In telecommunication, a digital transmission group is a group of digitized voice or data channels or both with bit streams that are combined into a single digital bit stream for transmission over communications media.
Digital transmission groups usually are categorized by their maximum capacity, not by a specific number of channels. However, the maximum digital transmission group capacity must be equal to or greater than the sum of the individual multiplexer input channel capacities.
See also[edit]

Digital Signal 1
Plesiochronous Digital Hierarchy

 This article incorporates public domain material from the General Services Administration document “Federal Standard 1037C” (in support of MIL-STD-188).

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