PM7344 datasheet(60/293 Pages) PMC

60 / 293 page

PM7344 S/UNI-MPH

DATA SHEET

PMC-950449

ISSUE 6

MULTI-PHY USER NETWORK INTERFACE

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

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

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