IDT82P2282_09 Datasheet, PDF (36/381 Pages) Integrated Device Technology – Dual T1/E1/J1 Long Haul / Short Haul Transceiver

IDT82P2282
DUAL T1/E1/J1 LONG HAUL / SHORT HAUL TRANSCEIVER
3.8.1.1.3 T1 Digital Multiplexer (DM) Format (T1 only)
The structure of T1 DM is illustrated in Table 14. The T1 DM is
made up of 12 frames. Each frame consists of one overhead bit (F-bit)
and 24 8-bit channels. Except for channel 24, all other channels carry
data. Channel 24 should be ‘0DY11101’. Its Frame Alignment Pattern is
‘100011011100’ in the F-bit. The fixed 6 bits in channel 24 are called
DDS.
The synchronization criteria of T1 DM format are selected by the
DDSC bit. When the DDSC bit is ‘0’, the T1 DM synchronization is
acquired if one correct DDS pattern is received before the first F-bit of a
single correct Frame Alignment Pattern. When the DDSC bit is ‘1’, the
T1 DM synchronization is acquired if a single correct Frame Alignment
Pattern is received and twelve correct DDS patterns before each F-bit of
the correct Frame Alignment Pattern are all detected.
The T1-DM synchronization is indicated by ‘0’ in the OOFV bit. The
RMFBI bit is set at the first bit of each T1 DM frame.
Table 14: The Structure of T1 DM
Frame No. In The T1 DM
F-Bit (Frame Alignment)
Ft
Fs
1
1
2
0
3
0
4
0
5
1
6
1
7
0
8
1
9
1
10
1
11
0
12
0
Note:
In Channel 24, the ‘D’ bit is used for data link, and the ‘Y’ bit is used for alarm. The other 6 bits are fixed and they are called ‘DDS’ pattern.
Channel 24
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
0DY11101
Functional Description
36
August 20, 2009