Date Code 20181001 SEL-3031 Instruction Manual
Installation
Overview
2.5
Regional conditions also impact the probability of signal fade. Generally, mountainous
terrain is more favorable, while tropical areas and those near large bodies of water are
less favorable. One of the results from a site survey is the fade margin. A fade margin
of 15 dB will yield good radio performance.
Site Survey
A line-of-sight path provides the most reliable transmission in all cases. As the distance
increases the need for a clear path becomes more critical in creating a reliable,
available radio link. If the radio path is short then a path study may not be needed. If
you have a clear line-of-site to the other location without obstructions to the Fresnel
zone (see Radio Path) then a path study is generally not needed. Longer distances may
require a path study, a visual path inspection, and a spectrum analysis of the area to
give a good indication of how high the antenna needs to be and how good the radio link
will be.
Radio Interference
The SEL-3031 shares a frequency spectrum with other services and FCC Part 15
(unlicensed) devices in ITU Region 2 (North, Central, and South America). This radio
should not be used in Chile or Peru because of the regulations defining frequency
allocation. Error-free communications may not be achievable in a given location, and
some level of interference should be expected.
Consider the following points when setting up your system:
➤ Use directional Yagi antennas helps to narrow the radio path and
provide the best path to prevent adjacent interference.
➤ If you suspect interference from a nearby, licensed system (such as a
paging transmitter), it may be helpful to use horizontal polarization
for all of the antennas in the network. Horizontal polarization can
help improve signal availability but will likely increase the path loss.
Horizontal polarization can provide an additional 20 dB of
attenuation to interference because most other services use vertical
polarization in these bands. Figure 2.2 demonstrates antenna
mounting for both vertical and horizontal polarization.
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