Fm receiver with detector for multi-path reception

Abstract

In an FM receiver having a circuit including RF and IF amplifiers for receiving a selected FM broadcast signal, and an FM detector for converting the selected FM broadcast signal to an audio signal which is applied through an audio amplifier to a loudspeaker for operating the latter and thereby producing a corresponding audible sound; the presence of amplitude-modulated components in the selected FM broadcast signal, for example, by reason of the multi-path reception of such broadcast signal at the antenna, is made effective to produce low frequency signals, for example, by amplitude-detecting the output of the IF amplifier, and such low frequency signals are selectively applied to the audio amplifier in place of the audio signal from the FM detector so that the loudspeaker produces a characteristic sound for indicating the existence of multi-path reception. Preferably, the gain of at least the IF amplifier is lowered when detecting the existence of multi-path reception, for example, by selectively applying the low frequency signals through a smoothing circuit to the IF amplifier as an automatic gain control signal for the latter, so that the limiter effect of the circuit for receiving a selected FM broadcast signal will not preclude the amplitude-detection of the IF amplifier output when the selected FM broadcast signal is at a high level.