Alcatel-Lucent MDR-8000, User Manual, Page: 67 / 130

5-9
5.9.3
Troubleshooting Performance Screen Errors
Path and intermod problems can occur that cause errors to be indicated on the Perfor-
mance monitor screens that are not severe enough to generate an alarm on the USI Alarm
and Status screen. Errors of this type fall into two categories: burst and dribbling errors.
The performance screens can be a useful tool in troubleshooting a radio with and without
alarms being indicated on the Status Alarm screen.
5.9.3.1 Troubleshooting Burst Errors
Burst errors are defined as multiple errors in a very short time. Burst errors can be caused
by many things, including loose connections on cable or waveguide at either end of the hop.
An aging oscillator can cause burst type errors. Burst errors can be identified by a high
number of
Errors
and low number of
Error Seconds
on the Performance screens. The
most probable cause of burst errors is a loose connection. Check/repair all shelf and exter-
nal cables and check all waveguide connections The next most probable cause is the crystal
on the crystal oscillator subboard at either end of the hop.If the radio has both A and B
XMTRS and RCVRS and both A and B are indicating burst errors, the fault is at the XMT
end of the hop. If only A is equipped and indicates burst errors, remove and replace the
crystal oscillator subboard on the on-line RCVR.
5.9.3.2 Troubleshooting Dribbling Errors
Dribbling errors are defined as small number of errors over long period of time (no frame
errors). Dribbling errors can be caused by a path problem, such as interference or fading,
or by a hardware problem such as a XMTR or PA that is being over driven, or high phase
noise in the XMTR or RCVR oscillator. Dribbling errors can be identified by observing the
Radio CRC Errors
(DS1),
Radio Errors
(DS3),
Receiver Errors
(OC3), or
RF Receiver
Errors (ETH) fields on the radio Performance screen. Typically, less than five Errors to one
Error Second identifies the fault as dribbling errors. Try isolating the transmitter by
switching transmitters in a protected system. You can further isolate a transmitter by
changing output levels using ATPC and or dropping the output power out of the XMTR to
the PA by one or two dB.
The DS1 radio performance screen has a Repeater CRC Error Sec field that indicates
errors over the repeater cable.
Two troubleshooting tips: 1) errors are displayed on the USI at the receive end in which
they are detected, and 2) these specific type of radio errors are not propagated down the
path.