JPS58174870A - Radar signal detector - Google Patents

Abstract

PURPOSE:To reduce the effect of clutter on detection performance of signals and noise of rapid changes by determining a primary threshold level reflecting a video average reception level and a correction factor. CONSTITUTION:An input video 1 from a receiver is inputted into a primary threshold signal detector 2 and a primary threshold generator 8. A primary threshold controller 3 outputs a correction factor 10 to keep the signal detection rate of the primary threshold signal detector 2 constant. The primary threshold generator 8 outputs the product of an average level of an input signal for a fixed period and a correction factor 10 to the threshold signal detector 2 as primary threshold level 9. The output thereof is provided outside as a target detection signal 7 after the removal of noise and clutter with a secondary threshold signal detector 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radar signal detection apparatus that extracts only useful signals from noise-containing signals input sequentially in time, such as radar received video.

A conventional device of this type is shown in FIG. In the figure, (1) is an input video from a receiver, and (2) is a primary threshold signal detector, which quantizes the input video (1) based on the primary threshold level. (3
) is a primary threshold controller that keeps the signal detection rate of the primary threshold signal detector (2) constant. (4
) is a noise level detector that measures the noise level and outputs it to the primary threshold controller (3) as basic data for creating the primary threshold level. (5) is a second-order threshold signal detector that separates the target from noise or clutter. (6) is a second-order threshold controller, so that the target detection rate is constant based on the detected target.
Modify the secondary threshold level to the secondary threshold signal detector (5).

Next, the operation will be explained. Input video from receiver (
1) is compared with the primary threshold level at that point in time by the primary threshold signal detector (2), and if it is above the primary threshold level, there is a signal, and if it is less than the primary threshold level, it is determined that there is no signal.
quantized into a value signal. This signal is counted by the primary threshold controller (3) for each subdivided area of the radar stock area, and is counted in the next scan so that the number of primary threshold signal detection outputs in each area is constant. Feedback is applied to the primary threshold level of . A noise level detector (4) measures the video level in areas without video signals from targets outside radar coverage. This measured value is used as a reference level when creating a primary threshold level in the primary threshold controller (3) as a video noise level.

The output of the primary threshold signal detector (2) includes the target as well as noise such as mountains, oceans, clouds, etc., and the secondary threshold signal detector (5) is used to remove these clutters.
) is entered. This secondary threshold detector (
5) In order to distinguish between a target and noise, a series of responses is compared with a certain reference value based on the number of responses within one antenna scan from a valid target determined by the radar constant, and the true It attempts to detect echoes close to the target) and is composed of, for example, a sliding window detector. 2
The secondary threshold controller (6) counts the output of the secondary threshold signal detector (5) for each subdivided area,
The result is fed back to the next scan to keep the output of the secondary threshold signal detector (5) constant.

Since the conventional radar signal detection device is configured as described above, the primary threshold signal detector (2) in FIG.
The primary threshold level for the current scan is set based on the collected echoes of the antenna one scan before for each area. For this reason, it is not possible to respond to sudden fluctuations such as changes in noise or clutter between immediately after the previous scan and the current scan. In addition, because the primary threshold level is divided into areas, even though noise and clutter are not uniformly distributed within the area, the average value is uniform, and the areas where you want to lower the threshold level are also high. There were some drawbacks, such as:

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional method, and uses the average value of the video level in a certain section before and after the video for which the primary threshold signal is to be detected as a reference, and then uses By creating a primary threshold level that reflects the number of primary threshold detection outputs in the previous scan obtained by the threshold controller, it is possible to eliminate sudden fluctuations in noise and clutter and It is an object of the present invention to provide a radar signal detection device in which detection performance is less affected by their distribution state.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a radar signal detection device according to an embodiment of the present invention. In the figure, (1) is the input video from the receiver, (
2) is a first-order threshold signal detector that detects a signal by comparing this human-powered video (1) with a first reference level;
8) is a primary threshold generator that calculates the average level of the human-powered video (1) and creates the first reference level (9), and (3) is a primary threshold signal detector (2).
The primary threshold control circuit outputs a correction coefficient of 00) to the primary threshold generator (8) so that the signal detection rate of the primary threshold signal detector (2) is constant. A secondary threshold signal detector (6) detects only the signal from the target by comparing the output with a second reference level and outputs a detection signal (7); This is a secondary threshold controller that creates or corrects the second reference value so that the signal detection rate of ) becomes constant.

Next, the operation will be explained.

Input video (1) from the receiver is input to a primary threshold signal detector (2) and a primary threshold generator (8). The primary threshold controller (3) applies a correction coefficient of 00 to the primary threshold generator (8) so that the signal detection rate of the primary threshold signal detector (2) is constant.
Output. The primary threshold generator (8) calculates the average level of the input signal over a certain period, multiplies the average level and the correction coefficient α from the primary threshold controller (3), and calculates the primary threshold value. It is output to the primary threshold signal detector (2) as a short level (9). The output of the primary threshold signal detector (2) has noise and clutter removed by a secondary threshold signal detector (5), and is output to the outside as a target detection signal (7).

Next, details will be explained using FIGS. 2 and 3.

FIG. 3 is a block diagram of the primary threshold generator (8) of FIG. 2. The primary threshold controller (3) calculates a correction coefficient (00) for keeping the signal detection rate constant based on the data from the primary threshold signal detector (2) obtained during the previous scan, The data is stored until the area is covered in the next scan. The primary threshold generator (8) receives the video signal (
1) is continuously calculated for a preset range, and read out from the calculator (11) so that the correction coefficient area is synchronized with the area to which the calculated average value belongs.

These are multiplied by the multiplier 021 in the primary threshold generator (8) and outputted to the primary threshold signal detector (2) as a primary threshold level (9). The primary threshold signal detector (2) has a delay circuit for the input signal (1), and synchronizes the comparison with the primary threshold level (9) within the primary threshold signal detector +21. is taking. The secondary threshold signal detector (5) is composed of, for example, a sliding window detector, and removes noise and clutter.

The secondary threshold controller (6) is still only used to keep the signal detection rate of the secondary threshold signal detector (5) constant.

2. In the above embodiment, the average value of the video is calculated by taking the average of a certain section before and after the video to be detected. It is also possible to use the average level as the average level, and in the case of jin, it is possible to further suppress false positives at a time when the level of clutter etc. changes rapidly.

As described above, according to the present invention, the average video reception level around the detected video and the correction coefficient for making the signal detection rate constant during the previous scan are reflected in determining the primary threshold level. This structure reduces the influence of sudden fluctuations in clutter and noise on signal detection performance, and even if the distribution of clutter and noise becomes unbalanced within one area, the signal detection performance remains the same in that area. This has the effect of making it almost uniform.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing a conventional radar signal detection device;
The figure is a block diagram showing one embodiment of the present invention, and FIG. 3 is a block diagram showing an example of the primary threshold generator (8) in FIG. 2. (1)...Input video from receiver, (2)...1
Next threshold signal detector, (3)...Primary threshold controller, (5)...Secondary threshold signal detector, (6)...Secondary threshold controller , (7
)...Target detection signal, (8)...Primary threshold generator, (9)...Primary threshold level, 0
0)...Correction coefficient (correction signal). Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Shin Kuzuno - Figure 1 Figure 2

Claims (1)

[Claims] (1) A primary threshold signal detector that compares video signals from the radar receiver obtained sequentially in time with a first reference level; and a first-order threshold signal detector that calculates the average level of the video signals and determines the first reference level. and a signal to correct the first reference value so that the signal detection rate of the first threshold signal detector is constant. a primary threshold controller for outputting, and a secondary threshold signal detection that compares the output of the primary threshold signal detector with a second reference level and detects only the signal from the target from the output. and a secondary threshold controller that controls the second reference value so that the signal detection rate of the secondary threshold signal detector is constant. .