User's Manual

Access P oint Hardw are Installation RF GPS Cable
Table 3 -8 Local GPS Antenna Mounting Consider ations
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1
The mounting pipe for the Local GPS Head should be mounted vertically with less
than five (5) degrees of tilt.
2
The Local GPS Head requires a clear view of the sky , preferably to within ten (10)
degrees of the horizon in all directions. The more sky that is observed increases
the number of potential satellites that can be tracked, resulting in better Local
GPS performance.
3
During normal operation, the Local GPS Head continuously tracks a minimum of
four (4) GPS satellites. However , it is theoretically possible to operate the BTS by
tracking only one (1) GPS satellite. Motorola does not recommend tracking only one
(1) GPS satellite unless there has been an accurate site survey .
4
Place the Local GPS Head where RF obstructions of the sky are minimal. The sky
includes everything to within ten (10) degrees of the horizon in all directions. RF
obstructions include buildings, towers, natural rock formations, snow , foliage, and
debris.
The mounting of the Local GPS head on antenna towers is not
recommended due to increased risk of damage due to lightning strikes. If
tower mounting is necessary the Local GPS head should mounted at the
lowest point possible and still maintain an unobstructed view of the sky .
5
Separate the Local GPS Head from other radiating sources. Excessive RF energy
can degrade the Local GPS Head’s ability to observe the GPS satellites. The Local
GPS Head receives on the GPS L1 frequency of 1575.42 MHz and incorporates
filters to minimize the effects of potential RF interference, however , strong radiants
can overwhelm the filters, thus degrading the units reception capability .
6
The Local GPS Head is rated for ambient air temperatures in the range -40 to +50
degrees C , and has ratings for humidity , shock, waterproofing, UV light resistance,
vibrations, salt, fog, ESD , EMI, and altitude.
7
An RF gain of between +10 dB and +26 dB should be provided to the Local GPS
receiver antenna input. The GPS antenna supplied in the CGDSGPSKITF4NM50
kit provides a nominal gain of +25 dB. The total signal loss from the
CGDSGPSKITF4NM50 antenna output and Local GPS antenna input must be less
than 15 dB at 1.575 GHz.
68P09277A59 -5 3 -11
Draft OCT 2006