| 摘要 |
PROBLEM TO BE SOLVED: To provide a portable telephone system which improves the output characteristic of a received voice signal regardless of the situation of noise caused by ambient noise, the quality of the voice signal and the existence/ absence of voice band limit. SOLUTION: A sound collecting microphone 40 detects noise around a portable telephone set, and a signal from the microphone 40 is applied to a noise detector 44 through an input interface 42. The detector 44 detects a noise level around the portable telephone system. An ATT control circuit 46 controls an ATT 12 on the basis of the noise level detected by the detector 44. As a result, when the noise around the portable telephone set is large, a large voice signal output is modulated and outputted, and when the noise around the portable telephone set is small, a small voice signal output is modulated and outputted. |
