COMMUNICATION SYSTEM USING DISTRIBUTED SWITCHING FOR TIME-DIVISION MULTIPLEXING OF VOICE AND DATA

摘要

A network having a single medium with a transmitting channel which is translated at a head end to a receiving channel. All the nodes of the system are coupled to both the transmitting channel and the receiving channel in a logical bus system with a physical tree-type layout. Time slots are defined by a timing mark generator, with each node detecting the timing marks on only the receiving channel. The time between each timing mark defines a frame, with each frame consisting of a plurality of time slots. Each node determines a skew time necessary for that node to transmit in a specified timeslot when it only receives the timing marks on the receive line and not on the transmit line. Each node is a different physical distance from the head end, resulting in each node transmitting at a different time relative to the received timing mark due to the differences in transmission time to the head end and back. Accordingly, each node transmits a test signal and measures the time after the transmission until it receives the test signal. This time, designated a skew time, is used for transmissions of information. Each node transmits at a time equal to the skew time in advance of the beginning of the timeslot following a timing mark.