Transmission Interface Handling DS1 1544 kbit/s
Fault supervision of each PCM line is performed according to:
•
ANSI T1.403, section 8
•
AT&T T1.5 SERVICE, paragraph 7
The configuration of fault supervision can only be performed when the
AO DP (Digital Path) is in state ”Disable”. The reporting to the BSC is
performed when the AO DP is in state “Enable”. When the AO DP is
enabled, all fault supervision states are set to zero.
Reports are sent to the BSC when the alarm status is changed or when
required from the BSC.
The fault supervision includes detection and reporting of the following
fault conditions:
•
LOF (Loss of Frame Alignment)
•
ERATE (Excessive Error RATE)
•
LOS (Loss Of incoming Signal)
•
AIS (Alarm Indication Signal),”Blue Alarm”
•
RAI (Remote Alarm Indication), “Yellow Alarm”
•
UAST (UnAvailable STate supervision). Consists of two
directions; upstream and downstream.
Fault handling is according to Diagnostic and Fault Handling
functionality.
LOS commences
At least 31 successive pulse positions with no pulses of either positive
or negative polarity have occurred.
LOS ceases
Recovery of frame alignment signal.
LOF commences
A LOF condition is declared when any two of five consecutive received
framing bits contain bit errors in the framing pattern or when LOS
condition is declared.
LOF ceases
Recovery of frame alignment signal.
ERATE commences
An ERATE condition is declared when the bit error rate is equal to or
greater than 1*10
–3
during time T. The number of CRC-6 errors is used
in this evaluation.
EN/LZT 123 2697
R5A
1998-08-13
205 (306)
© Ericsson Radio Systems AB
— All Rights Reserved —
