Go to Contents Precise Time and Frequency, Inc., 50L Audubon Road, Wakefield, MA 01880, USA ptf 3207A rev G
Tel: +1-781-245-9090 e-mail: info@ptfinc.com www.ptfinc.com pg. 16
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3: Installation/Configuration
Installing the GNS Antenna
For units that include the GPS, Glonass, Galileo, or multi receiver options, install the GNS antenna and
cable as described below.
Selecting a GNS 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 alongside high-energy cables
• Crimping or damaging the cable
Blocked signals and multipath cancellation significantly increase GNS 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 GNS Antenna
Mount the GNS antenna on an antenna mast (recommended) or on the peak of a building.
A mast is included with the GNS antenna mounting kit.
If you use a tall mast longer than 10 ft. (3.048 m), use guy wires for stabilization.
Notes:
• The ptf 3207A requires a 5 Volt-compatible antenna.
• Use an active splitter to connect a GNS antenna to multiple receivers. Also insure the splitter
includes one "DC pass through" channel for powering the antenna, and that the other channels
present a dummy load to the other receivers . The receiver front end has a sensing circuit to
insure the antenna is not over or under the DC load. Without a dummy load the receivers will
indicate a fault, and will not lock even though sufficient satellites may be in view. 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.
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