Transmission Interface Handling G.703 2048 kbit/s
Every detected fault situation is registered and regarded as a disturbance,
even if it does not last long enough to be recognised as a fault.
The DF is supervised and reported as the number of disturbances during
the BI. Both counters are handled separately.
Slip Frequency supervision
This supervision monitors the number of slips per time interval. A slip
is defined as where one frame (256 bits) is either lost or duplicated.
The SF counter is incremented by one for each slip on the PCM port
downstream.
The SF is supervised and reported as the number of slips during the BI.
Errored Seconds supervision
An ES is a second with at least one of the following events:
•
CRC-4 is OFF: At least one frame bit error
•
CRC-4 is ON: At least one CRC-4 error
•
LOF alignment
•
LOS
•
Slip
•
AIS
•
A-bit equal to “1” from the remote end
•
E-bit indication received from the remote end (only valid when
CRC-4 is used)
Two counters for errored seconds exist. Both are derived from the
downstream PCM port, but one is closely connected to downstream
faults while the other one is related to upstream faults.
The downstream counter is incremented by 1 for each second with at
least one of the events:
•
CRC-4 error (only valid when CRC-4 is used) or
•
Frame bit error (only valid when CRC-4 is not used) or
•
LOF or
•
LOS or
•
AIS or
•
Slip
The upstream counter is incremented by 1 for each second with at least
one of the events:
•
A-bit=”1” or
•
E-bit=”0” (only valid when CRC-4 is used)
ES are not counted during unavailable state.
Both ES counters are reported after each BI.
194 (306)
EN/LZT 123 2697
R5A
1998-08-13
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