GNSS 101: An Introduction

Time: Monday, September 24, 1:30 p.m. - 3:00 p.m.

A broad overview of the principles of satellite navigation, and the technologies that matured in the second-half of the 20th century, leading to the development of Transit, which became operational in 1964, followed by GPS in 1995. The principal technologies required for a global navigation satellite system are: stable space platforms in predictable orbits; global coordinate frames; spread spectrum signals; and ultra-stable clocks. These technologies made GNSS possible, but it’s the revolution in integrated circuits that led to a receiver chip, which adds about $1 to the cost of a smartphone, and can determine virtually instantaneously your position within a couple of meters, velocity within 5 cm/s, and time within 50 ns. These innovations have all brought about a transformation in how we move about, do commerce, and fight wars. As a preview to GNSS 102, this class will introduce GNSS signals and signal quality (C/No); measurements (pseudoranges); and sources of measurement errors (ionosphere, troposphere, and multipath).

Dr. Pratap Misra, an ION Fellow and Kepler Award recipient, has been active in the GNSS field for over 25 years, starting with a project at MIT Lincoln Laboratory aimed at combining measurements from GPS and GLONASS to improve navigation for civil aviation.

Using a Sextant: Celestial Navigation

Time: Monday, September 24, 1:30 p.m. - 3:00 p.m.

How do modern navigators use a sextant, chronometer, stars, and almanac information to solve for ship or aircraft position? The fundamentals are likely more straightforward than you realize! Today’s mariner typically uses six tools to solve for vessel position:

1. An almanac (or computer) that predicts precise location of celestial bodies as a function of time,
2. A reasonably accurate timepiece,
3. A device to measure elevation angle of a celestial body (e.g., sextant),
4. A “star finder,”
5. A navigational chart, and
6. A mathematical or tabular method to convert observations to contours (lines) of position.

This short course will cover some theory; however, the primary focus will be on the practice of using these six tools to solve for vessel position. Final discussions will focus on experiences with celestial navigation, with topics to include best times to shoot stars, horizon challenges, sources of error, and typical accuracy.

Dr. Richard J. Hartnett is a professor of Electrical Engineering at the U.S. Coast Guard Academy in New London, CT, having retired in 2009 from the USCG as a Captain (O-6). His current research interests include the mathematics of positioning, statistical signal processing methods in electronic navigation, and autonomous vehicle design.

Sensor Integration for Personal Navigation

Time: Monday, September 24, 1:30 p.m. - 3:00 p.m.

A review of the state-of-the-art navigation sensors and techniques suitable for personal and pedestrian navigation, with an extension to the unmanned aerial systems (UAS) navigation. Personal navigation (PN) is defined as navigation for military and emergency personnel, while pedestrian navigation refers to location/navigation/tracking of all other types of mobile users. An emphasis will be on navigation sensors and techniques in GNSS-challenged environments, such as, inertial measurement unit (IMU), wireless local area network, IR and RF transponders, and ultra-wideband (UWB) networks, as well as 2D and 3D active and passive imaging sensors. Following the technology overview, example implementations and performance assessment of selected navigation system prototypes will be presented. System design, as well as a summary of the performance analysis in the mixed indoor-outdoor environments, with the special emphasis on dead-reckoning (DR) performance, will be discussed.

Dr. Dorota A. Grejner-Brzezinska is the Lowber B. Strange Endowed Chair and the associate dean for research in the College of Engineering at The Ohio State University (OSU) and a director of the Satellite Positioning and Inertial Navigation (SPIN) Laboratory. Her research interests cover GPS/GNSS algorithms, GPS/inertial and other sensor integration for navigation in GPS-challenged environments, sensors and algorithms for indoor and personal navigation, and mobile mapping. She is a Fellow of the ION, RIN and IAG; recipient of the ION’s Kepler and Thurlow awards; and a past ION president.

GNSS 102: Measurements from Phones

Time: Monday, September 24, 3:30 p.m. - 5:00 p.m.

Learn to access and use GNSS measurements from Android phones, including how to collect, view, and process raw measurements. You will leave the class with sample data, Google software tools, and the knowledge of how to use them. This class is a follow-on to “GNSS 101 – An Introduction”. In 101 you learned what pseudoranges are. In this course, you will see how pseudoranges are created and create some yourself from Received Satellite Time using a spreadsheet on your laptop. You will also learn to do sophisticated analysis using Google’s GNSS Analysis Tools, including: measurement error versus C/No; ionosphere/troposphere; and urban multipath analysis.

Dr. Frank van Diggelen leads the Android Location Team at Google. He is a pioneer of A-GNSS, and invented techniques that are now industry standard. He holds over 90 issued U.S. patents on A-GNSS, and is the author of “A-GPS” the first textbook on Assisted GNSS. He is a Fellow of the RIN and ION, ION Kepler Award winner and teaches GPS at Stanford University.

Approaches for Resilient and Robust Positioning, Navigation and Timing (PNT)

Time: Monday, September 24, 3:30 p.m. - 5:00 p.m.

Diverse elements of the international infrastructure are critically reliant on GNSS for precise location and time, often in ways that are not obvious. This tutorial provides a high-level perspective on the effects of interference on GNSS receivers and offers some possible threat mitigation approaches and policy recommendations. The tutorial starts with a discussion of potential GNSS threats and vulnerabilities. Then, after a quick review of how receivers determine position, the focus is on the effects of various interference types on select signals. The effects of ground mobile propagation in limiting effective jammer range are examined. Mitigations such as adaptive arrays, and IMU aiding are discussed. Civil jamming examples and incidents are covered along with methods to detect, identify and militate against their effects. In particular, the importance of maintaining situational awareness for establishing environmental context is examined. Techniques for detecting civil spoofing and authenticating signals will be discussed.

Logan Scott has over 40 years of military and civil GPS systems engineering experience. He specializes in radio frequency signal processing and waveform design. He has pioneered approaches for building jamming-resistant digital receivers and has long advocated for hardening civil infrastructure. Logan is an ION Fellow and holds 41 U.S. patents.

Vision Navigation Using OpenCV

Time: Monday, September 24, 3:30 p.m. - 5:00 p.m.

This course will provide an introduction to using OpenCV to perform many of the functions that are commonly used in vision navigation. The course will briefly cover some of the theory, but much of the focus will be on live demonstrations of how OpenCV can be used for many common tasks, such as camera calibration, feature and descriptor extraction, brute force feature matching, robust outlier rejection (RANSAC), and calculation of translation and rotation using a monocular camera. This course is intended for those who want to have an initial introduction to practical vision navigation tools. Demonstration source code (written in Python) will be provided to the attendees at the end of the tutorial for their own further experimentation.

Dr. John Raquet is the director of the Autonomy and Navigation Technology (ANT) Center at the Air Force Institute of Technology, where there have been over 60 vision navigation related MS theses and PhD dissertations over the past 18 years. He has enjoyed giving 70 short courses to thousands of attendees from government, industry, and academia. Dr. Raquet is an ION Fellow and current ION president.