![](http://datasheet.mmic.net.cn/IDT--Integrated-Device-Technology-Inc/IDT82V2108BBG_datasheet_97518/IDT82V2108BBG_25.png)
IDT82V2108
T1 / E1 / J1 OCTAL FRAMER
Functional Description
15
March 5, 2009
3.2.1.1.3
CAS Signaling Multi-Frame
If the CRCEN (E1-030H) is ‘1’, after the CRC Multi-Frame has been
found, the Frame Processor starts to search for Signaling Multi-Frame
alignment pattern when the CASDIS (E1-030H) is ‘0’. If the CRCEN is
‘0’, after the Basic Frame has been found, the Frame Processor starts to
search for Signaling Multi-Frame alignment signal when the CASDIS
The Signaling Multi-Frame alignment pattern is located in the 1 – 4
bits of TS16 of Frame 0 of Signaling Multi-Frame. The pattern is ‘0000’.
Once the pattern is detected, the Signaling Multi-Frame synchronization
is acquired which is indicated with a logic ‘0’ in the OOSMFV (b5, E1-
036H). If the received Signaling Multi-Frame alignment signal does not
meet its pattern, the SMFERI (b1, E1-034H) will be set to ‘1’. The entire
content in TS16 of Frame 0 of Signaling Multi-Frame is ‘0000XYXX’. The
‘Y’ is for remote Signaling Multi-Frame alarm indication and the ‘X’s are
extra bits.
A new search of Signaling Multi-Frame alignment pattern is initi-
ated when the out of the Signaling Multi-Frame criteria set in the
SMFASC (b5, E1-031H) and the TS16C (b4, E1-031H) are met or when
it is out of Basic Frame synchronization.
3.2.1.2
Alarms & Bit Extraction
3.2.1.2.1
RED Alarm
RED alarm is declared when the out of Basic Frame synchroniza-
tion condition has persisted for 100 ms. RED alarm is removed when the
out of Basic Frame synchronization condition has been absent for 100
ms. The RED alarm status is reflected in the RED (b3, E1-037H).
The received data stream is out of Basic Frame synchronization
when any of the following conditions is met:
1) The Basic Frame has not been synchronized.
2) The received data stream meets the out of Basic Frame syn-
chronization criteria set in the BIT2C (b6, E1-031H).
3) There are excessive CRC errors in the received data stream.
Any one of the three conditions will be indicated by the OOFV (b6,
E1-036H).
The integration of RED alarm uses the following algorithm: The
algorithm monitors the occurrence of out of Basic Frame over a 4 ms
interval. A valid out of Basic Frame presence is accumulated when one
or more out of Basic Frame indications occurred during the 4 ms inter-
val. Each valid out of Basic Frame presence increases one accumula-
tion. An invalid out of Basic Frame presence is also accumulated when
there is no out of Basic Frame indication occurring during the 4 ms inver-
val. Each invalid out of Basic Frame indication decreases one accumu-
lation (until the accumulation is zero). The RED alarm is declared when
25 valid out of Basic Frame presences have been accumulated. The
RED alarm is removed when the out of Basic Frame presences reaches
0.
3.2.1.2.2
AIS Alarm
The AIS density criteria are determined by the AISC (b1, E1-031H).
That is, if it is out of Basic Frame synchronization and less than 3 zeros
are detected in a 512-bit stream, or if it is out of Basic Frame synchroni-
zation and less than 3 zeros are detected in each of 2 consecutive 512-
bit streams, the status will be reported by the AISD (b5, E1-037H).
Table 1: Structure of TS0 of CRC Multi-Frame
SMF
Basic Frame
No. / Type
the Eight Bits in Time Slot 0
1 (Si bit)
23
456
7
8
CRC-4
Multi-Frame
SMF I
0 / FAS
C1
00
110
1
1 / NFAS
0
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
2 / FAS
C2
00
110
1
3 / NFAS
0
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
4 / FAS
C3
00
110
1
5 / NFAS
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
6 / FAS
C4
00
110
1
7 / NFAS
0
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
SMF II
8 / FAS
C1
00
110
1
9 / NFAS
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
10 / FAS
C2
0
1
0
1
11 / NFAS
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
12 / FAS
C3
0
1
0
1
13 / NFAS
E1
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
14 / FAS
C4
0
1
0
1
15 / NFAS
E2
1
A
Sa4
Sa5
Sa6
Sa7
Sa8