Publications

Hot Publications

Advanced Techniques for Safety-of-Life Carrier Phase Differential GNSS Positioning with Applications to Triplex Architectures	Ph.D. Dissertation	G.N. Green	2017
Requirements for Secure Clock Synchronization	Journal Paper	L. Narula, T.E. Humphreys	Under Review
Assured Navigation and Timing	Presentation	T. E. Humphreys	2017
Robust Precise Location	Presentation	T. E. Humphreys	2017
Counter UAV Challenges	Presentation	T. E. Humphreys	2017
Exploiting antenna motion for faster initialization of centimeter-accurate GNSS positioning with low-cost antennas	Journal Paper	K. M. Pesyna, Jr., T. Novlan, C. Zhang, R. W. Heath, Jr., and T. E. Humphreys	2017
GNSS Signal Authentication via Power and Distortion Monitoring	Journal Paper	K. D. Wesson, J. Gross, T. E. Humphreys, and B. L. Evans	Under Review
Low-cost Precise Urban Positioning	Presentation	T.E. Humphreys	2016
Secure Perception in Connected Vehicles	Poster	T.E. Humphreys, L. Narula	2016
Dense RTK: Mass-Market Positioning for Automated Vehicles	Presentation	T.E. Humphreys	2016
Low-cost Precise Positioning for Automated Vehicles	Trade Magazine Article	M.J. Murrian, C.W. Gonzalez, T.E. Humphreys, K.M. Pesyna, Jr, D.P. Shepard, A.J. Kerns	2016
Attackers can spoof navigation signals without our knowledge. Here's how to fight back GPS lies	Magazine Article	T.E. Humphreys, M.L. Psiaki, B. Stauffer	2016
Data-Driven Generalized Integer Aperture Bootstrapping for Real-Time High Integrity Applications	Conference Paper	G.N. Green, M. King, T.E. Humphreys	2016
Requirements for Secure Wireless Time Transfer	Conference Paper	L. Narula, T.E. Humphreys	2016
On the Feasibility of cm-Accurate Positioning via a Smartphone’s Antenna and GNSS Chip	Conference Paper	T.E. Humphreys, M.J. Murrian, F. van Diggelen, S. Podshivalov, K.M. Pesyna	2016
A Dense Reference Network for Mass-Market Centimeter-Accurate Positioning	Conference Paper	M.J. Murrian, C.W. Gonzalez, T.E. Humphreys	2016
GNSS Spoofing and Detection	Journal Paper	M.L. Psiaki, T.E. Humphreys	2016
Sensor Deception Detection and Radio-Frequency Emitter Localization	Ph.D. Dissertation	J.A. Bhatti	2015
Advanced Techniques for Centimeter-Accurate GNSS Positioning on Low-Cost Mobile Platforms	Ph.D. Dissertation	K.M. Pesyna	2015
Fault Free Integrity of Mid-Level Voting for Triplex Differential GPS Solutions	Conference Paper	G.N. Green, M. King, T.E. Humphreys	2015
Toughening Techniques for GPS Receivers: Navigation Message Authentication	Presentation	T.E. Humphreys	2015
Statement on the Security Threat Posed by Unmanned Aerial Systems and Posssible Countermeasures	Testimony	T.E. Humphreys	2015
Accuracy in the Palm of Your Hand	Trade Magazine Article	K.M. Pesyna, R.W. Heath, T.E. Humphreys	2015
Development of a Micro-Mobility Analysis System Using Precise GPS Traces	Undergraduate Honors Thesis	S. Mukherji	2014
GNSS Security	Presentation	T. Humphreys	2014
Centimeter Positioning with a Smartphone-Quality GNSS Antenna	Conference Paper	K.M. Pesyna, R.W. Heath, T.E. Humphreys	2014
Adaptive Estimation of Signals of Opportunity	Conference Paper	Z.M. Kassas, V. Ghadiok, T.E. Humphreys	2014
GNSS Vulnerabilities and Threats	Presentation	T. Humphreys	2014
GNSS Spoofing Detection using Two-Antenna Differential Carrier Phase	Conference Paper	M.L. Psiaki, B.W. O'Hanlon, S.P. Powell, J.A. Bhatti, K.D. Wesson, T.E. Humphreys, A. Schofield	2014
A Testbed for Developing and Evaluating GNSS Authentication Techniques	Conference Paper	T.E. Humphreys, J.A. Bhatti, D.P. Shepard, and K.D. Wesson	2014
Secure Navigation and Timing Without Local Storage of Secret Keys	Ph.D. Dissertation	K. Wesson	2014
Ionospheric irregularities during a substorm event: Observations of ULF pulsations and GPS scintillations	Journal Paper	H. Kim, C.R. Clauer, K. Deshpande, M.R. Lessard, A.T. Weatherwax, G.S. Bust, G. Crowley, T.E. Humphreys	2014
High-Precision Globally-Referenced Position and Attitude via a Fusion of Visual SLAM, Carrier-Phase-Based GPS, and Inertial Measurements	Conference Paper	D.P. Shepard and T.E. Humphreys	2014
Analysis and Synthesis of Collaborative Opportunistic Navigation Systems	Ph.D. Dissertation	Z.M. Kassas	2014
Demonstration of a Space Capable Miniature Dual Frequency GNSS Receiver	Journal Paper	E.G. Lightsey, T.E. Humphreys, J.A. Bhatti, A.J. Joplin, B.W. O’Hanlon, and S.P. Powell	2014
Secure Perception for Autonomous Systems	Presentation	T. Humphreys	2014
A Blueprint for Civil GPS Navigation Message Authentication	Conference Paper	A.J. Kerns, K.D. Wesson, and T.E. Humphreys	2014
A Phase-Reconstruction Technique for Low-Power Centimeter-Accurate Mobile Positioning	Journal Paper	K.M. Pesyna Jr., Z.M. Kassas, R.W. Heath Jr., T.E. Humphreys	2014
Unmanned Aircraft Capture and Control via GPS Spoofing	Journal Paper	A.J. Kerns, D.P. Shepard, J.A. Bhatti, T.E. Humphreys	2014
Autonomous Adaptive Low-Power Instrument Platform (AAL-PIP) for remote high latitude geospace data collection	Journal Paper	C.R. Clauer, H. Kim, K. Deshpande, Z. Xu, D. Weimer, S. Musko, G. Crowley, C. Fish, R. Nealy, T.E. Humphreys, J.A. Bhatti, A.J. Ridley	2014
Receding Horizon Trajectory Optimization in Opportunistic Navigation Environments	Journal Paper	Z.M. Kassas and T.E. Humphreys	2015
Greedy Motion Planning for Simultaneous Signal Landscape Mapping and Receiver Localization	Journal Paper	Z.M. Kassas, A. Arapostathis, and T.E. Humphreys	2015
Hostile Control of Ships via False GPS Signals: Demonstration and Detection	Journal Paper	J.A. Bhatti and T.E. Humphreys	To Appear
Unhackable Drones: The Challenges of Securely Integrating Unmanned Aircraft into the National Airspace	Magazine Article	K. Wesson and T. Humphreys	2013
Real-Time GPS Spoofing Detection via Correlation of Encrypted Signals	Journal Paper	B.W. O'Hanlon, M.L. Psiaki, J.A. Bhatti, D.P. Shepard, T.E. Humphreys	2013
Secure PNT for Autonomous Systems	Presentation	T. Humphreys	2013
Precision Limits of Low-Energy GNSS Receivers	Conference Paper	K.M. Pesyna, R.W. Heath, and T.E. Humphreys	2013
Cost Analysis of Square Root Information Filtering and Smooting with Mixed Real-Integer State	White Paper	K. Pesyna Jr and T. Humphreys	2013
Achieving the Cramer-Rao Lower Bound in GPS Time-of-Arrival Estimation: A Frequency Domain Weighted Least-Squares Estimator Approach	White Paper	K. Pesyna, T. Humphreys	2013
Receding Horizon Trajectory Optimization for Simultaneous Signal Landscape Mapping and Receiver Localization	Conference Paper	Z. Kassas, J. Bhatti, and T. Humphreys	2013
Observability Analysis of Collaborative Opportunistic Navigation with Pseudorange Measurements	Journal Paper	Z.M. Kassas and T.E. Humphreys	2013
The Price of Anarchy in Active Signal Landscape Map Building	Conference Paper	Z. Kassas, T. Humphreys	2013
A Graphical Approach to GPS Software-Defined Receiver Implementation	Conference Paper	Z. Kassas, J. Bhatti, T. Humphreys	2013
A Combined Symmetric Difference and Power Monitoring GNSS Anti-Spoofing Technique	Conference Paper	K. Wesson, B. L. Evans, and T. Humphreys	2013
A Probabilistic Framework for Global Navigation Satellite System Signal Timing Assurance	Conference Paper	K.D. Wesson, B.L. Evans, and T.E. Humphreys	2013
GPS Spoofing & Implications for Telecom	Presentation	K. Wesson	2013
GPS Software-Defined Receiver and Radio Frequency Signal Landscape Simulator	Presentation	Z. Kassas	2013
Highlight: Collaborative Opportunistic Navigation	Magazine Article	Z.M. Kassas	2013
Motion Planning for Optimal Information Gathering in Opportunistic Navigation Systems	Conference Paper	Z. Kassas and T. Humphreys	2013
GPS Spoofing Detection via Dual-Receiver Correlation of Military Signals	Journal Paper	Psiaki, M.L., B.W. O'Hanlon, J.A. Bhatti, D.P. Shepard, and T.E. Humphreys	2013
Fusion of Carrier-Phase Differential GPS, Bundle-Adjustment-Based Visual SLAM, and Inertial Navigation for Precisely and Globally-Registered Augmented Reality	Masters Thesis	D. Shepard	2013
GPS Vulnerabilities and Implications for Telecom	Presentation	T. Humphreys	2013
Detection Strategy for Cryptographic GNSS Anti-Spoofing	Journal Paper	Humphreys, T.E.	2013
GAIN: Collaborative Opportunistic Navigation	Poster	Z. Kassas, T. Humphreys	2013
UAV Integration: Privacy and Security Hurdles	Presentation	T. Humphreys	2013
Extreme GPS: Limits of Security & Precision	Presentation	T. Humphreys	2013
Secure Navigation and Timing	Presentation	T. Humphreys	2012
Future Directions in GNSS Research	Presentation	T. Humphreys	2012
Initial GPS scintillation results from CASES receiver at South Pole, Antarctica	Journal Paper	K.B. Deshpande, G. S. Bust, C. R. Clauer, H. Kim, J. E. Macon, T. E. Humphreys, J. A. Bhatti, S. B. Musko, G. Crowley, and A. T. Weatherwax	2012
Evaluation of the Vulnerability of Phasor Measurement Units to GPS Spoofing Attacks	Journal Paper	D.P. Shepard, T.E. Humphreys, A.A. Fansler	2012
Position Paper: Secure Time Transfer for CPS	White Paper	K.D. Wesson, T.E. Humphreys, and B.L. Evans	2012
Probabilistic Secure Time Transfer: Challenges and Opportunities in a Sub-Millisecond World	Presentation	K. Wesson, T. Humphreys, B. Evans	2012
Statement on Privacy Issues Related to the Domestic Use of Unmanned Aerial Vehicles	Testimony	T. Humphreys	2012
The Texas Spoofing Test Battery: Toward a Standard for Evaluating GPS Signal Authentication Techniques	Conference Paper	T.E. Humphreys, J.A. Bhatti, D.P. Shepard, and K.D. Wesson	2012
Observability and Estimability of Collaborative Opportunistic Navigation with Pseudorange Measurements	Conference Paper	Z.M. Kassas and T.E. Humphreys	2012
Evaluation of Smart Grid and Civilian UAV Vulnerability to GPS Spoofing Attacks	Conference Paper	D.P. Shepard, J.A. Bhatti, T.E. Humphreys, A.A. Fansler	2012
Precise Augmented Reality Enabled by Carrier-Phase Differential GPS	Conference Paper	D.P. Shepard, K.M. Pesyna, and T.E. Humphreys	2012
Practical Cryptographic Civil GPS Signal Authentication	Journal Paper	Wesson, K., M. Rothlisberger, and T. E. Humphreys	2012
Going Up Against Time: The Power Grid’s Vulnerability to GPS Spoofing Attacks	Trade Magazine Article	D.P. Shepard, T.E. Humphreys, and A.Fansler	2012
Drone Hack: Spoofing Attack Demonstration on a Civilian Unmanned Aerial Vehicle	Trade Magazine Article	D.P. Shepard, J.A. Bhatti, and T.E. Humphreys	2012
Secure Civil Navigation and Timing	Presentation	T. Humphreys	2012
Statement on the Vulnerability of Civil Unmanned Aerial Vehicles and Other Systems to Civil GPS Spoofing	Testimony	T. Humphreys	2012
Observability Analysis of Opportunistic Navigation with Pseudorange Measurements	Conference Paper	Z.M. Kassas and T.E. Humphreys	2012
Constructing a Continuous Phase Time History from TDMA Signals for Opportunistic Navigation	Conference Paper	K.M. Pesyna Jr., Z.M. Kassas, T.E. Humphreys	2012
Development and Demonstration of a TDOA-Based GNSS Interference Signal Localization System	Conference Paper	J.A. Bhatti, T.E. Humphreys, and B.M. Ledvina	2012
Collaborative Opportunistic Navigation	Poster	Z. Kassas, K. Pesyna, T. Humphreys	2012
The GPS Dot and Its Discontents: Privacy vs. GNSS Integrity	Trade Magazine Article	T.E. Humphreys	2012
Evaluation of the Vulnerability of Phasor Measurement Units to GPS Spoofing Attacks	Conference Paper	D.P. Shepard, T.E. Humphreys, and A.A. Fansler	2012
Development and Testing of a Minaturized, Dual-Frequency GPS Receiver for Space Applications	Conference Paper	Joplin, A.J., E.G. Lightsey, T.E. Humphreys	2012
Straight Talk on Anti-Spoofing: Securing the Future of PNT	Trade Magazine Article	Wesson, K., D. Shepard, and T. Humphreys	2012
Know Your Enemy: Signal Characteristics of Civil GPS Jammers	Trade Magazine Article	Mitch, R.H., R.C. Dougherty, M.L. Psiaki, S.P. Powell, B.W. O’Hanlon, J.A. Bhatti, and T.E. Humphreys	2012
Development and Testing of a Miniaturized, Dual-Frequency, Software-Defined GPS Receiver for Space Applications	Masters Thesis	Joplin, A.J.	2011
A Collection of Observations and Advice on University Teaching	White Paper	T.E. Humphreys	2011
Radionavigation Robustness and Security	Presentation	T. Humphreys	2011
CubeSat-Sized GNSS Radio Occultation Experiments	Presentation	T. Humphreys	2011
GPS-assisted Femtocell Synchronization and Localization Through Tightly-Coupled Opportunistic Navigation	Poster	K. Pesyna, K. Wesson, R. Heath, T. Humphreys	2011
Tightly-Coupled Opportunistic Navigation for Deep Urban and Indoor Positioning	Conference Paper	Pesyna, Jr., K.M., Z.M. Kassas, J.A. Bhatti, and T.E. Humphreys	2011
Tightly-Coupled Opportunistic Navigation for Deep Urban and Indoor Positioning	Poster	Z. Kassas, K. Pesyna, J. Bhatti, T. Humphreys	2011
Characterization of Receiver Response to Spoofing Attacks	Conference Paper	Shepard, D.P. and T.E. Humphreys	2011
An Evaluation of the Vestigial Signal Defense for Civil GPS Anti-Spoofing	Conference Paper	Wesson, K.D., D.P. Shepard, J.A. Bhatti, and T.E. Humphreys	2011
A Proposed Navigation Message Authentication Implementation for Civil GPS Anti-Spoofing	Conference Paper	Wesson, K.D., M.P. Rothlisberger, and T.E. Humphreys	2011
Civilian GPS Spoofing Detection based on Dual-Receiver Correlation of Military Signals	Conference Paper	Psiaki, M.L., B.W. O'Hanlon, J.A. Bhatti, D.P. Shepard, T.E. Humphreys	2011
Signal Characteristics of Civil GPS Jammers	Conference Paper	Mitch, R.H., R.C. Dougherty, M.L. Psiaki, S.P. Powell, B.W. O'Hanlon, J.A. Bhatti, and T.E. Humphreys	2011
CASES: A Smart, Compact GPS Software Receiver for Space Weather Monitoring	Conference Paper	O'Hanlon, B.W., M.L. Psiaki, S. Powell, J.A. Bhatti, T.E. Humphreys, G. Crowley, G.S. Bust	2011
CASES: A Novel Low-Cost Ground-based Dual-Frequency GPS Software Receiver and Space Weather Monitor	Conference Paper	Crowley, G., G.S. Bust, A.Reynolds, I.Azeem, R.Wilder, B.W. O’Hanlon, M.L. Psiaki, S.Powell, T.E. Humphreys, and J.A. Bhatti	2011
Extending the Reach of GPS-assisted Femtocell Synchronization and Localization Through Tightly-Coupled Opportunistic Navigation	Conference Paper	Pesyna, Jr., K. M., K. D. Wesson, R. W. Heath, Jr., T. E. Humphreys	2011
GPS Spoofing and the Financial Sector	White Paper	Humphreys, T.E.	2011
Characterization of Receiver Response to Spoofing Attacks	Undergraduate Honors Thesis	D. Shepard	2011
State of the Art and Future Trends in Radionavigation	Presentation	T. Humphreys	2011
Indoor GPS: Tightly Coupled Opportunistic Navigation	Poster	K. Pesyna, K. Wesson, J. Bhatti, T. Humphreys	2010
GPS Spoofing Detection System	Poster	M. Psiaki, B. O'Hanlon, T. Humphreys, J. Bhatti	2010
Spoofing the Timing Signal: What Else is Vulnerable?	Presentation	T. Humphreys	2010
The GPS Assimilator: a Method for Upgrading Existing GPS User Equipment to Improve Accuracy, Robustness, and Resistance to Spoofing	Conference Paper	Humphreys, T.E., J.A. Bhatti, B.M. Ledvina	2010
Opportunistic Frequency Stability Transfer for Extending the Coherence Time of GNSS Receiver Clocks	Conference Paper	Wesson, K.D., K.M. Pesyna, Jr., J.A. Bhatti, T.E. Humphreys	2010
Advances in GNSS Equipment	Presentation	T. Humphreys	2010
GNSS Assimilator: A method for upgrading existing GNSS user equipment to improve accuracy, robustness, and resistance to spoofing	Trade Magazine Article	Humphreys, T.E., B.M. Ledvina	2010
Frontiers in Radionavigation	Presentation	T. Humphreys	2010
Radionavigation Integrity	Presentation	T. Humphreys	2010
Riding out the rough spots: Scintillation-robust GNSS carrier tracking	Presentation	T. Humphreys	2010
A data-driven testbed for evaluating GPS carrier tracking loops in ionospheric scintillation	Journal Paper	Humphreys, T.E., M.L. Psiaki, B.M. Ledvina, A.P. Cerruti, and P.M. Kintner, Jr.	2010
Modeling the effects of ionospheric scintillation on GPS carrier phase tracking	Journal Paper	Humphreys, T.E., M.L. Psiaki, and P.M. Kintner, Jr.	2010
Development and Field Testing of a DSP-Based Dual-Frequency Software GPS Receiver	Conference Paper	O’Hanlon, B.W., M.L. Psiaki, P.M. Kintner, Jr., T.E. Humphreys	2009
Receiver-Autonomous Spoofing Detection: Experimental Results of a Multi-antenna Receiver Defense Against a Portable Civil GPS Spoofer	Conference Paper	Montgomery, P.Y., T.E. Humphreys, and B.M. Ledvina	2009
Assessing the Civil GPS Spoofing Threat	Presentation	T. Humphreys, J. Bhatti, B. Ledvina, M. Psiaki, B. O'Hanlon, P. Kintner, P. Montgomery	2009
Exploiting Multicore Technology in Software-Defined GNSS Receivers	Journal Paper	Humphreys, T.E., J.A. Bhatti, T. Pany, B.M. Ledvina, B.W. O’Hanlon
Simulating Ionosphere-Induced Scintillation for Testing GPS Receiver Phase Tracking Loops	Journal Paper	Humphreys, T.E., M.L. Psiaki, J.C. Hinks, B.W. O’Hanlon and P.M. Kintner, Jr.	2009
A Multi-Antenna Defense: Receiver-Autonomous GPS Spoofing Detection	Trade Magazine Article	Montgomery, P.Y., T.E. Humphreys, B.M. Ledvina	2009
GNSS and Ionospheric Scintillation: How to Survive the Next Solar Maximum	Trade Magazine Article	Kintner, Jr., P.M., T.E. Humphreys, J. Hinks	2009
Evaluating GPS Receiver Robustness to Ionospheric Scintillation	Conference Paper	Hinks, J.C., T.E. Humphreys, B.W. O'Hanlon, M.L. Psiaki, P.M. Kintner, Jr.	2008
Assessing the Spoofing Threat: Development of a Portable GPS Civilian Spoofer	Conference Paper	Humphreys, T.E., B.M. Ledvina, M.L. Psiaki, B.W. O'Hanlon, P.M Kintner, Jr.	2008
Considerations for Future IGS Receivers	Conference Paper	Humphreys, T.E., L. Young, T. Pany	2008
A Technique for Determining the Carrier Phase Differences between Independent GPS Receivers during Scintillation	Conference Paper	Mohuiddin, S., T.E. Humphreys, M.L. Psiaki	2007
Searching for Galileo	Conference Paper	Psiaki, M.L., T.E. Humphreys, S. Mohiuddin, S.P. Powell, A.P. Cerruti, and P.M. Kintner, Jr.	2006
GNSS Receiver Implementation on a DSP: Status, Challenges, and Prospects	Conference Paper	Humphreys, T.E., M.L. Psiaki, P.M. Kintner, Jr., B.M. Ledvina	2006
The Semidiurnal Variation in GPS-derived Zenith Neutral Delay	Journal Paper	Humphreys, T.E., Kelly, M.C., Huber, N., Kintner, Jr., P.M.	2005
GPS Carrier Tracking Loop Performance in the presence of Ionospheric Scintillations	Conference Paper	Humphreys, T.E., M.L. Psiaki, P.M. Kintner, Jr., B.M. Ledvina	2005
Magnetometer-based Attitude and Rate Estimation for a Spacecraft with Wire Booms	Journal Paper	T.E. Humphreys, M.L. Psiaki, E.M. Klatt, S.P. Powell, P.M. Kintner, Jr.	2005
Analysis of Ionospheric Scintillations using Wideband GPS L1 C/A Signal Data	Conference Paper	Humphreys, T.E., Ledvina, B.M., Psiaki, M.L., Kintner, Jr., P.M.	2004