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.
GPS navigation device
Aspen Avionics introduced its Connected Panel system at the EAA AirVenture Oshkosh show in late July and expects the first applications to be available to customers by year-end. Connected Panel integrates certified avionics, in this case Aspen’s Evolution PFD and MFD glass-cockpit displays, with mobile devices. The first applications will be for the iPad; Aspen is planning Android apps as well.
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 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.
The ongoing controversy about whether LightSquared’s proposed network of 40,000 powerful ground-based stations transmitting high-speed Internet across the nation would interfere with adjacent GPS frequencies became more intense last month.
Following extensive reports of GPS interference, LightSquared announced last week that it would vacate its L-Band frequency adjacent to GPS and move to one further away to greatly reduce, but not eliminate, interference with satnav signals.
Since early reports indicate that LightSquared’s transmitters do, in fact, interfere with GPS signals, LightSquared yesterday announced that it would vacate the frequency that caused major GPS interference and move to one farther away, where tests had shown minimum interference. However, some GPS receivers would still be affected by the company’s 4G signals even in this frequency band.
The controversy over potential interference to GPS from LightSquared’s planned nationwide network of powerful 4G broadband retransmitting stations has now drawn Congress into the dispute. Letters expressing concern about adverse effects of the LightSquared network on GPS have been sent to the FCC by House and Senate members.
Two events last month intensified the confrontation between LightSquared, a private U.S. communications company, and U.S. government and industry GPS interests.