Patent ID: 9203454
Filing Date: 2015-12-01
Classification: H04B

Abstract:
1. Apparatus to reduce unwanted signal tones in a stereo frequency-modulation (FM) broadcast received via an antenna, the apparatus comprising: a frequency translator configured to translate the received stereo FM broadcast to an intermediate carrier frequency, a demodulation unit configured to demodulate the translated FM signal so as to form left-plus-right and left-minus-right amplitude-modulation (AM) signals, a filter configured to form a filtered signal by filtering one of the left-plus-right or left-minus-right AM signals to reject a narrow frequency band centered on a frequency of an unwanted tone, so as to suppress a sub-band of the left-plus-right or left-minus-right signal containing the unwanted tone, a summing unit for summing the filtered signal and the other of the left-plus-right and left-minus-right signals to produce a stereo audio signal.