3: Installation/Configuration; Installing The Gps Antenna; Selecting A Gps Antenna Site Outdoors; Mounting The Gps Antenna - Symmetricom XLi User Manual

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3: Installation/Configuration

Installing the GPS Antenna

For units that include the GPS option, install the GPS antenna and cable as described below.

Selecting a GPS Antenna Site Outdoors

Select a site that...
• Is the highest point available
• Offers a full 360° view horizontally, to within 10° vertically of the horizon
• Is higher than neighboring buildings/obstructions
• Is protected from strong radio frequency (RF) and microwave transmissions
• Is set away from RF-reflective surfaces that cause multipath interference
• Is set 3 ft. (1 m) away from other GPS antennas
Avoid...
• Mounting the antenna between tall buildings or next to walls and equipment
• Cable runs from the antenna to the receiver that exceed the specified length
• Patching multiple cables together to make a single cable run
• Running the cable through bulkheads and along side high-energy cables
• Crimping or damaging the cable
Blocked signals and multipath cancellation significantly increase GPS acquisition time. Multipath
cancellation is caused by reflected signals that reach the antenna out of phase with the direct signal due
to vertical reflective objects positioned to the side and above the antenna. To solve these problems, mast
mount the antenna at least 1 meter away from and above the reflecting surface.

Mounting the GPS Antenna

Mount the GPS antenna on an antenna mast (recommended) or on the peak of a building. The GPS
antenna kit includes special mounting brackets. For the mast, use 2-inch (5.08-cm) diameter water pipe
or conduit that is rigid enough to withstand high winds without flexing. Use guy wires to stabilize masts
longer than 10 ft. (3.048 m).
Notes:
• The XLi requires a 12 Volt-compatible antenna. Antennas not rated for 12 V will be damaged.
• Use a splitter to connect a GPS antenna to multiple receivers. Avoid using BNC "T" connectors.
• The L1 GPS antenna is designed to operate with up to 150 ft. (60.96 m) of RG-59 coax cable. An
optional Down Converter can be used for cable runs of 1,500 ft. (457.2 m) using RG-58 coaxial
cable.
XLi Time & Frequency System
XLi-man, Issue 8, 6/17/2008, Rev. H
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
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