Symmetricom TimeProvider 100 User Manual page 114

Chapter C
Installing Antennas
Recommendation: Symmetricom recommends that you consider the
following location and environment influences before installing the
GPS antenna:
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Developing a Grounding Scheme
In addition to determining where to locate and mount the antenna and cabling, you
should develop a grounding scheme. The purpose of the grounding scheme is to
provide some protection against voltage surges and static discharge. If transient
eliminators are used, they also need to be connected to the perimeter ground
system or bulkhead entrance panel that is connected to the perimeter ground
system.
Caution: To ensure proper grounding, observe these precautions
when installing the antenna:
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In general, follow local building codes when selecting a grounding scheme, wire
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size, and installation.
114 TimeProvider 100 User's Guide
If possible, provide the antenna with an unobstructed 360-degree
view of the sky from the horizon.
In general, do not allow obstructions that obscure the horizon (as
viewed from the antenna) by more than 10 degrees, as shown in
Figure C-1.
Locate the antenna well away from, and preferably in a plane
above electrical equipment such as elevators, air conditioners, or
other machinery.
To reduce the risk of lightning damage, do not place the antenna at
the highest point of the building.
Locate the GPS antenna at least 12 feet from metallic objects, if
possible.
Locate the antenna high enough to avoid drifted snow.
Locate the transient eliminator in a protected area to avoid contact
with standing water.
Locate the antenna within 30 feet of the point at which the antenna
cable enters the building.
Allow at least 10 feet of separation distance between GPS
antennas.
Surfaces above the plane of the unit that are between the antenna
and the horizon can produce reflected (multi-path) signals, which
can degrade the performance of the radio receiver.
Allow no sharp bends in the ground conductors.
Ensure that no painted surface insulates the transient eliminator or
grounding clamps.
Ensure that ground conductors are bonded to the metal enclosure
box (if used) and do not enter through an access hole.
Do not use soldered connections for grounding purposes.
Secure all grounding connections with mechanical clamp type
connectors.
098-00106-000 Revision A – March, 2009