Multi-speaker conferencing over narrowband channels
September 12, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesDigital conference bridge Sampled speech compression system Digital voice conferencer Apparatus and method for digital combination of delta modulated data Speech synthesizer having speech time stretch and compression functions Speech synthesis system utilizing variable frame rate Digital speech processing system having reduced encoding bit requirements Adaptive trunk-compression system with constant grade of service Very low rate speech encoder and decoder Compression of stored waveforms for artificial speech InventorAssigneeApplicationNo. 760021 filed on 09/12/1991US Classes:370/267, Digital summation370/477, Transmission bandwidth conservation379/202.01, Conferencing704/270, Application704/272Novelty itemExaminersPrimary: Olms, Douglas W.Assistant: Blum, Russell W. Attorney, Agent or FirmInternational ClassH04L 012/18AbstractA system for digital conferencing over narrowband channels which allows use by multiple simultaneous speakers and which allow for interfacing between vocoders which operate at different bit rates. The system takes advantage of the properties of multi-rate parametric vocoders (which includes the Sinusoidal Transform Coder and the Multi-Band Excitation Vocoder, as well as embedded coders), defined as parametric vocoders for whom the basic model and parameter set remain unchanged over a wide range of bit-rates. The system performs signal summation. To maintain quality for a single speaker while allowing multiple speakers, the system adaptively allocates channel bandwidth based on the number of speakers to be represented. This system also provides digital-to-digital conversion between narrow-band digitizers (vocoders) operating at different bit-rates. The system takes advantage of the characteristics of a particular class of coders, sine-wave based coders, which perform parameter estimation by sine-wave summation. Digital-to-digital conversion is performed by estimating the parameter set associated with the lower bit-rate digitizer from the parameter set associated with the higher bit-rate.Other References
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