STANDARD PRODUCT
PM5365 TEMAP
DATASHEET
PMC-1991148
ISSUE 3
HIGH DENSITY VT/TU MAPPER
AND M13 MULTIPLEXER
The DS3-FRMR decodes a B3ZS-encoded signal and provides indications of line
code violations. The B3ZS decoding algorithm and the LCV definition can be
independently chosen through software. A loss of signal (LOS) defect is also
detected for B3ZS encoded streams. LOS is declared when inputs RPOS and
RNEG contain zeros for 175 consecutive RCLK cycles. LOS is removed when
the ones density on RPOS and/or RNEG is greater than 33% for 175 ±1 RCLK
cycles.
The framing algorithm examines five F-bit candidates simultaneously. When at
least one discrepancy has occurred in each candidate, the algorithm examines
the next set of five candidates. When a single F-bit candidate remains in a set,
the first bit in the supposed M-subframe is examined for the M-frame alignment
signal (i.e., the M-bits, M1, M2, and M3 are following the 010 pattern). Framing
is declared, and 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.
During the examination of the M-bits, the X-bits and P-bits are ignored. The
algorithm gives a maximum average reframe time of 1.5 ms.
While the DS3-FRMR is synchronized to the DS3 M-frame, the F-bit and M-bit
positions in the DS3 stream are examined. An out-of-frame defect is detected
when 3 F-bit errors out of 8 or 16 consecutive F-bits are observed (as selected
by the M3O8 bit in the DS3 FRMR Configuration Register), or when one or more
M-bit errors are detected in 3 out of 4 consecutive M-frames. The M-bit error
criteria for OOF can be disabled by the MBDIS bit in the DS3 Framer
Configuration register. The 3 out of 8 consecutive F-bits out-of-frame ratio
provides more robust operation, in the presence of a high bit error rate, than the
3 out of 16 consecutive F-bits ratio. Either out-of-frame criteria allows an out-of-
frame defect to be detected quickly when the M-subframe alignment patterns or,
optionally, when the M-frame alignment pattern is lost.
Also while in-frame, line code violations, M-bit or F-bit framing bit errors, and P-
bit parity errors are indicated. When C-bit parity mode is enabled, both C-bit
parity errors and far end block errors are indicated. These error indications, as
well as the line code violation and excessive zeros indication, are accumulated
over 1 second intervals with the Performance Monitor (PMON). Note that the
framer is an off-line framer, indicating both OOF and COFA events. Even if an
OOF is indicated, the framer will continue indicating performance monitoring
information based on the previous frame alignment.
Three DS3 maintenance signals (a RED alarm condition, the alarm indication
signal, and the idle signal) are detected by the DS3-FRMR. The maintenance
detection algorithm employs a simple integrator with a 1:1 slope that is based on
the occurrence of "valid" M-frame intervals. For the RED alarm, an M-frame is
said to be a "valid" interval if it contains a RED defect, defined as an occurrence
of an OOF or LOS event during that M-frame. For AIS and IDLE, an M-frame
Proprietary and Confidential to PMC-Sierra, Inc. and for its Customers’ Internal Use
74
PMC [ PMC-SIERRA, INC ]
