Marine TV Antenna Interference

by Frank Lanier
Chesapeake Bay Magazine

The United States Coast Guard is warning that boaters watching those GILLIGAN’S ISLAND re-runs while underway could experience a similar three hour cruise. Some active marine television antennas are causing problems with onboard Global Positioning Systems (GPS) receivers, with symptoms ranging from inaccurate position information to total loss of GPS receiver signal acquisition and tracking ability.

Not worried because you don’t have a TV onboard? Think again – reports of interference occurring on vessels up to 2000 feet away from boats with active TV antennas have been recorded. If you’re experiencing signal degradation or recurring outages with your GPS receiver and have an active TV antenna installed, the Coast Guard recommends a simple on-off test of the antenna. If GPS receiver performance improves with the antenna turned off it may be the cause of interference, at which point you should contact the antenna manufacturer and tell them what’s happening. 

The Federal Communications Commission has identified the following antennas as potential sources of GPS interference:

1. Tandy MINI STATE Electronic Amplified UHF/VHF TV Antenna - Models 5MS740, 5MS750, and 5MS921.
2. Radio Shack’s Long Range Amplified Omni Directional TV Antenna - Model 15-1624.
3. Shakespeare’s SeaWatch - Models 2040/Code Date 02A00, and 2050/Code Date 03A00 (code dates are found on the antenna power supply).

The problem most likely includes other antennas and mariners identifying other models generating GPS interference should notify the Coast Guard Navigation Information Service at nisws@navcen.uscg.mil or (703) 313-5900.

GPS is a satellite-based radionavigation system that allows users to determine their position, velocity and time worldwide, 24 hours a day in any weather.