| 摘要 |
PURPOSE:To transmit an alarm signal without adding any control signal by inverting the polarity of a digital signal to be sent when alarm information is sent to a called station. CONSTITUTION:When the alarm signal is sent from, e.g., a station A to a station B, the switch 3 of the station A is changed over and a polarity inversion circuit 4 inverts the polarity of the sent digital signal. In this case, the station B uses the polarity inversion circuit 14 to decide the inverted polarity of the received digital signal and outputs an alarm signal from a terminal 6. This is applied similarly when the alarm signal is sent from the station B to the station A. |
