METHOD AND DEVICE FOR TUNING OF AMPLITUDE MODULATED RADIO RECEIVER

摘要

PURPOSE:To detect easily and accurately a tuning point by detecting demodulation outputs from an amplitude modulated radio receiver which correspond to plural predetermined positions of the waveform of a modulated wave signal and varying the frequency of a carrier signal to the frequency to which the amplitude modulated radio receiver is tuned to on the basis of the respective demodulation outputs. CONSTITUTION:A comparing circuit 20 compares levels of demodulation outputs of the radio receiver 4 at points t1 and t2 of sample holding time. When the frequency of the carrier signal from a carrier signal generating circuit 3 is f1 lower than the tuning frequency f0, the peak value P1a of the output of the radio receiver at the time t1 is higher than the peak value P2a of the output at the time t2, so the comparing circuit 20 supplies a high-level signal to a central processor 9. The central processor 9 increases the frequency of the carrier signal of the carrier signal generating circuit 3. When the frequency of the carrier signal attains to f0, the comparing circuit 20 compares peak values of demodulation outputs with each other to determine the frequency of the carrier signal at f0, thereby finishing the tuning operation.