JPS6166175A - Search radar - Google Patents

Abstract

PURPOSE:To control clutter with a simple construction and enable indication of only a target of an aircraft, etc., by handling a received video signal as the 2-dimensional image and allowing only a small-area video signal to be displayed in a PPI. CONSTITUTION:To a binary video signal-receiving signal by a binarized video signal an area number is provided for a non-signal-sending-pulse period by an area number allocating circuit 22 responding to a signal sending pulse 2 and an area measuring circuit measures its area by handling the signal-receiving video signal as a 2-dimensional image. Comparison is made on this measured area and the reference area and a display identifying circuit 27 identifies an area as clutter when the area exceeds the specified value and indication in a PPI indicating apparatus 5 corresponding to a delay transmitting pulse and a delay bearing antenna angular signal through a delay circuit 28 is be eliminat ed. By these arrangements, a simple construction becomes available for control ling clutters of mountains and architectural structures, etc. and limiting indica tion only to a target echo of aircrafts, etc.

Description

[Detailed description of the invention] [Technical field of invention] This invention eliminates clutter such as mountains and buildings.

This invention relates to the improvement of radar search equipment for detecting point targets such as aircraft.

[Prior art]

Conventional radar search devices display the received video signal of the search radar on a PP display.

FIG. 1 is a diagram showing an example of the configuration of a conventional device.
1) is a search radar, 121Fi transmission pulse signal, (3
) is the received video signal, (4) is the bearing antenna angle signal, and (5+id P p I indicator).

In Fig. 1, the search radar (11) rotates at a constant rate in the direction of the Habea link, and periodically radiates electromagnetic waves while transmitting the rotation angle as a bearing antenna angle signal (4), and at the same time transmits a transmission pulse signal +21.Target The reflected electromagnetic waves from the search radar (11)
3) and displayed on the FPI display (5).

Figure 2 shows the transmitted pulse signal (2) and received video signal (3)
In this example, (6) is the target echo 1° (71 is the clutter echo 1).

In Fig. 2, an electromagnetic wave is emitted from the search radar (11) at the timing of the transmission pulse signal (21), and the electromagnetic wave reflected by a point target such as an aircraft is a target echo 1 (with approximately the same pulse width as the transmission pulse signal (2)). Also, electromagnetic waves reflected by mountains, large buildings, etc., clutter echo 1 (7) with a pulse width larger than the transmitted pulse signal (2)
) is obtained as

FIG. 3 is a diagram showing an example of display on the CFIT tube surface of the PPI display device (5) of the conventional radar search device shown in FIG. 1, in which (8) is an example of PPI display, and (9) is Target echo 2, (
l [IFi clutter echo 2.

In Figure 3, a point target such as an aircraft is a transmitted pulse signal (
The target echo 1 (
61, displayed as target echo 2 (9). ``In addition, clutter such as mountains has a pulse width larger than the pulse width of the transmission pulse signal (2) and is displayed as a rattle echo 1 (71, clutter echo 2a1). Also, the reflection of the clutter is large in terms of intensity (amplitude).

Therefore, with the conventional radar search device as shown in FIG. 1, it is difficult and requires skill to detect targets such as aircraft on the CRT screen of the PP display (5).

[Summary of the invention]

This invention treats a received video signal as a two-dimensional image, assigns an area number (label) to the same block, measures the area for each area number (σ), and generates a binary video signal with an area number that has a larger area. The present invention provides a means for eliminating the drawbacks of the conventional method by displaying a binary video signal of an unreasonable area number of one area on a PPI display.

[Embodiments of the invention]

FIG. 4 is a diagram for explaining a video arrangement example when the display example shown in FIG. 3 is binarized, where 01 is an example of a binary video arrangement, and az is a pixel.

In FIG. 4, the horizontal thick awn of one pixel 0z corresponds to a lungi bin, and the vertical one is the radar transmission period.

When the display example shown in FIG. 3 is binarized, it becomes the pixel arrangement example shown in FIG. 4.

FIG. 5 is a diagram for explaining the outline of the operation of the area number assigning circuit shown in FIG. 1, and FIG. 5(a) is a diagram for explaining the area detection window. ) is a diagram for explaining area number storage 1/register string.

The oiFi area detection window 04 is an area number storage register string.

In the area detection window 031, A is located at the position of a pixel to which an area number has been assigned, and B, 0. D.

There is an E. Also, if the pixel width in the direction of separation is m pixels, then
The area numbers of the pixels to which area numbers have already been assigned are stored in the area number storage register column I over -i+4 m11 pixels. A, B.

The binary video values at positions 0, D, and B, respectively.

F(A) F(琲”(C), F(Ill,
F(E), B, O, D.

Indicates the area number of the pixel at position E, and the contents of j area storage register column I are respectively Ru+ e R(m*) +
When n(ml IR(m+1)) and the area number of the pixel at position A in the awn are N, the theory of area numbering is expressed by the following OI equations to equations (9).

F(A) = 0 RiN=0
...1llF(A)=1・F(B)-F(C Agency F(
1) Agency F (B) = 0 → 1i = k ... (2) However, is the area number storage register column (the smallest natural number among the area numbers not stored in 141, F (A) = F '
(B)=1-1"(cl=F(nl-'F(gl-09
N= R(n=(31F(A)=F(ml=
1, F (cl= F (D)= 0→N=R(m
l 1 )"'("F(Al=FfD)=1-F(0
)=0 →N=R(ml −(51F(
Al-F(cl-1, F(Bl-F(Dl=F(E)
-0→N=R(m-1)...(6) '(A)=F(0)=FtD>='-=)M=R(m-
1)-(1)F (A)=P (C)=F (E)
= 1, F(Dl-' →N=R(m 1).

R(ml1)=R(m-1)'
-181F(A)=F(Bl=F(c)=','(
D)-F(El-0=)N=R(m-i).

R(+i=R(ro-1)
(91) Therefore, scanning with the area detection window a3 is equivalent to scanning with 8 concatenations, and the same area number is assigned to the portion where the binary video signals are concatenated.

FIG. 6 is a diagram for explaining the outline of the output of the area numbering circuit @ shown in FIG. 1 when the binary video array example αb of FIG. 4 is input, 69 is an example of area numbering, 6e is an example of area numbering. Area number 1. The fin is area number 2. Cod is area number 3. Q9I
The r1 area number is 4.

The binary video signal a11Fi shown in FIG. 7 corresponds to the binary video array example α1+ shown in FIG. 4, and corresponds to the binary video array example 0.
11 to the area number assigning circuit (to), the target echo 1 (61H area number 20
D, clutter echo 1 (7) has area number IQG, target echo 2 (9) has area number 409. clutter eco-2
01! 'i area number 3QIn is output. Note that the clutter F-201 at the upper and lower ends are in the same area as shown in FIG. 6 because the search radar i11 shown in FIG. 1 rotates endlessly in the bearing direction and is input as a combined video signal. A number of 30 seconds will be given.

FIG. 1 shows one embodiment of the present invention, which includes:
is a binarization circuit, Oll is a binary video signal, container is an area number assigning circuit, (c) is an area number signal, (goods) is an area measurement circuit, (c) is an area area signal, and 翺 is a delayed area number signal. ,
@ is display judgment circuit, @ is delay circuit, kiln is delayed transmission pulse signal, mFi delayed bearing antenna angle signal, C3
1) is a binary display video signal.

In Figure 7, the received video signal (3) is binarized by a circuit
to generate a binary video signal c21+'e.

In other words, the area number assigning circuit changes from "0" to "0" from the time the transmission pulse signal (2) changes from "1" to "0" for each transmission pulse.
1'', a region number is assigned to each pixel according to formulas (11 to (9)) and a region number signal (c) is generated.The area measuring circuit Qme assigns a region number to each pixel. signal(
c) When 0 is other than 0, the area of the corresponding area number is increased by 1 and stored. The delay circuit (C) receives the area number signal (C), the transmission pulse signal (2), and the bearing antenna angle signal (4).
) are delayed by 14 times, and a delayed region number signal (a), a delayed transmission pulse signal generator, and a delayed bare link antenna angle signal (to) are transmitted. In addition, it can be expressed by the TddO1 formula. However, T(i is an integral multiple of the transmission repetition time of the search radar.

Td〉θB /l)B θB ; Transmission beam width δB in the bearing direction of the search radar: Rotational speed in the bearing direction of the search radar Area measuring circuit Q4 uses the delay area number signal (c) as an address to calculate the area of the corresponding area number. It is sent as a region area signal (c). The display judgment circuit compares the area area signal (c) with the reference area, and judges it as invalid when the area is greater than or equal to the reference area, and as valid when it is less than the reference area.
The binary display video signal 01), which is "0" when it is "0" and "1" when it is valid, is transmitted in its entirety. The PPI display (5) displays the delayed transmission pulse signal @, the delayed bearing antenna angle signal (to), and the binary display video signal C311.

FIG. 8 is a diagram showing an example of the display of the PPI display (5) shown in FIG. 1 on the CRT tube surface.

In FIG. 8, the clutter echo 1 (7
1. Two clutter echoes are erased and the target echo 1
+61. Only target echo 2 (9) is displayed.

〔Effect of the invention〕

In this way, according to the present invention, with relatively simple signal processing,
Since clutter such as mountains and buildings can be suppressed and only point targets such as aircraft can be displayed, aircraft can be easily detected, which can greatly contribute to reducing the burden on the operator.

[Brief explanation of drawings]

Figure 1 shows an example of the configuration of a conventional device.
9) J^・ Figure 2 is a diagram showing an example of the relationship between a transmitted pulse signal and a received video signal, Figure 3 is a diagram showing an example of a display of a conventional device, and Figure 4 is a diagram showing an example of a video arrangement. FIG. 5 is a diagram for explaining the outline of the operation of the area number assigning circuit, FIG. 6 is a diagram for explaining the outline of the output of the area number assigning circuit, and FIG. 1 is the configuration of one embodiment of the present invention. FIG. 8 is a diagram showing one display example of the device of the present invention, in which (11 is a search radar, (5) is a PPI display, (2) is a 2 (if conversion circuit), (221 is a The area number assigning circuit, Q4) is an area measuring circuit, and the @ symbol '1111000QQ is a delay circuit. In Figure 9, the same or corresponding parts are indicated by the same reference numerals.

Claims (1)

[Claims] 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; an area numbering circuit that assigns a number;
An area measuring circuit that measures the area (number of pixels) for each area number of this area numbering circuit, a delay circuit that delays the area number signal of this area numbering circuit, and an area for each delayed area number signal of this delay circuit. A display determination circuit that determines whether a delay area number signal is valid or invalid according to
A radar search device comprising a display device.