Viper SC+™ IP Router for Licensed Spectrum PN 001-5008-000 Rev. C
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2.4.
SITE SELECTION AND SITE SURVEY
2.4.1.
SITE SELECTION
For a successful installation, careful thought must be given to selecting the site for each radio. These requirements can
be quickly determined in most cases. Suitable sites should provide the following.
Protection from direct weather exposure.
A source of adequate and stable primary power.
Suitable entrances for antenna, interface, or other cabling.
Antenna location with an unobstructed transmission path to all remote radios in the system.
2.4.2.
SITE SURVEY
A Site Survey is an RF propagation study of the RF path between two points or between one point and multiple points.
UHF radio signals travel primarily by line of sight and obstructions between the sending and receiving stations will
affect system performance. Signal propagation is also affected by attenuation from obstructions such as terrain,
foliage, or buildings in the transmission path. A Site Survey is recommended for most projects to determine the optimal
RF paths for each link. This is especially true when more than one RF coverage area is required. A Site Survey will
determine the best unit location for the Relay Points.
2.5.
SELECTING ANTENNA AND LIGHTNING ARRESTOR COMBINATIONS
Very Important! Before you deploy your system you must read and understand this section.
RF engineers and installers have seen many types of radio installations over the years, and they know there are certain
details that must not be overlooked at any installation. Most radio installations contain some form of lightning
protection. However, the wrong combination of antenna and lightning arrestor can create high voltage transients on
the radio’s antenna port having devastating impacts on the life and reliability of modern day radio equipment.
2.5.1.
LIGHTNING ARRESTOR O VERVIEW
Lightning arrestors can take many forms. But some of the most common lightning arrestors use gas discharge tubes
that turn on when the voltage across their terminals exceeds the specified threshold. Under normal conditions, these
devices have very high impedance and no current flows through the device. When the turn on voltage threshold is
exceeded, the gas discharge tube turns on instantaneously and becomes a short.
This functionality works well to limit the magnitude of a transient from a nearby lightning discharge. However, it can
have very negative consequences if a gas discharge lightning arrestor is used with the wrong antenna.
