James Richard Stidham
Engineers at Beryl St, Westminster, CO

3934091, Jan 20, 1976

Dec 23, 1974

5/535487

James Richard Stidham - Broomfield CO

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

H04J 302

179 15AT

Port circuits in a time division switching system that have their outputs connected to a common summing bus by respective summing resistors have their output signals attenuated when the conversation is among port circuits on the same bus: the simultaneous closure of the respective time slot switches causes the summing resistor of one port to shunt the output from the other port. However, when the connection involves port circuits served by different summing buses, there is usually sufficient isolation between the buses to mask the shunting effect. The present disclosure shows an arrangement for selectively adding a compensating amplifier and an attenuating resistor to each distribution bus. When the call involves port circuits served by the same summing and distribution bus pair the amplifier completely compensates for all attenuation. When the call involves ports served by a different summing and distribution bus pair, there is no input shunting to reduce gain but now a pair of compensating amplifiers are involved and their input attenuating resistors are in shunt to ground reducing the gain to the normal level.

3997730, Dec 14, 1976

Aug 29, 1975

5/609038

James Richard Stidham - Broomfield CO

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

H04M 356

179 18BC

A conference circuit is disclosed for use in a time division switching system which has an incoming and an outgoing time division bus connected by a summing amplifier. During a conference call, a different group of conferee stations is connected to the incoming and outgoing buses by the switching system controller in each of a plurality of time slots dedicated to that call. Output signals from the connected stations are then applied to the incoming bus. The conference circuit is connected to the incoming and outgoing buses and includes storage and transfer circuitry. In each conference time slot, the storage circuitry stores the output signals generated by conferee stations connected during that time slot. Signals from conferee stations which were stored by the storage circuitry during previous time slot are combined by a combining means and the resulting sum is placed on the incoming bus. All signals on the incoming bus are then summed by the summing amplifier and the composite distributed to the conferee stations via the outgoing bus.