Inside GNSS Media & Research

MAR-APR 2018

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18 Inside GNSS M A R C H / A P R I L 2 0 1 8 T he fe der a l gover n ment i s r u more d to b e ne a r i ng a decision about Ligado Net- works' request to repurpose its satellite frequencies to also support a ground-based telecom network. ose frequencies neighbor the band used by GPS. Testing done both several years ago and more recently has shown such a sys- tem could seriously interfere with GPS receivers. Most federal agencies rely on GPS to support their missions using it for things like mapping, earthquake pre- diction, animal studies, environmental assessments and emerging capabilities like positive train control, which can prevent accidents. There are also new industries such as drones and driverless cars that require accurate, reliable GPS and the majority of the nation's critical infrastructure — everything from the internet and cell towers to the power grid and the stock exchanges — needs its exceptionally accurate timing data. Most of that infrastructure is reliant on, or becoming reliant on, GPS. T he L igado i s sue , ac cord i ng to sources, is pitting the agencies need- i ng GPS a ga i nst feder a l spe c t r u m managers on the hunt for bandwidth to address surging demand from com- mercial users. ose sources also say that the Air Force has been crystal clear on its opposition to Ligado's proposal but t he top echelons of t he Defense Department, specifically the Office of the Chief Information Officer, has not. DoD's pro-GPS stance was essential to putting the original network plan on hold in 2012. at plan was proposed by Ligado's predecessor LightSquared. They filed bankruptcy after the plan was set aside, emerging in 2015 with a modified proposal and, soon thereaer, a new name. As of press time the issue was expect- ed to come up at the March 22 meeting of the federal government's top coordi- nating and policy body for navigation and timing — the National Executive Committee for Space-Based Position- ing, Navigation, and Timing (the PNT E XCOM). E a rl ier meet i ngs had to be canceled so this was to be the first EXCOM of the Trump administration with some officials perhaps weighing the issue for the first time. Sources tell Inside GNSS that the members of the EXCOM seemed poised to take the next step — which would like- ly be the launch of an interagency team to develop an official position. at posi- tion would then be sent to the National Telecommunications and Information Administration (NTIA), which repre- sents government interests in spectrum decisions. e NTIA would then submit the letter along with its own recommen- dations to the FCC. All of this could be completed by the end of April 2018, said one expert familiar with the issue. Gap Analysis W it h s o mu c h at s t a k e a v i r t u a l nor'easter of new reports and filings hit Washington in early March. One of the most important is an interagency techni- cal analysis of five interference studies that was released just a week ahead of the meeting. Called the Gap Analysis, the assess- ment was done by the EXCOM's panel of technical experts, the National Space- Based PNT Systems Engineering Forum (NPEF). e interagency group mirrors the EXCOM in that it draws its expertise from more than a dozen agencies, can add experts as needed, and is chaired by the Departments of Defense and Trans- portation. e NPEF was asked to evaluate the methodologies used in the five tests, which all looked at interference issues raised by having a terrestrial LTE net- work operating in the frequencies neigh- boring the GPS L1 signal. The NPEF was told to base its work on the rec- ommendations of the EXCOM's other panel of top satellite navigation experts, Ligado Decision May Be At Hand DEE ANN DIVIS Dee Ann Divis has covered GNSS and the aerospace industry since the early 1990s, writing for Jane's International Defense Review, the Los Angeles Times, AeroSpace Daily and other publications. She was the science and technology editor at United Press International for five years, leaving for a year to attend the Massachusetts Institute of Technology as a Knight Science Journalism Fellow. WASHINGTON VIEW

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