| 摘要 |
PURPOSE:To transmit securely to a remote repeater with a simple facility, by providing with plural controlling signal outputting circuit which have electronic circuits connected to the output of a band-pass filter having a different inherent center frequency respectively and are connected to a pair of signal transmission lines in parallel so that electric power is supplied to the electronic circuits by a pair of other balance cables. CONSTITUTION:If a controlling signal of a specific frequency is sent to a pair of balance cables 1 from a controlling signal generator 8 installed on a terminal station equipment side, and if DC constant current is sent to a pair of balance cables 2 from a Dc constant current source 9, a controlling signal, which has a center frequency coincident with the said specific frequency and passes a filter 3, is amplified by an electronic circuit 4 and detected by a controlling signal detecting circuit 6 through a transformer 5 so that the controlling signal can be supplied only to a related repeater. Since the controlling is performed only when the controlling signal and Dc constant current are simultaneously sent, possibility that a controlling output is sent out of a controlling signal output circuit 10 by a noise or missoperation, etc., to cause erroneous controlling is very less. |
