PM5366-PI PMC-Sierra, Inc., PM5366-PI Datasheet - Page 80

• Manufacturer Part Number: PM5366-PI
• Description: HIGH DENSITY 84/63 CHANNEL VT/TU MAPPER AND M13 MULTIPLEXER
• Manufacturer: PMC-Sierra, Inc.

PRELIMINARY
DATASHEET
PMC-2010672
PROPRIETARY AND CONFIDENTIAL
(or distant multiframe) Alarm (bit 6 of timeslot 16 of frame 0 of the CAS
multiframe). Access is also provided to the "debounced" remote alarm and
remote signaling multiframe alarm bits which are set when the corresponding
signals have been a logic 1 for 4 (provided the RAIC bit is logic 1) and 3
consecutive occurrences, respectively, as per Recommendation O.162.
Detection of AIS and timeslot 16 AIS are provided. AIS is also integrated, and an
AIS Alarm is indicated if the AIS condition has persisted for at least 100 ms. The
out of frame (OOF=1) condition is also integrated, indicating a Red Alarm if the
OOF condition has persisted for at least 100 ms.
An interrupt may be generated to signal a change in the state of any status bits
(INF, INSMF, INCMF, AIS or RED), and to signal when any event (RAI, RMAI,
AISD, TS16AISD, COFA, FER, SMFER, CMFER, CRCE or FEBE) has occurred.
Additionally, interrupts may be generated every frame, CRC submultiframe, CRC
multiframe or signaling multiframe.
Basic Frame Alignment Procedure
The E1 framer searches for basic frame alignment using the algorithm defined in
ITU-T Recommendation G.706 sections 4.1.2 and 4.2.
The algorithm finds frame alignment by using the following sequence:
1. Search for the presence of the correct 7-bit FAS (‘0011011’);
2. Check that the FAS is absent in the following frame by verifying that bit 2 of
the assumed non-frame alignment sequence (NFAS) TS 0 byte is a logic 1;
3. Check that the correct 7-bit FAS is present in the assumed TS 0 byte of the
next frame.
If either of the conditions in steps 2 or 3 are not met, a new search for frame
alignment is initiated in the bit immediately following the second 7-bit FAS
sequence check. This "hold-off" is done to ensure that new frame alignment
searches are done in the next bit position, modulo 512. This facilitates the
discovery of the correct frame alignment, even in the presence of fixed timeslot
data imitating the FAS.
The algorithm provides robust framing operation even in the presence of random
bit errors; the algorithm provides a 99.98% probability of finding frame alignment
within 1 ms in the presence of 10
Once frame alignment is found, the INF context bit is set to logic 1, a change of
frame alignment is indicated (if it occurred), and the frame alignment signal is
monitored for errors occurring in the 7-bit FAS pattern and in bit 2 of NFAS
ISSUE 1
-3
bit error rate and no mimic patterns.
68
HIGH DENSITY 84/63 CHANNEL VT/TU MAPPER
AND M13 MULTIPLEXER
PM5366 TEMAP-84