Datasheet

DS2155
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Reader’s Note: This data sheet assumes a particular nomenclature of the T1 operating environment. In
each 125µs frame there are 24 8-bit channels plus a framing bit. It is assumed that the framing bit is sent
first followed by channel 1. Each channel is made up of eight bits that are numbered 1 to 8. Bit number 1
is the MSB and is transmitted first. Bit number 8 is the LSB and is transmitted last. The term “locked” is
used to refer to two clock signals that are phase- or frequency-locked or derived from a common clock
(i.e., a 1.544MHz clock can be locked to a 2.048MHz clock if they share the same 8kHz component).
Throughout this data sheet, the following abbreviations are used:
B8ZS Bipolar with 8 Zero Substitution
BOC Bit-Oriented Code
CRC Cyclical Redundancy Check
D4 Superframe (12 frames per multiframe) Multiframe Structure
ESF Extended Superframe (24 frames per multiframe) Multiframe Structure
FDL Facility Data Link
FPS Framing Pattern Sequence in ESF
Fs Signaling Framing Pattern in D4
Ft Terminal Framing Pattern in D4
HDLC High-Level Data Link Control
MF Multiframe
SLC–96 Subscriber Loop Carrier—96 Channels