JPS6352081A - Fruit removing circuit in radar - Google Patents

Abstract

PURPOSE:To enable fruit removal wherein response codes are misdecoded at low frequency by using a bracket coincidence signal and holding a code obtained by the coincidence of blackets. CONSTITUTION:A shift register 2 makes a bracket coincidence corresponding to last transmission time which is delayed by one-transmission time and a coincidence with the bracket of the current transmission time and a shift register 5 delays an input video so as to decide a code at the time of bracket coincidence. A coincidence circuit 6 performs the coincidence of the delayed input video with a currently inputted video to find the bracket coincidence. When the bracket coincidence is obtained, the register 7 stores a code found by the bracket coincidence and removes fruits after precluding the bit absence of the code. A code corresponding to the bracket coincidence after the fruit removal is outputted from a gate 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to automatic target identification in secondary radar.

[Conventional technology]

Figure @2 shows the conventional fruit removal method.

In the figure, (1) is the video input of the secondary radar, (2) is the shift register for delaying the video input by one transmission time, and (3) is the shift register for delaying the video input by one transmission time. A matching circuit matches the corresponding video with the video at the current transmission time, and (4) shows the video output after fruit removal.

Next, the operation will be explained. Input video (1) enters shift register (2). Shift register (2)
preserves the temporal relationship of the input video and shifts it to extend over one transmission time. 1 transmission time delayed video (shifted)
Check the match (3) between the output of register (2)) and the video currently input to shift register (2) (input video (1)).Response to previous transmission and response to current transmission If it is from your radar, the time relationship with respect to the transmission is the same, so there is a match, but if it is from another radar, the time relationship is different, so there is no match.In this way, after fruit removal Get video output.

[Problem that the invention seeks to solve]

Since the conventional fruit removal method is configured as described above, the bit of the secondary radar code sent as a serial 1.0 code must be set at the time of the previous transmission in order to respond to the previous transmission. However, even if a bit is set during all transmissions, it is dropped, resulting in bit loss. This leads to misreading of the code on the secondary radar.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and aims to provide a method for removing fruit without causing loss of bits in the response in the current transmission.

[Means for solving problems]

The method according to the present invention uses a plaquette coincidence signal by a framing pulse in fruit removal, and by delaying this signal by one transmission time, the response to the previous transmission obtained by matching the response to the current transmission, This is to remove the fruit.

[Operation] The fruit removal method of the present invention preserves the code obtained by placket matching by using the placket matching signal, and removes the fruit after preventing bit loss in the code.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is the video input of the secondary radar (2) is the shift register for delaying the plaquette match by one transmission time, and (3) is the plaquette match corresponding to the previous transmission time delayed by one transmission time. A matching circuit that matches the current transmission time with the placket, (4) is the placket match after fruit removal, and (5) is the placket match,
A shift register that delays the input video to determine the code at the time of a placket match, and (6) a match circuit that determines a placket match, which is concerned with matching the delayed input video with the intervening video. , (7) depends on the placket match when the placket matches. (8) is a gate for outputting the code for the placket match after fruit removal; (9) shows the code for the placket match after fruit removal.

Next, the operation will be explained. Input video (1) enters a shift register (5). Shift register (5)
preserves the temporal relationship of the input video and shifts it to a time delay that achieves Placket matching. Check the match (6) between the time-delayed video (output of shift register (5)) and the video currently input to shift register (5) (input video (1)) for which placket matching can be achieved. .

A match (6) output indicates that the secondary radar response has been established. At this time, if the output of the middle tap of the shift register (5) is latched by the register (7), the code is held without missing bits.

The placket match (output of match (6)) is input to the shift register (2), which preserves the time relationship of the placket match and shifts it so that it is delayed by one transmission time. 1 transmission time delayed placket match (shifted)
Match (3) is used to find a match between the output of register (2)) and the placket match (output of match (6)) currently input to shift register (2).

If the plaquette match due to the response to the previous transmission and the plaquette match due to the response to the current transmission are from your own radar, the time relationship with respect to the transmission is the same, so there is a match.If it is from another radar, the time relationship is the same. No agreement can be reached because the relationships are different. A gate (8) is applied to the output of the register (A) so that a code is output in response to a placket match when a match is found. In this way we obtain defruited placket matches and codes.

In addition, although the above embodiment is configured with shift registers, each of them may be configured with N M memories, and further registers (7)
may be latched at output (4).

〔Effect of the invention〕

As described above, since the present invention is configured to store the response code for the current transmission, it is possible to obtain a fruit removal method with less chance of misreading the response code. Furthermore, the effect of fruit removal can be obtained even for Δ10DEC, which has not been conventionally treated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a fruit removal circuit in a radar according to the present invention, and FIG. 2 is a block diagram showing a conventional fruit removal circuit. In the figure, <11 is the secondary radar input video, (2) is the shift register (3) is a match, (4) is the output after fruit removal (5) is the shift register (6) is a match, (7
) is the register, (8) is the gate, and (9) is the code output corresponding to the placket match after fruit removal. In the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] a first matching circuit that compares the current radar input video with a radar input video that has been delayed by a certain period of time and obtains a plaquette match; a second matching circuit for comparing the output of the matching circuit.