JPH0690280B2 - Multi-target tracking device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-target tracking device equipped with a phased array radar for simultaneously performing search and multi-target tracking by scanning a single beam. is there.

[Conventional technology]

FIG. 5 is a functional block diagram of a conventional multi-target tracking device using a typical phased array radar system. In the figure, (1) is a phased array antenna, (2) is a duplexer, (3) is a receiver, (4) is an angle measuring circuit, (5) is a distance measuring circuit, (6) is a transmitter, and (7) is a beam pointing controller.

The conventional multi-target tracking device using the phased array radar system is configured as described above, and the microwave power generated by the transmitter (6) is passed through the duplexer (2) to the phased array antenna (1). Supply to. Phased
The array antenna (1) radiates this microwave power in the pointing direction determined by the phase data of the beam pointing controller (7), receives the reflected wave from the target, and outputs the sum signal () by the built-in monopulse comparator. Distance signal)
And the difference signal (angle error signal) is created, and the duplexer (2)
And input to the receiver (3). The receiver (3) converts each of them into a video signal, the sum signal (distance signal) to the distance measuring circuit (5), and the difference signal (angle error signal) to the angle measuring circuit (4).
Supply to. The angle measuring circuit (4) and the distance measuring circuit (5) respectively calculate the target angle and the target distance from the supplied signals.

The search frame time (time required to search a predetermined space) Tf of such a multi-target tracking device is the sum of the time Ts required for searching and the time Tt required for target tracking, as in the following equation.

Tf = Ts + Tt (1) Tt is also determined by the number n of pulse hits required for tracking and the target number N of tracking as follows.

Tt = NnnPRI (2) [Problems to be solved by the invention] In the multi-target tracking device as described above, when the target motion is large, the beam width is increased when the target approaches a short distance. It may be located outside the field, and there was a problem of losing tracking. (This is because the diameter D of the beam width θb is proportional to the target distance Rt, and the target motion width exceeds D when the target approaches. ∴D
= 2 · Rt · tan (θb / 2)) When the number N of tracking targets increases, Tt increases and the search frame time Tf increases, resulting in a long system reaction time until the target is found. In addition to the above, there is a problem that the maximum detection distance performance defined by the cumulative detection probability is degraded. (This is R
(Max) = k · Ro · Tf - due to the fact of the collective wisdom of 1/8. Here, R (max) is the maximum detection distance defined by the cumulative detection probability, and Ro is the distance at which the detection probability is 50%. This invention has been made in order to improve such a problem, and utilizes the feature that a phased array radar can arbitrarily set the beam width by phase control, and uses the beam width during tracking according to the target distance. The objective is to obtain a system that achieves both the required tracking accuracy maintenance and the tracking time Tt reduction (prevention of an increase in the search frame time Tf) by controlling.

[Means for Solving the Problems]

The multi-target tracking device according to the present invention is equipped with a "transmission beam width calculation circuit" for calculating an appropriate value of a transmission beam width according to a target distance.

Moreover, in order to cope with the increase in the number N of tracking targets,
It is equipped with a "pulse hit number calculation circuit" for calculating an appropriate value of the pulse hit number n according to Rt. (This has tracking accuracy Inversely proportional to, and proportional to the square of Rt. [Operation] In the present invention, unlike the conventional tracking method of irradiating a target with a transmission wave having a constant beam width, the target tracking is performed by changing the beam width according to the target distance. Not only can tracking be prevented when the target angle measurement error is large, but the antenna gain G is controlled by changing the beam width, so tracking accuracy can be kept constant. (This has tracking accuracy Proportional to It is possible to keep constant. ) Also, unlike the conventional tracking method that irradiates a target with a transmission wave with a fixed number of pulse hits, the target tracking is performed by changing the number of pulse hits according to the target distance, so the search frame time due to the tracking significantly increases. Can be prevented.

〔Example〕

FIG. 1 shows an embodiment of the present invention. (1)
~ (7) is exactly the same as the above conventional device,
A transmission beam width calculation circuit (8) calculates a beam width suitable for tracking the target from the predicted distance of the target from the distance measuring circuit (5) and inputs it to the beam pointing controller (7).

In the multi-target tracking device configured as described above, the transmission beam width calculating circuit (the beam width diameter D becomes constant based on the target predicted distance Rt (output of the distance measuring circuit (5)) detected by the search. In 8), the beam width θb corresponding to the target predicted distance Rt is calculated by the following equation.

D = 2 · Rt · tan (θb / 2) ……………… (3) Here, if the value of D is determined, θb becomes the following formula.

θb = 2 · tan ^-1 (D / 2Rt) (4) This θb is output to the beam pointing controller (7), and the beam pointing controller (7) creates phase data corresponding to θb. Then, it outputs it to the phased array antenna (1), irradiates the tracking target with a beam, and receives the reflected wave.

Therefore, as compared with the conventional method of irradiating the tracking target with a beam with a constant beam width, the tracking target can be reliably put in the beam.

This situation is shown in FIG. 2 by taking the case where the target approaches from a long distance as an example.

In FIG. 2, (A) is a conventional method for tracking with a constant beam width, (A) is a sectional view thereof, (C) is a beam width variable tracking in the present invention, (D) is a sectional view thereof, a) is the beam width at the distance Rt ₁ , (b) is the motion width in the target angular direction, (c) is the diameter of the beam width (a) at the distance Rt ₁ ,
(D) is the diameter of the beam width (a) at the distance Rt ₂ , and (e) is the beam width in the present invention at the distance Rt ₂ .

Further, FIG. 2 also illustrates how the tracking time is shortened because the pulse repetition period can be set to correspond to the target distance.

In the above embodiment, the beam width is calculated corresponding to the target distance to prevent the search frame time from significantly increasing due to the tracking, but the target tracking is performed by changing the number of pulse hits according to the target distance. Therefore, the same operation can be expected.

FIG. 3 shows another embodiment in which the pulse hit number calculation circuit (9) is added, and the tracking accuracy σ is calculated from the target predicted distance Rt (output of the distance measurement circuit (5)) detected by the search. The pulse hit number calculation circuit (9) calculates the number of pulse hits corresponding to the target predicted distance Rt by the following equation so as to be constant.

^{n = k · θb 2 · Rt} 4 ........................ (5) where k is a constant determined by the multi-target tracking apparatus.

By inputting n calculated by the equation (5) into the beam pointing controller (7), the target can be irradiated with the number of pulse hits corresponding to the target predicted distance Rt.

Therefore, it is possible to significantly reduce the tracking time compared to the conventional method in which the beam is emitted to the tracking target with a fixed number of pulse hits.

Taking this situation as an example, the target approaches from a long distance,
It is shown in FIG.

In Fig. 4, (e) is the tracking time at the distance Rt ₁ ,
(F) is the tracking time at the distance Rt ₂ , (f) is the time required for tracking, (g) is the target echo per hit at the distance Rt ₁ , (h) is the target echo after pulse integration, (i) Is the target echo per hit at distance Rt ₂ .

Further, FIG. 4 also illustrates a state in which the tracking accuracy does not deteriorate because the tracking accuracy is proportional to the square of Rt as is known.

〔The invention's effect〕

As described above, according to the present invention, by adding the mechanism for calculating the transmission beam width corresponding to the target predicted distance, it is possible not only to prevent the tracking from being lost when the target motion is large, but also to keep the tracking accuracy constant. effective.

Also, by adding a mechanism for calculating the number of pulse hits corresponding to the target prediction distance, there is an effect of preventing an increase in the search frame time due to an increase in the tracking target.

[Brief description of drawings]

FIG. 1 is a system block diagram showing an embodiment of the present invention,
FIG. 2 is a diagram for explaining the operation and effect of that shown in FIG. 1, FIG. 3 is a system block diagram showing another embodiment of the present invention, and FIG. 4 is for explaining the operation and effect of that shown in FIG. FIG. 5 and FIG. 5 are system block diagrams of a conventional multi-target tracking device. In the figure, (1) is a phased array antenna, (2) is a duplexer, (3) is a receiver,
(4) angle measuring circuit, (5) distance measuring circuit, (6) transmitter, (7) beam pointing controller, (8) transmission beam width calculation circuit, (9) pulse hit number calculation Circuit, (a) beam width at distance Rt ₁ ; (b) movement width in target angular direction; (c) diameter of beam width (a) at distance Rt ₁ ;
(D) is the diameter of the beam width (a) at the distance Rt ₂ , (e) is the beam width of the present invention at the distance Rt ₂ , (f) is the time required for tracking, and (g) is the distance Rt ₁ . The target echo per hit, (h) is the target echo after pulse integration, and (i) is the target echo per hit at the distance Rt ₂ . The same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A phased array antenna provided with a phase shifter for controlling the phase of an element antenna, and a reception signal received by the phased array antenna is inputted via a receiver, and from the reception signal. By using a distance measuring circuit that measures the distance R _t to the target and the distance information obtained by the distance measuring circuit, the beam transmitted according to the target distance R _t so that the diameter D of the beam width becomes constant. And a means for calculating the width θ _b . 2. A phased array antenna provided with a phase shifter for controlling the phase of an element antenna, and a reception signal received by this phased array antenna is inputted via a receiver, and from the reception signal Using a distance measuring circuit for measuring the distance R _t to the target and the distance information obtained by the distance measuring circuit, the number n of pulse hits of transmission according to the target distance R _t so that the tracking accuracy becomes constant. And a multi-target tracking device.