An AM radio receiver comprises an RF amplifier, a first mixer that
converts the RF signal to a first intermediate-frequency signal, a first
bandpass filter that band-limits the first intermediate-frequency signal,
a second mixer that converts the output from the first bandpass filter to
a second intermediate-frequency signal, a second bandpass filter that
band-limits the second intermediate-frequency signal, an
intermediate-frequency amplifier that amplifies the output from the
second bandpass filter, an AM detector that demodulates the output from
the intermediate-frequency amplifier and provides output of an audio
signal, and a noise detector for detecting and eliminating ambient noise.
The noise detector comprises a first noise detector that detects noise
from the RF signal and eliminates the noise contained in the first
intermediate-frequency signal, and a second noise detector that detects
noise from the second intermediate-frequency signal and eliminates that
noise. The AM radio receiver further comprises a halting device that
halts the second noise detector for a predetermined period of time when
the first noise detector has detected noise. Thus, distortion of the
audio signal caused by redundant noise elimination operations is avoided
and noise contained in the second intermediate-frequency signal can be
detected and eliminated appropriately.