S/UNI®-JET Data Sheet
Released
Figure 52 Transmit DS3 Overhead
DS3 M-frame Period
TOHFP
TOHCLK
TOHCLK
TOHFP
X1
F1
C1
F2
C2
F3
C3
TOH
TOHINS
The Transmit DS3 Overhead diagram (Figure 52) shows the insertion of DS3 overhead bits using
the TOH input, along with the overhead insertion enable input, TOHINS. The TOHFP output is
set to logic one once per DS3 M-frame period (during the X1 bit position). In Figure 52, the data
sampled on TOH during the X1, C1, F2, and C2 bit positions is inserted into the DS3 overhead
bits in the transmit stream. The F1, F3, and C3 overhead bits are internally generated by the
S/UNI-JET . Table 45 illustrates the overhead bit order on TOH:
Table 45 DS3 Transmit Overhead Bits
M-subframe
DS3 Overhead Bits
1
2
3
4
F
5
C
6
F
7
C
8
F
1
2
3
4
5
6
7
X
F
C
1
2
1
2
1
2
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
X
P
P
F
F
F
F
F
F
C
C
C
C
C
C
F
F
F
F
F
F
C
C
C
C
C
C
F
F
F
F
F
F
C
C
C
C
C
C
F
F
F
F
F
F
M
M
M
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
307
PMC [ PMC-SIERRA, INC ]
