AMPLITUDE-MODULATED SIGNAL RECEIVER INCORPORATING HARMONIC INTERFERENCE CORRECTION PROVISION Russian patent published in 1997 - IPC

FIELD: radio engineering; broadcasting and radio communications. SUBSTANCE: receiver has series-connected amplitude detector 25 and adder 34, as well as beat signal shaper 26, switch 33 whose outputs are coupled with adder 34, series-connected first low- frequency filter 27, first additional amplitude detector 30, and comparison element 32 whose output is connected to control input of switch 33 and second input is connected to output of second additional amplitude detector 31 whose input is connected to output of high- frequency filter 28 whose input is connected to inputs of first low- frequency filter 27, beat signal shaper 26, and amplitude detector 25, amplifier-converter channel incorporating series-connected antenna 1, radio-frequency resonant amplifier 2, first frequency converter 3, first intermediate-frequency resonant amplifier 4, second frequency converter 6, and first resonant amplifier 7 of second intermediate frequency, as well as frequency synthesizer 5 whose outputs are connected to second inputs of first and second frequency converter 3 and 6, respectively; amplitude-modulated signal built up across output of amplifier-converter channel is separated into carrier-frequency signal and double side frequency signal by means of narrow-band carrier-frequency rejection filter 8, band filter 10, narrow-band carrier-frequency filters 9,10; then these signals are added in second adder 18 in appropriate proportions afforded by first adjustable carrier-frequency amplifier 11. Control is effected by gain control 12, high- and low-level comparators 13, 14, phase detector 20 with low-frequency filter 16, square-wave shapers 19,24, and amplitude limiter 22 with band filter 23. This control is effected according to interference level due to provision for separating interference from signal. Gain control of adjustable beat-signal amplifier is effected simultaneously. EFFECT: improved efficiency of interference correction due to increasing permissible threshold value of interference-to-signal ratio at receiver input. 1 dwg