SU568190A1 - Frequency shift compensator for communication channels - Google Patents

Description

generator i through the frequency discriminator 5, the other input of which is connected to the other input of the first 2 frequency mixer. The device works as follows. The frequency signal j Fg t D F, where D F is the frequency shift of the signal, is output from the communication channel to the first input of the first mixer 2 frequencies, to the second input of which the high frequency voltage ii is supplied from the reference generator 1, and frequency i is maintained constant. After multiplying the received signal with the reference voltage in the first 2 frequency mixer, a two-band signal is formed at its output, consisting of the lower side band -f F |, tuF) H of the upper side band (.f. This signal goes to band-pass filter 3, which passes only one of the side: new bands, for example, the upper f (r. i D FO. The received single-band signal is fed to the first input of the second frequency mixer 4. At the same time, the received signal (-D P) is fed to the first input frequency discriminator 5, in which he compares cs with a reference frequency P equal to the frequency of the signal from the reference oscillator 1 to its second input, depending on the sign of the frequency (shift of the received signal (D appears at the first or at the second output frequency discriminator 5. In accordance with these signals in the block, 6 of the reference frequency shift increases or decreases the frequency f о coming from the reference oscillator i by the value of A F. This frequency is fed to the second input of the second 4 frequency mixer, in which it multiplies with a single sideband signal coming from the bandpass filter 3. As a result of the multiplication, the frequency shift of the received signal is neutralized due to the well-known process of subtracting the reference

WITH

FC

Claims (2)

The frequencies h from the frequency of the single-band signal and at the output of the second mixer 4 the signal is received that is devoid of frequency shift Fd. For example, for the upper sideband, we get (3 FC, with a positive L F | o + Pc,) negative K The proposed device allows compensation of a constant frequency shift of almost unlimited & Maximum compensation compensation does not depend on the magnitude of the frequency shift and can be reduced to thousand fractions of a gerd. Apparatus for compensating frequency shift in communication channels, comprising a series-connected reference oscillator, a first frequency mixer, a band-pass filter and a second frequency mixer, as well as a frequency discriminator, characterized in that, in order to increase the dynamic range of the compensated frequency shift, the output reference generator is connected to another input of the second mixer frequency through the input of the reference frequency shift block, connected to the additional output of the reference generator through This is a discriminator whose other input is connected to another input of the first frequency mixer. Sources of information taken into account in the examination: 1. Gurov V. S, et al. Transmission of discrete information and telegraphy, M., Sv, 1974, p. 345. 2. Sartasov N. A. and others. Short-wave trunk radio receivers Va M., Svy, 1971, p. 210.