Symmetricom XLi IEEE 1588 User Manual

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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. 
Multipath cancellation and blocked signals are typically caused by 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.

Verify that the length of cable from the GPS antenna site to the XLi does not exceed the maximum GPS 
antenna lengths recommended to meet the GPS signal strength requirements. When calculating the 
total antenna cable length, include cable that is needed to meet safety and regulatory requirements, 
such as lightning arrestors and building code requirements for running coaxial cable from the exterior to 
the interior of a building. 

If possible, test the GPS signal reception of a particular site before mounting the antenna and running 
the cable indoors. Some sites may turn out to be unsuitable due to interference.

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The XLi requires a 12-volt compatible antenna. Antennas not rated for 12 V will be damaged.

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Use a splitter, not a BNC “T” connector, when connecting an antenna to multiple receivers. 

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The L1 GPS antenna is designed to operate with up to 150 ft. (45.72 m) of RG-59 coax cable. 

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A line amplifier is available for cable runs between 150 - 300 ft. (46 - 91 m) in length (RG-59).

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A down-converter kit is available for cable runs of 1,500 ft. (457.2 m) in length (RG-58).

Mount the GPS antenna on an antenna mast (recommended) or on the peak of a building. For the mast, 
use 2-inch (5.08-cm) diameter PVC 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). Avoid mounting the antenna on a 
tower, which requires a specialist to maintain.