LightSquared's plan to build a mobile broadband network on spectrum next to the GPS band could create major problems for U.S. farmers and aviators, critics of the proposal told lawmakers Wednesday.
The proposed LTE (Long Term Evolution) network could cause interference with airplane GPS systems and with precision devices that help farmers track fuel costs and minimize overlap while planting crops, witnesses told the U.S. House of Representatives Small Business Committee.
The aviation industry has used GPS technology in aircraft navigation systems for more than 20 years, said Tim Taylor, president and CEO, FreeFlight Systems, an aircraft electronics manufacturer based in Irving, Texas.
"The introduction of a nationwide broadband wireless network ... that compromises, or brings into question, the safety and security of airborne navigation equipment using Global Positioning System is simply not acceptable," he said. "There is not a simple or non-complex fix."
Adding interference filters to an estimated 1 million high-accuracy GPS devices used by farmers could cost up to US$800 million, said Rick Greene, precision agronomy manager with MFA an agriculture products cooperative in Columbia, Missouri. It could take years to refit all those devices with filters, Greene said.
"LightSquared must not be allowed to broadcast their signal in the upper or lower bands of GPS," Greene said. "Not today, tomorrow or ever until a feasible and economical resolution is found."
But the concerns expressed by Greene, Taylor, and pilot Dennis Boykin were overblown, said Jeff Carlisle, LightSquared's executive vice president. LightSquared has revamped its proposal to limit the amount of interference to GPS devices bleeding into the company's spectrum, he said.
Only a fraction of precision devices will need to be updated, with many operating in areas outside LightSquared's planned network, he said. Carlisle showed the committee a $6 interference filter, developed in weeks at LightSquared, that fits precision GPS units, he said. "It can be done, it can be done inexpensively, and it can be done quickly," he said.
GPS owners shouldn't have to pay to fix the interference problem when GPS devices are bleeding into other spectrum, Carlisle said. "Contrary to what the GPS manufacturers have told many of their users, at no time has LightSquared ever said GPS users should bear the cost of fixing their receivers," he said. "GPS manufacturers created this problem, GPS manufacturers should bear the cost of fixing it."
LightSquared, by operating on the spectrum it owns that's farthest away from GPS spectrum, will eliminate problems for more than 99 percent of GPS devices, Carlisle said. U.S. government testing has found "little to no degradation" on aviation devices, he said.
The LightSquared network shouldn't require any replacement of aviation receivers, he added. LightSquared will only move forward if aviation interference concerns are put to rest, he said.
But "little" degradation isn't good enough for devices used in airplane navigation, said Representative Sam Graves, a Missouri Republican and committee chairman. "The 'little' is what bothers me," Graves said. "In aviation, we deal with zero tolerances. If there's any concern out there, we're going to end up having to retrofit and filter."
Taylor agreed, saying aviation navigation systems need to work all the time. "We don't live in the world of 'little to no,'" he said. "We live in the world of certainty."
Representative Nydia Vel
"How do you recommend we proceed going forward?" she said to the critics. "Should an innovative technology be outright rejected without any attempts to find a technical solution?''
Greene, Taylor and Boykin all called on the U.S. Federal Communications Commission to conduct several more interference tests.
LightSquared has asked the FCC for approval to operate a hybrid satellite and land-based LTE mobile network. The company, which plans to sell its network as a wholesale service, is waiting for approval while the agency examines interference complaints from GPS groups.
Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is firstname.lastname@example.org.