363-206-285
Circuit Pack Descriptions
Issue 3 June 2001
7-71
Fault Detection Circuitry 7
The BBG4/BBG4B DS3 circuit pack has in-service and out-of-service built-in test
capability. In-service testing is continuous and errors are reported when they
occur to the SYSCTL via the intra-shelf control bus. An out-of-service test is
performed whenever the BBG4/BBG4B DS3 circuit pack is inserted or recovers
from a transient failure.
The incoming DS3 signal is monitored for bipolar threshold crossings in excess of
10
-3
or 10
-6
, LOS, DS3 OOF, and DS3 AIS. Incoming STS-1 signals are monitored
for STS AIS, STS LOP, and yellow and are also monitored for DS3 OOF and AIS.
Loopbacks 7
Two loopbacks are provided on the BBG4/BBG4B DS3. The terminal loopback
bridges the DS3 desynchronizer output signal (transmitted towards the DSX-3)
back into the DS3 synchronizer input. Operation of the loopback does not affect
the signal transmitted to the DSX-3. The facility loopback bridges the STS-1
output signal to the OLIU back towards the DSX-3. Operation of this loopback
does not affect the signal transmitted to the fiber. Both loopbacks are controlled by
the SYSCTL through the intra-shelf control bus.
Performance Monitoring 7
The BBG4/BBG4B DS3 circuit pack provides PM circuitry for the following
performance parameters:
â– STS path parameters derived from B3 coding violations
â– DS3 path parameters derived from P-bit coding violations
â– DS3 path parameters derived from frame and multiframe (F&M) bit errors
â– DS3 line errors based on B3ZS violations (BBG4B only)
â– DS3 P-bit and F&M bit PM for both directions of transmission (BBG4B only)
â– C-bit parity and FEBE performance monitoring for both directions of
transmission (BBG4B only).
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