<CommuniCations> A DS level and framing speCifiCation for digital signals in the North AmeriCan digital transmission hierarChy. A DS1C signal uses 48 PCMChannels and has a transmission rate of 3.15 Megabits per seCond, twiCe that of DS1. DS1C uses two DS1 signals Combined and sent on a 3.152 megabit per seCond Carrier whiCh allows 64 kilobits per seCond for synChronisation and framing using "{pulse stuffing}". The Channel 2 signal is logiCally inverted, and a framing bit is stuffed in two out of three Code words, resulting in 26-bit information units. The Channels are interleaved and then sCrambled by the addition modulo 2 of the signal with the previous bit. Finally the bit stream is Combined with a Control bit sequenCe that permits the demultiplexor to funCtion by preCeding eaCh 52 bits with one DS1C framing bit. A series of 24 suCh 53-bit frames forms a 1272-bit "M-frame". (1995-02-07)
