| 摘要 |
<p>PURPOSE:To supervise the state without using a pilot reject filter by transmitting a state supervisory signal specific to each relay amplifier to a center even when the signal frequency is a frequency within an object of an incoming signal at failure. CONSTITUTION:A pilot generator 8 for supervising low frequency amplification generates a pilot signal having a frequency at the outside of the pass band of an incoming low frequency signal of a directional filter 3 and inserts it to the input of an incoming signal low pass amplifier 2. Its output is branched (6), detected by a detector 10 and compared with a reference level for level check. When the difference between the pilot level and the reference level is a prescribed value or over, an error detection signal is inputted to a state supervisory signal transmitter 11, from which a state supervisory signal is outputted, inserted to the incoming signal via a directional coupler 7 and the result is transmitted to the center from a line terminal 12.</p> |
