NicatioNs> A DS level aNd framiNg specificatioN for digital sigNals iN the North AmericaN digital traNsmissioN hierarchy. A DS1C sigNal uses 48 PCM chaNNels 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 additioNmodulo 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)
