STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
will determine frame alignment within 4.4 ms 99 times out of 100. For SLC®96
format, the T1-FRMR will determine frame alignment within 9.9 ms 99 times out
of 100. For extended superframe format (ESF) and J1, the T1-FRMR will
determine frame alignment within 15 ms 99 times out of 100. For T1DM format,
the T1-FRMR will determine frame alignment within 1.125 ms 99 times out of
100.
Once the T1-FRMR has found frame, the incoming PCM data is continuously
monitored for framing bit errors, bit error events (a framing bit error in SF or
SLC®96, a framing bit error or sync bit error in T1DM, or a CRC-6 error in ESF
and J1), and severe errored framing events. The T1-FRMR also detects loss of
frame, based on a selectable ratio of framing bit errors.
The T1-FRMR extracts the Yellow alarm signal bits from the incoming PCM data
stream in SF and SLC®96 framing formats, and extracts the Y-bit from the T1DM
sync word in T1DM framing format. The T1-FRMR also extracts the SLC®96
data link in SLC®96 framing format (with external logic), extracts the facility data
link bits in the ESF and J1 framing formats, and extracts the R-bit from the T1DM
sync word in T1DM framing format.
The T1-FRMR can also be disabled to allow reception of unframed data.
9.4
E1 Framer
The E1 framing function is provided by the E1-FRMR block. The E1-FRMR block
searches for basic frame alignment, CRC multiframe alignment, and channel
associated signaling (CAS) multiframe alignment in the incoming recovered PCM
stream.
Once the E1-FRMR has found basic (or FAS) frame alignment, the incoming
PCM data stream is continuously monitored for FAS/NFAS framing bit errors.
Framing bit errors are accumulated in the framing bit error counter contained in
the PMON block. Once the E1-FRMR has found CRC multiframe alignment, the
PCM data stream is continuously monitored for CRC multiframe alignment
pattern errors, and CRC-4 errors. CRC-4 errors are accumulated in the CRC
error counter of the PMON block. Once the E1-FRMR has found CAS
multiframe alignment, the PCM data is continuously monitored for CAS
multiframe alignment pattern errors. The E1-FRMR also detects and indicates
loss of basic frame, loss of CRC multiframe, and loss of CAS multiframe, based
on user-selectable criteria. The reframe operation can be initiated by software
(via the E1-FRMR Frame Alignment Options Register), by excessive CRC errors,
or when CRC multiframe alignment is not found within 400 ms. The E1-FRMR
also identifies the position of the frame, the CAS multiframe, and the CRC
multiframe.
PROPRIETARY AND CONFIDENTIAL
39
PMC [ PMC-SIERRA, INC ]
