Preliminary Information
MT9076
Out of synchronization
YES
NO
Search for primary basic frame
alignment signal RAI=1, Es=0.
3 consecutive
incorrect frame
alignment
signals
YES
>914 CRC errors
in one second
NO
Verify Bit 2 of non-frame
alignment signal.
YES
NO
Verify second occurrence of
frame alignment signal.
No CRC
multiframe alignment.
8 msec. timer expired*
YES
Primary basic frame synchronization
acquired. Enable traffic RAI=0, E’s=0. Start
loss of primary basic frame alignment
checking. Notes 7 & 8.
CRC-4 multi-frame alignment
Signalling multi-frame alignment
Search for multiframe
alignment signal.
Start 400 msec timer.
Note 7.
Note 7.
YES
NO
RAI = 0
Multiframe synchronization
acquired as per G.732.
Note 7.
Start 8 msec timer.
Note 7.
Basic frame
alignment acquired
NO
YES
Find two CRC frame
alignment signals.
Note 7.
No CRC
Check for two consecutive errored
multiframe alignment signals.
multiframe
alignment.
Notes 7 & 8.
8 msec.
timer expired**
CRC multiframe
alignment
CRC-to-CRC interworking. Re-align to new basic
Parallel search for new basic frame
alignment signal.
frame alignment. Start CRC-4 processing. E-bits set
as per G.704 and I.431. Indicate CRC synchronization
achieved.
Notes 6 & 7.
Notes 7& 8.
400 msec timer expired
CRC-to-non-CRC interworking. Maintain primary
basic frame alignment. Continue to send CRC-4
data, but stop CRC processing. E-bits set to ‘0’.
Indicate CRC-to-non-CRC operation. Note 7.
*
only if CRC-4 synchronization is selected and automatic CRC-4
interworking is de-selected.
** only if automatic CRC-4 interworking is selected.
Figure 15 - Synchronization State Diagram
45
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