Abstract: Our audio processing system for use in teleconferencing systems includes a microphone, receiver, and substantially the same comb filter and frequency scaler at each station for reducing acoustic echo and increasing the margin of acoustic stability. The comb filters and frequency scalers cooperate with one another in that the frequency scalers each induces a shift in frequency which corresponds to the peak-to-trough spacing of the transfer function of the comb filters. Our audio processing system may also include auxiliary echo suppressors for reducing acoustic echo and increasing the margin of acoustic stability in systems having high and low transmission delays. Other devices may be employed for reducing noise and smoothing out the operation of individual components in the system.

Abstract: An audio processing system for use in teleconferencing systems having high and low transmission delays. The audio processing system utilizes complementary comb filters in combination with auxiliary echo suppressors, a frequency scaler, expander/gates and automatic level controlling devices to substantially improve acoustic stability margin and reduce far-end talker echo.

Abstract: A teleconferencing system 100 is disclosed having a video camera for generating a video signal representative of a video image of a first station B. A microphone array 150, 160 is also provided in the first station for receiving a sound from one or more fixed non-overlapping volume zones 151, 152, 153, 154, 155, 156, 157, 158, 159, into which the first station is divided. The microphone array is also provided for generating a monochannel audio signal 170 representative of the received sound and a direction signal indicating, based on the sound received from each zone, from which of the volume zones the sound originated. The teleconferencing system also includes a display device 120A at a second station A for displaying a video image of the first station.

Abstract: An audio processing system (100) for use in a teleconferencing system (10) utilizes complementary comb filters (42, 52, 220, 320) in combination with an echo suppressor (210, 310) and/or a frequency scaler (60, 120) to substantially improve acoustic stability margin and reduce far-end talker echo.

Abstract: A method of controlling the access of a plurality of nodes to a bus which interconnects the nodes in a daisy chain. The method enables each node in the network to keep track of the transmission requests of all other nodes. Each node will compare it's needs against all requests and will only transmit onto the network after it has let pass sufficient resources to satisfy the downstream nodes.

Abstract: A customer premises network for interfacing customer premises equipment with a broadband digital trunk and exchange network comprises a relatively large bandwidth optical broadcast bus for broadcasting downstream data to the customer premises equipment and a smaller bandwidth looped bus for transmitting upstream data from the customer premises equipment. The units of customer premises equipment are connected by the looped bus in a daisy chain.