| 摘要 |
PURPOSE:To prevent an abort timer from malfunctioning even if a noise is generated on a circuit by monitoring change points of transmitted data and deciding the completion of transmission, starting the abort timer on the completion of transmission, and recovering the circuit automatically with the clocking output of the abort timer. CONSTITUTION:The change point detecting circuit 28a of a transmitted data monitoring part 28 monitors change points of the transmitted data. The change point detection output of the change point detecting circuit 28a, on the other hand, resets the timer 28b. Therefore, when there is no change point within a specific time Rt, the timer 28b overflows and generates an off output. Thus, the timer 28b turns off and then the abort timer 23 is started to begin to clock the time. If the timer 28 is off continuously, the abort timer 23 finishes clocking a specific time Abt and overflows to turn on. Consequently, a relay 24 is energized to connect the contact 20 to the telephone set side, releasing the circuit. |
