LightSquaring a Circle?

LightSquared’s proposed terrestrial broadband wireless network threatens the viability of the Global Positioning System signal for military, civil, and commercial users in the United States, said Gen. William Shelton, head of Air Force Space Command, last week. “Based on the test results and analysis to date, the LightSquared network would effectively jam vital GPS receivers, and to our knowledge thus far, there are no mitigation options that will be effective in eliminating interference to essential GPS services in the United States,” Shelton told the House Armed Service Committee’s strategic forces panel on Sept. 15. Even the limited testing to date of the mitigation strategy that the Reston, Va.-based company has proposed—broadcasting in lower power and using only the lower 10 megahertz of its assigned frequencies—showed that “precision receivers and even cell phones were still affected,” he noted. Shelton said AFSPC remains open to ideas and mitigation strategies. Some have suggested installing filters on GPS receivers. But, “even if this is possible, we believe it would involve substantial financial cost and likely degrade the accuracy of high-performance receivers,” reads Shelton’s prepared statement “If there’s something else magic out there, we don’t know about it,” he told the panel.