PM4341AT1XC
DATA SHEET
PMC-900602
ISSUE 7
T1 FRAMER/TRANSCEIVER
standard superframe format (SF; also known as D4 format), the FRMR block will
determine frame alignment within 4.4ms 99 times out of 100. For SLC®96
format, the FRMR will determine frame alignment within 9.9ms 99 times out of
100. For extended superframe format (ESF), the FRMR will determine frame
alignment within 15ms 99 times out of 100. For T1DM format, the FRMR will
determine frame alignment within 1.125ms 99 times out of 100.
Once the FRMR has found frame, the internal INFRAME indication is set high
and 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 severe errored framing events. The
FRMR also detects loss of frame, based on a selectable ratio of framing bit
errors.
The 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 FRMR also extracts the SLC®96 data
link in SLC®96 framing format, extracts the facility data link bits in ESF framing
format, and extracts the R-bit from the T1DM sync word in T1DM framing format.
The FRMR can also be disabled to allow reception of unframed data. While the
FRMR is disabled, control of the FRAM block is relinquished for use as the
elastic store.
8.5 Framer/Slip Buffer RAM (FRAM)
The Framer/Slip Buffer RAM function is provided by the FRAMER RAM (FRAM)
block.The FRAM is used to store up to 4 frames of PCM data while the FRMR is
finding frame and up to 2 frames of PCM data during normal operation (i.e.
when accessed by Elastic Store).The FRAM is shared between the Elastic Store
(ELST) and the FRMR: when frame synchronization is lost, the FRMR takes
control of the FRAM and uses it to find frame; when frame synchronization is
determined, the FRMR relinquishes control of FRAM to ELST which buffers the
incoming PCM data.
8.6 Inband Loopback Code Detector (IBCD)
The Inband Loopback Code Detection function is provided by the IBCD block.
This block detects the presence of either of two programmable INBAND
LOOPBACK ACTIVATE and DEACTIVATE code sequences in either framed or
unframed data streams.The inband code sequences are expected to be
overwritten by the framing bit in framed data streams. Each INBAND
LOOPBACK code sequence is defined as the repetition of the programmed code
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
41
PMC [ PMC-SIERRA, INC ]
