Handbook

Denver Channelised CE
User/Maintenance Handbook
Handbook Nō.-50-063708HBKM Issue No:-2
Date:-03/11/2003
Page:-
46 of 51
7. MAINTENANCE
7.1 General Procedures
7.1.1 Fault Finding
In the event that the performance of the system is suspect, a methodical and logical approach
to the problem will reveal the cause of the difficulty. The System consists of modules within
a wall mounted, environmentally protected enclosure
Transmissions from the main base stations are passed though the system to the mobile radio
equipment; this could be a handheld radio or a transceiver in a vehicle. This path is referred
to as the downlink. The return signal path from the mobile radio equipment to the base
station is referred to as the uplink.
The first operation is to check the alarms of each of the active units and determine that the
power supplies to the equipment are connected and active.
This can be achieved remotely (via CEMS, the RS232 Cell Enhancer Management System,
if fitted), or locally with the front panel LED’s. The green LED on the front panel should be
illuminated, while the red alarm indicator should be off.
If an Alarm is on, then that individual shelf must be removed and individually tested against
the original test specification.
The individual amplifier units within the shelf have a green LED showing through a hole in
their piggy-back alarm board, which is illuminated if the unit is working correctly.
If an amplifier is suspect, check the DC power supply to the unit. If no other fault is
apparent use a spectrum analyser to measure the incoming signal level at the input and then
after reconnecting the amplifier input, measure the output level. Consult with the system
diagram to determine the expected gain and compare result.
In the event that there are no alarms on and all units appear to be functioning it will be
necessary to test the system in a systematic manner to confirm correct operation.