JPH0261580A - Radar video band compression apparatus - Google Patents

Abstract

PURPOSE:To display a radar video on a screen of a control scope without degrading resolutions by lowering a data rate to compress a frequency band thereof equivalently. CONSTITUTION:First, a video data memory 1 stores a radar video 6 by the sample interval unit and an amplitude comparison circuit 2 comparrs an amplitude value with a reference amplitude value 7. Here, the reference value 7 is a video amplitude value to provide a brightness visually recognizable with a control scope. Video data above the reference value 7 is extracted with a high fidelity while one below the reference value 7 is extracted by sampling at a long interval to ignore the data in the midway with a reduction in the amount of the data. Then, a speed conversion circuit 5 converts a sample video data 10 with two different kinds of sample intervals mixed into a data with a fixed interval to be transmitted to a communication channel. Thus, fidelity of information exceeding the reference value 7 is maintained thereby enabling compression of band without degrading resolutions of the radar video.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a band compression device for a radar video transmission device;
In particular, the purpose is to display radar video on the screen of a control scope, and in order to effectively transmit the section between the radar equipment and the control scope over a long distance using a line with low communication capacity, the data rate is reduced and the equivalent The present invention relates to a band compression device that compresses the frequency band of radar video.

[Prior Art] Conventionally, a band compression device for this type of transmission utilizes the redundancy of radar video displayed as a screen, and integrates the video over a predetermined number of sweeps in the azimuth direction and in the distance direction. - is to change the compression rate for direction and distance by expanding the radar video pulse width, regardless of the brightness of the screen at any position on the radar video screen, that is, regardless of the amplitude level of the radar video signal. Instead, the bandwidth of the entire screen was compressed by performing the same processing, and the data was transmitted via analog or digital communication lines.

[Problems to be Solved by the Invention] However, as the compression method of the conventional band compression device described above, the azimuth direction is an integral process between sweeps, and the video amplitude value is the average amplitude value of the integrated sweep section. If the echoes of two or more targets that are close to each other in the azimuth direction are included in the sweep section where the echoes of the two or more targets are integrated, the echoes of the two or more targets are integrated.

The azimuth resolution of the radar target deteriorates as a single target echo is averaged and synthesized, and in the distance direction, the video amplitude value becomes the maximum amplitude value in the distance section of the pulse expansion width due to pulse expansion processing in the distance direction. The disadvantage is that when the echoes of two or more nearby targets are within the pulse expansion width, they are combined and the echoes of the two or more targets become one target echo with the maximum value, resulting in a deterioration of the distance resolution of the radar target. be.

[Means for Solving the Problems] The radar video band compression device of the present invention includes a video data memory capable of writing digitized radar video data at sample time intervals and reading it at time intervals longer than the sample time intervals; an amplitude comparison circuit that compares the amplitude value of the video data with an amplitude reference value; a sampling control circuit that controls the readout time interval from the video data memory; a readout register that holds the readout video data; and a speed conversion circuit that converts video data at regular intervals to regular intervals.

[Operations] The operations of the radar video band compression apparatus of the present invention having the above-mentioned configuration will be explained below.

The human-powered radar video data sent to the device of the present invention has a sampling time interval sufficient to faithfully reproduce the video waveform, and the information has a frequency band or data rate that is inversely proportional to this sampling time interval. When the radar video is displayed, the brightness area that can be seen by the controller is less than 10% of the entire scope screen.The device of the present invention pays attention to this and increases the visible signal, that is, the video amplitude, from a certain reference value. The sampling interval is proportional to the data rate required for the final band compression ratio, since only video data such as large video data is used, and video data in sections where the video amplitude is smaller than the reference value is used as background video and as a signal to apply timing information. The video data is extracted from the radar data memory amplitude comparator, sampling control circuit, and readout register.

From radar data memory containing a mixture of video data that has faithful information at the same data rate as the sampling interval and has an amplitude above the reference value, and video data that has an amplitude less than the reference value at a data rate that has a sampling interval longer than the sampling interval. The sampled data read out and held in the readout register is processed by a speed conversion circuit, where video data with a sample interval data rate is slowed down, and video data with a sample interval longer than the sample interval is made faster, matching the speed of the line being sent. Bandwidth compression is possible by converting the entire radar video data to a constant data rate.

[Embodiment] Next, an embodiment of the radar video band compression apparatus of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a timing diagram showing the output of each block in the embodiment.

Radar video data 6 is A obtained by sampling analog radar video at fixed sampling time intervals and quantizing the video amplitude.
Figure 2 (a) shows the amplitude value of this digital data in an analog representation as the size of a pulse waveform, and this is the input to the band compression device. . The radar video 6 is first sequentially stored in the video data memory 1 in sampling interval units, and at the same time, the magnitude of the amplitude value is compared with the amplitude reference value 7 in the amplitude comparison circuit 2. A comparison gate is generated only in the interval shown in FIG. 2(b), and the amplitude comparison circuit 2 generates a sample interval control gate as shown in FIG. 2(C), which is expanded to the sample interval before and after the comparison gate. Generates 8. Sampling control circuit 3
controls the data readout interval from the video data memory 1 by the sample interval control gate 8, and when there is a gate signal, the sampling pulse has the same interval as the sampling interval, and when there is no gate signal, the sampling pulse has a sampling interval n1 @ longer than the sampling interval. 9, the video data is read from the video data memory 1, and this read data is held in the read register 4 at the same timing as the read timing. FIG. 2 shows an example where the read interval is three times the sample interval ( d) shows the sampling pulse 9 for data readout, and (e) shows the sample video data 10 as the output of the readout register. The sample video data 10 in which two different sample intervals coexist is converted into constant interval data by the speed conversion circuit 5, and FIG. 2(f) shows an example in which the constant interval is twice the sample interval, and the signal is compressed. The ratio is 1/2.

[Effects of the Invention] As explained above, in the radar video band compression device of the present invention, the video amplitude value that provides the visible brightness of the control scope, which is the final objective, is used as the reference amplitude value, and radar video data with an amplitude larger than that is set as the reference amplitude value. is faithfully extracted. Radar video data with an amplitude less than the standard amplitude value is sampled at long intervals, data in the middle is ignored, and the amount of data is reduced. When sent to the communication line, the data as a whole is reduced by the amount of data decreased. By converting the communication speed so that the data rate is reduced by a corresponding amount, the fidelity of information above the reference amplitude value can be maintained and the bandwidth can be compressed without degrading the resolution of radar video.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the radar video band compression apparatus of the present invention, and FIG. 2 is a timing diagram showing the operation of the block diagram of the embodiment. 1...Video data memory 2...
・Amplitude comparison circuit, 3... Sampling control circuit, 4...
...Read register, 5... Speed conversion circuit.

Claims (1)

[Claims] A video data memory that can write digitized radar video data at sampling time intervals and read it out at time intervals longer than the sampling time interval, and an amplitude comparison that compares the amplitude value of video data with an amplitude reference value and the amplitude size. The vessel and
It is characterized by comprising a sampling control circuit that controls the readout time interval from the video data memory, a readout register that holds the readout video data, and a speed conversion circuit that converts video data at irregular intervals to regular intervals. Radar video band compression device.