Tasks
GPS Receivers can be susceptible to reflected GPS signals called multipath signals. Mul-
tipath interference is caused by reflected signals that arrive at the antenna out of phase with
the direct signal. This interference is most pronounced at low elevation angles from 10 to 20
degrees above the horizon. The height of the mast/antenna may be extended upward to
lessen multipath interference. The antenna should also be at least three to six feet (1-2 m)
from a reflecting surface.
Use the criteria below to select a good outdoor site for the GPS antenna.
The best locations provide:
n Unobstructed views of the sky and horizon.
n Low electro-magnetic interference (EMI) and radio frequency interference (RFI) - away
from high-power lines, transmitting antennas, and powerful electrical equipment.
n Convenient access for installation and maintenance.
n Reasonable access for the antenna cable to reach the SyncServer.
n Safety from hazards to people and equipment.
Avoid:
n Overhanging foliage
n Blocked views
n Strong EMI RFI interference
n Multipath interference (caused by adjacent structures that reflect GPS signals)
Mounting structures:
n GPS antenna masts, vent pipes, or railings are usually satisfactory.
n Radio towers may require the services of a specialist, and may be subject to signal inter-
ference.
n Must be able to withstand very high winds.
If a good site is not available, consult Operating in "Window Mode" (on page 143).
Installing the GPS Antenna
1. Observe all relevant safety precautions and building code regulations. Avoid:
n Electrocution, RF, lightning, and falling hazards.
n RFI and EMI sources such as transmitting antennas.
n Crimping or making sharp bends in the cable.
2. Mount the standard L1 GPS antenna at the selected site:
n Position the GPS antenna vertically, with its top pointing toward the sky, and the
PVC mounting mast and connector pointing down.
n Secure the PVC mounting mast to the structure using the pipe clamps provided
with the antenna kit.
3. Run the antenna cable or cables to the SyncServer. Use a lightning arrestor and ground-
ing, as required to meet building and safety codes.
4.
Connect the antenna cable to the GPS Ant connector on the rear panel.
Page 142..........................................................................997-01520-02 Rev. F1
To Next Page
Loading...
