| 摘要 |
PURPOSE:To eliminate an unnatural feeling in a hand-free call by preventing a break of ambient noise caused by a break, etc., in conversation. CONSTITUTION:When a voice input having a prescribed level or higher is supplied from a microphone 1, an F.F13 is set through a comparator 8A and while a switch 3A is turned on through a driver 9A, a reception system switch 3B is turned off through a driver 9B, so that this state is held far as a transmitted voice input to the microphone 1 is cut off. Even if the transmission input is interrupted at a break in conversation, the F.F13 is still set and said switches 3A and 3B are not changed over. On the other hand, when a reception input arrives through a preamplifier 2B, a signal having a prescribed level is supplied to a comparator 8B through a control path switch 4B, so said F.F13 is reset to turn off the switch 3A, turning the switch 3B on. Then, even if a voice from an opposite side is interrupted temporarily at a break in conversation, the F.F13 is still reset, so the switches 4A and 4B of the control path are both closed. |
