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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
185
12
OPERATION
12.1 DS3 Frame Format
The TEMUX provides support for both the C-bit parity and M23 DS3 framing
formats. The DS3 frame format is shown in Figure 13.
Figure 31
- DS3 Frame Structure
X1
X2
P1
P2
M1
M2
M3
F1
F1
F1
F1
F1
F1
F1
C1
C1
C1
C1
C1
C1
C1
F2
F2
F2
F2
F2
F2
F2
C2
C2
C2
C2
C2
C2
C2
F3
F3
F3
F3
F3
F3
F3
F4
F4
F4
F4
F4
F4
F4
C3
C3
C3
C3
C3
C3
C3
84 bits
84 bits
84 bits
84 bits
84 bits
84 bits
84 bits
84 bits
M-subframe 1
M-subframe 2
M-subframe 7
M-subframe 6
M-subframe 5
M-subframe 4
M-subframe 3
Xx: X-Bit Channel
Transmit: The TEMUX inserts the FERF signal on the X-bits. FERF
generation is controlled by either the FERF bit of the DS3 TRAN
Configuration register or by detection of OOF, RED, LOS and AIS, as
configured by the TEMUX Master DS3 Alarm Enable register.
Receive: The TEMUX monitors the state and detects changes in the state
of the FERF signal on the X-bits.
Px: P-Bit Channel
Transmit: The TEMUX calculates the parity for the payload data over the
previous M-frame and inserts it into the P1 and P2 bit positions.
Receive: The TEMUX calculates the parity for the received payload. Errors
are accumulated in the DS3 PMON Parity Error Event Count registers.
Mx: M-Frame Alignment Signal
Transmit: The TEMUX generates the M-frame alignment signal (M1 = 0,
M2 = 1, M3 = 0).
Receive: The TEMUX finds M-frame alignment by searching for the F-bits
and the M-bits. Out-of-frame is removed if the M-bits are correct for three
consecutive M-frames while no discrepancies have occurred in the F-bits.
M-bit errors are counted in the DS3 PMON Framing Bit Error Event Count