| 摘要 |
PURPOSE:To exercise an economical and highly-reliable supervision, by making a PCM terminal equipment, using a coder and decoder with polygonal line companding characteristics, generate and detect a supervisory signal digitally in addition to an intra-office supervision by intra-office reflection. CONSTITUTION:In a PCM terminal equipment using a coder with polygonal line companding characteristics, a digital supervisory signal from reference digital code generating circuit 1 which generates one or several specific patterns in a segment of polygonal line companding law is decoded by decoder 5 into a PAM signal. Then, the PAM signal is decoded by decoder 10 into a digital supervisory signal, which is compared with a signal from the reference digital code generating circuit, so that when the both disagree each other, an alarm signal will be sent out. |
