Digital transceiver for full-duplex transmission of binary signals over a common line

Claim 1

A full-digital circuit arrangement connected with a local source of outgoing binary signals for the detection of incoming binary signals from a remote source communicating with said local source by way of a single tapped transmission line, said binary signals alternating between a low voltage level and a high voltage level, said circuit arrangement comprising: a line driver and a terminating impedance connected in series between the local source and the tap of the transmission line, the impedance reducing the voltage of the signal of the line driver, whereby the voltage at the tap is proportional to the sum of the voltages of concurrent incoming and outgoing signals; first and second logic-element voltage sensors with respective inputs connected in parallel to the tap of said transmission line, said first voltage sensor having a threshold lying at a lower intermediate level between said low voltage level and a median level of said high and low voltage levels, said second voltage sensor having a respective second threshold lying at a higher intermediate level between said median and high voltage levels; a local signal receiver having an input; and switch means controlled by said local source for selectively connecting the input of the local signal receiver only to the first voltage sensor when the signal of the local source is at the low voltage level and for connecting the input of the local signal receiver only to the second voltage sensor when the signal of the local source is at the high voltage level and for thereby supplying said signal receiver at all instants with an output signal from the respective voltage sensor varying in conformity with the voltage level of an incoming binary signal.