A Multiport Telephone Conference Bridge
Wolf Kuebler · IRE Transactions on Communications Systems · 1968
Conference bridges allow a number of remotely located telephone subscribers to hold a conference. A new bridge using solid-state circuitry and a plug-in module-type equipment arrangement has been designed. The number of participants in a conference call varies. The capability and flexibility required have been achieved by designing a 30-port bridge that can be subdivided into five separate 6-port groups. These groups can then be combined to service large or small groups of subscribers. When large numbers of two-wire subscribers are connected together, the sum of the returning echoes is substantial. In the new bridge, each port is equipped with a voice activated gain switch that keeps a fixed amount of loss in each of the two-wire loops.