SU1617648A1 - Follow-up receiver of pseudorandom signals - Google Patents

Abstract

The invention relates to a technique for receiving and processing broadband signals and can be used to monitor a pseudo-random signal delay (PSS). The purpose of the invention is to improve noise immunity. The following receiver PSS contains multiplier 1, band-pass filter 2, quadratic detector 3, synchronous detector 4, loop filter 5, controllable generator 6, controllable phase shifter 7, generator PSS 8, clock generator 9, quadrature detector 10, capture indicator 11, element 12, controlled attenuator 13, and comparators 14 and 15 include the comparators 14 and 15 and the element XOR 16. When the signal is detected and captured at the output by the detector 10 and the capture indicator 11, the amplitude is reduced the phase shift introduced into the clock sequence by the controlled phase shifter 7, which is equivalent to an increase in the average power of the signal in the tracking mode. 1 hp f-ly, 1 ill.

Description

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torus 4, looped filter 5, controlled oscillator 6, controlled fauna rotation 7, generator 8 SRP, clock generator 9, quadrature detector 10, pickup indicator II, element 12, adjusting the attenuator 13, and the composition of the indicator 11 captures include comparators 14 and 15 and the EXCLUSIVE OR element 16. Pr-and detections

The invention relates to a technique for receiving and processing broadband signals and can be used in a circuit for detecting and tracking a pseudo-random signal delay.

The aim of the invention is to improve noise immunity.

The drawing shows a structural electrical circuit of a pseudo-random signal receiver (PSS) receiver.

The following receiver PSS contains multiplier 1, band-pass filter 2, quadratic detector 3, synchronous detector 4, loop filter 5, controllable generator 6, controllable phase shifter 7, generator PSP 8, clock generator 9, quadrature output signal JPS 10, pickup detector P Element And 12 And Controlled Attenuator 13.

The capture indicator 11 includes a first comparator 14, a second comparator 15, and an element EXCLUSIVE OR 16.

The following MSS receiver operates as follows.

The signal modulated by the memory bandwidth and information symbols is fed to one of the inputs - multiplier 1. The modulation is phase shifting through 180 °. In the multiplier I, the signal is multiplied with the local SRP produced by the SRP 8 generator. At the output of the band-pass filter 2, a carrier frequency signal is modulated, modulated only by information from dM: solarly. The band of a uiltra is selected such: 7–6k often skips the transmission of information symbols, but does not miss the frequency of transmission of the elements of the memory bandwidth. The amplitude of the selected signal depends on the coincidence of the temporal position of the received and local SRP. If these bandwidths coincide, the amplitude is maximum, and if mutually shifted by one element or more, the amplitude is zero.

The generator PSP 8 forgates a local KOG1IYU P SP from the pulses of a controlled generator 6 passing through a controlled phase shifter 7. Under the influence of a rectangular signal from a clock generator 9 passing through a controlled attenuator 13, the controlled phase shifter 7 changes the temporal position of the pulse sequence is periodically towards one and the signal is captured at the output by the detector 10 and the capture signaling device 11) 15 s signals by which the amplitude of the phase shift introduced into the clock sequence decreases st controllable phase shifter 7, which is equivalent to increasing the average signal power in the tracking mode. zp f-ly, 1 ill.

cutting and retarding. As a result,

in the same way, the temporary position of the local SRP is also changed.

A quadratic detector 3 extracts a signal that is proportional to the square of the carrier amplitude. If the leading version of the local memory bandwidth is ahead of the received memory bandwidth, and the delayed version lags behind the received memory bandwidth by the same time interval, then the signal of the dead frequency at the output of the bandpass filter 2 has a constant amplitude. If the leading and delayed versions are located asymmetrically, then the signal at the output of the bandpass filter 2 becomes amplitude-manipulated. The envelope is distinguished by a quadratic detector 3. The span and phase of the envelope depend on the degree of asymmetry of the temporal position of the advancing and delayed versions of the local SRP relative to the received SRP. The synchronous detector 4, the reference input of which is connected to the clock generator 9, forms a constant voltage, the value and polarity of which are determined by the asymmetry

temporary position of PSP versions.

This voltage passes through a loop filter to the control input of the controlled oscillator 6 and, by changing its frequency and phase,

adjusts the temporary position of the leading and delayed versions of the local SRP to a symmetrical position relative to the received SRP.

When synchronized, the output of the bandpass filter 2 is a signal that

is detected by a quadrature detector 10. At its output, a ". At the end of the capture process, the signal zb iia appears at the output of the pickup detector P .... At the same time, at the output of the And 12 element also appears the "I, which acts on

the control input of the controlled aggenerator 13. The amplitude of the rectangular signal coming through the attenuator 3 of the control input of the controlled phase shifter 7 decreases to a certain value, as a result of which the delay and the advance of the local memory bandwidth decrease.

The signal at the output of the bandpass filter 2

is the output of the receiver. Him

the amplitude increases, which leads to

an increase in the signal-to-noise ratio at the output, i.e. to increase noise immunity. The detector 11 capture works as follows.

The voltage controlling the generator b from the output of the loop filter 5 is fed to the combined inputs of the comparators 14 and 15. The threshold of the comparator 14 is set slightly above the zero value, and the threshold of the comparator 15 is slightly below the zero value. These thresholds are selected based on the value of the dispersion of the noise at the output of the loop filter 5 in the capture mode. In this mode, the voltage from the output of the loop filter 5 is between the thresholds. Thus, after a seizure occurs, "O" appears at the output of the comparator 14, and at the output of the comparator 15 - "1. Then, at the output of the EXCLUSIVE OR element, 16 appears "1, which is a signal of the presence of capture.

If the signal disappears, the voltage at the output of the loop filter 5 may also be close to zero. Then, at the output of the pickup indicator 11, “I. But at the same time, the signal at the output of the bandpass filter 2 disappears, and the quadrature detector produces 0, the controlled attenuator 13 passes the square wave signal of the clock generator 9 without attenuation, with the result that the advance and delay of the local SRP are increased to half the duration of the SRP element. In this case, the next receiver is ready to capture the signal in case of its occurrence.

Claims (2)

1. Tracking receiver of pseudo-random signals, containing serially connected multiplier, band-pass filter, quadratic detector, synchronous detector, loop filter, controlled oscillator, controlled phase shifter and pseudo-random sequence generator (PSP), the output of which is connected to one of the multipliers, another the input of which is a signal input of a tracking receiver, as well as a clock generator, the output of which is connected to a reference input of a synchronous detector, characterized in that the noise immunity system, a quadrature detector, a pickup detector, an AND element and a controlled attenuator, which is connected between the clock generator output and the control input of the controlled phase shifter, are entered into it, and the output of the bandpass filter is connected to the quadrature detector input, the output of which is connected to the first element input And, to the second input of which the output of the loopback filter is connected through the pick-up detector, and the output of the element AND is connected to the control input of the controlled attenuator. 2. The tracking receiver according to claim 1, wherein the capture indicator consists of two comparators, the outputs of which are connected to the corresponding inputs of the EXCLUSIVE OR element, the output of which is the output of the capture indicator, whose input is the interconnected inputs of both comparators.