Chapter 3 Pre-Installation Gen 3 Site Controller System Manual
Antenna Installation
3-20 68P80801E30-A 5/1/2002
■ Tracking a minimum of four satellites during initial start-up or after loss of
power.
■ Tracking three satellites continuously for maximum reliability.
GPS Evaluation Kit
The Motorola GPS evaluation kit can be used to evaluate the site and
antenna mounting location prior to site acceptance. Although many GPS
receivers are available, the Motorola GPS evaluation kit includes the same
receiver and antenna used in the system. The data reported by this kit is the
same as that used by the system, if the antennas were installed in the test
locations.
The evaluation kit includes software programs and the instructions for
collecting the necessary site evaluation data. The necessary data includes:
■ number of visible satellites
■ number of satellites being tracked
GPS Antenna Requirements
The two GPS antennas should be mounted at least 10’ apart with an
unrestricted aerial down view to within 10° of the horizon in all directions.
This provides a degree of redundancy in case the antennas are damaged by
falling objects or inadvertent shadowing.
The antennas must be mounted high enough to clear the peak of the site
roof. For systems in the northern hemisphere, GPS antennas should be
mounted so that a clear view of the southern sky is maintained. For systems
in the southern hemisphere, GPS antennas should be mounted so that a clear
view of the northern sky is maintained.
Isolate the GPS antennas from RF interference by mounting the antennas at
least 12’ horizontally from other transmitting antennas.
Adjacent structures, such as trees or buildings, are obstructions due to their
wide, solid profiles. Mount the GPS antennas to clear these obstructions and
provide a clear path. Adjacent antenna towers at the RF site which protrude
into the required view have a minimal effect on GPS satellite reception and
are not obstructions.
Note: The color coding schemes identified within this manual are a
recommendation only. The purpose for identifying specific colors is
an attempt to obtain uniformity between sites. Other color schemes
may be used.
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