JPH0224589A - Correcting circuit of reference level of radar apparatus - Google Patents

Abstract

PURPOSE:To prevent a reference level corrected amount of a video from getting out of order by a method wherein an output of a noise level comparator circuit is not counted when a response due to clutter or the like is discriminated. CONSTITUTION:A video passed through a video amplifier 1 having an offset correction input and digitized by an A/D converter 2 is compared with a reference level set value 4 enabling the detection of noise in a comparator circuit 3, and when there is a video exceeding a reference value, it is detected as a hit. At the same time, the video is compared in a comparator circuit 8 with a clutter reference value 9 which is set corresponding to a large response due to clutter or the like, and the large response due to the clutter or the like is detected. Outputs of the comparator circuits 3 and 8 are supplied to a counter circuit 5 through a gate circuit 10 and a noise level at the time of absence of the clutter or the like is held in a register 6. Based on an output of the register 6, the amplifier 1 corrects an offset value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar device, and more particularly to a reference level correction circuit for correcting video level fluctuations.

[Conventional technology]

- In JIB, radar video has a varying reference level, and it is necessary to compensate for this variation in reference level in order to optimize target detection.

FIG. 3 is a diagram showing a reference level correction circuit of a conventional radar device. In the figure, l is a video amplifier with an offset correction input, 2 is an A/D converter, and 3 is an A/D conversion output and a reference value. 4 is a reference level setting circuit for noise level detection, 5 is a counter circuit that counts the number of hits, 6 is a register that holds the counting results, and 7 is a register that holds the counting results. This is a D/A conversion circuit that converts into an analog offset correction amount.

Next, the operation will be explained.

A comparison circuit 3 compares the video passed through the amplifier 1 and digitized by the A/D converter 2 with a reference level setting value 4 capable of detecting noise, and when there is video exceeding the reference value, it is detected as a hit.

These hints are counted by a counter circuit 5 at regular intervals, and the counting results are held in a register 6.

As the video reference level becomes higher, the video noise level also becomes higher and the number of hits detected by the comparator circuit 3 increases, so the value held in the register 6 also increases.

Conversely, as the video reference level becomes lower, the value held in register 6 becomes smaller. Therefore, by converting the output of the register 6 into an analog signal using the D/A converter 7, a reference level correction amount that follows the height of the video reference level can be obtained.

By inputting this reference level correction amount to the video amplifier l, fluctuations in the video reference level are corrected.

[Problem to be solved by the invention]

Conventional video reference level correction circuits are configured as described above, so if there is a response from a clutter or an interference wave, a normal offset/) correction amount cannot be obtained and the video reference level cannot be adjusted. There was a problem of making things even worse.

This invention was made to solve the above-mentioned problems, and it is possible to correctly correct the video reference level even when there is an input that is extremely large compared to noise, such as noise. The purpose is to obtain a reference level correction circuit for radar equipment.

Furthermore, the present invention is capable of reducing errors in video standard level correction due to the influence of input such as clutter, which is not very large compared to noise, or when input of wide clutter, etc. The purpose of this invention is to obtain a reference level correction circuit for a radar device that can perform the following steps.

[Means to solve the problem]

The reference level correction circuit for a radar device according to the present invention includes:
This circuit adds a reference value for identifying a response due to clutter, a comparison circuit, and a gate circuit to gate the output of the noise level comparison circuit in accordance with the comparison result.

Further, the reference level correction circuit for a radar device according to the present invention is the above-described one in which a weighted average circuit is added to the register that holds the counting results.

[Effect]

In the present invention, since no counting is performed for responses that are larger than noises caused by clutter, interference waves, etc., the counting results do not become large, and it is possible to prevent the video reference level correction amount from being greatly deviated.

In addition, in this invention, a weighted average circuit is added to the register that holds the counting results. Therefore, depending on the clutter that has a wide width, the counting result may become too small due to not counting or due to the clutter. Errors in the counting results that occur when the response is not so large compared to the noise can be reduced by weighted averaging the counting results.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, numerals 1 to 7 are exactly the same as the conventional device described above. 9 is a loudspeaker/level setting circuit for detecting responses from racks, etc. that are larger than noise; 8 is an A/D
A comparator circuit compares the converted output with the clutter reference value from the clutter level setting circuit 9, and 10 is a gate circuit that reduces noise caused by responses to clutter and the like.

In the reference level correction circuit of the radar device configured as described above, a response larger than noise such as clutter is detected by the clutter reference value 9 and the comparison circuit 8, which are set at a level that can detect this response. At this time, a hit due to the noise reference value 4 having a level lower than the clutter reference value 9 is also detected by the comparator circuit 3, but this hint is dropped by the gate circuit 10. Therefore, the counter circuit 5 does not operate in the case of a hit with a response larger than noise such as clutter.

In this way, by not changing the reference level correction amount due to a response larger than noise such as clutter, it is possible to perform appropriate reference level correction.

In this embodiment, if there is a response such as clutter that is smaller than the clutter amount reference value 9, the present invention has no effect, and in the case of wide clutter, etc., the counter circuit does not operate at all during this period. Therefore, the counting result will be smaller than if there were no gelafta.

FIG. 2 shows a reference level correction circuit for a radar device according to a second embodiment of the present invention. Reference numeral 111.11 is a weighted average circuit that weights and averages the counting results in order to reduce these influences. Multiplication circuit 12 that reduces the result to 1/N
, an adder circuit 13, a register 6 that holds the average value,
A multiplication circuit 14 that converts the previous average value to (N-1)/N.

In this embodiment, the weighted average circuit 11 calculates the current count result as 1/N, the previous count result as l/Nx (N-1)/N, and the count result as before the previous time as 1/NX ((N-1)/N )", the sum of the weighted values appears as an average value, so the influence of small racks, etc. can be suppressed to 1/N.

〔Effect of the invention〕

As described above, according to the present invention, since hits caused by racks and the like which are larger than noise are removed, it is possible to prevent the video reference level correction amount from being greatly deviated due to this.

Further, according to the present invention, since a weighted average circuit is added, it is possible to reduce the error in the side reference level correction amount due to a small rack or the like.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a reference level correction circuit of a radar device according to an embodiment of the present invention, and FIG.
FIG. 3 is a circuit diagram of a conventional video reference level correction circuit. In the figure, 1 is an amplifier, 2 is an A/D converter, 3 is a comparison circuit, 4 is a noise reference value, 5 is a counter circuit, 6 is a register, 7 is a D/A converter, 8 is a comparison circuit, and 9 is a Clutter reference value, 10 is a gate circuit, 11 is a weighted average circuit,
12 is a 1/N multiplication circuit, 13 is an addition circuit, and 14 is (N-
1)/N multiplication circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A for converting radar analog video into digital in the standard level correction device of radar equipment.
/D conversion circuit, a comparison circuit that compares the video noise level and a reference value, a comparison circuit that compares video clutter with the reference value and detects it, and a counter that counts only hits due to noise when there is no clutter. circuit, converts the counting results into analog reference level correction amount,
A reference level correction circuit for a radar device comprising a radar video amplifier and a D/A converter. (2) A for converting radar analog video into digital in the standard level correction device of radar equipment.
/D conversion circuit, a comparison circuit that compares the video noise level and a reference value, a comparison circuit that compares video clutter with the reference value and detects it, and a counter that counts only hits due to noise when there is no clutter. A reference level for a radar device that includes a circuit, a weighted average circuit that weights and averages the counting results, and a D/A converter that converts the output into an analog reference level correction amount and adds it to a radar video amplifier. correction circuit.