GPS/GNSS 101

Date/Time: Monday, September 11, 1:30 p.m. - 3:00 p.m. MDT
Room: Mineral Hall DE (Third Floor)

This course presents the fundamentals of the GPS, and other GNSS, and is intended for people with a technical background who do not have significant GPS experience. Topics covered include time-of-arrival positioning, overall system design of GPS, signal structure, error characterization, dilution of precision (DOP), differential GPS, GPS modernization, and other GNSS systems.

Dr. John Raquet is currently the director of IS4S-Dayton. Previously, he was the founding director of the Autonomy and Navigation Technology (ANT) Center at AFIT. He has published over 170 navigation-related conference and journal papers and taught 60 navigation-related short courses to over 3600 students in many organizations. He is an ION Fellow and past president. Dr Raquet holds a BS in Astronautical Engineering from the USAFA, an MS in Aero/Astro Engineering from MIT, and a PhD in Geomatics Engineering from the University of Calgary.

Space Applications of GNSS

Date/Time: Monday, September 11, 1:30 p.m. - 3:00 p.m. MDT
Room: Mineral Hall FG (Third Floor)

GNSS receivers have become standard equipment for near-earth satellites, providing the onboard position, velocity, and timing information required to support real-time operations. Furthermore, precise GNSS observations from both direct and indirect paths collected onboard these platforms are used to support scientific and commercial purposes including characterization of Earth’s atmosphere, measurement of ocean surface heights, and extraction of time varying features of Earth’s gravity field. New advances in receiver technology and detailed modeling of the environmental influences on GNSS satellites and signals continue to expand the utility of GNSS to ever finer orbit resolution, and higher altitude missions – even to the point of being planned to support lunar exploration missions. This short course will present an overview of the many applications of GNSS in space, and describe the unique challenges and requirements for its use in the space environment.

Dr. Penina Axelrad is Joseph T. Negler Professor of Aerospace Engineering Sciences at the University of Colorado Boulder. Her research interests include technology and algorithms for position, navigation, timing, and remove sensing – especially in spaceborne applications. She is a past ION president, a Fellow of ION and AIAA, and a member of the National Academy of Engineering.

GNSS Jamming and Spoofing – LEO as Fallback

Date/Time: Monday, September 11, 3:30 p.m. - 5:00 p.m. MDT
Room: Mineral Hall DE (Third Floor)

Intentional jamming and spoofing of GNSS signals is by now a widespread phenomenon. Especially common near conflict regions, but not limited to these, such interference erodes trust in GNSS and compromises safety in air and marine travel and shipping.

This tutorial will examine: 1) patterns of GNSS interference across the globe; 2) its effects on GNSS receivers; and 3) techniques for its detection and mitigation. The tutorial will highlight cooperative and non-cooperative use of signals from low-Earth-orbit (LEO) mega-constellations as an especially promising mitigation strategy. Compared to traditional GNSS, LEO constellations offer higher power, wider bandwidth, more rapid multipath decorrelation, and the possibility of stronger authentication and zero-age-of-ephemeris, all of which will enable greater accuracy and greater resilience against jamming and spoofing.

Dr. Todd E. Humphreys holds the Ashley H. Priddy Centennial Professorship in Engineering in the department of Aerospace Engineering and Engineering Mechanics at the University of Texas at Austin. He is director of the Wireless Networking and Communications Group and of the UT Radionavigation Laboratory, where he specializes in the application of optimal detection and estimation techniques to positioning, navigation, and timing. His awards include the UT Regents' Outstanding Teaching Award, the NSF CAREER Award, the ION Thurlow Award, and the PECASE. He is Fellow of the ION and of the RIN. He holds a BS and MS from USU and PhD from Cornell.

LEO PNT – Architectures and Performance Trades

Date/Time: Monday, September 11, 3:30 p.m. - 5:00 p.m. MDT
Room: Mineral Hall FG (Third Floor)

Several emerging providers are targeting Low Earth Orbit (LEO) to deliver complementary and alternative position, navigation, and time (PNT) to meet the stringent requirements of certain applications. Here, we examine the system architectural elements, similarities and differences to medium Earth orbit (MEO) global navigation satellite systems (GNSS), and performance trades that result. The result is a system that takes a different form than the now familiar arrangement of around thirty satellites in MEO each with an atomic frequency standard as is the case with GNSS, as it is often driven by fundamentally different requirements. LEO-based satellite navigation has the potential to introduce new signals to complement existing GNSS in MEO to provide resilience, security, and high precision to navigation users.

Dr. Tyler Reid is a co-founder and CTO of Xona Space Systems. Previously, Tyler worked as a research engineer at the Ford Motor Company in the localization and mapping group for self-driving cars. He has also worked as a software engineer at Google and as a lecturer at Stanford University, where he co-taught the GPS course. He is a recipient of the RTCA’s Jackson Award. Dr. Reid received his MSc and PhD in Aeronautics and Astronautics from Stanford University, where he worked in the GPS Research Lab.