| 摘要 |
PURPOSE:To prevent the deterioration in S/N due to a surrounding noise. CONSTITUTION:A voice signal from a microphone 11 is amplified by a microphone amplifier 12, and guided through a high pass filter 13 to a compressor circuit 14. The voice signal is level-compressed by the compressor circuit. In the compressor circuit, when an input signal level is larger than 0, a gain is allowed to be inversely proportional to the 1/2 power of the input level, and when the input signal level is less than 0, the gain is turned to a prescribed level. Then, an output (compressed signal) from the compressor circuit is applied through a low pass filter 15 to a radio part 16. Thus, in the compressor circuit, when the input level is less than 0, the gain is turned to the prescribed level, so that when a voice signal level is low (less than 0), the synthetic gain can be decreased, the surrounding noise which interrupts a voice can is hardly heard by the other party of speech, and the S/N can be improved.
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