Datasheet

DS21354/DS21554 3.3V/5V E1 Single-Chip Transceivers
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5.2. Synchronization And Resynchronization
Once synchronization is accomplished there are certain criteria that can cause a resynchronization. These
criteria are detailed in Table 5-2. Also see Figure 18-14 for a flow chart of the synchronization process.
Table 5-2. SYNC/RESYNC Criteria
FRAME OR
MULTIFRAME
LEVEL
SYNC CRITERIA RESYNC CRITERIA ITU SPEC.
FAS FAS present in frame N
and N + 2, and FAS not
present in frame N + 1
Three consecutive incorrect FAS
received
Alternate (RCR1.2=1) the above
criteria is met or three
consecutive incorrect bit 2 of
non–FAS received
G.706
4.1.1
4.1.2
CRC4 Two valid MF alignment
words found within 8 ms
915 or more CRC4 codewords
out of 1000 received in error
G.706
4.2 and 4.3.2
CAS Valid MF alignment word
found and previous time
slot 16 contains code other
than all zeros
Two consecutive MF alignment
words received in error
G.732 5.2