Abstract: A transceiver module for coupling between cells in a distributed intelligence network and a twisted pair line. The module receives power from the line and provides power to its respective cell. At the end of transmitting a packet, the transceiver transmits a code violation, then an anti-code violation to dissipate energy in the line. This is followed by clamping the line for the dead time between packets. N transceivers may be connected (without a cell) to form a repeater. The transceiver module may be used in a network having free topology; that is, an ideal transmission line, with terminators is not needed.

Abstract: A digital modem is connected to a CBX in a network. Data is transmitted to the digital modem in a data field of synchronous serial data frames. The digital modem converts the data into a digital signal corresponding to a time sampled analog signal representing the data. The converted digital signal is communicated to a digital to analog converter for transmission on a telephone line. Analog signals received on the telephone line are digitized, and then converted to data in the digital modem.