The Coalition to ‘Save Our GPS,’ through vice president and general counsel Jim Kirkland of founding member Trimble, has responded to claims by LightSquared, which is seeking approval for a terrestrial broadband communication service in a frequency spectrum very close to that of GPS.
Satellite navigation systems
Intelsat’s Galaxy 15 geostationary satellite, which ceased broadcasting the Waas signal covering some airports in Alaska on December 16, is now back under control.
Can GPS and LightSquared coexist? Within the civil and military GPS community, the answer has been emphatically and unequivocally, “No.” Until last week, that is. Attendees at the annual convention of the U.S. Institute of Navigation held in Portland, Ore., had been confident that the laws of physics made coexistence of the two impossible.
To the puzzlement of the GPS community and independent radio propagation experts, the FCC ruled on September 13 that LightSquared should conduct further tests of its signal transmissions on its alternate, lower L-band frequency farther removed from the GPS frequency. Tests on a LightSquared frequency closer to GPS earlier this year produced extreme interference.
LightSquared signed an agreement yesterday with Javad GNSS to develop a system that it claims will eliminate related interference issues between LightSquared’s planned 4G broadband network transmitters and high-precision GPS devices.
The former head of the New York State Police aviation unit has been charged with grand larceny for selling a state-owned Garmin 496 GPS to a fellow trooper. Retired Maj. Robert Kreppein is accused of selling the unit for $1,600 in 2008. Kreppein retired in July after media reports surfaced that he was being investigated for allegedly approving civilian flights on state police helicopters.
The GPS industry’s failure to comply with the Department of Defense’s receiver filtering standards is the root cause of potential interference issues involving LightSquared’s proposed broadband wireless network, the company has told the FCC.
Low-powered incoming GPS signals are allocated 1559-1610 MHz in the L-Band radio spectrum. The neighboring spectrum–from 1525-1559 Mhz–is allocated to other, equally low-powered, incoming satellite signals, such as Sky Terra’s. GPS receivers are open to signals above the blue line shown, but filter out signals below it, and require modification to accept Glonass.
Accord Technology’s NexNav mini GPS Waas Class Beta-1 sensor has been recognized by the FAA as meeting requirements outlined in Advisory Circular 20-165. The 20-165 requirements cover accuracy and other parameters that GPS sensors will need to meet standards for ADS-B operations. The FAA will require mandatory equipage with ADS-B out systems beginning in 2020.
LightSquared is running an advertising campaign in Washington, D.C., that includes prominent multiple advertisements along the platforms of downtown stations of the city’s Metro system serving Capitol Hill, FAA headquarters and other key government offices. Photo at left was taken this morning by an AIN staffer at L'Enfant Plaza Metro station.