USCG Notice to Mariners
INTERFERENCE TO GPS RECEIVERS FROM CONSUMER ELECTRONICS-GRADE ACTIVE VHF/UHF MARINE TELEVISION ANTENNAS The U.S. Coast Guard and Federal Communications Commission have ascertained that certain powered VHF/UHF marine television antennas are causing operational degradation in the performance of GPS receivers. This degradation in performance or interference may be realized as a display of inaccurate position information or a complete loss of GPS receiver acquisition and tracking ability. The interference interactions have been reported up to 2000 feet from the interference source. This interference has been associated, in some instances, with temperature extremes or proximity to a television broadcast site. If you are experiencing recurring outages or degradation of your GPS receiver, these may be caused by one of these antennas on your vessel or nearby. If you have a powered VHF/UHF antenna aboard your vessel, you should perform an on-off test of your TV antenna. If turning off the power to the antenna results in improvement in the GPS receiver performance, the antenna may be the source of interference in the GPS band. In that case, you should contact the manufacturer of the antenna and identify the symptoms. If the test is not positive and the GPS interference persists, you should contact the Coast Guard Navigation Information Service by e-mail or 703-313-5900, or through the web site at http://www.navcen.uscg.gov
