Todd E. Humphreys
YOU?
Author Swipe
View article: Timing Properties of the Starlink Ku-Band Downlink
Timing Properties of the Starlink Ku-Band Downlink Open
We develop signal capture and analysis techniques for precisely extracting and characterizing the frame timing of the Starlink constellation's Ku-band downlink transmissions. The aim of this work is to determine whether Starlink frame timi…
View article: Analysis of the Trusted Inertial Terrain-Aided Navigation Measurement Function
Analysis of the Trusted Inertial Terrain-Aided Navigation Measurement Function Open
The trusted inertial terrain-aided navigation (TITAN) algorithm leverages an airborne vertical synthetic aperture radar to measure the range to the closest ground points along several prescribed iso-Doppler contours. These TITAN minimum-ra…
View article: OFDM-Based Positioning with Unknown Data Payloads: Bounds and Applications to LEO PNT
OFDM-Based Positioning with Unknown Data Payloads: Bounds and Applications to LEO PNT Open
This paper presents bounds, estimators, and signal design strategies for exploiting both known pilot resources and unknown data payload resources in time-of-arrival (TOA)-based positioning systems with orthogonal frequency-division multipl…
View article: Pose-aware 3D Beamwidth Adaptation for Mobile Extended Reality
Pose-aware 3D Beamwidth Adaptation for Mobile Extended Reality Open
This paper presents a sensor-aided pose-aware beamwidth adaptation design for a conceptual extended reality (XR) Head-Mounted Display (HMD) equipped with a 2D planar array. The beam is tracked and adapted on the user side by leveraging HMD…
View article: MM3DGS SLAM: Multi-modal 3D Gaussian Splatting for SLAM Using Vision, Depth, and Inertial Measurements
MM3DGS SLAM: Multi-modal 3D Gaussian Splatting for SLAM Using Vision, Depth, and Inertial Measurements Open
Simultaneous localization and mapping is essential for position tracking and scene understanding. 3D Gaussian-based map representations enable photorealistic reconstruction and real-time rendering of scenes using multiple posed cameras. We…
View article: Ziv-Zakai-Optimal OFDM Resource Allocation for Time-of-Arrival Estimation
Ziv-Zakai-Optimal OFDM Resource Allocation for Time-of-Arrival Estimation Open
This paper presents methods of optimizing the placement and power allocations of pilots in an orthogonal frequency-division multiplexing (OFDM) signal to minimize time-of-arrival (TOA) estimation errors under power and resource allocation …
View article: 6G Takes Shape
6G Takes Shape Open
The contours of 6G -- its key technical components and driving requirements\n-- are finally coming into focus. Through twenty questions and answers, this\narticle defines the important aspects of 6G across four categories. First, we\nident…
View article: Purposeful co-design of OFDM signals for ranging and communications
Purposeful co-design of OFDM signals for ranging and communications Open
This paper analyzes the fundamental trade-offs that occur in the co-design of pilot resource allocations in orthogonal frequency-division multiplexing signals for both ranging (via time-of-arrival estimation) and communications. These trad…
View article: GNSS Software-Defined Radio: History, Current Developments, and Standardization Efforts
GNSS Software-Defined Radio: History, Current Developments, and Standardization Efforts Open
Taking the work conducted by the global navigation satellite system (GNSS) software-defined radio (SDR) working group during the last decade as a seed, this contribution summarizes, for the first time, the history of GNSS SDR devel-opment.…
View article: Purposeful Co-Design of OFDM Signals for Ranging and Communications
Purposeful Co-Design of OFDM Signals for Ranging and Communications Open
This paper analyzes the fundamental trade-offs that occur in the co-design of pilot resource allocations in orthogonal frequency-division multiplexing signals for both ranging (via time-of-arrival estimation) and communications. These trad…
View article: Signal Identification and Entrainment for Practical FMCW Radar Spoofing Attacks
Signal Identification and Entrainment for Practical FMCW Radar Spoofing Attacks Open
This paper proposes a method of passively estimating the parameters of frequency-modulated-continuous-wave (FMCW) radar signals with a wide range of structural parameter values and analyzes how a malicious actor could employ such estimates…
View article: Low-Cost Inertial Aiding for Deep-Urban Tightly Coupled Multi-Antenna Precise GNSS
Low-Cost Inertial Aiding for Deep-Urban Tightly Coupled Multi-Antenna Precise GNSS Open
A vehicular pose estimation technique is presented that tightly couples multi-antenna carrier-phase differential GNSS (CDGNSS) with a low-cost MEMS inertial sensor and vehicle dynamic constraints. This work is the first to explore the use …
View article: Signal Structure of the Starlink Ku-Band Downlink
Signal Structure of the Starlink Ku-Band Downlink Open
We develop a technique for blind signal identification of the Starlink downlink signal in the 10.7 to 12.7 GHz band and present a detailed picture of the signal's structure. Importantly, the signal characterization offered herein includes …
View article: All-Weather, Sub-50-cm, Radar-Inertial Positioning
All-Weather, Sub-50-cm, Radar-Inertial Positioning Open
Deploying automated ground vehicles beyond the confines of sunny and dry climes will require sub-lane-level positioning techniques that use radio waves, rather than near-visible light radiation. Like human sight, LiDAR and optical cameras …
View article: Carrier-phase and IMU based GNSS Spoofing Detection for Ground Vehicles
Carrier-phase and IMU based GNSS Spoofing Detection for Ground Vehicles Open
This paper develops, implements, and validates a powerful single-antenna carrier-phase-based test to detect Global Navigation Satellite Systems (GNSS) spoofing attacks on ground vehicles equipped with a low-cost inertial measurement unit (…
View article: Low-Cost Inertial Aiding for Deep-Urban Tightly-Coupled Multi-Antenna Precise GNSS
Low-Cost Inertial Aiding for Deep-Urban Tightly-Coupled Multi-Antenna Precise GNSS Open
A vehicular pose estimation technique is presented that tightly couples multi-antenna carrier-phase differential GNSS (CDGNSS) with a low-cost MEMS inertial sensor and vehicle dynamics constraints. This work is the first to explore the use…
View article: First results from three years of GNSS interference monitoring from low Earth orbit
First results from three years of GNSS interference monitoring from low Earth orbit Open
Observation of terrestrial GNSS interference (jamming and spoofing) from low Earth orbit (LEO) is a uniquely effective technique for characterizing the scope, strength, and structure of interference and for estimating transmitter locations…
View article: Unmanned Aerial Vehicle (UAV) Interception.
Unmanned Aerial Vehicle (UAV) Interception. Open
the potential payloads vary dramatically in their power consumption and duty cycles, a typical load profile has been selected to provide commonality for the propulsion power comparisons. Since missions vary widely with respect to ground co…
View article: Fused Low-Earth-Orbit GNSS
Fused Low-Earth-Orbit GNSS Open
Traditional Global Navigation Satellite System (GNSS) immunity to interference may be approaching a practical performance ceiling. Greater gains are possible outside traditional GNSS orbits and spectrum. GNSS from low Earth orbit (LEO) has…
View article: First results from three years of GNSS Interference Monitoring from Low Earth Orbit
First results from three years of GNSS Interference Monitoring from Low Earth Orbit Open
Observation of terrestrial GNSS interference (jamming and spoofing) from low-earth orbit (LEO) is a uniquely effective technique for characterizing the scope, strength, and structure of interference and for estimating transmitter locations…
View article: GNSS Interference Monitoring from Low Earth Orbit
GNSS Interference Monitoring from Low Earth Orbit Open
Observation of terrestrial GNSS interference (jamming and spoofing) from low-earth orbit (LEO) is a uniquely effective technique for characterizing the scope, strength, and structure of interference and for estimating transmitter locations…
View article: All-Weather sub-50-cm Radar-Inertial Positioning
All-Weather sub-50-cm Radar-Inertial Positioning Open
Deployment of automated ground vehicles beyond the confines of sunny and dry climes will require sub-lane-level positioning techniques based on radio waves rather than near-visible-light radiation. Like human sight, lidar and cameras perfo…
View article: Automotive Collision Risk Estimation Under Cooperative Sensing
Automotive Collision Risk Estimation Under Cooperative Sensing Open
This paper offers a technique for estimating collision risk for automated\nground vehicles engaged in cooperative sensing. The technique allows\nquantification of (i) risk reduced due to cooperation, and (ii) the increased\naccuracy of ris…
View article: TEX-CUP: The University of Texas Challenge for Urban Positioning
TEX-CUP: The University of Texas Challenge for Urban Positioning Open
A public benchmark dataset collected in the dense urban center of the city of Austin, TX is introduced for evaluation of multi-sensor GNSS-based urban positioning. Existing public datasets on localization and/or odometry evaluation are bas…
View article: Automotive-Radar-Based 50-cm Urban Positioning
Automotive-Radar-Based 50-cm Urban Positioning Open
Deployment of automated ground vehicles (AGVs) beyond the confines of sunny and dry climes will require sub-lane-level positioning techniques based on radio waves rather than near-visible-light radiation. Like human sight, lidar and camera…
View article: Deep-Urban Unaided Precise Global Navigation Satellite System Vehicle Positioning
Deep-Urban Unaided Precise Global Navigation Satellite System Vehicle Positioning Open
This paper presents the most thorough study to date of vehicular carrier-phase differential GNSS (CDGNSS) positioning performance in a deep urban setting unaided by complementary sensors. Using data captured during approximately 2 hours of…
View article: Deep urban unaided precise GNSS vehicle positioning.
Deep urban unaided precise GNSS vehicle positioning. Open
This paper presents the most thorough study to date of vehicular carrier-phase differential GNSS (CDGNSS) positioning performance in a deep urban setting unaided by complementary sensors. Using data captured during approximately 2 hours of…
View article: Accurate Collaborative Globally-Referenced Digital Mapping with Standard GNSS
Accurate Collaborative Globally-Referenced Digital Mapping with Standard GNSS Open
Exchange of location and sensor data among connected and automated vehicles will demand accurate global referencing of the digital maps currently being developed to aid positioning for automated driving. This paper explores the limit of su…
View article: Maximum-Likelihood Power-Distortion Monitoring for GNSS-Signal Authentication
Maximum-Likelihood Power-Distortion Monitoring for GNSS-Signal Authentication Open
We propose an extension to the so-called PD detector. The PD detector jointly monitors received power and correlation profile distortion to detect the presence of GNSS carry-off-type spoofing, jamming, or multipath. We show that classifica…