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.
Global Positioning System
When Rockwell Collins officially celebrated the first full-rate production delivery of its ARC-210 RT-1939(C) Generation 5 radio to PMA 209, the air combat electronics program office of the U.S. Naval Air Systems Command in late April, it marked a milestone.
One of the most important weapons development programs here in France is the INS/GPS+laser-guided variant of Sagem’s AASM (armement air-sol modulaire in French, now also known by its NATO name of SBU-38 Hammer). The AASM has been achieving good success in its INS/GPS- and INS/GPS+IR-guided versions, and the laser version will provide the significant ability to hit moving targets.
Israel Aerospace Industries (IAI) is showing off its latest precision-guided munition here at Le Bourget.
In accordance with the Federal Communication Commission’s January ruling, LightSquared must, in its June 15 final report on GPS compatibility tests, show that “it is clear that potential GPS interference concerns have been resolved.” But hold that applause, GPS users.
“The test data discussed today makes clear that there is substantial interference to GPS if LightSquared turns on high-powered terrestrial facilities in the spectrum next door to GPS,” Trimble vice president and general counsel Jim Kirkland said today at an event sponsored by the National Space-Based PNT Advisory Board. Kirkland is also a founding member of the Coalition to Save Our GPS.
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.
Satellite communications provider Inmarsat and aviation standards organizations have been working on a solution to a lesser-publicized aspect of the planned LightSquared broadband wireless network–the potential for the system’s high-power transmitters to interfere with satcom as well as GPS navigation signals.
LightSquared documents submitted to the FCC last week reveal that its transmitters were transmitting at only half power during the tests recently conducted in the Las Vegas area to check for interference with GPS receivers. This means that any interference detected by the GPS units could be as much as half that expected when the LightSquared transmitters operate at their eventual planned power levels.