LINE CONCENTRATION DISTRIBUTING SYSTEM

摘要

PURPOSE:To avoid collisions of signals on a transmission line by transmitting the test signal from a central device prior to the transmission of a significant signal and controlling the transmission timing of signals sent to the central device from each terminal in accordance with the response given from a line concentration distributing terminal. CONSTITUTION:A control signal generating circuit in a central device produces a test signal (word synchronizing signal SOi plus common test control signal DTt) to each line concentration distributor 12 in a test mode preceding a normal data transmission mode. Then the difference (delay time) is measured for each distributor 12 between the time point when the test signal is delivered from the central device and the time point when the response signal delivered from each distributor 12 in response to the reception of the test signal is received by the central device. In a transmission start timing set mode, the signal transmission timing is decided based on the above-mentioned delay time. While the distributor 12 detects the word synchronizing signal by a control signal detecting circuit 37 and then transmits immediately a word synchronizing signal SIj to the center device via a transmitter 36 in response to the subsequent test control signal.