Datasheet

DS26514 4-Port T1/E1/J1 Transceiver
19-5856; Rev 4; 5/11 51 of 305
9.9.2 E1 Framing
The E1 framing consists of FAS, NFAS detection as shown in Table 9-14.
Table 9-14. E1 FAS/NFAS Framing
CRC-4
FRAME
#
TYPE 1 2 3 4 5 6 7 8
0
FAS
C1
0
0
1
1
0
1
1
1
NFAS
0
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
2
FAS
C2
0
0
1
1
0
1
1
3
NFAS
0
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
4
FAS
C3
0
0
1
1
0
1
1
5
NFAS
1
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
6
FAS
C4
0
0
1
1
0
1
1
7
NFAS
0
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
8
FAS
C1
0
0
1
1
0
1
1
9
NFAS
1
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
10
FAS
C2
0
0
1
1
0
1
1
11
NFAS
1
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
12
FAS
C3
0
0
1
1
0
1
1
13
NFAS
E1
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
14
FAS
C4
0
0
1
1
0
1
1
15
NFAS
E2
1
A
Sa4
Sa5
Sa6
Sa7
Sa8
C = C bits are the CRC-4 remainder; A = alarm bits; Sa = bits for data link.