Conferencing communications system

Abstract

A telephone conferencing system in which all input signals are twice applied to a circulating signal loop firstly in real time and secondly delayed by an interval equal to the delay of the circulating loop. The delayed signal cancels the first applied signal after circulation of the first applied signal to all other subscribers but before its return to the originating subscriber. The telephone conferencing system includes a network having a plurality of input/output line appearances which apply and receive signals to the network. The network consists of a signal circulating loop in which the signal circulates in a predetermined loop direction from line appearance to line appearance. At each line appearance signals are added to, received from, and deleted from the loop to provide a single circulation of each signal applied to the loop by each line appearance. Each signal beginning at the orginating line appearance thus circulates in the loop and is received by each of the other output line appearances until the signal has circulated around to the originating line appearance. There the signal is deleted from the loop ahead of the corresponding output line appearance by inserting to the loop an inverted version of the signal delayed by an interval equal to one loop circulation interval. The network loop may be implemented in analog or digital form. In the digital form shown the network is capable of establishing or terminating several mutually exclusive conference networks using separate loops linking different groups of input/output line appearances. Additionally nonblocking network interconnections are shown for establishing conferences between line appearances associated with several different networks.

Dependencies are inferred from the claim text.