JPS63206679A - Stagger trigger type pulse radar apparatus - Google Patents

Abstract

PURPOSE:To obtain a good detection characteristic, by providing first and second transmission trigger generators and the changeover device of both trigger generators. CONSTITUTION:Usually, a changeover device 7 is changed over so that the output from the first transmission trigger generator 1 is sent to a transmitter 2 in such a state that there is no multi-order echo clutter. The transmitter 2 transmits the pulse signal synchronous to the trigger signal from the generator 1 and a receiver 3 receives the reflecting signal from a target to guide the same to a moving target detector 4. Herein, the clutter of a short distance is erased and the moving target is detected in such a state that a blind speed is removed. When the multi-order echo clutter is generated, said clutter can not erased by a PRF stagger trigger system and, therefore, a clutter detector 6 detects the azimuth of the multi-echo clutter from the non-erased clutter and the changeover device 7 is changed over so that the output from the second transmission trigger generator 5 is sent to the transmitter 2 only in the azimuth concerned. By this method, the multi-order echo clutter can be erased and the blind speed is removed even with respect to the moving target.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a staggered trigger type pulse radar device suitable for use in search radar devices and the like.

[Prior Art] Generally, in a pulse radar device having a moving target detector (MTI), a detection performance deterioration phenomenon called blind speed occurs. I.

S kolnik “Radar Handbook”
McGraw-H1llInternation
al Book Company, pp17-38-
P RF (Pu
lse Repetition Frequency
y: Pulse repetition period) There is a staggered trigger method. FIG. 4 is a block diagram showing the configuration of a PRF staggered trigger type pulse radar device. In the figure, 1 is a transmission trigger generator that changes the generated pulse period little by little for each pulse repetition period, and 2 is a transmission trigger generator. The transmitter receives the transmission trigger signal from 1 and generates and transmits a transmission pulse signal synchronized with the transmission trigger signal, and 3 is the transmitter 2.
a receiver for receiving, with an antenna, a reflected signal (echo) of a pulse signal transmitted from a moving target and reflected by a moving target, etc.;
is a moving target detector that detects a moving target based on the reflected signal received by the receiver 3.

Next, the function and operation of the conventional staggered trigger type pulse radar device will be explained with reference to FIGS. 5(a) to 5(d).

FIG. 5(a) shows the transmission trigger signal from the transmission trigger generator 1 when no stagger is performed, that is, when the repetition period of the transmission pulse signal output from the transmitter 2 is always a constant value T. Output waveforms are shown. At this time, the response characteristic of the received reflected signal in the moving target detector 4 to the Doppler frequency becomes as shown in FIG. 5(b), with a null (
level zero point) occurs.

The speed of a moving target that produces such a Doppler frequency 17 (2T) is called a blind speed, and a moving target with this speed is canceled by the moving target detector 4 and cannot be detected, like clutter with a speed of 0. This is the phenomenon of detection performance deterioration in pulse radar equipment.

In order to prevent this detection performance deterioration phenomenon, the above-mentioned PR
The F staggered trigger method is used, and in a device to which this method is applied, as shown in FIG. T1. T2. T3
．． ...+Tn is changed little by little and output. As a result, the Doppler response in the moving target detector 4 becomes as shown in FIG. 5(d), and the blind speed frequency fo is approximately 1/(2X (T1.T2..)
, the least common multiple of Tn)), and blind speed can be eliminated within the practical Doppler frequency range.

[Problems to be Solved by the Invention] Since the conventional staggered trigger type pulse radar device is configured as described above, it is possible to eliminate blind speed. There was a problem that echo clutter could not be erased.

To explain this using FIGS. 6(a) to (c), FIG. 6(a) shows the transmission trigger sequence of the PRF staggered trigger method, and FIG. 6(b) shows the reception from the short-range clutter in the range TA. This shows an echo string.

At this time, the received echo within each pulse repetition period is -3
= It is observed an equal amount of time after the transmission trigger signal is output, so
It is correctly erased by the moving target detector 4.

On the other hand, FIG. 6(c) shows a received echo train from a multi-order echo clutter in a range TB that exceeds the transmitted pulse repetition period. At this time, since the pulse repetition period is different, the observation time of the received echo is differs for each pulse repetition period, as shown by Tel to TC3 in the figure, and the moving target detector 4 cannot find a correlation and cannot eliminate the clutter, making it difficult to obtain good detection characteristics with the pulse radar device. I won't be able to do it.

This invention was made in order to solve the above-mentioned problems, and it is possible to eliminate the blind speed with respect to a moving target and also eliminate multi-order echo clutter, so that good detection characteristics can be obtained. The purpose of this invention is to obtain a staggered trigger type pulse radar device.

[Means for Solving the Problems] A staggered trigger type pulse radar device according to the present invention includes a first transmission trigger generator that changes the generated pulse period little by little for each pulse repetition period, and a first transmission trigger generator that changes the generated pulse period little by little for each pulse repetition period. a second transmission trigger generator that gradually changes the above-mentioned first transmission trigger generator according to the detection result of the moving target detector.
The transmitter is equipped with a switch that can switch the output from the second transmission trigger generator for transmission.

[Function] The staggered trigger type pulse radar device according to the present invention has the following features:
Normally, in a state where there is no multi-order echo clutter, the output from the first transmission trigger generator is transmitted by a switch, and the generated pulse period is changed little by little for each pulse repetition period, and the moving target detector is moved. While blind speed to the target is removed, when multi-order echo clutter occurs, the above switch transmits the output from the second transmission trigger generator and gradually changes the pulse repetition period for each scan (azimuth scan). The moving target detector cancels multi-order echo clutter and eliminates the blind speed.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
In the figure, 1 is the first transmission trigger generator of the PRF stagger that changes the generated pulse period little by little for each pulse repetition period, 2 is the first transmission trigger generator that receives a transmission trigger signal, and 2 generates a transmission pulse signal synchronized with the same transmission trigger signal. 3 is a receiver that receives the reflected signal (echo) of the pulse signal transmitted from the transmitter 2 and reflected by a moving target, etc., and 4 also receives the reflected signal received by the receiver 3. This is a moving target detector (MTI) that detects moving targets.

Further, 5 is a second transmission trigger generator of a scan time stagger that changes the pulse repetition period little by little for each scan (azimuth scan), and 6 is a multi-order echo from the remaining clutter in the output of the moving target detector 4. A clutter detector that determines the clutter direction, 7 is a switch, and this switch 7 is
Depending on the detection result of the moving target detector 4 obtained via the clutter detector 6, the output of the first transmission trigger generator l is output if there is no multi-order echo clutter, and the output of the first transmit trigger generator l is output when there is no multi-order echo clutter, If so, the output of the second transmission trigger generator 5 is switched to be sent to the transmitter 2.

□Next, the operation will be explained. Normally, in a state where there is no multi-order echo clutter, the switch 7 is switched so that the output from the first transmission trigger generator 1 is sent to the transmitter 2. transmits a transmission pulse signal synchronized with the transmission trigger signal from the first transmission trigger generator 1, and the receiver 3 receives the reflected signal (echo) from the moving target and transmits the same signal to the moving target detector. Leads to 4.

Here, close-range clutter is canceled and moving targets are detected with blind speed removed. In addition,
The detailed operation is exactly the same as that of the conventional device, so the explanation will be omitted.

On the other hand, if multi-order echo clutter occurs from a long distance that exceeds the transmission pulse repetition period, the clutter cannot be eliminated by the PRF staggered trigger method. appears. The clutter detector 6 detects the direction of the multi-order echo clutter from this remaining trace, and switches the switch 7 so that the output from the second transmission trigger generator 5 is sent to the transmitter 2 only in the corresponding direction. Switch.

In the second transmission trigger generator 5 of the scan time stagger, the pulse repetition period of the transmission trigger signal is constant (T□) within a scan, as shown in FIG. 2(a).

At this time, the received echo train from the multi-order echo clutter in the range TB becomes as shown in Figure 2 (b), and the observation time Tc of the received echoes is constant within each pulse repetition period, so the moving target can be detected. The clutter is properly eliminated by the device 4.

Also, the blind speed removal effect on the moving target at this time will be explained with reference to FIGS. 3(a) to (g). First, FIGS.
1 to n times). As shown in FIGS. 3(a) to (Q), the pulse repetition period within each scan is constant, but the pulse repetition period is changed from T1 to T1 for each scan. T.

...+Tn, and a transmission trigger signal that is gradually changed is output from the second transmission trigger generator 5.

In addition, FIGS. 3(d) to (f) are scans (1 to 1), respectively.
Figure 3 (
As shown in d) to (f), each scan produces a blind speed, but since this speed changes from scan to scan, the Doppler responses of multiple scans are averaged and expressed as shown in Figure 3 (g). This will remove blind speed.

As described above, according to this embodiment, when multi-order echo clutter occurs, the second transmission trigger generator 5 of the scan time stagger is used for this multi-order echo clutter direction, so that the moving target detector 4 In this method, multi-order echo clutter can be eliminated, and blind speed of a moving target can also be eliminated when averaged between scans, so a pulse radar device with good detection characteristics can be obtained.

Note that blind speed is always removed regardless of scanning for directions other than multi-order echo clutter directions.
A first transmit trigger generator 1 with RF staggered trigger is used.

Furthermore, in the above embodiment, multi-order echo clutter is automatically detected by the clutter detector 6, and the switching operation of the switch 7 is performed based on the output from the clutter detector 6. Multi-order echo clutter may be determined on the scope and the scan time stagger direction may be manually set, and in this case, the same effects as in the above embodiment can be achieved.

[Effects of the Invention] As described above, according to the present invention, since the second transmission trigger generator of the scan time stagger is applied to the multi-order echo clutter direction, it cannot be eliminated using only the first transmission trigger of the PRF stagger. Not only can multi-order echo clutter be eliminated, but also the blind speed of a moving target can be eliminated, resulting in the effect of obtaining an object with good detection characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a staggered trigger type pulse radar device according to an embodiment of the present invention, FIG. 2(a),
(b) is an explanatory diagram of the operation of the apparatus of this embodiment against multi-order echo clutter, FIGS. 3(a) to (g) are explanatory diagrams of the operation of the apparatus of this embodiment with respect to a moving target, and FIG. A block diagram showing the configuration of a staggered trigger type pulse radar device, FIGS. 5(a) to 5(d) are explanatory diagrams of the operation of the conventional device with respect to a moving target, and FIGS. 6(a) to (c) are multi-dimensional diagrams of the conventional device. FIG. 3 is an explanatory diagram of an operation for echo clutter. In the figure, 1---first transmission trigger generation circuit, 4
・-moving target detector, 5- second transmission trigger generation circuit, 7-.- switching device. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a pulse radar device having a moving target detector,
The moving target detector is provided with a first transmission trigger generator that changes the generated pulse period little by little for each pulse repetition period, and a second transmission trigger generator that changes the pulse repetition period little by little for each scan. A staggered trigger type pulse radar device, characterized in that a switch is provided that can switch and transmit the output from the first and second transmission trigger generators according to the detection result.