SU696621A1 - Autocorrelation meter of clock frequency of pseudorandom signals - Google Patents

Description

I

The invention relates to pseudo-random signal processing devices and can be used in radio engineering devices for various purposes using pseudo-random sequence modulation.

A pseudo-random signal auto-correlation clock is known, comprising a series-connected synchronous detector, a display unit, a delay unit, a multiplier and a band-pass filter, the other inputs of the multiplier and the delay unit are combined and are the input of the device I.

However, this autocorrelation meter has a long tuning time for the measured value.

The aim of the invention is to increase the measurement speed.

To do this, an autocorrelation clock of frequency of pseudo-random signals containing serially connected synchronous detector, display unit, delay unit, multiplier and band-pass filter, with other inputs of the multiplier and delay unit

The first and second additional band-pass filters and a quad are entered and are the input of the device. The outputs of the band-pass filter are connected through a series-connected quad and the first additional band-pass filter to the input of a synchronous detector, the other input of which is not multiplied. :

FIG. 1 shows the structural electrical scheme of the proposed meter; in fig. 2 graphically shows the dependence of the amplitude of the harmonics of the clock frequency on the delay time.

The autocorrelation clock of a pseudorandom signal has a series-connected synchronous detector 1, an indication unit 2, a delay unit 3, a multiplier 4 and a band-pass filter 5, the first 6 and second 7 additional band-pass filters and a quadr 8.

The autocorrelation clock meter operates as follows. The multiplier 4 and block 3 convolve the input signal. The result of this procedure in the range of delays from O to g | , where TI is the discrete duration of the pseudo-random signal, there will be dependences of the amplitudes of the clock frequency harmonics on the delay (Fig. 2). Note that the maximum of the first harmonic corresponds to the minimum of the second harmonic. The negative region in the delay range from 0 to Hz for the second harmonic interprets the fact that the phase is reversed. Thus, the dependence of the second harmonic on the delay can be used to tune the delay unit 3 to the maximum amplitude of the first harmonic. One more property of the second harmonic of the clock frequency can be noted: information manipulation on the delay of the received pseudo-random signal does not lead to phase manipulation of the selected second harmonic, which does not cause amplitude parasitic modulation at the output of the second additional bandpass filter 7. At the output of the band filter 5 phase modulation occurs in tact with information manipulation, therefore, to remove it, it is necessary to square the oscillations of the clock frequency followed by filtering to doubled clock frequency, which is carried out sequentially by the quad 8 and the first additional band-pass filter 6. Thus, the synchronous detector 1 receives oscillations at twice the clock frequency, and at one of the inputs their phase does not depend on the setting of the 3 delay block, and on the other - depends. In addition, the amplitude of oscillations at the first input does not depend much on the setting of the delay unit, and on the second one it will increase dramatically. is in the vicinity. The delay is therefore Therefore the oscillations at the first input of the synchronous detector can be considered as reference. In this case, at the output of the synchronous detector 1, the spin-off error signal, the absolute value of which is the greater, the more the delay unit setting differs from Tc / 2. However, when flipped to one side or the other, the sign of the error signal 6 14 which is used for discrimination setting. The input delay unit 3 is tuned by the error signal in the direction of decreasing the latter. In the steady state and with the presence of a signal at the input of the entire device, the average value of the error signal will be zero and the dispersion will depend on the input signal-to-noise ratio. In display unit 2, the magnitude of the error signal is eliminated and its belonging to a predetermined neighborhood of zero is determined. The width of the neighborhood is determined by the confidence probability of the measurements. With such an accessory, the display unit issues a command to measure the clock frequency of a pseudo-random signal, which can be determined either directly by measurements at the output of the second band-pass filter, or indirectly by tuning the output tunable delay unit. Invention Ph o Autocorrelation — A pseudo-random clock frequency meter containing a series-connected synchronous detector, a display unit, a delay unit, a multiplier, and a bandpass filter, the other inputs of the multiplier and the delay unit being combined and being the device input, differing in that, in order to increase the measurement speed, the first and second additional band-pass filters and a quad are introduced, with the output of the band-pass filter through the series-connected quad and the first Accessory bandpass filter connected to the input of the synchronous detector, another input of which via an additional second bandpass filter connected to the output of multiplier. Sources of information taken into account during the examination 1. Application No. 2464629 / 18-09, cl. H 04 L 7/02, 1977, according to which a decision is made to issue an author's certificate.

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