AM RECEIVING CIRCUIT, PARTICULARLY FOR DETECTING AN ELECTRIC FIELD STRENGTH IN A WEAK ELECTRIC FIELD STRENGTH ENVIRONMENT AND PERFORMING SOUND QUALITY CORRECTION ACCORDING TO THE DETECTED ELECTRIC FIELD STRENGTH

摘要

PURPOSE: An AM receiving circuit is provided to suitably correct sound quality for restraining a sound offensive to the ear by detecting a reception electric field strength even when a reception broadcast wave electric field strength is weak. CONSTITUTION: An IF(Intermediate Frequency) signal unit(16) amplifies an IF signal generated from received broadcast waves and outputs it. An AM detector(20) detects an AM modulation signal from the IF signal and outputs it. A sound quality corrector(22) corrects sound quality of the output signal of the AM detector(20). A BPF(Band Pass Filter)(34) extracts a carrier frequency component from the IF signal. An integrator(36) integrates the output of the BPF(34), converts the strength of the carrier of the IF signal into a DC voltage, and outputs it. A sound quality is corrected according to the DC voltage outputted from the integrator(36).