Channel control system for loop type signal transmission channel

Abstract

A channel control system for a scattered loop type information transmission channel has posts that are linked in a single loop and are served both ways by the same loop. Each post consists of an A-system working in one direction and a similar B-system working in the opposite direction. A mode switch circuit switches between a relay mode for relaying the signal and a terminal mode for separating the A and B systems and returning the signal. Each system has a detection circuit for detecting a channel carrier signal OFF and a carrier ON-OFF signal transmission circuit and a monitor circuit for approach and circulation of the channel code. The mode switch circuit of a post which has detected a channel carrier signal OFF switches to the terminal mode and returns a carrier ON-OFF signal, while a post which has detected a carrier ON-OFF signal switches to the terminal mode and continues to issue a second carrier ON-OFF signal. A portion of the loop which contains a source of the channel carrier signal OFF is cut off from the rest of the loop containing no such source and when the monitor circuit of a post in the terminal mode confirms that the channel code has been circulated to both sides of the loop which has been cut off, its mode switch circuit switches the post to the relay mode and merges itself into the loop when the channel carrier signal OFF has vanished.