JPH0432790A - Tracking radar device - Google Patents

Abstract

PURPOSE:To fine the best pulse repetitive frequency(PRF) by easy arithmetic by setting weight data for plural PRFs. CONSTITUTION:The tracking radar device removes a clutter from a received signal obtained by a receiver 12 through a fast Fourier transforming circuit 13 to detect a target by a target detecting circuit 14, and a tracking device 15 finds a predicted value of the target, which is tracked. Further, PRFs are calculated 20 from the predicted value and a transmitter 17 sends signals, PRF by PRF. Different weight is set for radar range cells of a distance direction and a speed direction for the different PRFs and stored in a weighting memory 21 and a circuit 20 performs weighting by using the distance predicted value and speed predicted value found by the tracking device 15 and selects the PRF with maximum weight among the PRFs. Consequently, the optimum PRF for evading a blind due to the overlap between the Doppler frequency of the target and a PRF can be calculated.

Description

[Detailed description of the invention] [Summary] Fast Fourier transform (FFT) is performed from received radio waves.
The target is tracked by removing clutter and detecting the target using the pulse repetition frequency (PRF) circuit.
Regarding a tracking radar device that has the function of emitting radio waves to a target at every repetition frequency, the PRF is calculated based on the predicted value output from the tracker in order to avoid blinding caused by the overlap between the target Doppler frequency and the PRF. In order to find the optimal PRF using simple calculations, different weights are set for radar range cells in the distance direction and velocity direction for each of multiple different PRFs, and these are stored in the weighting memory. The PRF calculation circuit performs weighting using the weights in the weighting memory based on the distance predicted value and speed predicted value obtained by the tracker, and selects the PRF with the largest weight among the plurality of PRFs. The configuration is such that it can be taken out.

[Industrial application field]

In the present invention, the FF7 circuit removes clutter from the received radio waves, detects the target, and tracks the target.
The present invention relates to a tracking radar device having a function of emitting radio waves to a target for each RF.

When using radar to detect and track moving targets such as aircraft, and when emitting radio waves to the target for each PRF, avoid blinding caused by the overlap between the target's Doppler frequency and the PRF. In order to do this, the PRF is calculated based on the predicted value output from the tracker. Therefore,
There is a need to easily and reliably perform such PRF calculations.

(Prior Art) FIG. 5 shows a block diagram of an example of the conventional technology. In the figure, after a reflected wave from a target is received by an antenna 11,
Both the distance signal and the angle signal are phase-detected in the receiver 12, components (clutter) around integral multiples of PRF are removed in the FFT circuit 13, and then distance and angle are measured in the target detection circuit 14 to detect the target. be done. The tracker 15 calculates a predicted distance Rp to the target and a predicted speed Rp of the target based on the information from the target detection circuit 14,
Track the target. On the other hand, the PRF is calculated in the PRF calculation circuit 16 as described later, and the transmitter I7 transmits radio waves based on the PRF from the PRF calculation circuit I6, and is radiated into space via the antenna 11.

Here, if the target Doppler frequency overlaps around an integer multiple of the PRF, so-called blinding will occur, so in order to avoid this, the target Doppler frequency is calculated from the speed prediction value hp calculated by the tracker 15 in the PRF calculation circuit 16. Based on this calculation, a PRF that does not cause blindness is calculated.

[Problems to be Solved by the Invention] In the above conventional example, the PRF calculation in the PRF calculation circuit 16 is performed using only the speed prediction value Rp obtained by the follower 15, so the optimum PRF is calculated too accurately. However, there were problems that caused limitations in system design. Furthermore, the PRF calculation circuit 16 performs complicated calculations using the speed prediction value Rp, which has the problem of requiring a large-scale calculation circuit. Therefore, it is possible to obtain a more optimal PRF by performing PRF calculation using both the predicted distance value Rp and the predicted speed value Rp, but if
The calculation in the RF calculation circuit 16 becomes even more complicated, resulting in an impractical problem.

The present invention makes it possible to obtain the optimal PRF with a simple calculation when calculating the PRF based on the predicted value output from the tracker in order to avoid blinding caused by overlap between the target Doppler frequency and the PRF. The purpose is to provide a tracking radar device.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention. The present invention provides receiver 12
The target detection circuit 14 detects the target by removing clutter from the received signal obtained by the follower 1.
5, the predicted value of the target is calculated and the target is tracked, while the predicted value is used to calculate the PRF in the PRF calculation circuit 20.
This is applied to a tracking radar device that calculates and extracts the PRF and sends a transmission signal from the transmitter 17 based on the PRF. In the figure, reference numeral 21 denotes a weighting memory in which different weights are set and stored for radar range cells in the distance direction and speed direction for each of a plurality of different PRFs. In the present invention, in the PRF calculation circuit 2°, weighting is performed using the weights in the weighting memory 21 based on the predicted distance value and the predicted speed value obtained by the tracker 15.
Among the RFs, the PRF with the largest weight is selected and extracted.

[Effect]

In the present invention, weight data is set for a plurality of PRFs, and weighting is performed using the weight data based on the predicted distance value and the predicted speed value. Therefore, the calculation in the PRF calculation circuit can be performed in a conventional system that does not use weight data. It can be implemented easily and requires only a simple arithmetic circuit. In addition, weight data is set for both the distance direction and the speed direction, and weighting is performed based on both the predicted distance value and the predicted speed value, so in the conventional example, calculations were performed using only one predicted value. The optimal PRF can be calculated more accurately than in the previous example.

〔Example〕

FIG. 2 shows a block diagram of an embodiment of the present invention, in which the same components as in FIG. 5 are given the same numbers. In FIG. 2, 20 is a PRF calculation circuit which calculates PRF using the predicted distance value Rp and the predicted speed value Rp output from the follower 15. A weighting memory 21 stores distance direction weights and velocity direction weights for each of a plurality of PRFs, as will be described later. The other configurations are the same as the conventional example shown in FIG.

Here, FIG. 3 shows an example of distance direction weights and velocity direction weights stored in the memory 21. Regarding distance direction weights, as shown in the same figure (A), PRFO, PRFI,
PRF2. -, PRFn each have an individual PRF (repetition frequency), and rOJ NJ r21 · for each radar range cell in the distance R (proportional to time) direction.
...The weight is set. On the other hand, regarding the velocity direction weight, as shown in FIG.
As a result, for example, PRFI-PRF3 has rOJ r for each radar range cell in the velocity R (proportional to frequency) direction.
The following weights are set: 21r4J r6J r8J r6J...

Now, the target is detected and the tracker 15 sends the signal as shown in Fig. 4 (
It is assumed that a distance predicted value Rp as shown in A) and a speed predicted value Rp as shown in FIG. Since the weighting memory 21 stores weights as shown in FIG.
Regarding the direction, as shown in Figure 4 (A), PRFI is
4".

PRF2 is weighted with r6J, PRF3 is weighted with "2", while in the speed R direction, as shown in FIG. Based on such weighting, the following PRF calculations are performed: PRF I...4+8=12 PRF2...6+4=10 PRF 3...2+2=4, and the PRF with the largest value among these is selected. Ru. Similarly, the predicted distance value Rp°
and speed prediction value Rp', if so, PRF 1...1
PRF2 is selected by the following calculation: +4=5 PRF 2...3+6=9 PRF3...I+4=5.

If two PRFs with the maximum value are found as a result of PRF calculation, depending on the purpose of the radar, select the one with the larger weight in the distance direction, or select the one with the weight in the velocity direction, for example. Just choose the larger one.

The PRF calculated and selected in this way is
7, and a radio wave based on this PR,F is sent out and radiated into space via the antenna 11. In this case, since the PRF calculation is performed by weighting based on the predicted value, the calculation can be easily realized compared to the case where the PRF calculation is performed simply based on the predicted value. Since the PRF calculation is performed using both of the speed prediction values Rp, PRF calculation is performed using only the speed prediction value Rp.
The optimal PRF can be calculated more accurately than a system that performs RF calculations. Furthermore, by setting the weighting method according to the purpose of the radar used, the optimum PRF can be obtained for various different systems.

Note that depending on the purpose of the radar, it may be sufficient to use only the predicted distance value (or only the predicted speed value), so in this case, the distance prediction value Rp (or the predicted speed value Rp) obtained by the tracker 15 may be used. The PRF may be selected by weighting. For example, in a system that only needs to use the predicted distance value, PRF2 is selected without indicating the maximum value in the example shown in FIG. 4(A), and in a system that only needs to use the predicted speed value, the example shown in FIG. 4(B) In the example shown in , the PRFI indicating the maximum value is selected.

〔Effect of the invention〕

As explained above, according to the present invention, since the PRF calculation is performed by weighting based on the predicted value, the calculation can be performed more easily than when the PRF calculation is performed solely based on the predicted value. , a simple arithmetic circuit is required, and PRF can be calculated using both the predicted distance value and the predicted speed value.
Since calculation is being performed, PR is performed using only the speed prediction value.
The optimal PRF can be calculated more accurately than a system that performs F calculations.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a diagram explaining weights in the distance direction and speed direction in the present invention, and FIG. 4 is a diagram in the present invention. FIG. 5 is a block diagram of a conventional example. In the figure, 1 is an antenna, 2 is a receiver, 3 is an FFT circuit, 4 is a target detection circuit, 5 is a follower, 7 is a transmitter, 20 is a PRF calculation circuit, and 21 is a weighting memory. A diagram of the principle of the present invention. A block diagram of an embodiment of the present invention. Diagram range cell explanation diagram

Claims (1)

[Claims] (1) Clutter is removed from the received signal obtained by the receiver (12), the target is detected by the target detection circuit (14), and the target is predicted by the tracker (15). While tracking the target by calculating the predicted value, the pulse repetition frequency (PRF) calculation circuit (20) calculates and extracts the optimum PRF using the predicted value, and transmits from the transmitter (17) based on the PRF. In a tracking radar device that transmits a signal, a weighting memory (21) is provided in which different weights are set and stored for radar range cells in the distance direction for each of a plurality of different PRFs, and the PRF calculation circuit ( 20), the follower (1
Weighting is performed using the weight of the weighting memory (21) based on the predicted distance value (Rp) obtained in step 5), and the PRF with the largest weight among the plurality of PRFs is selected and extracted. tracking radar equipment. (2) Clutter is removed from the received signal obtained by the receiver (12), the target detection circuit (14) detects the target, and the tracker (15) calculates the predicted value of the target to detect the target. In a tracking radar device that uses the predicted value to calculate and extract a PRF in a PRF calculation circuit (20), and sends a transmission signal based on the PRF from a transmitter (17), a plurality of different For each PRF, a weighting memory (21) is provided in which different weights are set and stored for radar range cells in the velocity direction, and in the PRF calculation circuit (20), the tracker (1
Weighting is performed using the weight of the weighting memory (21) based on the speed prediction value (Rp) obtained in step 5), and the PRF with the largest weight among the plurality of PRFs is selected and extracted. tracking radar equipment. (3) Clutter is removed from the received signal obtained by the receiver (12), the target is detected by the target detection circuit (14), and the predicted value of the target is obtained by the tracker (15). In a tracking radar device that uses the predicted value to calculate and extract a PRF in a PRF calculation circuit (20), and sends out a transmission signal based on the PRF from a transmitter (17), a plurality of different For each PRF, a weighting memory (21) in which different weights are set and stored for each radar range cell in the distance direction and speed direction is provided, and in the PRF calculation circuit (20), the following Vessel (1
Weighting is performed using the weights in the weighting memory (21) based on the predicted distance value (Rp) and the predicted speed value (Rp) obtained in step 5), and the PRF with the largest weight among the plurality of PRFs is A tracking radar device characterized by selective extraction.