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Section 14. Troubleshooting Guide
sections following illustrate things to look for and tests to perform to
troubleshoot RF operations.
14.6.1 Checking RF Components and Connections
Before testing RF signal strength, there are several things that should be done
to verify that the right RF components are in place.
1. Check that the RF modem has the correct switch ID set on the DIP switches.
(This is a common problem and should be checked first.)
2. Check the type and brand of the radio. In general, the radios in a network
should be the same type.
3. Check that the radio is set for the right frequency. With a programmable
radio, verify that the correct frequency and other settings are set properly. If
the radio is crystal based there should be a label showing the frequency. If not,
you will have to test the radio with a programmable scanner or frequency
analyzer.
4. Check the cable connecting the radio to the RF modem. Different
combinations of radios and RF modems require specific cables to make the
right connections. For questions in this area, contact the network installer or
Campbell Scientific.
5. Check that the antenna is the right type (directional or omnidirectional) and
is designed for the frequency being used. Most antennas will have labels
identifying the frequency range. Make sure the antenna is mounted for a clear
line-of-sight and that directional antennas are properly oriented.
6. Make sure the antenna is the right impedance to match the system. This is
almost always 50
Ω
. This should match the cable connecting the antenna to the
radio and the radio connection.
7. Check that the cable connecting the radio to the antenna matches the
impedance of the antenna and the radio. This is almost always 50
Ω
.
One simple, but very effective, technique is to swap out components. Use
components from a part of the network that you know is working, and swap
them out one at a time to isolate a faulty hardware component.
14.6.2 RF Signal Strength Testing
Once you have verified that the right equipment is in place, make sure that all
of the components have power. Then you are ready to proceed with
performance testing.
To test a station’s radio/cable/antenna transmission capabilities, a directional
watt meter is needed such as the Bird Electronic Corporation’s Model 4304A
Wattmeter. Proper connectors are also needed to place the watt meter in series
between the radio and antenna cable. A voltmeter is required to measure the
battery voltage of the datalogger with and without radio transmission.
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