US Patent 7929997 Noise detecting apparatus and AM broadcast receiving apparatus

A noise detecting apparatus detecting presence or absence of noise in a received signal, comprising: a first band selecting unit configured to select a first signal of a first frequency band that does not include a frequency band of the received signal and is higher than a center frequency of the received signal; a second band selecting unit configured to select a second signal of a second frequency band that does not include the frequency band of the received signal and is lower than the center frequency of the received signal; a signal selecting unit configured to compare strength of the first signal selected by the first band selecting unit and strength of the second signal selected by the second band selecting unit to select the signal of lower strength; and a comparing unit configured to compare the strength of the signal selected by the signal selecting unit with a predetermined threshold to output a signal depending on a result of the comparison.