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STANDARD PRODUCT
PM8315 TEMUX
DATASHEET
PMC-1981125
ISSUE 7
HIGH DENSITY T1/E1 FRAMER WITH
INTEGRATED VT/TU MAPPER AND M13 MUX
PROPRIETARY AND CONFIDENTIAL
110
9.32 DS3 Mapper Drop Side (D3MD)
The DS3 Mapper DROP Side (D3MD) block demaps a DS3 signal from an
STS-1 (STM-0/AU3) payload. The asynchronous DS3 mapping consists of 9
rows every 125 μs (8 KHz). Each row contains 621 information bits, 5 stuff
control bits, 1 stuff opportunity bit, and 2 overhead communication channel bits.
Fixed stuff bytes are used to fill the remaining bytes. The asynchronous DS3
mapping is shown in Table 6.
Table 6
- Asynchronous DS3 mapping to STS-1 (STM-0/AU3)
J1
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
STS
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
POH
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
2 x 8R
RRCIIIII
25 x 8I
2 x 8R
CCRRRRRR
26 x 8I
2 x 8R
CCRROORS
26 x 8I
R: Fixed Stuff bit - set to logic ‘0’ or ‘1’
C: Stuff Control bit - set to logic ‘1’ for stuff indication
S: Stuff Opportunity bit - when stuff control bit is ‘0’, stuff opportunity is I bit
O: Overhead communication channel
I: DS3 payload information
9.32.1 DS3 Demapper
The D3MD performs majority vote on the received C-bits. If 3 out of 5 C-bits are
‘1’s, the associated S bit is interpreted as a stuff bit. If 3 out of 5 C-bits are ‘0’s,
the associated S bit is interpreted as an Information bit. The information bits are
written to an elastic store and the Fixed Stuff bits (R) are ignored.
Given a path signal label mismatch (PSLM) or path signal label unstable (PSLU),
the D3MD ignores the STS-1 (STM-0/AU3) SPE and writes a DS3 AIS pattern to
the elastic store. In addition, the desynchronization algorithm assumes a nominal