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AssigneeNippon Telegraph & Telephone Public Corporation
InventorsKen-ichi Noda, Shuzo Saito
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A plurality of speech channels uses only one speech analyzer-synthesizer by Time-Multiplexing-Demultiplexing (sampling and processing) the speech channels sequentially. On the transmission side, speech signals of a plurality of channels are multiplexed by a pulse code modulation system, a partial autocorrelation coefficient and an excitation signal which constitute a feature parameter of the speech are extracted from the multiplexed signals by means of a speech analyzer for respective digital outputs corresponding to respective speech signals, and the extracted feature parameter is multiplexed again and then transmitted to the receiving side. On the receiving side, the received multiplexed signal of the feature parameter is applied to a speech synthesizer on a time division basis for reproducing a multiplex pulse code modulation signal of the speech wave, and the reproduced signal is distributed among respective channels.
A multiplex speech transmission system comprising a transmitting apparatus and a receiving apparatus, said transmitting apparatus including means for multiplexing respective speech signals of a plurality of speech channels constituting at least two groups thereof by subjecting said speech signals to pulse code modulation, speech analyzing means for extracting a feature parameter signal including a partial autocorrelation coefficient and an excitation source signal from each of said multiplexed pulse code modulation speech signals, time division multiplexing means for further multiplexing said extracted feature parameters from the signals of one of said groups with the feature parameters from the signal of at least one other of said groups, and means for transmitting said further multiplexed feature parameter signals over a transmission line;
A multiplex speech transmission system comprising transmitting apparatus and receiving apparatus, said transmitting apparatus including a plurality of speech channels which are divided into a plurality of groups, said speech channels of respective groups each having a plurality of channel gates connected to sample speech signals of said respective channels for forming pulse amplitude modulation signals, means for encoding and multiplexing the pulse amplitudes of the pulse amplitude modulation signal outputs from said plurality of channel gates to provide a plurality of pulse code modulation signals, signal analyzer means for extracting feature parameters from the pulse code modulation signals of said respective speech channels, each one of said feature parameters comprising a partial autocorrelation coefficient and an excitation source signal, and a time division multiplexing circuit for time multiplexing the outputs of respective speech analyzers of respective groups and for transmitting the multiplexed outputs over a transmission line, and said receiving apparatus including a digital code distributor for separating the transmitted outputs of said time division multiplexing circuit sent over said transmission line into time division multiplex signals of respective groups, a plurality of speech synthesizers responsive to the time division multiplex signals of respective groups from said digital code distributor for converting said time division multiplex signals into multiplexed pulse code modulation signals, a plurality of decoders responsive to the outputs from respective speech synthesizers for converting said outputs into pulse a amplitude modulation signals corresponding to respective speech channels, and a plurality of low pass filters supplied with the outputs of respective decoders corresponding to respective speech channels.
Dependencies are inferred from the claim text.