Noise attenuation circuit for amplitude modulated radio and method therefor

摘要

A noise attenuation circuit (43) is provided for reducing noise in an RF stage of an AM radio receiver. A RF amplifier (44) amplifies an RF signal with amplitude modulated audio information from the signal path of an AM receiver. An AM detector (46) receives the amplified RF signal and removes the audio information. A high-pass filter (47) filters out a majority of the audio information. A noise pulse couples through the hi-pass filter (47) which is detected by a pulse detector (48) when above a predetermined threshold voltage. The pulse detector (48) enables an RF timer (49) for generating a pulse of a predetermined width. The RF timer enables a RF attenuator (51) for attenuating the RF signal in the signal path of the AM receiver. The RF attenuator (51) attenuates an average noise pulse to a level approximately equal to the magnitude of an unmodulated RF signal.