Bt8370/8375/8376
AppendixA
Fully Integrated T1/E1 Framer and Line Interface
A.5 E1 Frame Format
Tables A-6 and A-7 define the frame format time slot 0-bit allocations for ITU-T
CEPT and IRSM CEPT, respectively.
Table A-6. ITU–T CEPT Frame Format Time Slot 0-Bit Allocations
SMF
Frame #
Time Slot 0 Bits 1 to 8 of Each Frame
1
2
3
4
5
6
7
8
0
1
C1/Si
0/Si
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
SA4
1
1
SA5
1
0
SA6
0
1
SA7
1
1
SA8
1
A
0
I
2
C2/Si
0/Si
3
A
0
SA4
1
SA5
1
SA6
0
SA7
1
SA8
1
4
C3/Si
1/Si
5
A
0
SA4
1
SA5
1
SA6
0
SA7
1
SA8
1
6
C4/Si
0/Si
7
A
0
SA4
1
SA5
1
SA6
0
SA7
1
SA8
1
8
C1/Si
1/Si
9
A
0
SA4
1
SA5
1
SA6
0
SA7
1
SA8
1
II
10
11
12
13
14
15
C2/Si
1/Si
A
0
SA4
1
SA5
1
SA6
0
SA7
1
SA8
1
C3/Si
E/Si
A
0
SA4
1
SA5
1
SA6
0
SA7
1
SA8
1
C4/Si
E/Si
A
SA4
SA5
SA6
SA7
SA8
Note:
1. SMF indicates the sub-multiframe. This partitioning is used in the CRC-4 calculation.
2. Si bits are International Spare Bits.
3. A bit is used to indicate a remote alarm condition (active-high).
4. SA4 to SA8 are spare bits that may be recommended by ITU–T for use in specific point-to-point applications (e.g., transcoder
equipment conforming to Recommendation G.761).
5. SA4 to SA8 where these are not used should be set to 1 on links crossing an international border.
6. E bit is used to indicate a CRC-4 error. The normal state is both bits set to 1, when a CRC-4 error is detected one of the E bits
is set to 0.
7. C1 to C4 bits are used to carry the CRC-4 code.
8. Time slot 0 that contains the 0011011 sequence is defined as the FAS word and Time Slot 0 that does not contain the FAS is
the Not-Word.
N8370DSE
Conexant
A-9
CONEXANT [ CONEXANT SYSTEMS, INC ]
