peb2035 ETC-unknow, peb2035 Datasheet - Page 47

• Manufacturer Part Number: peb2035
• Description: Communications Advanced Cmos Frame Aligner
• Manufacturer: ETC-unknow

Synchronization Procedure
For multiframe synchronization the FAS bits are observed. Synchronous state is reached if at least
one framing candidate is definitely found, or the synchronizer is forced to lock onto the next
available candidate (CCR.FRS).
72-Frame Multiframe
As a special kind of the 12-frame structure, an alternate use of the FS-bit pattern is defined for
carrying data link information. This is done by stealing some of redundant multiframing bits after the
transmission of the 12-bit framing header (refer to table 9). The position of A and B signaling
channels (bit robbing mode) is defined by zero-to-one and one-to-zero transitions of the FS bits and
is continued when the FS bits are replaced by the data link bits. The use of this 24-bit data link
channel, however, is not specified by the ACFA. For access to these bits refer to section General.
Remote Alarm is indicated by setting bit 2 to zero in each channel. An additional use of the D bits
for alarm indication is user defined and must be done externally.
In addition to CAS-BR, CCS and CAS-CC are also applicable to this multiframe structure.
Synchronization Procedure
In the synchronous state terminal framing (FT bits) and multiframing (FS bits of the framing header)
are observed independently. Further reaction on framing errors depends on the selected sync/
resync procedure (via bit EMOD.SSP):
Semiconductor Group
EMOD.SSP = ‘0’: terminal frame and multiframe synchronization are combined
Two errors within four/five framing bits (via bit RC1.SLC) of one of the above will lead to the
asynchronous state for terminal framing and multiframing. Additionally to the bit RSR.LOS, loss
of multiframe alignment is reported via bit FSR.MLOS.
The resynchronization procedure starts with synchronizing upon the terminal framing. If the
pulseframing has been regained, the search for multiframe alignment is initiated. Multiframe
synchronization has been regained after two consecutive correct multiframe patterns have been
received.
EMOD.SSP = ‘1’ : terminal frame and multiframe synchronization are separated
Two errors within four/five terminal framing bits will lead to the same reaction as described above
for the ‘combined’ mode.
Two errors within four/five multiframing bits will lead to the asynchronous state only for the
multiframing. Loss of multiframe alignment is reported via bit FSR.MLOS. The state of terminal
framing is not influenced.
Now, the resynchronization procedure includes only the search for multiframe alignment.
Multiframe synchronization has been regained after two consecutive correct multiframe patterns
have been received.
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PEB 2035