| 摘要 |
PURPOSE:To supervise the open line of a voice band line by detecting whether or not the state of being open or earth for SS, SR signals of a voice in-band signal equipment respectively is consecutive for a set time or over. CONSTITUTION:A signal detection circuit 2 receives the state of the SS, SR signals of the voice in-band signal equipment 1 of signal system at non-talking and gives an output only at the state of SS: open and SR: earth. When an input from the signal detection circuit 2 is consecutive for a preset time or over, a timer circuit 3 gives an output of open line information as a contact signal. Thus, the titled equipment has an effect of supervision of open voice band line by having only to detect whether or not the SS, SR signals of the voice in-band signal equipment connected between both ends of the voice band line is consecutive for a preset time or over for the open/earth state respectively. |
