JPH03138589A - Pulse compressing radar device - Google Patents

Abstract

PURPOSE:To prevent a false image from being inputted to a long-pulse receiver by using a signal composing device which composes a sent signal of short pulses and long pulses and a frequency separator which separates a received signal into two frequencies. CONSTITUTION:The short/long pulse composite sent signal which is composed 3 of the short-pulse sent signal a1 and FM-modulated long-pulse sent signal b1 of different center frequency is radiated 5 in space. Then its reflected signal from a target is received 5 and distributed by a signal distributor 6A to short- pulse and long-pulse receiving band-pass filters 6B and 6C, the filter 6B outputs a short-pulse, only a short-pulse received signal a2 nearby the frequency component of the short-pulse signal, the timing is delayed 9 to send a signal a3 to a signal selector 10. Then the filter 6C generates and sends only a long-pulse received signal b2 nearby the FM-modulated long-pulse frequency component to the selector 10. The selector 10 composes the long/short-pulse composite received signal (d) of the signals a3 and b2 with time and outputs the signal a3 or (d) selectively. Consequently, the false image is prevented from being inputted to the long-pulse receiver 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulse compression radar device having a long pulse width, and more particularly to a pulse compression radar device in which frequency modulation is performed on pulses.

[Conventional technology]

Generally, in a radar device, the transmitted signal leaks to the receiver, so that the signal cannot be received for a period of time relative to the transmitted pulse width. In particular, pulse compression radar devices have a relatively long pulse width, which results in a long period of time during which signals cannot be received, resulting in the problem of not being able to see targets at short distances.

The pulse compression radar device shown in FIG. 3 has solved these problems. This pulse compression radar device will be explained with reference to the operating waveform diagram of FIG. 4.

A switching signal g is input to the input terminal 31. The switching signal g is input to the transmission frequency/short pulse switch 23 and the reception frequency/short pulse switch 26. Each switch 23
and 26 perform switching operations based on this switching signal g.

Short pulse transmission signal e output from the short pulse transmitter 21
1 passes through the transmission frequency/short pulse switch 23 and is radiated into space from the antenna 25 via the circulator 24. The signal reflected from the target is received again by the antenna 25 and sent to the circulator 24. Receiving perimeter/short pulse switch 26
The signal is input to the short pulse receiver 27 through the . The short pulse receiver 27 processes the input signal and then outputs this signal. The short pulse signal e2 from the short pulse receiver 27 is delayed by a time T through the delay line 29, and
This becomes a short pulse signal e3. This short pulse signal e3 is input to the signal selector 30.

On the other hand, after transmitting and receiving short pulses for a certain period of time (T,), a long pulse transmitting and receiving command is sent to the input terminal 31 of the long/short pulse switching signal g. The long pulse transmission signal f from the long pulse transmitter 22 is transmitted through the transmission frequency/short pulse switch 23.
It passes through the circulator 24 and is radiated from the antenna 25. The signal reflected from the target is transmitted to antenna 25. Circulator 24. The signal passes through the reception frequency/short pulse switch 26 and is input to the long pulse receiver 28 . The long pulse reception signal f2 processed and output by the long pulse receiver is input to the signal selector 30.

The signal selector 30 time-synthesizes the input short pulse reception signal e3 and long pulse reception signal f2 to generate a long/short pulse combined reception signal. The generated long/short pulse combined reception signal is output from the output terminal 32.

In this way, the pulse compression radar device shown in Fig. 3 transmits and receives short pulses corresponding to the compressed pulse width for the time of the long pulse width for pulse compression, and then transmits them as long pulses to perform pulse compression. This is a long/short pulse combination method that combines the received signal.

This method compensates for the drawbacks of conventional pulse compression radar systems.

[Problem to be solved by the invention]

The above-mentioned pulse compression radar device shown in FIG. 3 has the following drawbacks. That is, all short pulses received after the short pulse transmission/reception time (T5) are input to the long pulse receiver 28, which is a pulse pressure IW receiver (t) for long pulses, resulting in a false image.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pulse compression radar device that can eliminate such drawbacks and prevent false images from being input to a long pulse receiver.

[Means to solve the problem]

The present invention provides an antenna unit that radiates a signal consisting of long pulses and short pulses into space and receives this signal reflected by a target, and a pulse generator that outputs a composite reception signal from the short pulse reception signal and the long pulse reception signal. a first transmitter that generates a short pulse; and a pulse compression radar device that has a center frequency different from that of the second short pulse and that is frequency modulated after the short pulse is generated in the first transmitter. a second transmitting section that generates a long pulse, and a signal consisting of a short pulse and a long pulse, which combines the short pulse from the first transmitting section and the long pulse from the second transmitting section; a signal combining unit that outputs the received signal from the antenna unit to the antenna unit; a frequency separation unit that separates the received signal from the antenna unit into two frequencies; a frequency output of one of the frequency separators that receives and processes the output;
a first receiving section that outputs a short pulse reception signal to the pulse synthesis section; and a first receiving section that receives the other frequency output of the frequency separation section, performs pulse compression processing, and outputs a long pulse reception signal to the pulse synthesis section. It is characterized by having two receiving sections.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. The pulse compression radar device shown in FIG. 1 includes a short pulse transmitter 1, a long pulse transmitter 2, a signal synthesizer 3,
It is composed of a circulator 4, an antenna 5, a frequency separator 6, a short pulse receiver 7, a long pulse receiver 8, a delay line 9, and a signal selector 10.

Further, the frequency separator 6 includes a signal splitter 6A, a short pulse reception bandpass filter 6B, and a long pulse reception bandpass filter 6C.

Such a pulse compression radar device uses a frequency-modulated transmission signal with a long pulse width.

The short pulse transmitter 1 transmits a short pulse transmission signal a1 of short pulses.
will occur.

After the short pulse is generated by the short pulse transmitter, the long pulse transmitter 2 generates a long pulse transmission signal b1 having a center frequency different from that of the short pulse and subjected to frequency modulation.

The signal synthesizer 3 combines the short pulse transmission signal a and the long pulse transmission signal S to generate a short/long pulse combined transmission signal C.

The antenna 5 radiates the short/long pulse combined transmission signal C that has passed through the circulator 4 into space.

A signal splitter 6A of the frequency separator 6 receives signals received by the antenna 5 and passes through the circulator 4 (one signal into two signals).
Distribute into frequencies.

The short pulse reception bandpass filter 6B extracts only signals near the frequency components of the short pulse signal from the received signal distributed by the signal distributor 6A.

The long pulse reception bandpass filter 6C extracts only signals near the frequency components of the long pulse signal from the received signal distributed by the signal distributor 6A.

The short pulse receiver 7 includes a bandpass filter 6B for short pulse reception.
It receives and processes the short pulse reception signal from , and generates the short pulse reception signal a2.

The long pulse receiver 8 includes a long pulse reception bandpass filter 6C.
A long pulse reception signal b2 is generated by performing pulse compression processing on the long pulse reception signal b2.

The delay line 9 delays the short pulse received signal a2 from the short pulse receiver 7 to generate a short pulse received signal a3.

The signal selector 10 selects the short pulse received signal a3 from the delay line 9 and the long pulse received signal b2 from the long pulse receiver 8.
are time-synthesized to generate a long/short pulse combined reception signal d.

Next, the operation of this pulse compression radar device will be explained with reference to the operational waveform diagram in FIG.

The short pulse transmitter 1 transmits short pulse transmission signals a,
is generated and output to the signal synthesizer 3.

On the other hand, the long pulse transmitter 2 transmits a short pulse transmission signal a.

After the generation of , a long pulse transmission signal S having a center frequency different from that of the short pulse and subjected to frequency modulation is generated. The long pulse transmitter 2 then outputs this long pulse transmission signal S to the signal synthesizer 3.

The signal synthesizer 3 combines the output of the short pulse transmitter 1 and the output of the long pulse transmitter 2, and generates a short pulse transmission signal a1.
and long pulse transmission signal S, respectively become short/long pulse combined transmission signal C. This short/long pulse combined transmission signal C passes through the circulator 4 and is radiated into space from the antenna 5.

The signal reflected by the target is received again by the antenna 5 and becomes a received signal. This received signal is transmitted to the circulator 4
The signal is input to the signal splitter 6A of the frequency separator 6. The signal distributor 6A distributes this received signal to a short pulse reception bandpass filter 6B and a long pulse reception filter 6.
Send to C.

The bandpass filter 6B for short pulse reception extracts only the frequency component of the short pulse signal from the distributed reception signal,
A short pulse reception signal a2 is output.

The delay line 9 delays the short pulse received signal a2 by a time Td to generate a short pulse received signal a3. Then, this short pulse reception signal a3 is output to the signal selector 10. Further, the long pulse reception bandpass filter 6C extracts only the vicinity of the frequency component of the frequency-modulated long pulse signal from the distributed reception signal, and generates the long pulse reception signal Mb2. Then, the long pulse reception signal b2 is output to the signal selector 10.

The signal selector 10 time-synthesizes the input short pulse reception signal a3 and long pulse reception signal b2 to generate a long/short pulse combined reception signal d. The generated long/short pulse combined reception signal d is output from the output terminal 11. That is, the output of the long pulse receiver 8, which is a pulse compression receiver, is saturated within the transmission pulse width as in the conventional case, and the target cannot be detected, so the signal selector 1
0, the output of the short pulse reception bandpass filter 6B whose timing is adjusted by the delay line 9 is selected when receiving a short range target, and the output of the pulse compression receiver 8 is selected when receiving a medium speed target.
The output of is selected and output to the output terminal 11.

〔Effect of the invention〕

As explained above, the present invention uses a signal synthesizer that combines short pulse transmitter output and long pulse transmitter output, and a frequency separator that separates the received signal into two frequencies. This has the effect of eliminating one false image that is input to the receiving section which compresses the pulses.

[Brief Description of the Drawings] Fig. 1 is a configuration block diagram showing an embodiment of the present invention, Fig. 2 is an operational waveform diagram of the embodiment of Fig. 1, and Fig. 3 is a conventional pulse compression radar. A configuration block diagram showing an example of the device. FIG. 4 is an operational waveform diagram of the pulse compression radar device of FIG. 3. ■...Short pulse transmitter 2...Long pulse transmitter 3...Signal combiner 4...Circulator 5...Antenna 6...Frequency Separator 6A...Signal splitter 6B...Short pulse reception bandpass filter 6C...
Long pulse reception bandpass filter 7...Short pulse receiver 8...Long pulse receiver 9...Delay line 10...Signal selector

Claims (1)

[Claims] (1) An antenna unit that radiates a signal consisting of long pulses and short pulses into space and receives this signal reflected by a target;
A pulse compression radar device comprising a pulse synthesis section that outputs a composite reception signal from a short pulse reception signal and a long pulse reception signal, comprising: a first transmission section that generates a short pulse; and a short pulse generation section in the first transmission section. a second transmitter that generates a frequency-modulated long pulse having a center frequency different from that of the short pulse after pulse generation; and a short pulse from the first transmitter and a long pulse from the second transmitter. a signal combining section that combines the long pulses of the short pulses and the long pulses and outputs a signal consisting of the short pulses and the long pulses to the antenna section; a frequency separating section that separates the received signal from the antenna section into two frequencies; and the frequency separating section. receive and process the frequency output of one of the
a first receiving section that outputs a short pulse reception signal to the pulse synthesis section; and a first receiving section that receives the other frequency output of the frequency separation section, performs pulse compression processing, and outputs a long pulse reception signal to the pulse synthesis section. 1. A pulse compression radar device comprising: two receiving sections.