PROCESS AND CIRCUIT ARRANGEMENT FOR CONVERTING FREQUENCY-MODULATED SIGNALS THROUGH AT LEAST ONE INTERMEDIATE FREQUENCY INTO LOW-FRQUENCY SIGNALS

摘要

The intermediate-frequency signals are produced by mixing (3) with an oscillator voltage (4), whereby they are filtered by filters (5) and demodulated (7). The oscillator voltage or the resonance frequency of the filter or filters are followed-up by a control voltage derived from the demodulated signal corresponding to the intermediate frequency. The perturbatory phase modulation occurring as a result of the control lag is compensated by opposite-phase phase-modulation (2), which is superposed on the intermediate frequency. In this, the phase modulation is achieved by a phase modulator (2) which is connected with the output of a demodulator (7) by a matching circuit (9). Another possibility for achieving phase modulation of the intermediate frequency is to modulate the oscillator of the mixing stage.