Subsampling of a DPCM Speech Channel to Provide Two “Self-Contained” Half-Rate Channels
1981; Institute of Electrical and Electronics Engineers; Volume: 60; Issue: 4 Linguagem: Inglês
10.1002/j.1538-7305.1981.tb03069.x
ISSN2376-7154
Autores Tópico(s)Blind Source Separation Techniques
ResumoWe consider the following channel-splitting problem: it is required to split a B-bits/s speech-code sequence into two “self-contained” B/2-bits/s components, either of which can be used to reproduce acceptable speech; also, if both components are available at a receiver, it must be possible to reproduce speech with full B-bits/s quality. We propose a solution where for interesting values of B, the speech quality resulting from half-rate receptions approximately equals that from conventional full-rate receptions at B/2 bits/s. In the proposed solution, 3.2kHz speech is sampled at 12 kHz and coded using PCM or differential PCM. The output sequence of code-words is split into odd- and even-word sequences. A full-rate receiver with access to both of the subchannels simply reconstitutes the output sequence prior to decoding, while a half-rate receiver with only the odd (or even) subchannel estimates the even (or odd) components by nearest-neighbor interpolation.
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