A group of GPS vendors and users has challenged mobile startup LightSquared's credibility in a response to the company's new plan for a hybrid satellite and LTE mobile network.
LightSquared either knew or should have known about apparent interference between its proposed LTE (Long-Term Evolution) network and receivers for GPS (Global Positioning System) before it requested a waiver from the U.S. Federal Communications Commission (FCC) to operate the network, the Coalition to Save Our GPS said in a paper released late Friday. After LightSquared received a conditional waiver in January, a mandatory series of tests revealed serious interference.
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The fledgling carrier plans to offer wholesale mobile services over satellites and a land-based LTE network. But the LTE system would operate in radio spectrum near to that used by GPS, raising concerns about degraded navigation capabilities. In January, the FCC said LightSquared could build and operate the network if it didn't interfere with GPS receivers. The carrier was required to form a working group to test the technologies together, and that group filed its findings last week.
After the tests showed significant interference to GPS from transmissions in the upper band of LightSquared's spectrum, the company devised a new plan in which it would start out by launching services on a lower band. On Friday, the GPS group jumped on that change of direction with strong criticism.
"The utter failure of LightSquared's initial deployment plans to pass interference tests raises fundamental questions about the representations LightSquared made to the FCC," the Coalition said. "The current strong indication is that whatever LightSquared told the FCC prior to January 2011 was highly inaccurate, to a degree that verges on negligence."
Based on the outcome of its earlier plan, the Coalition also questioned LightSquared's assessment that operating only in the lower band would spare 99.5 percent of GPS receivers from interference. The group then picked apart the carrier's 37-page proposal, challenging specific statements made by LightSquared.
Responding to LightSquared's charge that interference was caused by GPS vendors that made receivers with inadequate filters, the Coalition said LightSquared itself offers GPS-related services outside the GPS band. These GPS augmentation services, which give users such as surveyors and farmers more accurate location data, are offered via satellite by both LightSquared and satellite operator Inmarsat. GPS manufacturers have to make devices that use LightSquared's spectrum so that they can take advantage of LightSquared's own services, the Coalition said.
On Monday, LightSquared acknowledged that it sells GPS augmentation services to OmniStar, a division of Trimble Navigation, which resells the services to users in construction, agriculture and other areas. Trimble has been a leading critic of LightSquared's plans.
The group also challenged LightSquared's view that the interference problem could be solved with inexpensive filters. "The only device LightSquared produced for testing was an antenna with filters so extreme that they would filter out more than 95 percent of the GPS signals as well, with an extremely severe penalty to receiver performance," the Coalition wrote. The group has said before that there are no filters available that could solve the interference problem. Retrofitting existing GPS receivers so they could work after LightSquared's launch would take at least 15 years, because devices such as in-car navigation systems are replaced on long cycles. LightSquared said there are already suitable filters for cell phones that cost about five cents each.
However, the Coalition laid the ultimate blame for the interference problem at the FCC's door. "It is and was the FCC's responsibility to identify and proactively address GPS interference issues to protect the substantial investment the federal government has in GPS," the paper said.