| 摘要 |
PURPOSE:To prevent the malfunction of the switching of transmission/reception in advance and to obtain a stable call state by adding a function that generates a noise section display signal discriminating the noise section over the specified level to a sound discrimination circuit. CONSTITUTION:When a level difference between a noise component A2 and a sound signal component A1 exists, the first comparator 38 generates a sound discriminating signald Vo the signal section of which becomes at an H level corresponding to the sound signal component A1 by comparison of a peak value voltage VC1 with a VC2. Also at the second comparator 44, a level discriminating signal VN which becomes at the H level in a level section that the peak value voltage VC1 is over a reference voltage VrefN is generated by comparison of the peak value voltage VC1 with the reference voltage VrefN. As a result, in an AND circuit 48, the level discriminating signal VN and the inverted signal Vo of the sound discriminating signal Vo that is obtained through an inverter 46 are added and a noise display signal VNO the high leveled noise section of which becomes at H level by AND of both is obtained. |
