PM7344 S/UNI-MPH
DATA SHEET
PMC-950449
ISSUE 6
MULTI-PHY USER NETWORK INTERFACE
9.3
T1/E1 Framer (FRMR)
The framing function is provided by the FRMR block. This block searches for the
framing bit position in the incoming data stream. It searches for the framing bit
pattern for the following T1 frame formats: SF, and ESF. When searching for
frame, the FRMR examines each of the 193 (SF), or each of the 4*193 (ESF)
framing bit candidates. For the E1 frame format, the FRMR searches for frame
alignment and CRC multiframe alignment in the incoming stream.
The time required to find frame alignment to an error-free PCM stream
containing randomly distributed channel data (i.e. each bit in the channel data
has a 50% probability of being 1 or 0) is dependent upon the framing format. For
SF, the FRMR determines frame alignment within 4.4ms, 99 times out of 100.
For ESF the FRMR determines frame alignment within 15ms, 99 times out of
100. For E1 formatted signals, the FRMR determines frame alignment within
1ms, 99 times out of 100.
When the FRMR has found T1 frame alignment, the incoming data is
continuously monitored for framing bit errors, CRC-6 error events (ESF only),
and severe errored framing events. The FRMR also detects loss of frame,
based on a selectable ratio of framing bit errors.
When the FRMR has found E1 frame alignment, the incoming data is monitored
for frame alignment signal bit errors. Upon detecting CRC multiframe alignment,
the FRMR monitors the incoming data for CRC multiframe alignment pattern
errors, and CRC-4 errors. The FRMR also detects loss of frame, and loss of
CRC multiframe, based on user-selectable criteria.
The FRMR extracts the yellow alarm signal bits in T1-SF and T1-ESF framing
formats. The FRMR extracts and debounces the remote alarm indication signal
in the E1 framing format.
9.4
Alarm Integrator (ALMI)
The Alarm Integration function is provided by the ALMI block. This block detects
the presence of T1 yellow, red, and AIS Carrier Fail Alarms (CFA) in SF and ESF
formats. The block also detects the presence of E1 red CFA and AIS CFA. The
alarm detection and integration is compatible with the specifications defined in
ANSI T1.403-1989, TR-TSY-000191, and Q.516.
For T1 formats, the ALMI block declares the presence of yellow CFA when the
yellow pattern has been received for 425 ms (± 50 ms); the yellow CFA is
removed when the yellow pattern has been absent for 425 ms (± 50 ms). The
presence of red CFA is declared when an out-of-frame condition has been
present for 2.55 sec (± 40 ms); the red CFA is removed when the out-of-frame
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
44
PMC [ PMC-SIERRA, INC ]
