User's Manual

455U-D Radio Modem Module User Manual
Page 60 © Jan 2008
4.5 Radio Path Testing
To carry out a radio path test, you will need two 455U modules. One module will be “fixed”
and the other “mobile”. Both units will need power supplies and antennas. The power supply
for the mobile unit is normally a 12V battery, but make sure that the battery is fully charged -
batteries with low voltage will lead to low radio power which will affect the test result.
The object of the test is to determine whether radio paths are reliable, marginal or unreliable.
A reliable path will have a margin of at least 10dB above the minimum required signal level in
good weather - this margin is enough to ensure that the radio path remains reliable in poor
conditions, and with changes in antennas and environment over time. A marginal path will
work reliably in good conditions, however may fail during poor conditions or if the landscape
changes over time. A margin of 10 dB is recommended as a safe minimum.
Set up as per section 4.4.1 to carry out a BER test.
Procedure:
 Configure the modules on the bench to communicate with each other in Unacknowledged
mode.
 When the modules are close to each other, carry out a BER test without any antennas
connected, to make sure that the modules will communicate with each other.
 Set up the fixed module in one of the test positions - this is normally at a control centre or
repeater site. Fix the antenna in a temporary fashion. You will need to make an initial
assessment on how high the antenna should be mounted.
Diagnostics information
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