TUNING-FREQUENCY SEARCH DEVICE FOR A FREQUENCY-MODULATION RADIO RECEIVER

摘要

1. Tuning-frequency search device for a frequency modulation radio receiver which is mobile with respect to transmitter stations transmitting on different transmission frequencies, the receiver comprising an asynchronous demodulator (2) provided with frequency synthesizer means (3) for generating different tuning frequencies corresponding to the different transmission frequencies, characterized in that it comprises counter means (4) for counting for each tuning frequency and for a duration T the number of pulses appearing at the output of the asynchronous demodulator when the phase of the signal resulting from the addition of the useful signal to the momentary noise component has a value which is a multiple of pi/2, and recognizing means (5) for recognizing the tuning frequency for which the number of pulses appearing at the output of the asynchronous demodulator is minimum, this frequency being the desired tuning frequency, the recognizing means supplying the control signal of the different tuning frequencies synthesizer means (3).