigning circuit, 26 is an area number signal, 27 is a centroid detection circuit, 28 is an area measuring circuit, 29 is a delay circuit, 30 is a delay area number signal, 31 is an area area signal, 32 is a The area gravity center point (R, θ) signal, 33 is a target determination circuit.

In FIG. 1, the operations of the search radar 1, the transmitted pulse signal 2, the received video signal 3, the bearing antenna angle signal 4, and the PPI display 5 are the same as in FIG. 6, and their explanations will be omitted.

The binarization circuit 23 converts the received video signal 3 into a threshold value 23.
A binary video signal 24 is generated which is "0" when the value is less than A, and "1" otherwise. As shown in FIG. 7, the area number assigning circuit 25 assigns an area number to each pixel according to equations (1) to (9) during the valid period of the received video for each transmission pulse, and outputs the area number signal 26. generate. When the area number signal 26 is other than 0 for each pixel, the area measuring circuit 28 increments and stores the area of the corresponding area number by 1. Center of gravity detection circuit 2
When the area number signal 26 is other than "0", 7 is determined and stored at the center of gravity position (R, θ) of the corresponding area number using equation (10).

Th: Threshold P (R, θ): Received video amplitude of pixel (R, θ) When the binary video signal = 0 K = 0 When the binary video signal = 1 K = 1 The delay circuit 29 uses the area number 26. delayed by Td,
A delay area number signal 30 is sent out. Note that the delay time Td needs to satisfy equation (11). however,
Td is an integral multiple of the transmission repetition time of the search radar 1.

Td＞θB/θ・B...(11) θB: Transmission beam width in the bearing direction of the search radar θ・B: Rotation speed in the bearing direction of the search radar The area measuring circuit 28 described above also receives the delay area number signal 30. As the address, the area of the corresponding area number is sent as the area area signal 31. Similarly, the center of gravity detection circuit 27 receives the delay area number signal 3.
The gravity center point position (R, θ) with 0 as the address is sent as the area gravity point (R, θ) signal 32.

A target determination circuit 33 receives a region area signal 31 and a region gravity center point (R, θ) signal 32, and receives a region area signal 31 and a region gravity point (R, θ) signal 32.
When 1 is larger than the reference value, the area centroid point (R,
θ) The signal 32 is invalidated. When the area area signal 31 is smaller than the reference value, the area gravity center point (R, θ) signal 32 is enabled, and the target position (R, θ) signal 7A is activated.
Send as. At the same time, an acquisition signal 7B indicating that the target has been detected is also sent out.

FIG. 5 is a diagram for explaining the target position (R, θ) signal 7A in FIG.
θ) signal. When the binary video signal 24 in FIG. 1 is output as shown in FIG. 2, area numbers as shown in FIG. 4 are assigned, and area numbers 119 and 321 with large areas are suppressed. Target 1 position (R, θ) signal 34 and target 2 position (R, θ) signal 35 are target position (R, θ) signal 7
A is detected and sent to the PPI display 5 and other equipment such as a tracking radar. The PPI display 5 receives the target position (R, θ) signal 7A and displays the target indication mark 13 at the corresponding position on the CRT screen.

〔Effect of the invention〕

As described above, according to the present invention, clutter such as mountains and buildings can be suppressed and point targets such as aircraft can be automatically detected, which greatly contributes to shortening target detection time and reducing the burden on the operator. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment according to the present invention, FIG. 2 is a diagram showing an example of a video arrangement, FIG. 3 is a diagram for explaining the operation outline of the area number assigning circuit, and FIG. is a diagram for explaining the outline of the output of the area number assigning circuit, and FIG. 5 is a diagram for explaining the outline of the output of the area number assigning circuit.
6 is a diagram showing the configuration of a conventional device, FIG. 7 is a diagram showing the relationship between a transmitted pulse signal and a received video signal, and FIG. 8 is a diagram showing a conventional device shown in FIG. 6. It is a diagram showing an example of a display on a PPI display of a radar search device, in which 1 is a search radar, 7A is a target position (R, θ) signal, 23 is a binarization circuit, 23a is a threshold value, and 25 is an area number assignment. circuit, 27 is a center of gravity detection circuit, 28 is an area measurement circuit, 29 is a delay circuit,
33 is a target determination circuit. In the drawings, the same or corresponding parts are designated by the same reference numerals.

Claims (1)

[Claims] 1. A search radar for obtaining a received video signal reflected from a target object such as an aircraft, a binarization circuit that binarizes the received video signal of this search radar, and a binary video signal of this binarization circuit. an area number assigning circuit that assigns an area number; an area measuring circuit that measures an area (number of pixels) for each area number of the area number assigning circuit; a received video signal for each area number of the area number assigning circuit; a center point detection circuit for detecting the center point position of the video amplitude difference between the binarization circuit and a threshold; a delay circuit for delaying the area number signal of the area number assigning circuit; and a delayed area number signal output from the delay circuit. a target determination circuit for determining whether the center of gravity position of the center of gravity detection circuit is valid or invalid according to the area of each area; and means for transmitting the effective center of gravity position of the target determination circuit as a target position signal. A radar search device characterized by: