Recommended Periodic Checks; Troubleshooting; Troubleshooting Rcvr Lockup Problems; Troubleshooting Performance Screen Errors - Alcatel MDR-8000 User Manual

RECOMMENDED PERIODIC CHECKS

5.4
Perform XMT local oscillator frequency verification (Para. 5.14) and XMTR Output Check
(Para. 5.15) one year after initial setting and at 5-year intervals thereafter to correct for
possible drift caused by aging.

TROUBLESHOOTING

5.5
The digital radio system is equipped with alarm circuitry and automatic switching (in hot-
standby, frequency diversity, and space diversity configurations) to provide protection
against loss of traffic. This automatic switching, coupled with adaptive equalization of mul-
tipath distortion, provides protection against equipment outage and propagation varia-
tions. Because of the finite life of electronic equipment, failures occur.
Troubleshoot using alarm troubleshooting Figure 5 - 1 through Figure 5 - 10. After insulat-
ing the fault to the most probable cause, replace modules or repair as directed. The Module
replacement Matrix identifies the alignment procedures to be performed after a module
has been replaced.

Troubleshooting RCVR Lockup Problems

5.5.1
The radio is operational when the RCVR is locked onto the associated farend XMTR fre-
quency. Normally lockup occurs within minutes after power is applied. Successful lockup is
indicated by not having the channel alarm (Chan Alm) lit on the RCVR front panel.
Slow Lockup At Initial Turnup
5.5.1.1
Slow lockup at initial turnup is defined as lockup occurring five minutes or more after pow-
erup. If the radio is non-standby/no space diversity (one RCVR in A side), replace the RCVR.
If radio is non-standby space diversity or hot-standby (two RCVRs, A and B sides) problem
is probably the XMTR at the farend of the hop. The most common cause of slow lockup is
incorrect carrier null. First try switching XMTRs. If this clears the problem, perform carrier
null (Para. 5.16, Para. 5.17, or Para. 5.18) and XMTR/PA calibration procedure (Para. 5.19/
Para. 5.23) on the off-line XMTR. If the problem is not cleared, replace the XMTR.
5.5.1.2 Slow Lockup During Normal Operation
Slow lockup after a bad fade or other temporary interruption is defined as lockup occurring
less than a second after RSL is restored. Troubleshooting this type of slow lockup requires
knowing what the RSL is. Check RSL using the procedure in Appendix E.
If the RSL is at least 4 to 5 dB above RCV threshold, the two most probable causes are car-
rier leakage and the RCVR local oscillator. Perform carrier null test (Para. 5.16, Para. 5.17,
or Para. 5.18) on the farend XMTR. If slow lockup continues, remove and replace the
RCVR crystal oscillator subboard.
If the RSL is below or 1 to 3 dB above RCVR threshold, wait until RSL improves to at least
4 to 5 dB above RCVR threshold before starting troubleshooting.

Troubleshooting performance Screen Errors

5.5.2
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.
5-3