Fast On-Line Speech/Voiceband--Data Discrimination for Statistical Multiplexing of Data with Telephone Conversations

This paper concerns the design of a speech/data discriminator with the speed and accuracy required for statistical multiplexing of speech and high-speed baseband data on a single telephone line. The structure proposed for the discriminator combines the information from two parallel processes. The first process, even though slow, accurately recognizes the speech/data nature of the signal. This nature is determined by statistical pattern classification applied to simple zero-crossing-type parameters extracted from the signal filtered in a PCM representation. The second process has temporal accuracy in detecting transition events, from speech to data and vice versa. This detection is provided by special parameters which supply tentative transition markers. This paper applies these processes to the case of 9600 bit/s modems and describes a complete discrimination algorithm which is fit for microprocessor technology. The simulation results provided indicate a very low error rate and demonstrate that transitions are detected exactly or within one or two sampling intervals.