Appendix A: Additional Technical Information
150-402-102-01, Revision 01
46
July 27, 1998
HRU-402 List 2
The BER option also uses this (BPVT/CRC) TEC to generate an alarm if
enabled. The HLU combines the one second TEC counts in both directions
for the last 60 seconds. The line unit uses this one minute Total System Error
Count (TSEC) to generate an alarm if it exceeds the selected BER threshold
of (1E-6 or 1E-7) as follows:
•
BER option=1E-6. Alarm is generated if TSEC>92
•
BER option=1E-7. Alarm is generated if TSEC>9
Once initiated, the alarm clears when the TSEC drops below its associated
threshold count. For irregular intermittent errors, the alarm can come and go
in intervals as short as one second. Alarms usually require the full 60 seconds
or longer to clear depending on the frequency of the transient errors. This
BER option is always present in any line unit circuit since it is independent
of the versions of the other HiGain modules in the circuit.
Remote DS1 Alarm (RDA) Option
The Receive Loss of Signal (RLOS) alarm output at the HLU can be inhibited
by disabling the RDA option. This prevents a LOS condition at the DS1 input
to the HRU-402 List 2 from activating a system alarm output at the HLU.
However, the HLU front panel Status LED still flashes red and the ALRM
RLOS message is displayed to alert the user of the LOS state. LOS is sent
towards the network from the HLU. This option prevents the common
occurrences of a CPE LOS condition from generating recurring alarms and
Alarm Indication Signal (AIS) payloads.
