Originally featured on BroadcastEngineering.com
1/18/2012 12:40 PM
Even before the FCC can rule on an updated plan by LightSquared for 4G broadband service, it’s already in deep trouble.
The 2012 Defense Authorization act, passed by Congress in December, bars the FCC from approving systems that interfere in any way with military GPS. A FCC working group warned about the same time that LightSquared’s system would cause serious interference with GPS.
Also, the U.S. National Space-Based Positioning Navigation and Timing Committee (PNT) has unanimously drawn the conclusion that the LightSquared network and Global Positioning System cannot co-exist, without involving potentially harmful consequences.
According to the committee, the use of LightSquared's network could eventually “cause harmful interference to many GPS receivers.” Apart from that, the committee members also suggested that LightSquared could also prove to be harmful for the GPS-powered Ground Proximity Warning System (GPWS).
This week, LightSquared again refuted the government’s claims, charging it has used “obsolete” testing devices “that don’t reflect reality.” It called the entire process “rigged” and “shrouded in secrecy.” The company thinks the tests are set-up to fail due to the involvement of GPS manufacturers.
LightSquared wanted to set its service up next to the frequencies used by GPS satellites, and wants to build 40,000 ground transmitters to transmit 4G wireless signals in a band at 1525 to 1559 MHz. This would be next to the 1559 to 1610 MHz band GPS satellites use to transmit navigation signals.
However, there were warnings that interference from LightSquared’s plan would create GPS dead zones across the United States. There was concern that strong signals near the 4G transmitters would drown out the faint satellite navigation signals reaching the ground, a worry backed up by subsequent tests.