| 摘要 |
PURPOSE:To control quickly the collision of a signal even when a line concentrating and distributing terminal is connected newly to a pair of transmission lines by detecting the collision of a signal in a collision detecting circuit, correcting the sending-out timing of a signal to a central device from the line concentrating and distributing terminal in response to the result of detection to control the collision of a signal. CONSTITUTION:A synchronizing signal detecting circuit 43 detects the line concentrating and distributing device 33 outputting a signal to be inputted to a central device 32 from a line concentrating transmission line 39. A collision detecting circuit 45 detects the collision of a signal on the line concentrating transmission line 39, and a space- over detecting circuit 47 detects a blank between the signals on the line concentrating transmission line 39, and both outputs are inputted to a control signal generating circuit 49. The control signal generating circuit 49 generates a signal corresponding to whether a collision and a blank exist between the signals or not. A distributing circuit 75 divides separately a time division multiplex signal, outputs it at every line concentrating and distributing device 33 for transmission, and inputs it to a switchboard 77. This switchboard 77 divides said signal for each telephone 35, executes a switching processing to obtain again the signal of every line concentrating and distributing device 33 and to output. |
