Topic summary
NRZI
Extracted from the Wikipedia article Non-return-to-zero.
Synchronized non-return-to-zero
Synchronized NRZI (SNRZI) and group-coded recording (GCR) are modified forms of NRZI. In SNRZI-M, each 8-bit group is extended to 9 bits by a 1 in order to insert a transition for synchronisation.