![](http://datasheet.mmic.net.cn/330000/PM8315_datasheet_16444435/PM8315_126.png)
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
111
ratio of data to stuff bits carried in the S bits (1 out of 3 S bits is assumed to be
an information (data) bit). DS3 AIS is shown in Table 7.
Table 7
- DS3 AIS format.
X (1)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
X (1)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
P (p)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
P (p)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
M (0)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
M
(1)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
M
(0)
D
F (1)
D
C (0)
D
F (0)
D
C (0)
D
F (0)
D
C (0)
D
F (1)
D
valid M-frame alignment bits (M-bits), M-subframe alignment bits (F-bits), and
parity bit of the preceding M-frame (P-bits). The two P-bits are identical, either
both are zeros or ones.
all the C-bits in the M-frame are set to zeros
the X-bits are set to ones
the information bit (84 Data bits with repeating sequence of 1010..)
9.32.2 DS3 Demapper Elastic Store
The elastic store block is provided to compensate for frequency differences
between the DS-3 stream extracted from the STS-1 (STM-0/AU3) SPE and the
incoming CLK52M. The DS3 Demapper extracts I bits from the STS-1
(STM-0/AU3) SPE and writes the bits into a 128 bit (16 byte) elastic store. Eight
bytes are provided for SONET/SDH overhead (3 bytes for TOH, 1 byte for a
positive stuff, 1 byte for POH) and DS3 reserve stuffing bits (2 bytes for R bits,
and 3 overhead bits which is rounded-up to 1 byte). The remaining 8 bytes are
provided for path pointer adjustments.
Data is read out of the Elastic Store using a divide by 8 version of the input
CLK52M clock. If an overflow or underflow condition occurs, an interrupt is
optionally asserted and the Elastic Store read and write address are reset to the
startup values (logically 180 degrees apart).