INCOMING DIRECTION TRANSMISSION TIMING DECISION SYSTEM FOR STAR TYPE OPTICAL SUBSCRIBER SYSTEM

摘要

PURPOSE:To reduce the system build-up cost, to decrease a guard time for incoming communication and to improve the efficiency of communication by deciding an incoming data transmission timing based on a result of distance measurement between an exchange station and each subscriber. CONSTITUTION:An exchange station 1 sends a pulse signal to each of subscribers 31-3n and each of the subscribers 31-3n sends back the pulse signal to the exchange station and a phase comparator 8 of the exchange station compares the phase of the pulse signal sent by itself with the phase of the received pulse signal to detect a phase difference. Then a counter 12 and a coding circuit 11 calculate the distance between the exchange station and each subscriber based on the phase difference and to calculate a transmission timing of a corresponding incoming signal. In the case of usual data communication, the exchange station utilizes outgoing communication to send the transmission timing information to each subscriber and each subscriber sends incoming data for the exchange station based on the transmission timing information.