This report describes a way in which six companded p.c.m. high-quality sound channels could be multiplexed to form a bit-rate of 2-048 Mb/s, including error protec¬tion and about 1 kb/s of signalling information. The predicted performance of such a system is discussed and compared to that of the existing 13-channel multiplex system which employs linear coding.nThe proposed system uses a near-instantaneous digital companding technique that permits the number of bits in each audio sample word to be reduced from 13 to 10.nWith this proposed 6-channel system, the sound quality would be virtually in¬distinguishable from that achieved with the existing 13-channel multiplex and the per¬formances of the two systems in the presence of errors would be similar. The only significant difference between the two systems would be that, with the &channel system, the mean time taken to re-frame after a break in transmission would be about 616 ms compared to about 16 ms for the 13-channel system. However, this is considered to be acceptable for most applications of such a 6-channel system.
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