DEVICE FOR DISCRIMINATING AMPLITUDE MODULATING STEREOPHONIC BROADCASTING SYSTEM

摘要

PURPOSE:To prevent a malfunction due to noise components even if there is a noise component in a pilot signal frequency band by including a hysteresis comparator for waveform shaping of a pilot signal in a separating circuit. CONSTITUTION:A SUB signal (sub channel signal) obtained in the modulating circuit 14 of a CPM system is led to a pilot filter 2 to take out a pilot signal component. The output of the pilot filter 2 is led to the input terminal of a differential discriminating circuit 5 and a hysteresis comparator 3. The hysteresis comparator 2 is a circuit for waveforming a pilot filter output signal into a pulse waveform and has a function of waveforming while eliminating the effect of the noise component of low level voltage superposed on the pilot signal. The output of the hysteresis comparator 3 is led to the input terminal of a frequency discriminating circuit 4.