CBUPRI/E1 SBUPRI-23/30 User Manual
80-14005000-01
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2.5.1 Physical PRI Error conditions
•
AIS/Blue received (Alarm Indication Signal - from local NT)
•
RAI/Yellow received (Remote Alarm Indication - from remote NT)
•
RED Loss of Frame Alignment
•
RED Loss of signal
•
Detection of CRC Errors
The last three are all locally sensed conditions from the NT.
2.5.2 Consequent Actions to Error Conditions
A number of consequential actions take place when one or more of the
error conditions listed in the section above occur. These are detailed in
the following sub-sections.
2.5.2.1 Remote Alarm Indication
RAI is transmitted from a remote unit as a result of detecting any of the
following:
•
Loss of signal
•
Loss of Frame Alignment
•
Received Alarm Indication Signal/Blue
2.5.2.2 CRC Error Information
CRC Error Information is generated in the PRI (see section
2.4.1
) as a
result of the following:
•
Loss of Signal (But only when Loss of Frame Alignment has not yet
occurred)
•
Detection of Incoming CRC Errors. When excessive errors are
detected, line re-synchronisation is performed. At this point the unit
detecting errors will issue a Red alarm.
