Telenetics Corporation FT100 S, Installation And Operation Manual

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T1 Overview
C-4 FT 100S
kbps (7 bits per DS0) data can be transmitted without the inherent error
due to signaling. Voice transmission is unaffected by robbed bit
signaling.
ESF Framing
Figure C-2 shows the Extended Superframe Format (ESF). ESF format
or Fe framing is the newest DS1 framing format. This format extends
the multiframe structure from a 12 frame superframe to a 24 frame
extended superframe. Data channeling for ESF framing is the same as
SF (24 DS0 channels per frame), but the function of the framing (F) bit
position in each frame is redefined for ESF. The new F bit contains the
following three functions:
•
Cyclic redundancy check
•
Facility data link
•
Framing pattern sequence
This redefinition of the F bit allows several new features for mainte-
nance and performance monitoring which are not available with SF
framing.
The Cyclic Redundancy Check (CRC-6) is an error check sequence
which is transmitted in the F bit position. The T1 receiving equipment
receives this sequence and compares it with a locally computed check
value which is based on the received data in all DS0 channels in the
extended superframe. This process gives the equipment the ability to
detect most errors which occur in the DS1 signal. The CRC-6 data is
transmitted at a rate of 2 kbps.