JPH0339636B2 - - 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]

In conventional radar search devices, the received video signal of the search radar is displayed on the PPI display, and the operator uses a trackball or the like to place a marker on the target on the PPI display, and the position is recorded as a target position (R, θ) signal. It was sent out as.

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 an acquisition 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 operator identifies the target and clutter on the CRT screen of the PPI display 5, indicates the target with the track ball 6, and outputs the output of the track ball to 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. Electromagnetic waves reflected from a point target such as an aircraft are obtained as target echoes 1 and 8 having approximately the same pulse width as the transmitted pulse signal 2. Further, electromagnetic waves reflected by mountains, large buildings, etc. are obtained as clutter echoes 1 and 9 having a larger pulse width than the transmitted pulse signal 2.

Figure 8 shows the conventional radar search device shown in Figure 6.
1 is a diagram showing an example of 1 display on the PPI display 5, and 1
0 is a PPI display example, 11 is a date mark echo 2, 12 is a Kuratsuta echo 2, and 13 is a target indicator marker.

In FIG. 8, point targets such as aircraft are displayed as target echoes 1 and 8 and target echoes 2 and 11, each having a pulse width that is approximately the same as the pulse width of the transmitted pulse signal 2. In addition, for clutter such as mountains, the transmission pulse signal 2
are displayed as clutter echoes 1 and 9 and clutter echoes 2 and 12 with a pulse width larger than the pulse width of . 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 echoes 1 and 8, and sends out the output of the trackball 6 at that position as the target position (R, θ) 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 a target position (R, θ) signal 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 detect the target.

[Purpose of the invention]

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, a means for 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.

[Operation] In the device according to the present invention, a received video signal is binarized to generate a binary video signal, an area number is assigned to the binary video signal in a two-dimensional array, and an area for each area number is assigned. and position (angle, distance)
Measure. Depending on the measured area of each area number, the target position (angle, distance) with a large area is invalidated, the target position (angle, distance) with a small area is valid, and the valid target position (angle, distance) is By this detection, a point target such as an aircraft is automatically detected.

〔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.

FIG. 3 is a diagram for explaining the outline of the operation of the area number assigning circuit 25 shown in FIG. 1, in which 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 will be assigned from now on, 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)=F(E)=0→N =R
(m-1), R(1)=R(m-1) ......(9) Therefore, by scanning with the area detection window 16, the parts where the binary videos are connected are the same area. A number will be assigned.

FIG. 4 is a diagram for explaining the outline of the output of the area number assigning circuit 25 shown in FIG. 1 when the binary video array example 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, target echoes 1 and 8 have area numbers 2 and 20, Kuratsuta echoes 1 and 9 have area numbers 1 and 19, and target echoes 2 and 11 have area numbers 4 and 2.
2. Kuratsuta Echo 2 and 12 are area numbers 3 and 21
is output as Note that the clutter echoes 2 and 12 at the upper and lower ends are input as a combined video signal because the search radar 1 shown in FIG. 6 rotates endlessly in the bearing direction.
As shown in the figure, the same area numbers 3 and 21 are assigned.

FIG. 1 shows one embodiment of the present invention, in which 23 is a binarization circuit, 24 is a binary video signal, 25 is an area number assigning circuit, 26 is an area number signal, and 27 is a brightest checker. output circuit, 28 is an area measuring circuit, 29 is a delay circuit, 30 is a delay area number signal,
31 is a region area signal, 32 is the region's brightest point (R,
θ) signal, and 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 received video signal 3 is binarized by a binarization circuit 23 to generate a binary video signal 24. As shown in FIG. 7, the area number assigning circuit 25 assigns 1 number according to equations (1) to (9) during the valid period of the received video for each transmission pulse.
A region number is assigned to each pixel, and a region number signal 26 is generated. The area measuring circuit 28 increments and stores the area of the corresponding area number by "1" when the area number signal 26 is other than "0" for each pixel. The brightest point detection circuit 27 compares the maximum amplitude of the corresponding area number when the area number signal 26 is other than "0" with the amplitude of the current pixel, and determines the position (angle, distance) and amplitude of the larger amplitude. Store. The delay circuit 29 delays the area number signal 26 by Td and sends out a delayed area number signal 30. Note that the delay time Td needs to satisfy equation (10). However, Td shall be an integral multiple of the transmission repetition time of the search radar.

Td＞θB/θ〓B……(10) θB: Transmission beam width in the bearing direction of the search radar θ〓B: Rotation speed in the bearing direction of the search radar In addition, the above-mentioned area measuring circuit 28 uses the delay area number signal 30 is used as an address, and the area of the corresponding area number is sent out as the area area signal 31. Similarly, the brightest point detection circuit 27 detects the delay area number signal 3.
With 0 as the address, a region brightest point (R, θ) signal 32 is sent out.

The target determination circuit 33 receives the region area signal 31 and the region brightest point (R, θ) signal 32, and receives the region area signal 31 and the region brightest point (R, θ) signal 32.
When 1 is larger than the reference value, the brightest point of the area (R,
θ) The signal 32 is invalidated. When the area area signal 31 is smaller than the reference value, the area brightest 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. is 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 a 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 one embodiment according to the present invention, FIG. 2 is a diagram showing an example of a video arrangement, and FIG. 3 is a diagram showing an example of a video arrangement.
The figure is a diagram for explaining the operation outline of the area number assigning circuit, FIG. 4 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.
θ) signal, FIG. 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 an example of a radar display. In the figure, 1 is a search radar, 2 is a binarization circuit, 7A is a target position (R, θ) signal, 2
5 is an area number assigning circuit, 27 is a brightest point detection circuit,
28 is an area measurement circuit, 29 is a delay circuit, and 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 for binarizing the received video signal of the search radar, and a binary video signal of the binarization circuit. An area number assigning circuit that assigns an area number, an area measuring circuit that measures the area (number of pixels) for each area number of the area number assigning circuit, and the brightest point of the area for each area number of the area number assigning circuit. a brightest point detection circuit for detecting the position; a delay circuit for delaying the area number signal of the area number assigning circuit; and a delay circuit for delaying the area number signal of the area number assigning circuit; A radar search device comprising: a target determination circuit for determining whether a brightest point position is valid or invalid; and means for transmitting a valid brightest point position of the target determination circuit as a target position signal.