JPS61205882A - Radar equipment - Google Patents

Abstract

PURPOSE:To enable the diffusion of a spectrum in pulse radar, by using one cycle portion of a noise pseudo-code (PRC) as a spectrum diffusion code and using PRC as a correlation code at a receiving time. CONSTITUTION:The continuous wave of a carrier wave oscillator 1 is converted to a pulse like carrier wave on the basis of the timing signal from a pulse signal generator 16 by a pulse modulator 17. Further, an one cycle PRC generatort 15 generates a n-bit binary code line corresponding to one cycle of PRC by the timing signal of the generator 16 and said code line is allowed to irradiate a target from an antenna 13 through a balanced modulator 3. The reflected wave of the target allows a synchronous detector 9 to output control voltage VC to a voltage control PRC generator 7 through a frequency converter 5 so that the code line corresponding to one cycle of PRC contained in the output signal of an intermediate frequency amplifier 6 coincides with the output PRC line of said generator 7. The PRC line of the generator 7 and the code line of the generator 15 are inputted to a distance measuring device 10 and a distance is measured by two code lines and the outputs of a phase detector 8 and the measuring device 10 receive signal processing to be displayed on a display device 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spread spectrum radar device.

[Conventional technology]

Figure 4 is a diagram showing an example of a spread spectrum radar device using pseudo noise codes (hereinafter referred to as PRC). In Figure 1, +11 is a carrier wave oscillator, and (2) is a binary code string corresponding to positive and negative voltages. (3) is a balanced modulator that applies phase modulation of 0° and 180 @ according to the binary code string of PRC generated in (2) above, (4) is a power amplifier, (5) ) is a frequency converter, (6
) is an intermediate frequency amplifier that amplifies a signal to an excessive magnitude,
(7) generates the same PRC as (2) above, and the PRC
A voltage-controlled PRC generator that can vary the pulse repetition frequency by controlling the control voltage.

(8) is the intermediate frequency amplifier output signal of (6) above and (
)) A phase detector that correlates with the PRC train of the PRC generator of A synchronization detector that detects the synchronization of the PRC signal included in the output signal and outputs the control voltage Vc to the voltage-controlled PRC generator of (7) above, III is the PRC generator of (2) above and (7) above.
I is a distance measuring device that measures the distance to a target from the PRC signal of the voltage-controlled PRC generator, and I is a signal processor.

α2 is a display, (13 is an antenna, α4 is a superstition carrier wave signal from the power amplifier in (4) above, and guides it to the above antenna (0), and the reflected signal that has been irradiated from the antenna to the target object and reflected from the above ((4)). 5) is a circulator connected in a direction leading to the frequency converter.

A spread spectrum radar device using conventional PRC is
The distance to the target is measured by the property of the autocorrelation function of PRC. PRC is composed of infinite repetitions of a one-period code string (a,) consisting of finite length n bits, and its autocorrelation function ρ (k) can be written as follows.

a FIG. 5 is a diagram showing equation (1) in the case of n-15.

A conventional spread spectrum radar device using PRC is configured as described above, and the continuous wave generated by the carrier wave oscillator 11J is generated by a binary code string corresponding to the positive and negative voltages generated by the PRC generator (2). 0 due to balanced modulator (3)
and 180° phase modulation.

The power amplifier (4) amplifies the power to the required level, and then the light is irradiated from the air iα3 toward the target via the circulator Q4. The reflected wave reflected by the target object is again guided by the antenna 0 through the circulator (14i) to the frequency converter (5) as a received signal.The frequency converter (5) converts the received signal to an intermediate frequency. It is input to the frequency amplifier (61) and amplified to the required power.The phase detector (8) detects the PR in the output signal of the intermediate frequency amplifier (6).
Correlate C with the output signal of the voltage controlled PRC generator (7). The phase detector (9) uses the property of the autocorrelation function in equation (1) that when two PRC sequences match, the amplitude is n, and when they are separated by 1 bit or more, the amplitude is -1, and the intermediate frequency amplifier (6)
The control voltage Vc is output to the voltage controlled PRC generator (7) so that the PRC string included in the output signal of the voltage controlled PRC generator (7) matches the PRC string output from the voltage controlled PRC generator (7). Above voltage control P
PRC train of RC generator (7) and P of PRC generator (2)
The RC string is input to the distance measuring device d, and the above two PRC
Measure distance. The output of the phase detector (8) and the output of the distance measuring device a1 are subjected to signal processing by a signal processor 1ITJ and then displayed on a 2nd display aS.

[Problem that the invention seeks to solve]

As mentioned above, in conventional spread spectrum radar equipment, P
Since the property of the autocorrelation function of RC is used, a continuous wave is used as a carrier wave due to the restriction that PRC has an infinite length. However, when continuous waves are used, the isolation between the radar transmitter and receiver cannot be achieved sufficiently due to only the cable circulator installed in front of the antenna, and the transmitted signal leaks into the receiver, causing the receiver to fail. There was an interim point where transmission power was restricted due to saturation.

It is an object of the present invention to provide a spread spectrum radar device that uses a pulse modulated wave as a carrier wave as a transmission wave and has the same effect as a continuous wave.

[Means for solving problems]

The spread spectrum pulse radar device according to the present invention uses, as a spectrum spread code, a binary code string consisting of n bits per cycle of PRC, which is constituted by a pulse of 1 hit/second, and each binary value is 01.18G''. The carrier wave is pulse-modulated to a pulse width of 7 seconds, and each of the carrier wave pulses is subjected to n-bit phase modulation to be used as a transmission signal.

During reception, it is used as a PRC'i phase code consisting of repetitions of the same code string used for the modulation.

[Effect]

In this invention, the following properties of the cross-correlation function are used.

That is, (b) is a periodic sequence of length n, and (cj) is Ib
) is a finite length sequence of length n obtained by extracting one period of the above (b) and (C1).
is equal to (autocorrelation function ρbbOc of b l)
,do. Namely.

” ””””Obl””n-2bn-1bO”l””’
n-2bn-1bObl””n-sing°°.

tc, s-...00...' OOb ob 1'...
When b, -2bn, oo...0...

Therefore, phase modulation of 0°, 180' is applied to the pulsed carrier wave by a code string consisting of n bits for one period of PRC,
At the time of reception, by taking the correlation with the PRC sequence using a phase detector, the continuous wave carrier is phase-modulated with PRC, and at the time of reception, the same form as the correlation function obtained by taking the correlation with the same PRC used during modulation is obtained. The correlation function is obtained.

〔Example〕

FIG. 1 is a diagram showing a one-pointed embodiment of the present invention.

Hl, (3) to α-ken are completely the same as the above-mentioned conventional device. α-Shi generates a binary code string consisting of one period of PRO, which is composed of a pulse of 1 bit T/n seconds and one period is n bits, and always generates the same code string by correlating positive and negative voltages to each binary value. A one-period PRC generator, ae applies pulse modulation with a pulse width of 7 seconds to the carrier wave, and one-period PRC generator.
A pulse signal generator that provides a timing signal for generating a code string to the RC generator r1!9.

(lη is a pulse modulator that adds pulse modulation from the pulse generator to the carrier wave using the signal from the pulse signal generator αe.

The brocade is a transmission/reception switch that connects the antenna (13) to the power amplifier (4) during transmission, and connects the antenna (I3) to the frequency converter (5) during reception.

FIG. 2 is a diagram showing the relationship between each part of a transmission signal.

Figure 2(a) shows the output of the pulse modulator (7).
b) is the output of the one-period PRC generator α→, as shown in Fig. 2(C).
schematically shows the output of the balanced modulator (3). Figure 3 shows the relationship between each part of the received signal. Figure 3 (a) shows the output of the intermediate frequency amplifier (6), and Figure 3 (b) shows the relationship included in the output of the intermediate frequency amplifier (6). Figure 3 (C) shows the code string for one period of the PRC that is generated by the voltage-controlled PRC generator (7
) schematically represents a PRC string output from

In the spread spectrum pulse radar device configured as described above, the continuous wave generated by the carrier wave oscillator (11) is converted into a pulsed carrier wave with a pulse width of 7 seconds by the timing signal from the pulse generator and the pulse modulator αη. One period P due to the timing signal from the generator αG
The RC generator (19) generates a binary code string for one period of the n-bit PRC, and the pulsed carrier wave is converted to 0@, 180" by the balanced modulator (3) corresponding to the positive and negative voltages of the binary code string. n
It undergoes phase modulation consisting of bit repetition. after that,
The power is amplified to the required power by the power amplifier 6 (41), and is irradiated toward the target from the antennas α via the transmitter/receiver switch Ql.

The reflected wave reflected by the target object is sent back to the frequency converter (1m) as a received signal via the transmitter/receiver switch αIIt- from the air i (1m).
5). The received signal is converted to an intermediate frequency by the frequency converter (5), inputted to the intermediate frequency amplifier (6), and amplified to the required power. The phase detector (9) correlates the code string for one cycle of PRC in the output signal of the intermediate frequency amplifier (6) with the PRC of the voltage controlled PRC generator (71).The output of the phase detector (9) is ( 2) According to the property of the cross-correlation function in equation 2, if the code string for one period of PRC and PRC match, the amplitude is n, and if they are separated by j bits or more, the width is -1 or 0. Using this property, the output of the intermediate frequency amplifier (6) is The control voltage Vc is outputted to the voltage control PRC generator (7) so that the code string of one PRC period included in the signal matches the output PRC string of the voltage control PRC generator (7).The voltage side 1
The PRC string of the iII PRC generator (7) and the code string of the one-period PRC generator (I!19) are input to the distance measuring device σ,
The distance is measured using the above two code strings. Phase detector (
8) The output and the output of the distance measuring device aa are processed by the signal processor αυ and then displayed on the display σ2.

In the figure, the transmitter/receiver switcher can be configured not only by a switcher but also by a circulator, or a combination of a circulator and a switch for securing the receiver.

〔Effect of the invention〕

As explained above, the present invention enables spectrum spreading in a pulse radar by using one cycle of PRC as a spread spectrum code and using PRCf as a correlation code during reception.

Further, there is an advantage that a distance resolution corresponding to the PR01 bit length can be obtained by modulating the pulse radar transmission wave for one PRC period and correlating the received signal with the PRC at the time of reception. Also.

Since the radar device according to the present invention uses one period of PRC as a spread spectrum code, there are countless spread spectrum codes, and the radar device is highly resistant to damage. Furthermore, since one period of PRC is used as the radar device spread spectrum code according to the present invention, there are spread codes that are infinitely long, and the transmission peak power can be lowered compared to pulse compression using Barker codes.

[Brief explanation of the drawing]

Figure 1 shows conventional spread spectrum radar using continuous wave (ψ) transmission, and Figure 2 shows PRC with 15 bits per cycle.
FIG. 3 is a diagram showing an embodiment of the present invention, FIG. 4 is a diagram schematically showing the relationship between each part of the transmitted signal, and FIG. 5 is a diagram showing the relationship between each part of the received signal. It is a figure shown typically. In the figure, (1) is a carrier wave generator, (2) is a PRC generator, (3) is a balanced modulator, (4) is a power amplifier, and (5) is a balanced modulator.
) is a frequency converter, (6) is an intermediate frequency amplifier, (7) is a voltage controlled PRC generator, (8) is a phase detector, and +9) is a synchronous detector. (II is a distance measuring device, aυ is a signal processor, α2 is a display device, α row is an antenna, α 荀 is a circulator, and 噌 is a one-cycle PR
C generator, αe is a pulse signal generator, aη is a pulse modulator, (IS is a transmission/reception switch. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] a carrier wave generator for generating a carrier wave for a radar transmitter; a pulse modulator for pulse-modulating the carrier wave with a pulse width T (T is a real number) seconds;
n is a natural number) A balanced modulator that applies phase modulation of 0° and 180° bits, and a pseudo-noise code consisting of n bits of 1 bit T/n seconds to cause this balanced modulator to perform phase modulation. a one-period pseudo-noise code generator that generates one period as a binary voltage code string; and a pulse that provides timing for generating a pulse modulation signal and a binary voltage code string to the pulse modulator and the one-period pseudo-noise code generator. A signal generator, a power amplifier that amplifies the phase-modulated pulse carrier wave as a transmission wave to the required power, an antenna that irradiates the transmission wave toward the target and receives the reflected wave from the target as the reception wave, and a receiver. a frequency converter that converts the waves into an intermediate frequency; a transmitting/receiving switch that connects the antenna to a power amplifier when transmitting and to a frequency converter when receiving; an intermediate frequency amplifier that amplifies the intermediate frequency to a required power; A voltage-controlled pseudo-noise code generator whose pulse repetition frequency can be varied by a control voltage and which generates a pseudo-noise code of infinite repetitions of a binary code string used for phase modulation of a carrier wave as a binary voltage code string; a phase detector that correlates the binary voltage code string of the pseudo-noise code generator with the output of the intermediate frequency amplifier; and a phase detector that correlates the binary voltage code string of the pseudo-noise code generator with the output of the intermediate frequency amplifier; a synchronization detector that detects the degree of synchronization of one period of the pseudo-noise code contained in the output of the amplifier, generates a control voltage in a voltage-controlled pseudo-noise code generator for synchronization, and generates a synchronization signal;
a distance measuring device that measures a distance to a target using a synchronization signal of the synchronization detector, a binary voltage code string of the one-period pseudo-noise code generator, and a binary voltage code string of the voltage-controlled pseudo-noise code generator; A radar device comprising: a signal processor that processes the output of the phase detector and the distance measuring device; and a display that displays the output of the signal processor.