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As launch looms, threat from Ligado returns

Matteo Luccio


“The new LightSquared business plan and the new FCC rules significantly expand the terrestrial transmission increasing the potential for interference to GPS receivers,” the U.S. departments of Defense and Transportation (DOD and DOT) wrote to the Federal Communications Commission in 2011 after the FCC granted the company permission to offer broadband via its satellite and base station networks to a wide variety of mobile broadband partners. The move — heralded by supporters as hastening the advent of 4G services across the country, especially in underserved communities — sent shockwaves across the GNSS/PNT community, which opposed the plan forcefully for the threat it posed to GPS.

Reborn in December 2015 as Ligado Networks, the company obtained the FCC’s unanimous approval in April 2020 for the use of spectrum near the L-bands used by GPS for its 5G network. It is scheduled to launch its first deployment at the end of September.

Nearly all the federal government, including DOD and DOT, as well as most manufacturers of GNSS receivers, are very strongly opposed. On September 9, the National Academies of Science, Engineering and Medicine’s Committee to Review FCC Order 20-48 will release its independent evaluation of the issue, as mandated by the 2021 National Defense Authorization Act.

The study, begun in May 2021, considered three issues:

1. Which of two prevailing proposed approaches for evaluating harmful interference is most effective to mitigate the risk of harm.

2. The potential for harmful interference from Ligado to mobile satellite services — such as Iridium.

3. The feasibility and practicality of the remedies proposed by the FCC.

A summary of the report can be found here.

Welcome Penny Axelrad

I am very pleased to announce that Prof. Penina “Penny” Axelrad has joined GPS World’s Editorial Advisory Board.
Penny is a University of Colorado (CU) Distinguished Professor in the Ann and HJ Smead Department of Aerospace Engineering Sciences. She received her B.S. and M.S. degrees in Aeronautical and Astronautical Engineering from MIT and her Ph.D. in Aeronautics and Astronautics from Stanford University. She has been a member of the faculty at CU since 1992, serving as primary advisor for 25 Ph.D. graduates and many M.S. and undergraduate research students.

Penny has been active in research on GPS and PNT technology and applications for aircraft, spacecraft and remote sensing, as well as estimation of satellite orbits and attitude, since 1985, co-authoring more than 60 journal papers and 130 conference papers. She has served as principal investigator or co-investigator on grants and contracts totaling $17 million. She is a Fellow of the Institute of Navigation and the American Institute of Aeronautics and Astronautics, and a member of the National Academy of Engineering. Since 2013 she has served as a member of the National Space-Based Positioning, Navigation and Timing (PNT) Advisory Board.

I overlapped with Penny at MIT in the mid-1980s. Now, nearly 40 years later, I look forward to her contributions to this magazine.

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