| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable a speech with little audible noise in a portable telephone set. SOLUTION: In a PHS telephone set 10, because of its compactness, noise from a wiring pattern on the substrate or the noise by the radio wave from an antenna which enters in the reception side is easily reproduced by a receiver 16. A microphone 11 picks up not only a transmission signal but also surrounding noise and tends to transmit them to the other party of communication. When a transmission level detection part detects the level of the transmission signal and it is below the reference level, the transmission gain of a transmitter attenuator part 12 is made small. When the level detected by a received level detection part 15 is below the reference level, a receiver attenuator part 14 is controlled and the level of a noise outputted from the receiver 16 is lowered. When there is the transmission signal or a reception signal, the gain is raised and the influence of the noise is reduced by using a masking effect in the ear.</p> |
