Nortel DMS-100 Series Maintenance Manual page 118

3-2 SMS signaling
Format of a DS-1 frame
Framing bit
Voice channel 1
S 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Channel frame
Ft frame 1 Fs frame 2 Ft frame 3 Fs frame 4
Note: Ft = frame timing bit
Fs = frame signaling bit
The previous figure also shows a superframe. A superframe contains 12
channels. A DDL frame, which does not appear in the previous figure,
consists of six superframes or 72 channel frames.
The 24-bit pattern conveys three types of information:
The frame pattern sequence (FPS) is 001110. Every fourth framing bit that
begins at the fourth bit carries an FPS bit. The FPS and the cyclic
redundancy check (CRC) define an in-frame condition.
The 4Kbit per second facility data link (FDL) bit begins with the first
framing bit. Every other frame carries an FDL messaged bit.
297-8231-550 Standard 09.01 August 1998
Voice channel 2
frame pattern sequence
facility data link performance
cyclic redundancy check
185 186 187 188 189 190 191 192
Channel frame
Super frame
Voice channel 24
Fs frame 12