SU1370793A1 - Follow-up filter for handling phase-manipulated pseudorandom radio signal - Google Patents

Abstract

This invention relates to telecommunications, radio engineering, and increases immunity to interference. The filter contains a delay tracking system 1, a 2 frequency control system. The system 1 contains multipliers 3 and 6, a band-pass filter 4, a detector unit 5, low-pass filters 7 and 11, an adder 8, a controlled clock frequency generator 9, a pseudo-random sequence shaper 10, a functional converter 12, and a scan signal generating unit 13. System 2 comprises a reference controlled oscillator 14 and a low-pass filter 15. Unit 5 contains a phase detector, a phase shifter, a synchronous detector, two limiters. 4 il. with b

Description

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The invention relates to telecommunications, radio engineering, and can be used in radio engineering systems using phase-manipulated pseudo-random radio signals.

The purpose of the invention is to increase noise immunity.

FIG. Figure 1 shows a structural functional diagram of a tracking filter for processing a phase-manipulated pseudo-random radio signal (FM PTS); Fig. 2 shows timing diagrams illustrating the delay scanning process; in fig. 3 - dependencies that clarify the work of limiters; in fig. 4 shows an embodiment of the detector unit.

The following filter for processing FM PCR contains a delay tracking system (CVD) 1, an automatic frequency control system 2, (AFC), the CVD 1 contains the first multiplier 3, the band pass filter (PF) 4, the detector block 5, the second multiplier 6, the first low-pass filter 7 (LPF), the adder 8, the controlled oscillator (UG) 9 clock frequency, the shaper 10 of the reference pseudo-random sequence (FO PSP), the third LPF 11, the functional converter (AF) 12 and the block 13 of the formation of scanning signals ( FSS). The system 2 of the AFC and the reference UG 14 and the second low pass filter 15. The detector unit 5 contains a phase detector (PD) 16, a phase shifter 17, a synchronous detector (SD) 18, the first and second limiters 19 and 20.

The following filter for processing FM PSR works as follows.

The input FM PSR and the signal from the output of the FO of the PSP 10 are fed to the corresponding inputs of the first multiplier 3, which together with the FS 4 calculates the values of the intercorrelation function of these signals at the intermediate (carrier) frequency, i.e. The signal at the output of the FS 4 is a quasharmonic oscillation at the intermediate (carrier) frequency with an amplitude determined by the value of the mutual correlation function. This signal is fed to the corresponding input C 18, from the output of which the signal of amplitude modulation, which occurs when scanning for a delay relative to the input signal of the signal from the output of FO PSP 10, through the first limit

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reader 19, respectively, is fed to the corresponding input of the second multiplier 6 and through the third low-pass filter 11 and OP 12 to the input of the FSS unit 13, which at the corresponding output forms a reference signal from the second input of the second multiplier 6. From the other output of the FSS unit 13 a meander signal arrives at the corresponding input of the adder 8, to another input of which an error signal is received from the output of the second multiplier 6 through the first low-pass filter 7. The signal from the output of the adder 8 is fed to the input of the UG 9 clock frequency, the output signal of which It uses the FO of the SRP 10 when generating the reference signal for the first multiplier 3. Thus, the meander scan signal causes a discontinuous periodic change in the voltage supplied to the UG of 9 tons of active frequency, which generates a change in the clock frequency according to the same law. An abrupt change in the clock frequency causes a sawtooth phase change, i.e. the delay signal at the output of the FO PSP 10, i.e. continuous delay scan is performed. The span of the sawtooth scan is determined by the steepness of the adjustment characteristic of the HS 9 clock frequency, the amplitude and duration of the meander signal period generated by the FSS unit 13. In addition, at the output of the second multiplier 6, synchronously with the delay scan, the signs of the half-periods of the amplitude modulation signals change. The error signal in CVD 1 is enclosed in the magnitude and sign of the constant component | at the output of the second multiplier 6, which is made by the first low-pass filter 7. The signal of the error determines the value of the clock frequency, phase, delay, relative to which scanning occurs (Fig. 2). The size of the scanning area is controlled by a circuit from the third LPF 11, which smoothes (averages) the signal from the output of the first limiter 19, and the OP 12. The average value of the signal at the output of the first limiter 19 depends on the value of the signal-to-noise ratio (FIG. 3). The FC 12 has a generally non-linear characteristic of signal transmission from input to output and, if necessary, provides a change in the slope of the dependence of the signal level change from the output of the third LPF 11 when the signal-to-noise ratio changes. Thus, the level of the signal at the input of the FSS unit 13 is determined by the signal-to-noise ratio and determines the scan range for bad (Fig. 2a) and large (Fig. 2b) signal-to-noise ratios, in the latter case, the SWZ 1 operates along ramps. equivalent trapezoidal mutually correlated function obtained by amplitude limiting.

The signal generation for the operation of system 2 of the AFC, in this case the phase-controlled AFC, provides CVD 1 by maintaining a continuous synchronization of the signal from the output of the FO of the SRP 10 to the received FM PCR. The output signal of PD 16, depending on the phase difference of the oscillations from the outputs of the PF 4 and the reference UG 14, through the second limiter 20 and the second LPF 15 enters the controlled input of the reference UG 14, which changes the frequency of the reference oscillation, which also goes to another the input of LED 18, providing the selection of the signal of amplitude modulation, which is necessary for the work of SWD 1.

Claims (1)

Invention Formula A tracking filter for processing a phase-shifting pseudo-random radio signal, containing a series-connected first multiplier, band-pass filter, detector unit, second multiplier, and first low-pass filter (LPF), series-connected controlled clock generator and shaper of the reference pseudo-random sequence (PSP), block generating scan signals, the reference output of which is connected to another input of the second multiplier, the signal input of the first multiplier is the device input, the second low-pass filter connected in series and the reference controlled oscillator, the output of which is connected to the corresponding input of the detector unit, the other output of which is connected to the input of the second low-pass filter, in terms of the fact that, in order to increase the noise immunity, a 5 adder and a third low-pass filter and a functional converter were introduced, The output of which, via the scan signal generation unit, is connected to the reference input 0 of the adder, the output and another input of which is respectively connected to the input of the controlled clock frequency generator and the output of the first low-pass filter, and the output of the imaging unit of the reference 5 PSP is connected to another input of the first multiplier, while the third input The low-pass filter is connected to the output of the detector unit, which is designed as a series-connected syn- chronous detector and a first limiter, a series-connected phase detector and a second the limiter, phase shifter, the signal inputs of the synchronous and phase detectors are combined and are the input of the detector unit, the output of which is the output of the first limiter, while the reference input of the synchronous detector is connected to the reference input of the phase detector and is the reference input of the detector unit, the other output of which is the output of the second limiter.  f 2,0 / V P-.l, 0 -r 9 sixteen 20 IS 13 Jt ..J (rU8.