| 摘要 |
PURPOSE:To shorten the time when a jarring tone is heard in the course of call, by releasing a relay in case when a frame synchronizing signal has been received even once. CONSTITUTION:In the initial state, an FF6 is set, contact of a relay 7 is closed, and when a digital signal is inputted to a conductor 11, this signal becomes an acoustic signal, is outputted from a loudspeaker 8, and presence of the digital signal is displayed acoustically. In this way, when the first frame synchronizing signal is detected from a frame synchronization detection part 2, the FF6 is reset, the relay 7 is opened, and the acoustic output from the loudspeaker 8 is annihilated. Accordingly, since it has been made unnecessary to take an annihilation point of the acoustic output from the loudspeaker 8, from an output of a deciding part 5, the time when a jarring signal is heard. |
