JPH0493684A - Phased array radar unit - Google Patents

Abstract

PURPOSE:To dispense with any acquisition phase in removing an unnecessary reflected wave out of a stationary, low-speed target and an untrackable separation target at time of detection, by calculating a distance variation in the detected target, inputting it into a tracking start filter, and setting an initial value to the speed vertex. CONSTITUTION:A distance variation calculator 14 calculates a desired distance variation in use of such a relationship that a distance error by Doppler frequency modulation is proportioned to those of Doppler frequency and transmitting pulse width, by the detected distance from a signal detector 8 and the transmitting pulse width from a waveform generator 10. This result is fed to a judging circuit 15 as well which drives a gate circuit 16 when the absolute value of the detected distance is approximated to zero and a separation target is the case, and it is recommended that a distance count value, a distance variation calculated value and a signal detecting signal are all made to as not to be inputted into a tracking start filter 11. With this constitution, an unnecessary signal of a stationary, low-speed target or the like and an untrackable separation target are not taken into an acquisition phase, thus a radar resource is savable.

Description

[Detailed Description of the Invention] Industrial Application Field] This invention employs a pulse compression method to automatically detect targets,
This invention relates to shortening reaction time and saving radar resources (1 hour of power) in a phased array radar device that performs acquisition and tracking.

[Conventional technology]

FIG. 2 shows the configuration of a conventional phased array device disclosed in, for example, Japanese Unexamined Patent Publication No. 62-169072. In section 1, fl) is a phased array antenna (2) for reception. (3) is a switch circuit, (4
) is a positive pulse compressor, (5) is a negative pulse compressor, and (6) is MT! circuit, (7) is a pulse integrator, (8)
is a signal detector, and (9) is a distance calculator.

(10) is a waveform generator, and fll+ is a tracking start filter.

(12) is a tracking maintenance filter, and t13) is a beam controller.

A conventional phased array radar device is configured as described above, in which the signal received by the phased array antenna +l) passes through the receiver (2), and the signal frequency modulated to positive polarity is transmitted to the positive pulse compressor ( 4), the negative frequency modulated signal 1 is switched to the negative polarity pulse compressor (5), and the switch circuit (3) receives switching signals from the waveform generator (10), respectively, and the stationary signal 1 is switched to the negative pulse compressor (5). , is input to an MTI circuit (6) that suppresses low-speed unnecessary signals. Here, the received signal is controlled by the third Z and I4 so that the number of positive polarity modulated signals and negative polarity modulated signals is the same within one dow time as shown in FIG. The positive polarity signal and negative polarity signal that have passed through the MTI circuit (6) are each sent to a pulse integrator (7).
The signal is integrated at the signal detector (8) and input to the signal detector (8). The signal detector (8) sends a signal indicating that a signal has been detected (signal detection signal) to the tracking start filter (11), and also detects the respective pressure distances fiRp (distance at which the positive polarity signal is detected), R, (detected distance of negative polarity signal!
! ) into the distance calculator (9). At this time, the polarity of the modulation is as shown in Figure 4, and when the modulation frequency undergoes Doppler modulation, the distance at which the health-compressed signal appears deviates from the true target distance, resulting in the following: A known distance error occurs.

RP=Ra+△RP RN=Rknee△RN △Rp”△R, (o:f,) Here, RT・True target distance △RP, difference between positive polarity signal distance and true target distance △RN Difference f between the negative polarity signal distance and the true target distance, - Doppler frequency △R2 is shown in Figure 5 (a), △R9 is shown in Figure 5 (b) - Calculate the target distance R and use the tracking start filter (11).The processing frequency is different between the tracking start filter (11) and the following (tracking maintenance filter (12)), but when the signal detection signal from the signal detector (8) is "present".

Using this target distance R, equivalent tracking processing (target position,
speed estimation and prediction).

In other words, in order to start tracking, the estimated value of the target's velocity must be converged within a required range within a short time, so the tracking start filter (11) controls the beam controller by giving the target target position. f+, 3 is controlled to irradiate the target with a beam from the phased array antenna (1) at high frequency (this is called the eye-stroke acquisition phase), and when the estimated speed of the target converges, the target is tracked. The tracking maintenance filter (12) then controls the beam controller (13) at the required beam irradiation rate and directs the beam from the phased array radar antenna (1) to the target. (This is called the tracking phase.) This situation is shown in Figure 6. In the 6th section, A is the acquisition phase, B is the tracking phase, and a
b is the beam irradiation time in the acquisition phase, and b is the beam irradiation time in the tracking phase.

[Problem to be solved by the invention] In the conventional phased array radar device as described above,
Since the input to the tracking start filter (11) is only angle information and distance information, there is a problem in that the convergence time is long, or in other words, a large amount of radar resources must be consumed for target acquisition.

In addition, unnecessary reflected waves that cannot be completely eliminated by the MTT circuit (6) (for example, reflected waves from large buildings, large buildings, ships, mountains, stationary targets, and low-speed targets) are automatically detected. , to enter the mtm phase, the tracking start filter (
11) converges, it is determined based on the calculated speed value and rejected, which means that a lot of radar resources are consumed, and for example, when tracking a distant target is not required. In this case, since the distant target is automatically detected and the acquisition phase is entered, it is necessary to spend a large amount of radar resources to reject it. There was a problem in that the number of targets that could be tracked was severely limited.

This invention has been made to solve these problems.It shortens the convergence time of the tracking start filter to shorten the reaction time, and eliminates unnecessary reflected waves and tracking at the time of target detection before entering the target acquisition phase. The object of the present invention is to obtain a phased array radar device capable of removing unnecessary distant targets.

[Means for solving problem 1] The phased array radar device according to the present invention calculates the polarity from the transmission pulse width and the target distance measured from the signal received by positive polarity pulse compression and negative polarity pulse compression. The distance change rate of the target is calculated and inputted to the tracking start filter, and based on the value and polarity of the distance change rate, stationary, low-speed targets, and distant targets are distinguished, and the detection signal, distance information,
A gate circuit is provided to prevent distance change rate information from being input manually to the tracking start filter.

[Operation] In this invention, the rate of change in the distance of the detected target is calculated and inputted to the tracking start filter, and the speed ring is initialized, so the tracking start filter can start from a speed close to the actual speed. , unnecessary reflected waves from stationary and low-speed targets, and distant targets that do not need to be tracked are removed at the time of detection, eliminating the need for an acquisition phase for them.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.
) to (13) are completely the same as the above-mentioned conventional device.

(14) is a distance change rate calculator, [15] is a judgment circuit (
16) is a gate circuit.

In the phased array radar device configured as described above, in the distance change rate calculator (14).

The known relationship is that the distance error due to Doppler frequency modulation is proportional to the Doppler frequency and the transmission pulse width T, depending on the detection distance Rp and the transmission pulse width from the signal detector (8) and the transmission pulse width T from the waveform generator (10). The distance change rate Ry of the target is calculated as follows using .

At Uni 7.・Wavelength of the transmitted wave C Speed of light T Transmitted pulse width (pulse compression surface pulse width) Pulse width after pulse compression This result is also sent to the judgment circuit 115), and in the 7 judgment circuit (15), the value of 1 and 1 is zero. When close to , and when the polarity of R1 is positive (for a distant target), the gate circuit (1B)
is driven so that the distance calculation value, distance change rate calculation value, and signal detection signal in this case are not manually input to the tracking start filter (11).

[Effects of the Invention] As described above, in the present invention, since the tracking start filter can start up at a speed close to the actual speed, the time required for the acquisition phase can be shortened. In other words, the reaction time can be shortened by that much, and the lake resources can be saved. In addition, since unnecessary signals such as stationary and low-speed targets and distant targets that do not require tracking are not entered into the acquisition phase, relay relay
This not only saves time, but also prevents saturation of the radar equipment due to such costs.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of a phased array radar device according to the present invention, Fig. 2 is a block diagram of a typical conventional phased array radar device, and Fig. 3 is a conventional positive pulse compression within the dwell time. FIG. 4 is a diagram showing the time allocation of transmission pulses for compressing negative polarity pulses.
The figure is for explaining the distance error between the positive pulse compression signal and the negative pulse compression signal, and Figure 6 is for explaining the difference in frequency of beam projection time in the conventional acquisition phase and tracking phase. This is a diagram. In the figure, (14) is the distance change rate calculator, f15)
is a lower window circuit, and (16) is a gate circuit. Note that in FIG. 1, the same reference numerals indicate the same or equivalent parts. Diagram Modulation Shonkinkyo Diagram

Claims (1)

[Claims] Automatic target detection using a tracking start filter and tracking maintenance filter that uses a pulse compression method and inputs the pulse compressed signal through a signal detector and target distance calculator.
In a phased array radar device that performs acquisition and tracking, the distance error that occurs in the compressed signal due to Doppler frequency modulation from the target is used to calculate the target distance from the distance error, the transmitted pulse width, and the compressed pulse width. A distance change rate calculator that calculates the rate of change and outputs it to the tracking start filter, a determination circuit that sends out unnecessary signals from the distance change rate value calculated by this distance change rate calculator, and an output of the determination circuit. and a gate circuit connected to the input stage of the tracking start filter in order to prevent unnecessary signals from being input to the tracking start filter.