JPS63145980A - Radar instrument - Google Patents

Abstract

PURPOSE:To enable a target in unnecessary signals to be detected by correcting the phases of received signals of long pulse for long range by using intertransmission phase differences obtained from received signals of short pulse for short range. CONSTITUTION:Long pulse for long range and short pulse for short range both generated from a transmitter 3 are emitted from a transmitting and receiving antenna 1 via a transmission and reception changeover device 2. Reflected signal from a target is received with time lag in accordance with range. The output signal of a long range receiver 4 is the combination of signals with large amplitude spreading in range direction, such as sea clutter or the like and signals from the target. Since a phase change in the transmission of the signal spreading in the range direction, such as sea clutter or the like has not large difference depending on the range, phase correction is conducted by a long range phase corrector 8 from the output of a short range receiver 5 stored in a memory 7 by using phase difference obtained by a phase difference detector 6. Signals that have passed a long range moving target indicator filter 9 are removed with unnecessary signal sand displayed (15) via a pulse compressor 10 and an amplitude detector 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention provides short pulses for short distances and long distances 1i[
Regarding c, it relates to a radar device that detects a moving target over a wide distance range by transmitting a long pulse that is modulated to become an equivalently short pulse through pulse compression processing after reception.

[Conventional technology]

Conventionally, there was a device for this building as shown in Figure 3. In the figure, (1) is an antenna for both transmitting and receiving purposes.

(2) connects the antenna (1) to the transmitter (3) when transmitting, and connects the receiver (4) for long-distance receiving and the receiver (51) for short-distance.
The transmitter/receiver switch (3) connects the two buildings with different frequencies to short pulses for short distances, and pulse compression processing after reception for long distances to create equivalently short pulses. A transmitter that outputs modulated long pulses (
4) is a long-distance receiver that receives a carrier wave modulated with a long pulse that has been modulated to become an equivalent short pulse through pulse compression processing after long-distance reception; (51 is a short-distance receiver); αυ is a short-range receiver that receives a carrier wave modulated with short pulses, αυ is a long-range receiver (a pulse compressor that compresses the signal received at 41 in the distance direction, and αJ is a short-pulse coverage area from transmission to A switch that selects the receiver for close range (5) and the pulse compressor for long range pulse coverage, and (6) detects the phase difference between transmissions for each range bin and calculates the average in the range direction. Phase difference detector (1G is a phase difference detector (6) that detects the phase of the signal selected by switch a3
The fi71 is a phase corrector that corrects the phase difference obtained in the MTI (Moving
The amplitude detector αS is a display device that displays the amplitude signal output from the amplitude detector.

Next, the operation will be explained using FIG. 4. Figure 4 (a
t is a transmission signal generated by the transmitter (31), 0g is a long-distance long pulse, α9 is a short-distance short pulse, and long-distance long pulse U and The short pulse C1q for short range passes through the transmitter/receiver switch +21 and is radiated from the transmitter/receiver antenna fi+.Reflected signals from a target such as an aircraft are received with a delay corresponding to the distance. Figure 4 (bl) shows the output of the long-distance receiver +41 when there is one at a long distance.
The output of 5) is shown in FIG. 4 (C1).

Figure 4 (The part indicated by the broken line in BL is the part that is not actually output because the transmitter/receiver switch (2) is on the transmitting side. Figure 4 Q) L's long-distance receiver (4) The output is:

It is compressed in the distance direction by the pulse compressor αυ as shown in Figure 4 (
It becomes like di. The switch a3 switches from the short-range receiver (51) to the pulse compressor at the timing shown in FIG. After being detected and phase corrected by the phase corrector I, the signal reflected by the clutter spread in the distance direction from the sea surface etc. is removed by the MTI filter wholesaler, converted into an amplitude signal by the amplitude detector α, and displayed on the display α9. be done.

[Problem that the invention seeks to solve]

Conventional radar equipment is configured as described above, and has an MTI filter after pulse compression, so if there is a large received signal such as a reflection from the sea surface, the signal may be saturated in the pulse compression section even though it can be suppressed by the MTI filter. This poses a problem in that it becomes impossible to detect targets located at the same distance.

This invention was made to solve these problems, and the object is to obtain a radar device that can prevent saturation of pulse compression due to large received signals such as reflections from the sea surface and can detect targets. It is something.

[Means for solving problems]

The radar device according to the present invention includes a phase difference detector that detects the phase difference between transmissions from the output of a short-range receiver, a memory that holds the detection result until the next transmission, and a long-distance The system is equipped with a long-distance phase corrector for correcting the phase of the output of the receiver, and a short-distance phase corrector for correcting the phase of the output of the short-range receiver.

[Effect]

In this invention, the phase of the received signal from the far cell is corrected using the phase difference between transmissions determined from the received signal from the short distance.

〔Example〕

FIG. 1 shows an embodiment of a radar device according to the present invention.

(1) to (6), α1. a3~(US is exactly the same as the above conventional device. (7) is a memo IJ that maintains the phase difference between transmissions detected by the phase difference detector (6) until the next transmission, 1g+ is a long distance For the output of the receiver (4).

Memo January 711111: A long-distance phase corrector that performs phase correction using the held value (91 is a long-distance phase corrector (MTI that removes unnecessary signals such as sea surface reflections included in the output of 81) filter, aυ is a short-range receiver (51
α2 is a short-distance phase corrector that performs phase correction using the output of the phase difference detector (6) for the output of the short-distance phase corrector αυ. It is an MTI filter.

Next, the operation of the above embodiment will be explained with reference to FIG. FIG. 2 (al is the output signal of the long-range receiver (41), which is the sum of a large-amplitude signal spread in the distance direction due to reflections from the sea surface, and a signal from the target.

This is because the phase change between transmissions of signals spread in the distance direction, such as those caused by sea surface reflections, does not vary greatly depending on the distance.

Using the phase difference determined by the phase difference detector (6) from the output of the short-range receiver +51 held in Memo January 71.

Long-distance phase corrector (81 performs phase correction and long-distance M
The signal that has passed through the TI filter +9+ has unnecessary signals such as sea surface reflections removed and becomes as shown in Figure 2 (bl), and the output of the pulse compressor (1 (I) is as shown in Figure 2 (c)).

〔Effect of the invention〕

As described above, according to the present invention, the phase difference between transmissions obtained from the short-distance short-pulse reception signal is used to correct the phase of the long-distance long-pulse reception signal, and the MTI filter suppresses unnecessary signals. Since the pulse compression is performed from the beginning, the target in the unnecessary signal can be detected without the pulse compression being suppressed by the unnecessary signal.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of a radar device according to the present invention, Fig. 2 is a diagram showing signals of each part to explain its operation, and Fig. 3
The figure is a configuration diagram of a conventional radar device. FIG. 4 is a diagram showing signals of each part for explaining the operation. In the figure, (1) is an antenna, and (2) is a transmitter/receiver switch. (3) is a transmitter, (41 is a long-range receiver, (51 is a short-range receiver, (6) is a phase difference detector, (71 is a memo'
Jttst is a long-distance phase corrector, (9) is a long-distance M
TI filter. aυ is a pulse clamper, full is a phase corrector for short distances, α2 is an MTI filter for short distances, tL3 is a switch, α center is an amplitude detector, α is a display, US is a phase corrector, αη is an MTI In the filter, ag is a long pulse, and 9 is a short pulse. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] An antenna for transmitting and receiving, a transmitter, a long-distance receiver, a short-distance receiver, a transmitting/receiving switch for connecting the antenna to the transmitter or the long-distance receiver and the short-distance receiver, and the short-distance receiver. a phase difference detector that receives the output of the distance receiver as an input; a memory that holds the output of the phase difference detector; a long-distance phase corrector that receives the output of the long-distance receiver and the output of the memory; A long-distance MTI (Moving Target I) that uses the long-distance phase corrector output as input.
ndicator) filter, a pulse compressor that receives the output of the long-range MTI filter, a short-range phase corrector that receives the short-range receiver output and the phase difference detector output, and a short-range phase corrector that receives the short-range receiver output and the phase difference detector output as input; A short distance MTI filter that receives the output of the corrector as an input, a switch that selects the output of the pulse compressor and the output of the short distance MTI filter, an amplitude detector that receives the signal selected by the switch as input, and the amplitude detector. A radar device characterized by comprising a display device that receives an output as an input.