GPS World, March 2011

Policy and system news and developments GPS Galileo GLONASS SYSTEM THE Test Data Predicts Disastrous GPS Jamming by FCC Authorized Broadcaster R epresentatives of the GPS industry presented to members of the Federal Communications Commission FCC laboratory evidence of interference with the GPS signal by a proposed new broadcaster on January 19 of this year The meeting and subsequent filing did not dissuade FCC International Bureau Chief Mindel De La Torre from authorizing Lightsquared to proceed with ancillary terrestrial component operations installing up to 40000 high power transmitters close to the GPS frequency across the United States The document describing the testing states that the Lightsquared initiative will have a severe impact on the GPS band and will create a disastrous interference problem for GPS receiver operation to the point where GPS receivers will cease to operate complete loss of fix when in the vicinity of these transmitters On January 26 the FCC waived its own rules and granted permission for the potential interferer to broadcast in the L Band 1 1525 MHz 1559 MHz from powerful land based transmitters This band lies adjacent to the band 1559 1610 MHz where GPS and other GNSSs operate The FCC called for further testing to be led by LightSquared and completed by June 15 Prior to the decision representatives of the U S GPS Industry Council and GPS manufacturers Garmin and Trimble presented Experimental Evidence of Wide Area GPS Jamming That Will Result from LightSquareds Proposal to Convert Portions of Effect Distance Jamming is detected 357 miles 5756 meters Loss of service in the urban canyon 179 miles 2884 meters Loss of fix in the open sky 066 miles 1059 meters EFFECTS OF JAMMING by a simulated LightSquared signal on a Garmin nüvi 265W consumergrade GPS receiver L Band 1 to High Power Terrestrial Broadband to five members of the FCCs Office of Engineering and Technology including its chief two members of the FCC International Bureau one from the Public Safety and Homeland Security Bureau and two from the Wireless Telecommunications Bureau See www gpsworld com jammed for a full PDF of Experimental Evidence of Wide Area GPS Jamming The document conveys results of testing on a common portable consumer automotive navigation device and on a common general aviation receiver The consumer GPS device began to be jammed at a power level representing a distance of 36 miles 58 kilometers from the simulated LightSquared transmitter The consumer device lost a fix at 066 miles 11 kilometers from the transmitter The Federal Aviation Administration FAA certified aviation receiver began to be jammed at a distance of 138 miles 221 kilometers and experienced total loss of fix at 56 miles 90 kilometers from the transmitter During the laboratory testing GPS signals were simulated by a Spirent GSS6560 GPS simulator representing a constellation of 31 GPS satellites the current configuration LightSquareds signal was simulated using a Rhode Effect Distance Jamming is detected 1376 miles 22137 meters 10 dB loss of sensitivity 985 miles 15853 meters Loss of fix in the open sky 560 miles 9018 meters EFFECTS OF JAMMING by a simulated LightSquared signal on a Garmin GNS 430W aviation grade GPS receiver GPS World March 2011 www gpsworld com 14