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IDT82V2108
T1 / E1 / J1 OCTAL FRAMER
Functional Description
18
March 5, 2009
3.2.2
T1/J1 MODE
In T1/J1 Mode, the Frame Processor searches for the frame align-
ment patterns in standard Super-Frame (SF) or in Extended Super-
Frame (ESF) framing formats. The format is chosen by the ESF (b4, T1/
J1-020H). The searching algorithm of T1 or J1 is determined by the
JYEL (b3, T1/J1-020H). The Frame Processor acquires frame alignment
per ITU-T requirement.
When frame alignment is achieved, the Framer Processor contin-
ues to monitor the received data stream. The Frame Processor declares
the framing bit errors and bit error events, if any. The Frame Processor
can also detect out-of-frame events based on selectable criteria.
The Frame Processor can also be disabled to receive unframed
data.
3.2.2.1
Synchronization Searching
All the frame synchronization function can only be executed when
the UNF (b6, T1/J1-000H) is logic 0.
3.2.2.1.1
Super Frame (SF) Format
The structure of T1/J1 SF format is illustrated in
Table 3. The SF is
made up of 12 frames. Each frame consists of a one-bit overhead - F Bit
and 24 8-bit channels. If two consecutive valid Frame Alignment Pat-
terns - ‘100011011100’ for T1 or ‘10001101110X’ for J1 - are received in
the F-Bit in the received data stream, the SF synchronization is
acquired. The same pattern is a mimic pattern if it is received in the data
stream other than F-bit. If a mimic pattern exists during the frame
searching procedure, the synchronization will not be declared and the
MFP (b1, T1/J1-022H) will be set to indicate the presence of a mimic
pattern.
3.2.2.1.2
Extended Super Frame (ESF) Format
The structure of T1/J1 ESF format is illustrated in
Table 4. The ESF
is made up of 24 frames. Each frame consists of a one-bit overhead - F
Bit and 24 8-bit channels.
The pattern of the Frame Alignment Pattern is ‘001011’, which is
located from Frame 4 in every 4th F-bit position.
When the ESFFA (b5, T1/J1-020H) is set to ‘0’, the ESF synchroni-
zation is acquired if four consecutive Frame Alignment Patterns are
detected in the F-Bit in the received data stream. The same pattern is a
mimic pattern if it is received in the data stream other than F-bit. If a
mimic pattern exists during the frame searching procedure, the synchro-
nization will not be declared and the MFP (b1, T1/J1-022H) will be set to
indicate the presence of a mimic pattern.
When the ESFFA (b5, T1/J1-020H) is set to ‘1’, the synchronization
will be declared when 6 consecutive Frame Alignment Patterns are
received error free and the CRC-6 checksum is also error free. In this
condition, the existence of mimic patterns will not be considered.
Table 3: SF Format
Frame No. in SF
F-Bit
(Frame Alignment)
the Bit in Each Channel
Data Bit
Signaling Bit
11
1 - 8
-
20
1 - 8
-
30
1 - 8
-
40
1 - 8
-
51
1 - 8
-
6
1
1 - 7
A (bit 8)
70
1 - 8
-
81
1 - 8
-
91
1 - 8
-
10
1
1 - 8
-
11
0
1 - 8
-
12
X*
1 - 7
B (bit 8)
Note:
* ‘X’ should be logic 0 in T1 FAS.
‘X’ can be logic 0 or 1 in J1 FAS because this position is used as Yellow Alarm Indication
bit.
Table 4: ESF Format
Frame No.
in ESF
F-Bit Assignment
the Bit in Each Channel
FAS
DL
CRC
Data Bit
Signaling Bit
1-
DL
-
1 - 8
-
2-
-
C1
1 - 8
-
3-
DL
-
1 - 8
-
40
-
1 - 8
-
5-
DL
-
1 - 8
-
6
-
C2
1 - 7
A (bit 8)
7-
DL
-
1 - 8
-
80
-
1 - 8
-
9-
DL
-
1 - 8
-
10
-
C3
1 - 8
-
11
-
DL
-
1 - 8
-
12
1
-
1 - 7
B (bit 8)
13
-
DL
-
1 - 8
-
14
-
C4
1 - 8
-
15
-
DL
-
1 - 8
-
16
0
-
1 - 8
-
17
-
DL
-
1 - 8
-
18
-
C5
1 - 7
C (bit 8)
19
-
DL
-
1 - 8
-
20
1
-
1 - 8
-
21
-
DL
-
1 - 8
-
22
-
C6
1 - 8
-
23
-
DL
-
1 - 8
-
24
1
-
1 - 7
D (bit 8)