JPS6230979A - Radar equipment - Google Patents

Abstract

PURPOSE:To achieve a higher countermeasure performance preventing the saturation of a receiver in a spectrum diffusion radar by detecting a jamming radio wave exceeding the receivable intensity of electric fields to switch the pseudo noise code (PRC). CONSTITUTION:The level of the reception output is judged with a level decision unit 22 through an antenna 13, a transmission/reception switch 18, a directive connector 21 and the like and when the level exceeds a specified value, the reception of a jamming radio wave exceeding the receivable intensity of electric fields is determined. In response to the decision output, a PRC selector 23 switches the PRC signal from a one-cycle varying PRC generator 19 to control the transmission radio wave. This can prevent the saturation of a receiver due to a jamming wave thereby achieving a higher countermeasure performance of a spectrum diffusion radar.

Description

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

[Conventional technology]

Figure 4 shows the pseudo-noise code (Pseudor-andomo
ode; hereinafter referred to as PRO) is a diagram showing an example of a spread spectrum radar device using
) is a carrier wave generator, α is a pulse consisting of 1 bit T/n seconds, and (3) consists of a binary code string consisting of one period of PRO whose period is n bits. A one-period PRO generator that corresponds to positive and negative voltages and always generates the same code string, αe applies pulse modulation with a pulse width of 1 second to the carrier wave, and a timing signal that generates a code string to the -period PRO generator O9. A pulse modulator that adds pulse modulation with a pulse width of 1 second to the carrier wave by the signal of Q71 pulse signal generator Oe, (3) is 0° according to the binary code string of PRO generated in Q'3 above. and a balanced modulator that applies 180J phase modulation, (4) is a power amplifier, (
5) is a frequency converter, and (6) is an intermediate frequency amplifier that amplifies the signal to an appropriate level.

(7) is a voltage-controlled PRO generator that generates the same PRO as the above aS and whose pulse repetition frequency can be varied by the control voltage VC; (8) is the intermediate frequency amplifier output signal of (6) above and the above (7) PRO generator PRO
The phase detector (9) takes the correlation with the PRO column of (7) below and the PRO column of (6) above, which is input to the phase detector of (8) above.
) detects the synchronization of the FILO signal included in the output signal of the intermediate frequency amplifier, and applies the control voltage ■ to the voltage control PRO generator in (7) above.

A synchronous detector that outputs
PRO of the O generator and the voltage controlled PRO generator of (7) above
αB, a distance measuring device that measures the distance to a target from a signal
is a signal processor, α2 is a display, α■ is an antenna, and 0 seconds is a transmission/reception switch that connects antenna 03 to the power amplifier (4) when transmitting, and connects antenna 0 to the frequency converter (5) when receiving. .

FIG. 2 is a diagram showing the relationship between each part of the transmission signal.
FIG. 2(a) schematically shows the output of the pulse modulator αη, FIG. 2(b) schematically shows the output of the -period pao generator t1, and FIG. 2fcl schematically shows the output of the balanced modulator (3). Fig. 3 shows the relationship between each part of the received signal, Fig. 3 fal is the output of the intermediate frequency amplifier (6), and Fig. 3 ka) is included in the output of the intermediate frequency amplifier (6). An example of the code for one period of PRO is shown in FIG. 3 (cl schematically represents the PRO train output from the voltage-controlled PRO generator (7).

In the spread spectrum pulse radar device configured as described above, the continuous wave generated by the carrier wave oscillator (1) becomes a pulsed carrier wave with a pulse width of 1 second on the pulse modulator surface by a timing signal from the pulse generator. Furthermore, one period PR is generated by the timing signal from the pulse generator OG.
The O generator (19) generates a binary code string for n-bit PRO periods, and the pulsed carrier wave is converted to θ° and 180° by a balanced modulator (3) corresponding to the positive and negative voltages of the binary code string. It undergoes phase modulation consisting of repeating n bits.Then, it is amplified to the required power by a power amplifier (4), and transmitted through the transmitter/receiver switch OS to the target object through the antenna A3.It is reflected by the target object. The reflected wave is again guided by the antenna α3 to the frequency converter (5) as a received signal via the transmitter/receiver switch OS.The received signal is converted to an intermediate frequency by the frequency converter O9 and input to the intermediate frequency amplifier (6). The phase detector (9) correlates the PRO-period code string in the output signal of the intermediate frequency amplifier (6) with the PRO of the voltage-controlled PRO generator (7). .The output of phase detection (9) is determined by the properties of the cross-correlation function in equation (2), and the code string for PRO-period and PRO
If they match, the amplitude is n, and if they differ by 1 bit or more, the amplitude is -1 or 0.Using the property that the PRO-period code string included in the output signal of the intermediate frequency amplifier (6) and the output of the voltage-controlled PRO generator (7) Control voltage V so that the PRO columns match
C! Pressure control PRO generator (7) outputs K.

PRO train and one period P of the above voltage controlled PRO generator (7)
The code string from the I'LO generator α is input to the distance measuring device αG, and the distance is measured using the above two code strings. The output of the phase detector (8) and the output of the distance measuring device 01 are sent to the signal processor αB.
After signal processing is performed, the signal is displayed on the display Q3.

[Problem that the invention seeks to solve]

As described above, in the conventional spread spectrum radar device, the transmission signal spectrum is spread by phase modulation using Pl'LO, so the transmission frequency is difficult to detect. In addition, since the property of FILO's autocorrelation function is used for reception,
If the PRO used for spreading during transmission is not used as a demodulated signal, the carrier signal during transmission will not be recovered and will be further spread, which makes it inherently resistant to external interference. However, the same P as using pao used during modulation
If the receiver is interfered with by an interfering radio wave whose spectrum is spread by the RO and has a field strength higher than -H that the receiver can receive, the receiver misinterprets the interfering radio wave as a reflected wave of the original transmitted signal.

There was a problem that the receiver was saturated.

The object of the present invention is to obtain a spread spectrum radar with improved anti-jamming properties.

[Means for solving problems]

The spread spectrum pulse radar device according to the present invention uses, as a spread spectrum code, a binary code string consisting of n bits per period of PRO, which is constituted by a pulse consisting of 1 bit T/n seconds, and each binary value has a value of 0°, 180°
The carrier wave is pulse-modulated to a pulse width of 1 second, and each of the carrier wave pulses is subjected to n-bit phase modulation as a transmission signal.

At the time of reception, PRO consisting of repetitions of the same code string as the above-mentioned modulation is used as a correlation code, and when receiving an interference signal, PRO is changed.

[Effect]

In this invention, when receiving a jamming radio wave modulated by the same PRO used for spread spectrum modulation at the time of transmission, the interference caused by the jamming radio wave is suppressed by changing the PRO for modulation at the time of transmission and demodulation at the time of reception to another PRO. suppress.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention.

fly, +31~(61, (81~03. ae~α
The seconds are exactly the same as in the conventional device described above. O9 is 1 pit)
A binary code string consisting of one period of PRO, which is composed of pulses of T/n seconds and one period is n pits, is generated with positive and negative voltages corresponding to each binary value. A one-period variable PRO generator that can generate a binary code string by selecting another PRO without changing the conditions, c!
Reference numeral 1 designates a voltage-controlled variable PRO generator which generates the same PRO as αj, whose pulse repetition frequency can be varied by a control voltage vc, and which can select the same PRO as Q9 by a control signal from another. Also, Ca1l
is a directional coupler that divides the received signal power from the transmitter/receiver switch t's at a fixed ratio; @ is the output from the directional coupler and the output of the synchronization detector (9); A level determiner that generates a control signal if the outputs of (c) and (9) are above a specified level; @ is a control signal from the level determiner (c), and @ is the variable period PRO generator a.
j, voltage-controlled variable PRO generator ωK There is a PRO selector ↑ that generates a control signal for PRO selection.

The normal operation of the spread spectrum pulse radar device constructed as described above at °C is the same as that described in the prior art.

The operation when a spread spectrum radar device, which is a feature of the present invention, is used and is disturbed by a radio wave having a field strength higher than that which can be received by a receiver modulated by °C.R PRO will be described. The jamming radio waves are processed in the same way in the spread spectrum radar device receiver without distinguishing them from the original transmitted signal return waves, and the jamming radio waves are mistakenly recognized as the transmitted signal return waves. Therefore, the received signal power by the output of the directional coupler Qυ and the output of the synchronization detector (9) are input to the level determiner (c), and the output of the directional coupler Ca1l and the output of the synchronization detector (9) are input to the level determiner (c). When the output exceeds a predetermined determination level, it is determined that an interfering radio wave having a field strength higher than that which can be received by the receiver has been received, and a control signal is output to the PRO selector. The same PRO selector @ generates a PRO selection signal to the one-cycle variable PRO generator Q'll and the voltage-controlled variable PRO generator ■, thereby generating the same-cycle 0T variable pito generator Q9. Voltage control variable P]' Vary the PRO generated by the LO generator (■).

〔Effect of the invention〕

As explained above, this invention is applicable to a spread spectrum radar device using PRO as a spread spectrum code.
If the spread spectrum radar equipment receiver receives interference with a field strength higher than that which can be received by the RO, the received signal power and the output of the synchronization detector are determined, and PR is performed.
Switching O has the effect of preventing the receiver from becoming saturated.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram schematically showing the relationship between each part of a transmitted signal, FIG. 3 is a diagram schematically showing the relationship between each part of a received signal, and FIG. The figure shows a conventional spread spectrum radar device. In the figure, (1) is a carrier wave generator, (3) is a balanced modulator, (4) is a power amplifier, (5) is a frequency converter, and (6) is a
) is an intermediate frequency amplifier, (7) is a voltage controlled pno generator,
(8) is a phase detector, (9) is a synchronization detector, 01 is a distance measurement device, Qll is a signal processor, (13&? indicator,
0( is an antenna, 09 is a one-period PRO generator, Oe is a pulse signal generator, 071 is a pulse modulator, 0-positive is a transmission/reception switch, Q9 is a one-period variable PRe generator, ■ is a voltage control variable The PRO generator, QB is a directional coupler, (2) is a level judger, and @ is a PRO selector. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A carrier wave generator that generates a carrier wave for a radar transmitter, a pulse modulator that pulse-modulates this carrier wave to a pulse width of T seconds, and a balanced modulation that applies n-bit 0° and 180° phase modulation to this carrier wave. In order to perform phase modulation on the balanced modulator and the balanced modulator, one cycle consisting of n bits of a pseudo-noise code of T/n seconds is generated for each binary voltage code, and the pseudo-noise code string is a selectable one-period variable pseudo-noise code generator; a pulse signal generator that provides timing for generating a pulse-modulated signal and a binary voltage code to the pulse modulator and one-period variable pseudo-noise code generator; a power amplifier that amplifies the pulsed carrier wave as a transmitted wave to the required power; an antenna that irradiates the transmitted wave toward a target and receives a reflected wave from the target as a received wave; A directional coupler that divides and outputs power at a constant rate, a frequency converter that is connected to one of its outputs and converts the received wave to an intermediate frequency, and a power amplifier that converts the above antenna into a power amplifier for transmission and a power amplifier for reception. A transmitter/receiver switcher that is sometimes connected to a directional coupler, an intermediate frequency amplifier that amplifies the above intermediate frequency to the required power, and a binary amplifier that can vary the pulse repetition frequency using a control voltage and that is used for phase modulation of the carrier wave. Generates a pseudo-noise code string by infinite repetition of each code as a binary voltage code string,
a voltage-controlled variable pseudo-noise code generator capable of varying a pseudo-noise code string in accordance with the one-period variable pseudo-noise code; a binary voltage code string of the voltage-controlled variable pseudo-noise code generator; and an output of the intermediate frequency amplifier. and a phase detector that takes the correlation between a synchronization detector that detects and generates a control voltage to the voltage-controlled variable pseudo-noise code generator for synchronization and generates a synchronization signal, and a synchronization signal of the synchronization detector and the one-period variable pseudo-noise code generator A distance measuring device that measures the distance to the target using a binary voltage code string, a signal processor that processes the output of the phase detector and the output of the distance measuring device, and a display that displays the output of the signal processor. and a level determiner that determines the levels of the output of the synchronous detector and the output of the directional coupler and generates a control signal for selecting a pseudo noise code; A radar device comprising a noise code generator and a pseudo-noise code selector that generates a pseudo-noise code selection signal for the voltage-controlled variable pseudo-noise code generator.