Abstract: In an amplification system comprising an amplifier, a loudspeaker, normally open contacts connected in series between the amplifier and the speaker, and a power supply for the amplifier having relatively long buildup and decay times of its output voltage in response respectively to the connection and disconnection of the power supply to and from the a.c. line, means are provided responsive to the connection of the power supply to the a.c. line for delaying the closing of the normally open contacts until after the power supply voltage has built up to its full operating potential for eliminating the transient audio signals from the amplifier associated with power supply voltage buildup from being reproduced by the loudspeaker. Means are also provided for opening the contacts quickly after the power supply is disconnected from the a.c. line for eliminating the distorted audio signals from the amplifier associated with power supply decay from being reproduced by the loudspeaker.

Abstract: This invention relates to an improved system for changing the bandwidth of an intelligence-bearing electrical signal so that it can be transmitted within said changed bandwidth and to a counterpart system for changing the bandwidth, following transmission, so that a good replica of the original signal is obtained at a receiving terminal. The bandwidth compression and expansion are obtained through time-delay expansion and compression. This invention uses the fact that the time delay characteristics of a charge-coupled device is a function of the clocking frequency. The desired time delay variation can be achieved by varying this clocking frequency correspondingly. A single delay line, with a sawtooth variation of clock frequency, is a feature of the invention.

Abstract: A method and apparatus for providing improved telephonic conferences is presented. A speaker is selected for each conferee from the signals of the other conferees. The peak values of the speaker signal establish a variable reference level which another conferee must first exceed in order to become the new speaker and establish a new reference level. The reference level is continuously allowed to decay so that new speakers may gain the floor when the current speaker's peak signals fall below the peak signals of another speaker. Both an analog and a digital embodiment of the invention are presented. A specific feature of the invention involves directing all signals of other conferees to all conferees and each conferee station selects the loudest signal (maximum amplitude) for that conferee.

Abstract: An error-free, data telecommunication system designed for continuous high speed error-free data communications over dial-up voice grade circuits comprising a high speed data transmission section including internal data buffering and a low speed reverse channel ARQ (automatic request for repeat) receiver and a high speed data receiving section including a low speed reverse channel ARQ transmitter whereby high speed data and reverse ARQ signaling are transmitted simultaneously over a two wire dial-up network. The system is capable of half-duplex, two wire operation and full-duplex, four wire operation.