JP2001133541A - Pulse compression radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent pulse compression loss and increase of a range-side-lobe of a pulse compression radar device. SOLUTION: This pulse compression radar device is equipped with a distributor 6, placed between an antenna 1 and a circulator 2, and a switch 7, placed between a circulator 2 and a high-frequency amplifier 8. The pulse compression radar device compresses pulses by a correlation processing of the received signal and the reference signal generated from the output signal of the transmitter, the deformation of amplitude and phase caused by a transmitter 4 being considered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus, and more particularly to a pulse compression radar apparatus that performs pulse compression by using a modulated transmission signal and correlating a received signal with a reference signal generated based on the transmission signal.

[0002]

2. Description of the Related Art The pulse compression method is a technique for satisfying both mutually contradictory issues of an increase in detection distance and an improvement in distance resolution. Using a transmission signal modulated by frequency modulation, code modulation, or the like, pulse compression is performed based on the correlation between the reception signal and a reference signal generated based on the transmission signal. One example of a pulse compression radar is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-14612.
No. 7 (Japanese Patent No. 2659340) “Radar device”
(Hereinafter, referred to as a conventional example).

[0003] A conventional radar device, as shown in FIG.
Antenna (antenna) 101, circulator 102, modulated signal generator 103, transmitter 104, COHO oscillator 1
05, high frequency amplifier 108, phase detector 109, A / D
Converter 110, pulse compressor 111, MTI 112, M
DF113, LOG / CFAR114, data processor 1
15 and a display 116.

In this conventional example, a reference signal is directly generated from a signal generated by a modulation signal generator (transmission code generator) 103, and pulse compression is performed by correlation processing with a received signal. However, radio waves are radiated into space through the transmitter 104, the circulator 102, and the antenna 101.
Therefore, the actual received signal is affected by amplitude and phase distortions caused by the transmitter 104. Further, the amplitude and phase distortions are not always constant and are affected by environmental conditions such as temperature. Therefore, in the conventional example, since pulse compression is performed using a signal before input to the transmitter 104, that is, a preset output signal of the transmission code generator, pulse compression is performed during correlation processing between the reception signal and the reference signal. This causes a decrease in compression gain and an increase in range side lobe.

[0005]

As described above, in the prior art, a reference signal is directly generated from a signal before input to a transmitter, and pulse compression is performed by correlation processing between the reference signal and a received signal. In addition, there is a problem that the pulse compression gain is reduced and the range side lobe is increased.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to avoid a decrease in pulse compression gain and an increase in range side lobe, and to improve the performance of radar detection.

Another object of the present invention is to perform pulse compression using a reference signal generated from an output signal of a transmitter, thereby avoiding a decrease in pulse compression gain and an increase in range side lobe, and a radar detection capability. To improve the performance of

[0008]

In order to solve the above-mentioned problems, a pulse compression radar device according to the present invention employs the following characteristic configuration.

(1) A modulation signal from a modulation signal generator,
A pulse that transmits a signal modulated by amplitude, phase, frequency, etc. and a combination thereof to a space via a transmitter, a circulator, and an antenna, and performs a correlation process with a received signal based on a reference signal when a reflected signal from an object is received. In the compression radar device, a distributor disposed between the circulator and the antenna, and a switch disposed between the circulator and a high-frequency amplifier at a subsequent stage are provided, and after passing an output signal from the transmitter to the circulator, A pulse compression radar device for distributing to the switch by the distributor.

(2) The pulse compression radar apparatus according to the above (1), wherein a reference signal used for correlation processing at the time of pulse compression is a signal generated based on a transmission signal affected by amplitude and phase distortions by the transmitter. .

(3) A modulated signal, which is modulated by amplitude, phase, frequency and the like and a combination thereof, is transmitted to a space via a transmitter and a transmission system having an antenna, and a correlation process is performed via a reception system at the time of reception. In a pulse compression radar device for performing and displaying a target, a pulse compression radar device configured to transmit a transmission signal from the transmitter to the antenna and to transmit the transmission signal to the reception system to serve as a reference signal for the correlation processing. Radar equipment.

(4) The pulse compression radar apparatus according to (3), wherein the reception signal from the antenna and the transmission signal from the transmitter are output to the reception system via a switch.

(5) A modulation signal generator for generating a modulation signal and outputting it to a transmitter, and a transmitter for modulating a transmission signal in accordance with the input modulation signal and transmitting a radio wave from the antenna to space via a circulator. A distributor that transmits an output signal from the transmitter after passing through the circulator to the antenna and outputs the signal to a reception processing system, and an input signal from the distributor to the reception processing system and transmission via the circulator. A switch for switching a reception signal as a reflection signal from an object to be output to a subsequent processing circuit of the reception processing system, and performing a predetermined radar signal processing on the signal input to the subsequent processing circuit and applying a pulse. A pulse compression radar device comprising: a signal processing circuit that performs a compression process.

(6) The pulse compression radar apparatus according to (5), wherein the compression processing is performed based on an output signal from the transmitter after passing through the circulator, which is an output of the switch.

In the above, the switching timing of the switch is synchronized with the transmission / reception timing of the radar device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of a preferred embodiment of a pulse compression radar device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a preferred embodiment of a pulse compression radar apparatus according to the present invention. The pulse compression radar apparatus of the present invention shown in FIG. 1 includes an antenna 1, a distributor 6, a circulator 2, a modulation signal generator 3, a transmitter 4, a COHO oscillator 5, a switch 7, a high frequency amplifier 8, a phase detector 9, A / D converter 10, pulse compressor 11, MTI 12, MDF 13, LOG / CFAR1
4. It is composed of a data processor 15 and a display 16. That is, the pulse compression radar apparatus shown in FIG. 1 is different from the conventional example shown in FIG. 7 in that a distributor 6 and a switch 7 are arranged or added before and after the circulator 2, respectively. The configuration is the same as that described above.

Next, the operation of the pulse compression radar apparatus according to the embodiment of the present invention will be described with reference to the block diagram of FIG. The modulation signal generated by modulation signal generator 3 is input to transmitter 4. In the transmitter 4, the transmission signal is modulated according to the input modulation signal, and COHO
Radio waves are transmitted from the antenna 1 to the space via the circulator 2 and the distributor 6 in synchronization with the signal of the oscillator 5. At the same time, the output signal of the transmitter 4 is input to the switch 7 after passing through the circulator, together with the reception signal which is a reflection signal from the object via the distributor 6.

The switch 7 switches the signal at a timing synchronized with the transmission / reception timing. The signal input to the high-frequency amplifier 8 is amplified, synchronized with the signal of the COHO oscillator 5, and transmitted to the phase detector 9. Phase detected.
The phase-detected signals (I and Q signals) are converted to digital signals by an A / D converter 10 and then input to a pulse compressor 11.

The pulse compressor 11 performs a correlation process based on the received signal and a reference signal generated from the signal passed through the transmitter 4. The output signal of the pulse compressor 11 is M
TI (Moving Target Indicator) 12, MDF (Mul
ti-Doppler Filter) 13, LOG / CFAR (Log / C
In the onstant false alarm rate (14), unnecessary signals such as clutter are removed. And data processing 15
, The signal is subjected to correlation processing and the like, input to the display 16 and displayed.

As described above, in the pulse compression radar device of the present invention, the distributor and the switch are respectively provided before and after the circulator that receives the signal of the transmitter, and the distortion of the amplitude and phase by the transmitter is taken into consideration. The distributor is configured to distribute a part of the output signal of the transmitter, which is sent to the antenna via the circulator, to the high-frequency amplifier via the switch.

As described above, the signal from the transmitter is subjected to high-frequency amplification, phase detection, and A / D conversion in the same manner as the reception signal, and is generated in the pulse compressor from the reception signal and the transmission signal affected by the transmitter. The correlation processing of the reference signal obtained is performed. These series of means generate a reference signal necessary for correlation processing from a signal including the influence of the amplitude and phase distortion of the transmitter in pulse compression, and directly generate a reference signal from a signal before input of the transmitter, In contrast to the technique of performing pulse compression by correlation processing with a received signal, it is possible to avoid a decrease in pulse compression gain and an increase in range side lobe.

Next, the operation of the embodiment of the pulse compression radar apparatus according to the present invention will be described in more detail with reference to FIGS.

FIG. 2 shows a vector diagram of the I / Q combined signal when the transmitter 4 has no amplitude distortion and has phase distortion θ. In FIG. 2, A indicates the amplitude, which is constant regardless of time. It is assumed that the phase distortion θ changes linearly on the time axis. On the other hand, FIG.
5 shows a vector diagram of an I / Q combined signal when there is no phase distortion and there is amplitude distortion (AA (t)). A
(T) shows the amplitude after time t when the amplitude changes with time due to the characteristics of the transmitter 4. Further, in the transmitter 4, amplitude distortion and phase distortion may occur simultaneously in the combination of FIG. 2 and FIG.

FIG. 4 is a waveform diagram showing sampling points in a transmission pulse. 1 to n indicate sampling points in the transmission pulse width τ. Therefore, the sampling points of the reference signal generated from the transmission signal respectively correspond to the sampling points of the transmission signal.

Based on the definitions of FIG. 2 to FIG. 4, the reduction of the pulse compression gain and the avoidance of the increase of the range side lobe will be described with reference to specific examples. FIG. 5 shows an example of a signal waveform after pulse compression when the transmitter 4 has no amplitude distortion and phase distortion. FIGS. 5A, 5B and 5C show a transmission signal, a reception signal and a reference signal, respectively. Set the conditions as follows. Modulation method: Code modulation method (Barker code 3) Total number of samplings in transmission pulse: n = 3 Reference signal (c) within reception time range (from movement start point to movement end point) for received signal (b) ) To move one range bin at a time. The range bin indicates a sampling point in a unit of distance resolution. Since there is no amplitude distortion and phase distortion in the transmitter 4, the signals of each range bin of the received signal (b) are represented by a = Aej0, b = Aej0, and c = Aej.
π, reference signals are a '= e-j0, b' = e-j0, c '= e
Assuming -jπ, the amplitude after pulse compression of each range bin is obtained as shown below.

The same result is obtained in both the present system and the conventional system. A, 0, 3A, 0, A (the method of the present invention and the conventional method) where | a · c ′ | = A | a · b ′ + bc · ||| a · a ′ + b · b '+ C · c' | = 3A | ba '+ c · b' | = 0 | ca · a '| = A

Next, FIG. 6 shows an example of a signal waveform after pulse compression when only phase distortion occurs in the transmitter 4. Assuming that the phase distortion θ = 30 °, the phase distortion amount Δθ for each range bin is 15 ° (= π / 12) according to the following equation (1). Δθ = θ / (n−1) (1) Further, range bins k of a, b, and c are respectively set as k = 1, 2,
3, the received signal is expressed as a = Ae by the following equation (2).
j0, b = Aejπ / 12, and c = Aej (π + π / 6). a, b, c = Aej (φ + (k−1) Δθ) (2) The reference signal is a ′ = e−j0, b ′ =
e−j0, c ′ = e−jπ, and in the method of the present invention, a ′ = e−
Since j0, b ′ = e−jπ / 12 and c ′ = e−j (π + π / 6), when there is phase distortion, the amplitudes after pulse compression of the present invention and the conventional method are as follows. As shown. In the conventional method, the pulse compression gain decreases and the range side lobe increases. A, 0.26A, 2.93A, 0.26A, A (conventional method) where: | a · c ′ | = A | a · b '+ bc · | | 0.26A | a · a' + B · b ′ + c · c ′ | = 2.93A | ba · a ′ + c · b ′ | = 0.26A | ca · a | = A A, 0,3A, 0, A (method of the present invention) Here, | a · c ′ | = A | a · b ′ + bc · | ′ | = 0 | a · a ′ + b · b ′ + c · c ′ | = 3A | ba · a ′ + c · b ′ | = 0 │c ・ a'│ = A

The preferred embodiment of the pulse compression radar device according to the present invention has been described in detail in comparison with the prior art. However, it should be understood by those skilled in the art that the present invention should not be limited to only such an embodiment, and various modifications can be made without departing from the gist of the present invention.

[0030]

As can be understood from the above description, the pulse compression radar apparatus of the present invention generates a reference signal necessary for correlation processing from a signal including the influence of the amplitude and phase distortion of the transmitter, and refers to the reference signal. Since pulse compression is performed by correlation processing between the signal and the received signal, it is possible to avoid a decrease in pulse compression gain and an increase in range side lobe.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a preferred embodiment of a pulse compression radar device according to the present invention.

2 is a vector diagram of the pulse compression radar apparatus of FIG. 1 in a case where there is no amplitude distortion and there is a phase distortion.

FIG. 3 is a vector diagram of the pulse compression radar apparatus of FIG. 1 in a case of (with amplitude distortion and no phase distortion).

FIG. 4 is a conceptual diagram showing a position of a sampling point in a transmission pulse.

FIG. 5 is a diagram illustrating an example of a signal waveform after pulse compression when the transmitter has no amplitude distortion and no phase distortion.

FIG. 6 is a diagram illustrating an example of a signal waveform after pulse compression when a transmitter has phase distortion.

FIG. 7 is a block diagram illustrating a configuration of a conventional radar device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 Circulator 3 Modulation signal generator 4 Transmitter 5 COHO oscillator 6 Divider 7 Switch 8 High frequency amplifier 9 Phase detector 10 A / D converter 11 Pulse compressor 12 MTI 13 MDF 14 LOG / CFAR 15 Data processor 16 Display

Claims (9)

[Claims] 1. A modulation signal from a modulation signal generator, wherein the amplitude,
A pulse compression radar that transmits a signal modulated by phase, frequency, etc. and a combination thereof to a space via a transmitter, a circulator, and an antenna, and performs a correlation process with a received signal based on a reference signal when a reflected signal from an object is received. In the apparatus, a distributor disposed between the circulator and the antenna, and a switch disposed between the circulator and a high-frequency amplifier at a subsequent stage are provided, and the distribution is performed after passing an output signal from the transmitter to the circulator. A pulse compression radar apparatus, wherein the pulse compression radar signal is distributed to the switching device by a switching device. 2. The signal according to claim 1, wherein a reference signal used for correlation processing at the time of pulse compression is a signal generated by the transmitter based on a transmission signal affected by amplitude and phase distortions. Pulse compression radar device. 3. The pulse compression radar device according to claim 1, wherein the switching timing of the switching device is a timing synchronized with a transmission / reception timing of the radar device. 4. A modulated signal, which is modulated by amplitude, phase, frequency and the like and a combination thereof, is transmitted to a space via a transmitter and a transmission system having an antenna, and a correlation process is performed at the time of reception via a reception system. A pulse compression radar device for displaying a target by transmitting a transmission signal from the transmitter to the antenna and transmitting the transmission signal to the reception system as a reference signal for the correlation processing. Pulse compression radar device. 5. The pulse compression radar apparatus according to claim 4, wherein a reception signal from said antenna and a transmission signal from said transmitter are output to said reception system via a switch. 6. The pulse compression radar device according to claim 4, wherein the switching timing of the switch is a timing synchronized with the transmission / reception timing of the radar device. 7. A modulation signal generator for generating a modulation signal and outputting it to a transmitter, a transmitter for modulating a transmission signal in accordance with the input modulation signal, and transmitting a radio wave from an antenna to space via a circulator, A distributor that transmits an output signal from the transmitter after passing through the circulator to the antenna and outputs the signal to a reception processing system, and an input signal from the distributor to the reception processing system and transmitted through the circulator. A switching unit that switches a reception signal as a reflection signal from an object and outputs the signal to a subsequent processing circuit of the reception processing system, and performs predetermined radar signal processing on a signal input to the subsequent processing circuit and performs pulse compression. A pulse processing radar device comprising: a signal processing circuit for performing processing. 8. The pulse compression radar apparatus according to claim 7, wherein said compression processing is performed based on an output signal from said transmitter after passing through said circulator, which is an output of said switch. 9. The pulse compression radar device according to claim 7, wherein the switching timing of the switching device is a timing synchronized with the transmission / reception timing of the radar device.