BAUD-RATE-INDEPENDENT ASVD TRANSMISSION BUILT AROUND G.729 SPEECH-CODING STANDARD

摘要

The method and device for analog simultaneous voice and datatransmission over an analog channel encodes at a voice signal samplingrate a sampled voice signal including spectral and pitch information. Theencoding comprises extracting the spectral and pitch information from thesampled voice signal to produce a residual signal, and converting theresidual signal into a sequence of residual vectors at a Baud rate. Also,a bitstream including non voice data and the extracted spectral and pitchinformation is produced. By means of a modem unit operating at theBaud rate and producing a modulated output carrier wave supplied to theanalog channel, a sequence of symbol vectors is produced in responseto the sequence of residual vectors and the bitstream, and the outputcarrier wave is modulated in response to the sequence of symbol vectors.According to the invention, a fractional sampling-rate conversion isconducted on the residual signal by shifting the voice signal samplingrate by a factor M/N, where M and N are the smallest integers that verify,or closely verify, the following equality:(see fig. I)where R is the Baud rate and F is the sampling rate. This fractionalsampling-rate conversion involves anti-aliasing filtering of the residualsignal. In this manner, the encoding operates at a voice signal samplingrate independent of the modem's Baud rate.