Handbook

PBL UHF1/1A 1 & 2 Air Interface
Maintenance Handbook
H/book Number:-60-055900HBKM
Issue No:-2
Date:-20/10/2003
Page:-
81 of 85
7.1.2 Downlink
Confirm that there is a signal at the expected frequency and strength from the base station. If
this is not present then the fault may lay outside the system. To confirm this, inject a
downlink frequency signal from a known source at the master site BTS input and check for
output at the remote site feeder output.
If a signal is not received at the output it will be necessary to follow the downlink path
through the system to find a point at which the signal is lost. The expected downlink output
for the given input can be found in the end-to-end test specification.
7.1.3 Uplink
Testing the uplink involves a similar procedure to the downlink except that the frequencies
used are those transmitted by the mobile equipment.
7.1.4 Fault repair
Once a faulty component has been identified, a decision must be made on the appropriate
course to carry out a repair. A competent engineer can quickly remedy typical faults such as
faulty connections or cables. The exceptions to this are cable assemblies connecting
bandpass filter assemblies that are manufactured to critical lengths to maintain a 50-ohm
system. Care should be taken when replacing cables or connectors to ensure that items are of
the correct specification. The repair of component modules such as amplifiers, tuned cavities
or bandpass filters will not usually be possible in the field, as they frequently require
specialist knowledge and test equipment to ensure correct operation. It is recommended that
items of this type are replaced with a spare unit and the faulty unit returned to AFL for
repair. If spare parts need to be ordered from AFL, be sure to quote the serial number of the
Cell Enhancer/Repeater and the serial number [and frequencies] of the module(s) to be
replaced.