Obstructions and interference
The following types of obstructions and possible sources of interference need to be
considered:
•
Hills, mountains, trees and surrounding plant life.
•
Adjacent buildings or any large sky obstructing structures such as grain elevators,
airplane hangers, bridges, overhead roadways, etc.
•
Water towers or any close range large metal objects that could cause excessive sky
obstruction.
•
Any locations where birds or animals may easily nest or build on or around the
antenna.
•
Any collocated RF transmission antennas, TV stations, cable television cables, or
arc-welding equipment.
•
High-voltage lines will not cause interference with GPS signal reception.
•
Self-supporting or guyed towers will generally not block the GPS signal.
•
Trees do not totally block but rather degrade GPS reception, especially during periods
of heavy rain or snow. Consider if increased summer plant life could also become a
problem.
•
If a GPS antenna is mounted to a monopole antenna mast, it must be mounted a
minimum distance (D) from the monopole such that less than 12.5% of a contiguous
surface area of a hemisphere around the antenna is blocked by the monopole. The
GPS antenna must be spaced a minimum distance D = 1.61 x R (where R is the radius
of the monopole at the attachment point of the GPS antenna), from the outside surface
of the monopole.
Example:
Monopole radius (inches) R = 12
D = (1.61 x 12)
D = 19.3" minimum
This example assumes, of course, that the monopole is the only obstruction to be
considered, and constitutes a contiguous 12.5% blockage of the sky. This condition would
constitute a contiguous blockage in one quadrant of the hemisphere.
GPS antenna installation
GPS antenna installation (general)
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9927 Dist BTS Outdoor
401-703-516
Issue 1
March 2012
Alcatel-Lucent – Proprietary
Use pursuant to applicable agreements
E-3