Circuit for delaying the modulation of fm - signals

摘要

PROBLEM TO BE SOLVED: To satisfactorily eliminate the higher harmonics even with use of an LPF that has the comparatively slow blocking characteristic by converting the frequency of the higher harmonic of the demodulation signal contained in an arithmetic output signal into the higher frequency. ;SOLUTION: A limiter amplifier 11 applies the amplitude limit amplification to an input signal S11 that undergone the FM modulation. The 1st to 3rd delay circuits 12 to 14 produce the 1st to 3rd signals S13 to S15 which are delayed against the signal S12 by a time (preferably 1/8, 1/4, 3/8, etc.) that is successively increased within a time shorter than 1/2 signal cycle that is set when the output signal S12 of the amplifier 11 is shifted by the maximum frequency in the positive direction. The signal S12 is multiplied by the signal S13 by a 1st multiplier circuit 15, and the signal S14 is multiplied by the signal S15 by a 2nd multiplier circuit 16. Then the output signal S16 of the circuit 15 is added to the output signal S17 by an adder circuit 17.;COPYRIGHT: (C)1997,JPO