JPS6348486A - Radar equipment - Google Patents

Abstract

PURPOSE:To display the image of a target with high resolution by outputting a signal which is compressed by a cross range compressor in a cross-range direction to a display device without compressing it in a range direction, and displaying the signal on the display device corresponding to cross-range resolution. CONSTITUTION:Reflected pulses are inputted to a receiver 4 and amplified. A phase compensator 5 compensates the phase of a received signal by 4piR(t)/lambda for each sent pulse so as to compensate phase variation based upon the movement of the target. Then, the cross-range compressor 7 obtain the cross range resolution which is lambda/(2omegaT) to a rotating target or Rlambda/(2vyT) to a moving target. Thus, the signal which is given the high resolution in the cross-range direction is inputted to a brightness information converting device 9 to obtain the cross- range resolution in cell units, and brightness information of a cell is converted into an amplitude.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for imaging a target with high resolution using a radar device.

[Conventional technology]

Figure 3 shows, for example, M, J, Pr1ckett and C,C.

r Pr1ciples of Inv by Chen
else 5yntheticAperture Ra
dar (I S A R) Imaging-Principles of anti-synthesis open radar device imaging JEASCON'80. P.

FIG. 2 is a block configuration diagram showing a conventional radar device described in Patent Nos. P, 340 to 345. In the figure, 1 is a transmitter, 2
is a transmitting/receiving switch, 3 is an antenna, 4 is a receiver, 5 is a phase compensator, 6 is a range compressor, 7 is a cross range compressor,
8 is a display.

Figures 4 (!L) and (b) are, for example, J-M, S
r AN/APS-134(V) written by m1th
Maritime 5urvei-11ance R
adar - maritime surveillance radar equipment” (Reference r Adva
nce in Radar-Advances in radar equipment JP, P
.

36 to 40) are diagrams showing a high-resolution image of a target ship using the conventional radar device 1 disclosed in Patents 36 to 40, and a diagram showing a manner in which the same target ship causes a pitching motion.

5 and 6 are diagrams showing the relationship between the conventional radar device and the rotation axis of the target, and also diagrams showing the relationship between the radar device and the moving direction of the target.

Next, the operation of the above conventional radar device will be explained.

The IJ near FM modulated pulse generated by the transmitter 1 is transmitted from the antenna 3 via the transmitter/receiver switch 2. This transmitted signal is reflected by the target and again antenna 3.
The signal is input to the receiver 4 via the transmitter/receiver switch 2 and amplified. In the phase compensator 5, for this amplified signal,
Depending on the distance R(t) from antenna 3 to the eyelid, 4π
A signal with a phase given by R(t)/λ is multiplied by each transmitted pulse to compensate for phase changes due to target movement. Here, λ is the transmission wavelength. The signal whose phase has been compensated by the phase compensator 5 is subjected to pulse compression by the range compressor 6. The frequency band of the linear FM modulation pulse is B
Then, this range compressor 6 provides a resolution Δrj-C/2B in the range direction. Here, C is the speed of light. The output of the range compressor 6 is input to a cross-range compressor 7, where cross-range compression is performed using rotational movement or movement of the target. For example, if the target is a ship, its rotational motion corresponds to pitch, roll, and yaw.

First, in FIG. 5, it is assumed that the target exists at the origin O, and that it is rotating as an axis of rotation in the OB force direction. Further, it is assumed that the radar device is located on the X-axis and observes a target located at the origin O. The target rotation axis OB is O
E force direction OD force direction is decomposed, but OE force direction component is X
It does not contribute to the generation of Doppler signals for radar devices located on the axis. However, the OD force direction component gives a Doppler effect to the radar device located on the X axis. Therefore, the axis passing through the origin 0 and perpendicular to the straight line ODI is defined as the cross-range axis, and the cross-range compressor 7
cross-range compression is performed. The range direction is the axis that connects the radar device and the target regardless of the rotation direction of the target, and in this case is the X axis. If the angular velocity at which the target rotates in the OD force direction is ω, and the observation time is T, then the resolution Δr,L in the cross range axis direction is given by λ/(2ωT).

Now, as shown in Figure 4fb), it is assumed that the length direction of the target ship coincides with the X axis in Figure 5, and this target is
Assuming that pitch movement is performed with the axis as the pitch axis, the resolution in the range direction, that is, the X-axis direction, is C/2B, and the resolution in the cross-range direction, that is, the two-axis direction is λ.
/(2ωT) is obtained, for example, as shown in Fig. 4(a).
It is possible to obtain a brightness-modulated, high-resolution image as shown in the figure below.

Such an image is displayed on the display 8.

In addition, as shown in Fig. 6, when the target moves from the origin 0 on the Xy-axis plane at a velocity V in the OB force direction, assuming that the radar device is located on the X-axis, the velocity vector of the target is Although each component in the X-axis direction and the y-axis direction is decomposed, the component in the X-axis direction does not contribute to cross-range compression. The component in the y-axis direction contributes to cross-range compression, and if the velocity component is Maa and the observation time by the radar device is T, then the resolution in the y-axis direction is given by Rλ/(2vyT). Therefore, in this case as well, the same effect as explained in FIGS. 4 and 5 can be obtained, and the brightness-modulated high-resolution image shown in FIG. 4 (&) can be obtained.

[Problems to be solved by the invention] Since the conventional radar device described above has a groove bottom as described above, when radio waves are emitted from the radar device toward a target, it is possible to prevent the radio waves from going behind the target. In some cases, there was a problem that compression could not be achieved in the range direction.

This invention was made to solve this problem, and it is an object of the present invention to obtain a radar device that can display a high-resolution image of a target even when radio waves from the radar device cannot go around behind the target. With the goal.

[Means for solving problems]

The radar device according to the present invention removes the range compressor, outputs the signal compressed in the cross-range direction by the cross-range compressor to the display without compressing it in the range direction, and uses the display to support cross-range resolution. It is displayed as follows.

[Effect]

In the radar device of the present invention, a high-resolution image of the target can be displayed by arranging the outputs of the cross-range compressor in a bar graph according to the size of the output and displaying them on the display. .

〔Example〕

FIG. 1 is a block configuration diagram showing a radar device that is an embodiment of the present invention. The same or equivalent parts as those of the conventional device shown in FIG. Further explanation will be omitted. In the figure, reference numeral 9 denotes a luminance information conversion device that converts the cross-range resolution of the cross-range compressor 7 in units of cells and converts the luminance information of this cell into amplitude.

FIG. 2 is a diagram showing a high-resolution image of a target obtained by the radar device of FIG. 1.

Next, the operation of the radar device according to the sixth embodiment of the present invention will be explained. Pulses generated by a transmitter 1 shown in FIG. 1 are directed to a target via a transmitter/receiver switch 2 and an antenna 3. The pulse reflected at the target is sent back to the antenna 3. The signal is input to the receiver 4 via the transmitter/receiver switch 2 (-) and is amplified.

In the phase compensator 5, in order to compensate for the phase change due to the movement of the target, a phase compensation of 4πRft)/λ is applied to the received signal for each transmitted pulse, similar to the above-mentioned conventional radar device shown in Figure 'g3. be done. After that, in the cross-range compressor 7, the cross-range compressor λ/(2ωT) for a rotating target and Rλ/(2v
The cross-range resolution given by yT) is obtained.

The signal with high resolution in the cross-range direction is input to the frequency information converter fi9i, the cross-range resolution is set to a cell unit, and the brightness information of this cell is converted into amplitude. This output is input to the display 8, and the horizontal axis is set in the cross-range direction as shown in FIG. Displays the amplitude of

〔Effect of the invention〕

As explained above, this invention has a radar load of
The range compressor has been removed, and the signal compressed in the cross-range direction by the cross-range compressor is output to the display without being compressed in the range direction, and the display is configured to display according to the cross-range resolution. , -At
It can be configured easily and inexpensively, and
This provides an excellent effect in that a high-resolution image of the target can be displayed on the display while maintaining a high cross-range resolution.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a radar system 1 which is an embodiment of the present invention, Fig. 2 is a diagram showing a high-resolution image of a target obtained by the radar device shown in Fig. 1, and Fig. 3 is a diagram showing a conventional radar system. A block diagram showing the radar device of FIG. 4, tal and t.
bl is a diagram showing a high-resolution image of a target ship using a conventional radar device, and a diagram showing how the same target ship causes a pitching motion. FIG. 2 is a diagram showing the relationship between the target and the rotation axis, and a diagram also showing the relationship between the radar device and the moving direction of the target. In the figure, 1...transmitter, 2...transmission/reception switch,
3... Antenna, 4... Receiver, 5... Phase compensator, 6... Range compressor, 7... Cross range compressor, 80. . Display device, 9... brightness information conversion device. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] a transmitter that generates a transmission pulse, an antenna that can radiate the output from this transmitter as a radio wave and receive radio waves reflected by a target, a receiver that amplifies the output of this antenna, and the target. a phase compensation means capable of compensating for the output of the receiver a phase error based on the oscillation of the antenna; cross-range compression means capable of compressing the beam of the antenna in a direction orthogonal to a straight line connecting the target and the target to improve resolution;
Luminance information converting means capable of generating a signal that can be displayed as an amplitude of the output corresponding to the resolution of the cross-range compression means in a certain arbitrary axis direction, and a display for displaying the signal obtained by the luminance information converting means. A radar device characterized by being equipped with a device.