| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gain control circuit for an FM receiver which cuts down a reproduced audio output in accordance with the magnitude of a noise component of a desired signal in a received signal. <P>SOLUTION: The gain control circuit includes a noise level measurement circuit 6 and a preamplifier 5. The noise level measurement circuit 6 measures a noise level in an audio signal Sa1 output from an FM detector 4, and outputs a control signal Sc corresponding to the noise level. The preamplifier 5 reduces an output according to the value of the control signal Sc. The use of the gain control circuit can reduce the volume of a speaker according as a received field strength decreases to increase a noise component in the audio signal Sa1, to whereby reduce discomfort caused by unpleasant noise. <P>COPYRIGHT: (C)2013,JPO&INPIT |
