The LightSquared panel at the 2011 Survey Summit in San Diego, Calif. Photo by Michael L. Binge, LS, GISP

A proposal by LightSquared to use a lower block of 10 mHz frequencies in the L band for its wholesale nationwide 4G-LTE network met with fierce objections from surveyors and other high-precision GPS users during the 2011 Survey Summit and ACSM Annual Conference in San Diego held in July. During a plenary session presentation, Jeff Carlisle, executive vice president of regulatory affairs for LightSquared, said that the company understands the importance of GPS to the United States and is taking steps to prevent and minimize interference. He pointed out that the proposed broadband network has been in development for 10 years and that the network would be vital to serve the rapidly growing need for broadband service while creating competition to help drive down costs. Following a battery of comprehensive tests to determine the scope of interference, LightSquared identified a 10 mHz portion of the spectrum farthest away from GPS that showed significantly less interference. “The data points to mitigation that can be achieved,” Carlisle said.

He noted that LightSquared is committed to funding the cost of developing filters for receivers to prevent interference and is willing to work with GPS manufacturers to find ways to make GPS more robust. “This is not a zero-sum game,” he said. “We see an opportunity for a win-win.”

However, attendees at the Survey Summit disagreed. Speaking on behalf of the Coalition to Save our GPS, Trimble Vice President Peter Large said that the new LightSquared proposal did nothing to resolve the problems for high-precision GPS users. “The new proposal looks a lot like the original,” he said, adding that significant and harmful interference was still evident at the 10 mHz level.

Large emphasized that the coalition is not anti-broadband or anti-LightSquared but is dedicating to protecting GPS. “This is not a GPS receiver, filter or design problem,” he said. “It is a problem of incompatibility.”

Attendees explored the issue further during a panel discussion moderated by ROWE Professional Services President John Matonich. Despite Carlisle’s reassurances, the general consensus was that the economic impact on surveyors and others who rely on high-precision GPS equipment would be staggering if LightSquared is permitted to move forward with its proposed network.

LightSquared’s website, and the Coalition to Save our GPS is For additional coverage of the Survey Summit and continued updates on the LightSquared issue,