2025 Seminars

Event Details

• Time: 3:00 - 4:00 p.m. Eastern Time
• Format: Zoom

Abstract

This talk examines GPS/GNSS spoofing detection and recovery methods that use antenna-array data and blind signal processing. The methods enable Direction-of-Arrival (DoA) spoofing detection and recovery without requiring the antenna array to be calibrated or recalibrated. They use the singular-value decomposition of a matrix of post-correlation signal phasors for the available satellite and antenna-element combinations. The ratio of the second-largest singular value to the largest provides a useful measure of DoA diversity. A small ratio indicates insufficient diversity and a likely attack from a single spoofing direction. In that case, the corresponding singular-value-decomposition direction vector in antenna space can be used to place a null toward the spoofer, reducing its jamming effect on authentic signals and potentially recovering an authentic navigation solution. The techniques are evaluated against live-broadcast spoofing data from a yacht in the Mediterranean in June 2014 and from northern Israel in 2024. Blind DoA-based detection performed well in both cases. Recovery was effective for the yacht data but performed poorly for the northern Israel data, potentially because of spoofer multipath and the use of an array with only two antennas.

Speaker Bio

Mark L. Psiaki has held the Kevin T. Crofton Faculty Chair in Aerospace and Ocean Engineering at Virginia Tech since 2016. He is Professor Emeritus of Mechanical and Aerospace Engineering at Cornell University, where he served on the faculty from 1986 to 2016. He received a B.A. in Physics and M.A. and Ph.D. degrees in Mechanical and Aerospace Engineering from Princeton University. He is a Fellow of both the Institute of Navigation (ION) and the American Institute of Aeronautics and Astronautics (AIAA), and is a recipient of the ION Kepler Award and the AIAA Mechanics and Control of Flight Award. He has published more than 85 journal articles and 180 technical articles, chapters, reviews, and patents. His research interests include GPS/GNSS technology, applications, and resilience; remote sensing; spacecraft attitude and orbit determination; and estimation, filtering, and detection.

Event Details

• Time: 10:30 a.m. Eastern Time
• Format: Zoom

Abstract

The effort to encode data efficiently for storage and communication stretches from Tiro's shorthand in the Roman Republic through Morse code and the source-coding foundations established by Shannon and Fano. Conventional source models generally represent data as sequences of symbols with independent or weakly dependent distant elements, an approach that underpins many compression methods in use today. More recently, graph structures have been used to capture complex dependencies in data. These structures are poorly represented by conventional models, making standard compression methods suboptimal and motivating new approaches to graph compression. This talk introduces the developing field of graph compression, discusses practical challenges and proposed solutions, and presents results concerning the information-theoretic limits of compressing graphs.

Speaker Bio

Justin P. Coon received a B.Sc. degree with distinction in electrical engineering from the Calhoun Honors College at Clemson University in 2000 and a Ph.D. in communications from the University of Bristol in 2005. From 2004 to 2013, he held research positions at Toshiba Research Europe Ltd., including Research Manager, where he led research on physical-layer communications and network modeling. He was a Visiting Fellow in the School of Mathematics at the University of Bristol from 2010 to 2012 and a Reader in its Department of Electrical and Electronic Engineering from 2012 to 2013. He joined the University of Oxford in 2013 and is currently Professor of Engineering Science and the Emmott Fellow in Engineering at Oriel College.

Dr. Coon received Toshiba's Distinguished Research Award for his work on 4G systems and has received three best-paper awards. He has published widely in IEEE and American Physical Society journals and conferences and is a named inventor on several dozen patents. He has served as an editor for several IEEE journals and has chaired or co-chaired multiple IEEE conferences. His current research interests include graph compression, data privacy, and communications.