| 摘要 |
PURPOSE:To generate a proper call tone in response to the quantity of surrounding noise by adding a switch circuit switched by a control section and a noise detection section. CONSTITUTION:The switch circuit 8 provided to an output side of an amplifier section 5 and switched by the control section 11 and the noise detection section 9 detecting a noise from a sounding element 6 through the switching of the said switch circuit 8 are added. The noise detection section 9 is connected to the sounding element 6 for a prescribed time before the reception of the call signal and after it to detect surrounding noise. When a high noise exists, an amplification factor of the amplifier section 5 is increased and when low, the amplification factor is decreased, then the control section 11 switches the output of the amplifier section 5 to the sounding element 6. |
