Streamed live and recorded for on-demand viewing.
Video and papers posted the day of the session for on-demand viewing.
Unless otherwise noted, all times are in Central Daylight Time (CDT)

6:00 a.m. - 7:15 a.m. PST


Fundamentals of Time and its Measurement

Registration fee:
$400 if registered and paid by January 4
$450 if payment is received after January 4

The action of measuring relies on a clock at its very endpoint but involves a complex process where the fundamental element is the time scale. Requisites on a time scale depend on its applications; this means not only its metrological quality represented by the minimum required levels of stability and accuracy, but also other factors as traceability to national/international standards, security, resilience, robustness, accessibility. The elements to consider are the clocks and the algorithms for their connection; the link to a reference; the infrastructure supporting its maintenance and dissemination; the eventual legal implications. This tutorial will present the fundamental elements for time measurement and discuss the various time scales designed for different applications.

Dr. Elisa Felicitas Arias Dr. Felicitas Arias directed the BIPM Time Department during 18 years. She retired end of 2017, but continues contributing to time metrology and space reference frames programs at Paris Observatory.

7:30 a.m. - 8:45 a.m. PST


Time Transfer Protocols

Registration fee:
$400 if registered and paid by January 4
$450 if payment is received after January 4

Time has provided technology a common reference to define when something has happened, schedule tasks or synchronize actions. However, a time reference is not useful if it cannot be accessed periodically by those devices that require time-awareness. Time transfer is key to propagating a global reference and needs to fulfill the specific requirements for each application in terms of reliability, accuracy, simplicity and cost among others. Those requirements have led to a heterogeneous ecosystem of time transfer technologies.

In this talk, the state-of-art time transfer mechanisms that are broadly used in the industry are introduced, including examples of their adoption in the industry and references to the latest public results that have been released. This presentation focuses on time transfer protocols to distribute time information from the reference to the time consumers, how they make it and their adoption and limitations.

Francisco Girela Francisco Girela is the Americas Tech Responsible at Seven Solutions. He holds a Master's degree in Telecommunications Engineering and is working on his PhD. He has specialized in ultra-accurate time transfer systems and the development and integration of the White Rabbit technology in real life industrial applications.

9:00 a.m. - 10:15 a.m. PST


Microwave Oscillators

Registration fee:
$400 if registered and paid by January 4
$450 if payment is received after January 4

Microwave oscillators have been the first atomic clocks developed in the early 1950’s which have paved the way to the present definition of the SI second in 1967 using the microwave transition of the 133 Cs atom. Beside cesium beam primary clocks, numerous secondary standards are using microwave transitions such as rubidium standards and hydrogen masers. From the early developments, numerous improvements have been made for the atomic preparation and detection (optical pumping, laser cooling, coherent population trapping) while still probing their reference microwave transition.

In this tutorial we will first address the theoretical description of microwave interactions (Bloch equations). Then we will describe the differences and advantages of each clock types (Rb cell, H- maser, Cs thermal beam clock, atomic fountains, chip scale clocks …). Finally we will conclude on some challenges we must address at our industrial level to turn such clock technology from a laboratory prototype to an industrial turn-key product.

Dr. Patrick Berthoud Dr. Patrick Berthoud received his Ph.D. in physics from the University of Neuchâtel, Switzerland in 2000 on laser cooling of atoms. After a postdoctoral fellowship at JILA in Boulder, CO, USA, in 2001, he has developed several microwave clock prototypes for ground and space applications at the Observatory of Neuchâtel, Switzerland. In 2008 he joined Oscilloquartz SA, Switzerland as Chief Scientist focussing on the development and industrialization of Cesium thermal beam clocks.

6:00 a.m. - 7:15 a.m. PST


Optical Oscillators

Registration fee:
$400 if registered and paid by January 4
$450 if payment is received after January 4

Taking advantage of advances in low noise laser local oscillators and femtosecond frequency combs, optical frequency standards have surpassed the performance of the cesium microwave frequency standards upon which the SI second is based, and they are on the cusp of transitioning from scientific experiments to mainstream tools for metrology and fundamental physics. These standards are based on optical transitions in trapped and laser cooled atoms or ions and they derive their performance advantages from high transition frequencies, narrow transition linewidths, and small fractional systematic frequency shifts. State-of-the-art optical frequency standards are now reaching fractional frequency instabilities below 10 -16 at 1 s and systematic uncertainties near 10 -18.

This tutorial will cover cavity-stabilized laser local oscillators and optical frequency standards, including both optical lattice and trapped-ion clocks. After an introduction to the basic operating principles and building blocks, performance limitations and techniques to achieve high stability and accuracy will be presented. Finally, the tutorial will conclude with a discussion of the planned redefinition of the SI second based on optical frequency standards, and applications ranging from relativistic geodesy to tests of fundamental physics.

Dr. David R. Leibrandt Dr. David Leibrandt received his Ph.D. in Physics from the Massachusetts Institute of Technology. Since 2009, he has been with the Time and Frequency Division of the National Institute of Standards and Technology in Boulder, Colorado, where he currently leads the trapped-ion optical atomic clock and precision measurement experiments within the Ion Storage Group. Highlights of his research include the development of optical atomic clocks based on quantum-logic spectroscopy of aluminum ions with record systematic uncertainty below 10 -18 as well as laser frequency stabilization based on compact, portable Fabry-Perot cavities and spectral-hole burning.

7:30 a.m. - 8:45 a.m. PST


Optical Transmission

Registration fee:
$400 if registered and paid by January 4
$450 if payment is received after January 4

High precision timing is not only based on new clocks, but also on the techniques to transfer the time signal to the user. While wireless radio transmission has been used extensively, both terrestrial and via satellite, the utilization of optical properties though fiber has several advantages. The performance of optical time transfer can be tuned to accurately detect the phase of an optical signal which makes it the ultimate choice for comparison of optical clocks, but also at lower requirements of precision, the advantage of optical fiber lies in the robustness and security. While the necessary bandwidth is low, the requirements for stability and symmetry are huge, and not easily handled. The difference in transfer of frequency in comparison to time is also fundamental, since it relates either to the momentary change in phase or delay, or the accumulated changes. This tutorial will demonstrate the background of fiber optics, from the physics of light confinement in glass fibers to the limitations that must be overcome, including attenuation, dispersion, polarization, and environmental variations. It will conclude with the presentation of the latest state-of-the-art time and frequency transfer results, which have been experimentally demonstrated around the globe.

Dr. Per Olof Hedekvist Dr. Per Olof Hedekvist received his PhD 1998 from Chalmers University of Technology in Sweden. After a post-doc at Caltech in California and a few years as Associate Professor at Chalmers, he joined RISE Research Institutes of Sweden in 2005, working mainly on fiber-based techniques for time transfer. Presently he is also Sr. Scientist working with the NMI management in Sweden.

7:30 a.m. - 10:30 a.m. PDT


Watch Now



Why, How and When Redefining the SI Second

Dr. Elisa Felicitas Arias
Long Term Visitor at LNE/SYRTE, Observatoire de Paris, France

A new generation of frequency standards, operating in optical wavelengths achieved uncertainties of parts in 1018, facing metrology to consider a future redefinition of the SI second. In preparation for this, the Consultative Committee for Time and Frequency (CCTF) maintains a list of frequencies recommended as secondary representations of the second measured at various laboratories. The roadmap towards the redefinition in under revision based on the progress in the assessment of these optical frequency standards and the perspectives for operating highly accurate time and frequency transfer techniques without distance limitations. This conference presents the present situation, the future perspective, and the impact in other fields of science.

Dr. Arias directed the BIPM Time Department during 18 years. She retired end of 2017 but continues contributing to time metrology and space reference frames programmes at Paris Observatory.

Google's Use of 3D Building Models to Solve Urban GNSS

Dr. Frank van Diggelen

When GPS/GNSS was first developed in the 1970s, it was premised on line-of-sight signals with expected civilian accuracy of tens of meters. Almost immediately, commercial industry pioneers began to use GPS outside its intended design envelope. Almost all the accuracy, signal processing, and use-case limitations were solved: Differential GNSS, Carrier phase positioning, Assisted GNSS, High Sensitivity, and even GNSS in space. The one big unsolved problem is inaccuracy in cities.

GNSS constructively places you on the wrong side of street, or the wrong city block, in a situation where line-of-sight (LOS) signals are blocked, because the receiver tracks the non-line-of-sight signals (NLOS) reflected off buildings, and the entire system assumes line-of-sight time-of-flight. Now Google has deployed a system that solves this problem.

Using Google’s vast database of 3D building models, the asymmetric NLOS propagations are modeled so that the NLOS pseudorange errors can be corrected, leading to 50 to 90% reduction in Wrong-Side-of-Street occurrences from GNSS in phones.

In this talk, we will review the problem, and previous attempts to find a solution - revealing the deeply embedded difficulties facing researchers. Then we will give an overview of the Google solution, the rollout in Android phones, and before/after results.

Dr. Frank van Diggelen is a Principal Engineer at Google, where he leads the Android Core-Location Team. He also teaches GPS: he and Prof. Per Enge created an on-line GPS course, offered through Stanford University and Coursera and available on YouTube.

van Diggelen is a pioneer in Assisted GNSS, the technique that allows GPS to work in cell phones. He is the inventor of coarse-time GNSS navigation, co-inventor of Long Term Orbits for A-GNSS, and holds over 90 issued US patents on A-GNSS. He is the author of “A-GPS” the first textbook on Assisted GNSS, and Co-editor of PNT in the 21st Century” (Morton, van Diggelen, Spilker, and Parkinson), the latest book on GNSS and Navigation. He is Executive Vice President of the Institute of Navigation and a Fellow of the ION and the Royal Institute of Navigation (UK), and past recipient of both the Thurlow and Kepler awards of the ION.

Previously, he was a Navigation Officer in the South African Navy. He obtained his bachelor’s degree from the University of the Witwatersrand, South Africa, and Ph.D. in electrical engineering from Cambridge University, England.

12:30 p.m. - 1:30 p.m. CDT


Presentation of Awards

Watch the Awards Ceremony

The ION Annual Awards and Fellows Ceremony took place on January 28, 2021.

On-Demand Sessions

On-Demand sessions will remain available for 30 days.

ITM Session

Session Chairs:

Fabian Rothmaier
Stanford University
Barbara Clark
Federal Aviation Administration

1. An Assessment of the Difficulties Spoofing Live Sky vs Simulated GNSS Signals
G. Buesnel, M. Hunter, D. Martin, Spirent Communications, UK
2. Broadcast Data Authentication Concepts for Future SBAS Services
Luciano Tosato, Andrea Dalla Chiara, Oscar Pozzobon, QASCOM, Italy; Guillermo Fernandez Serrano, Alessandra Calabrese, GMV, Spain; Chris Wullems, Adrian Perrig, Mikael Mabilleau, GSA; Giovanni Vecchione, RHEA
3. Dynamic Time Warping (DTW) based GNSS Interference Detection Algorithm for Edge Devices
Wilbur Myrick, Daniel Goff, and Stanley Radzevicius, ENSCO, Inc.
4. AGC on Android Devices for GNSS
Dong-Kyeong Lee, Nicholas Spens, Benon Gattis, Dennis Akos University of Colorado Boulder
5. GNSS Spoofing Mitigation in the Position Domain
Fabian Rothmaier, Yu-Hsuan Chen, Sherman Lo, Todd Walter, Stanford University
6. GNSS Spoofing Discrimination Method Based on Doppler Frequency Double Difference for Multiple Independent Moving Receivers
Zhongxiao Wang, Hong Li, Jian Wen, Mingquan Lu, Tsinghua University, China
7. Key Management Concepts for Future SBAS Services
Luca Canzian, Luciano Tosato, Andrea Dalla Chiara, Oscar Pozzobon, Qascom, Italy; Mikael Mabilleau, GSA
8. Leveraging Worldwide, Publicly-Available Data to Create an Automated Satnav Interference Detection System
John Stader and Sanjeev Gunawardena, Air Force Institute of Technology
9. Management of Active Data and Authentication in Future SBAS Receivers
Chris Wullems, Luciano Tosato, Andrea Dalla Chiara, Oscar Pozzobon, Qascom, Italy; Guillermo Fernandez Serrano, Mikael Mabilleau, GSA
10. Performance Analysis and Tests for GNSS Spoofing Detection Based on the Monitoring of Cross Ambiguity Function and Automatic Gain Control
Tao Zhang, Xin Chen, Di He, Shanghai Key Laboratory of Navigation and Location Based Services, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, China; Yi Jin, State Grid Shanghai Municipal Electric Power Company, China
11. SBAS Message Authentication: A review of Protocols, Figures of Merit and Standardization Plans
Ignacio Fernández Hernández, European Commission, Belgium; Todd Walter, Andrew M. Neish, Jason Anderson, Stanford University; Mikael Mabilleau, European GNSS Agency/RHEA, Belgium; Giovanni Vecchione, European Commission/RHEA, Belgium; Eric Châtre, European Commission, Belgium
12. Time Synchronized Signal Generator GNSS Spoofing Attacks against COTS Receivers in over the Air Tests
Ronny Blum, Nikolas Dütsch, Jürgen Dampf, Thomas Pany, Universität der Bundeswehr Munich, Germany
ITM Session

Session Chairs:

Dr. Jinsil Lee
KAIST, South Korea
Dr. Michael Felux
zurich University of Applied Sciences, Switzerland

1. A Signal Quality Monitoring Algorithm Based on Chip Domain Observables for BDS B1C Signal
Xiang Wang, Department of Electronic Engineering, Tsinghua University, China; Yang Gao, Beijing Satellite Navigation Center, China; Xiaowei Cui, Gang Liu, Department of Electronic Engineering, Tsinghua University, China; Mingquan Lu, Department of Electronic Engineering, and Beijing National Research Center for Information Science and Technology, Tsinghua University, China
2. Analysis of BDS B1C/B2a Acquisition, Tracking and Data Demodulation Thresholds for Civil Aviation
Chuanrui Wang, Xiaowei Cui, Department of Electronics Engineering, Tsinghua University, China; Xiao Li, Beijing Hualong Tong Science and Technology Co,.Ltd, China; Gang Liu, Department of Electronics Engineering, Tsinghua University, China; Mingquan Lu, Department of Electronics Engineering and Beijing National Research Center for Information Science and Technology, Tsinghua University, China
3. ARAIM for Military Users: ISM Parameters, Constellation-Check Procedure and Performance Estimates
Alec Katz, Sam Pullen, Sherman Lo, Juan Blanch, Todd Walter, Stanford University; Andrew Katronick, Mark Crews, Robert Jackson, Lockheed Martin
4. Investigation into September 2020 GPS SVN 74 Performance Anomaly
Todd Walter, Zixi Liu, Juan Blanch, Stanford University; Kristy Pham, John Mick, William Wanner, William J. Hughes FAA Technical Center
5. Nominal Range Error Analysis of BDS for ARAIM
Hengwei Zhang, Yiping Jiang, The Hong Kong Polytechnic University, China
6. Vertical Protection Level Optimization Method for BDS/GPS Navigation System
Ershen Wang, Xidan Deng, Shenyang Aerospace University, China; Jing Guo, China Academy of Civil Aviation Science and Technology, China; Gang Tong, Pingping Qu, Yi Zhang, Noncommissioned officer Academy, Institute of Army and Air Defense Forces, China; Tao Pang, Shenyang Aerospace University, China
7. Reevaluating the Message Loss Rate of the Wide Area Augmentation System (WAAS) in Flight
Matthew J. Hirschberger, Sherman Lo, Todd Walter, Stanford University
PTTI Session

Session Chairs:

Dr. Joerg Hahn
ESA, The Netherlands
Katarzyna Oldak

1. Hardening Accurate Timing Receivers Against Low-cost 1PPS Spoofing
Yoav Zangvil, Technion Institute of Technology, Regulus Cyber Gal Cohen, Technion Institute of Technology, Regulus Cyber
2. Advancements in the GIANO Project: Galileo based Timing Receiver for Increasing Critical Infrastructures Resilience
Piotr Dunst, Jerzy Nawrocki, Edoardo Detoma, Space Research Center PAS, Poland; Pawel Nogas, PikTime Systems, Poland; Livio Marradi, Gianluca Franzoni, Marco Puccitelli, Roberto Campana TAS-I, Italy; Roberto Muscinelli, BIP, Italy; Valeria Catalano, Ciro Gioia, Antonio Danesi, European GNSS Agency
3. Galileo System Status
Jörg Hahn, Daniel Blonski, G. Galluzzo, Paolo Zoccarato, ESA, The Netherlands
4. Comparing the Timescales in Public, Precise Ephemeris Products
William Konyk, National Geospatial-Intelligence Agency
5. IPPP Links for UTC: Comparison to Existing Techniques
Gérard Petit and Frédéric Meynadier, BIPM, France
ITM Session

Session Chairs:

Dr. Çagatay Tanil

2. Development of a Navigation and Information Service for a University Library
Guenther Retscher and Alexander Leb, Department of Geodesy and Geoinformation, TU Wien, Austria
3. Evaluating INS/GNSS Availability for Self-Driving Cars in Urban Environments
Kana Nagai, Matthew Spenko, Ron Henderson, and Boris Pervan, Illinois Institute of Technology
4. Exploring the Chip Scale Atomic Clock Within a GPS Disciplined Oscillator
Luke Littleton-Strand, Filip Nedelkov, University of Colorado Boulder; Erin Griggs, Trusted Space, Inc.; Dennis Akos, University of Colorado Boulder, Stanford University
5. Multipath Rejection Using Multicorrelator Based GNSS Receiver With an Extended Kalman Filter
Christian Siebert, Institute of Communications and Navigation, German Aerospace Center (DLR), & Chair of Navigation, RWTH Aachen University, Germany; Andriy Konovaltsev, Institute of Communications and Navigation, DLR, Germany; Michael Meurer, Institute of Communications and Navigation, DLR, & Chair of Navigation, RWTH Aachen University, Germany
6. Performance Analysis of GNSS Spoofing Mitigation Techniques based on Array Antennas in Various Spoofing Scenarios
J. H. Noh, B. H. Gong, Y. S. Lee, B. C. Jung, S. J. Lee, Department of Electronic Engineering, Chungnam National University, Republic of Korea; H. H. Choi, Satellite Navigation Team, Korea Aerospace Research Institute, Republic of Korea
7. Positioning Performance in Deep Pit Mines using GNSS Augmented with Locata
Maria J. Evans, The Pennsylvania State University-Brandywine; Sean Evans Eagen, Virginia Polytechnic Institute and State University
8. Scalability and Latency Analysis of the Centralized 3D Mapping Aided GNSS-Based Collaborative Positioning
Guohao Zhang, Hoi-Fung Ng, Li-Ta Hsu, Interdisciplinary Division of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University, Hong Kong; Han Gao and Dingzhong Yao, Huawei Technology
ITM Session

Session Chairs:

Dr. Jiwon Seo
Yonsei University, South Korea
Sriramya Bhamidipati
University of Illinois at Urbana-Champaign

1. A Feasibility Study on Smartphone Localization using Image Registration with Segmented 3D Building Models based on Multi-Material Classes
Max Jwo Lem Lee and Li-Ta Hsu, Interdisciplinary Division of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University, Hong Kong
2. Resilient Distributed Positioning Networks: A New Approach to Extreme Low-Latency, High-Precision Positioning and Timing
Brian G. Agee, B3 Advanced Communication Systems
3. Evaluation of Sensor-Agnostic All-Source Residual Monitoring for Navigation
Andrew Appleget, Robert C. Leishman, and Jonathon Gipson, Air Force Institute of Technology
4. Evaluation of Ground Vehicle Protection Level Reduction due to Fusing GPS with Faulty Terrestrial Signals of Opportunity
Mu Jia, Joe Khalife, and Zaher M. Kassas, University of California, Irvine
5. Precise Real-Time Relative Orbit Determination for Large-Baseline Formations Using GNSS
Vincent Giralo and Simone D’Amico, Space Rendezvous Laboratory, Stanford University
6. Real-Time Horizontal Velocity Estimation of a Landing Craft using Computer Intelligence
Lavanya Karthikeyan, Department of Computer Science and Engineering, Amrita School of Engineering-Bangalore, India; Malavika R. Nair, Department of Computer Science and Engineering, Amrita School of Engineering-Bangalore, India; S.V. Apoorva, BMS Institute of Technology and Management, India; Vinod Kumar, UR Rao Satellite Centre, India
PTTI Session

Session Chairs:

Dr. Elizabeth Laier English
National Physical Laboratory, UK
John Clark

1. Time Determination for Network Analytics
Charles Barry, Luminous Cyber
2. An Analysis of Performance Statistics Reported by the NTPv4 Reference Implementation and Their Effect on Calibration Uncertainty
Andre Charbonneau and Marina Gertsvolf, National Research Council Canada
3. The WRITE (White Rabbit for Industrial Timing Enhancement) Project Update
Elizabeth Laier English, Belinda Eglin, Adam Parsons, Conway Langham, Peter Whibberley, NPL, UK; Davide Calonico, INRIM, Italy; Anders Wallin, VTT, Finland; Peter Jansweijer, NIKHEF, Netherlands; Paul-Eric Pottie, Paris Observatory, France; Erik Dierikx, Marijn Van Veghel, Yan Xie, VSL, Netherlands; José Luis Gutiérrez, José López-Jiménez, Javier Díaz, Seven Solutions, Spain; Carsten Rieck, RISE, Sweden; Hermann Virgile, Francois Kecskemeti, Thales, France; Sapia Adalberto, Massari Maurizio, Leonardo, Italy; Luca Liberati, OPNT, Netherlands
4. Geostamp for Legal Time Traceability and 4D GIS Applications
Brooks Harris, EdlMax, Cambrea Ezell, ALV, and Son VoBa, Sync-n-Scale
5. A Metrological White-Rabbit Link between two UTC(k) Labs
P. Waller, C. Plantard, ESA/ESTEC, European Space Research and Technology Centre, The Netherlands; E. Dierikx, M. van Veghel, VSL, Dutch Metrology Institute, The Netherlands; R. Smets, A. van den Hil, SURF, Dutch ICT cooperative for Education and Research, The Netherlands
6. CLONETS-DS – Clock Network Services-Design study Strategy and Innovation for Clock Services Over Optical-fibre Networks
Josef Vojtech, Vladimir Smotlacha, Radek Velc, Rudolf Vohnout, CESNET, Czech Republic; Tara Liebisch, Harald Schnatz, Physikalisch-Technische Bundesanstalt, Germany; Tryfon Chiotis, Guy Roberts, Vincenzo Capone, GÉANT VERENIGING; Artur Binczewski, Wojbor Bogacki, Krzysztof Turza, Poznan Supercomputing and Networking Center, Poland; Paul-Eric Pottie, Philip Tuckey LNE-SYRTE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC, France; Davide Calonico, Istituto Nazionale di Ricerca Metrologica, Italy; Ronald Holzwarth, Ben Sprenger, Menlo Systems, Germany; Ondej Cíp, Lenka Pravdová, Simon Rerucha, Institute of Scientific Instruments of the CAS, v.v.i. (ISI), Czech Republic; Javier Díaz Alonso, Eduardo Ros Vidal, University of Granada, Spain; Trinidad García, José López, Seven Solutions S.L., Spain; Ulrich Schreiber, Jan Kodet, Technical University of Munich, Germany; Jürgen Kusche, Simon Stellmer, Dieter Meschede Rheinische, Friedrich-Wilhelms-Universität; Bonn Robert Urbaniak, Piktime Systems sp. z o.o., Poland; Przemysaw Krehlik, Lukasz Sliwczyski, AGH University of Science and Technology, Poland; Anne Amy-Klein LPL, Université Sorbonne Paris Nord, CNRS, France; Nicolas Quintin Réseau, National de Télécommunications pour la Technologie, l'Enseignement et la Recherche, France; Alwyn Seeds, University College London, UK; Bruno Desruelle, Vincent Ménore, Jean Lautier-Gaud, Martin Rabault Muquans, Talence, France
PTTI Session

Session Chairs:

Dr. Bin Jian
National Research Council, Canada
Dr. Tetsuya Ido
NICT, Japan

1. Measurement of the Frequency Ratio of 115In+ ion Clock and 87Sr Optical Lattice Clock
N. Ohtsubo, Y. Li, N. Nemitz, H. Hachisu, K. Matsubara, T. Ido, and K. Hayasaka, National Institute of Information and Communications Technology, Japan
2. Absolute Frequency of 87Sr at 1.8×10-16 Uncertainty by Tracing NICT-Sr1 to Remote Primary Frequency Standards
Nils Nemitz, Hidekazu Hachisu, Tadahiro Gotoh, Fumimaru Nakagawa, Hiroyuki Ito, Yuko Hanado, and Tetsuya Ido, National Institute of Information and Communications Technology, Japan
3. Absolute Frequency Measurement of the NRC’s Strontium ion Clock Using the GPS PPP Method
Bin Jian, Pierre Dubé, and Marina Gertsvolf, National Research Council Canada
ITM Session

Session Chairs:

Dr. Sandra Verhagen
Delft University of Technology, The Netherlands
Dr. Erin Kahr
Hexagon, Canada

1. A Feasibility Study on the Position Hypothesis Based RTK with the Aids of 3D Building Models
Hoi-Fung Ng and Li-Ta Hsu, Interdisciplinary Division of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University, China
2. Attitude Determination and RTK Performances Amelioration Using Multiple Low-Cost Receivers with Known Geometry
Xiao Hu, Paul Thevenon, Christophe Macabiau, ENAC, Université de Toulouse, France
3. BIE using multivariant t-distribution and the iFlex method for GNSS PPP
Viet Duong, Hemisphere GNSS (USA) Inc., USA; Suelynn Choy, School of Science, RMIT University, Australia; Chris Rizos, School of Civil and Environmental Engineering, University of New South Wales, Australia
4. Square Root Information Filtering Method of GPS / BDS Dynamic Precise Point Positioning in Complex Environment
Hepeng Wang, Huixia Li, Hang Guo, Ping Jiang, Cong Huang, School of Information Engineering, Nanchang University, China
PTTI Session

Session Chairs:

Dr. James Camparo
The Aerospace Corporation
Jamie Mitchell

1. An Advanced-CSAC Testbed for Next-Generation Space Missions: Overview and Recent Results
Zachary Warren, Hunter Kettering, and James Camparo, Physical Sciences Laboratories, The Aerospace Corporation
2. A Testbed for Low-SWaP Atomic Clock Ensemble Development
Christopher Flood, Michael Q. LaBarge, Luciana Schement, Henry Dixon, Penina Axelrad, University of Colorado Boulder
3. Adapting a Timescale Kalman Filter for Fast Synchronization of High Frequency Oscillators
Sarah Withee, Kami Okusaga, Johns Hopkins Applied Physics Lab
4. Measuring the Temperature Dependence of Collision Shifts for Optical Transitions
Hunter Kettering, Travis Driskell, James C. Camparo, The Aerospace Corporation
ITM Session

Session Chairs:

Dr. Zak Kassas
University of California Irvine
Dr. Tyler Reid
Xona Space Systems

1. Autonomous Lunar Satellite Navigation System: Preliminary Performance Assessment on South Pole
Mauro Leonardi, Gheorghe Sirbu, University of Rome "Tor Vergata" Department of Electronic Engineering, Italy; Cosimo Stallo, Massimo Eleuteri, Carmine Di Lauro, Claudia Iannone, Ersilia Del Zoppo, Thales Alenia Space, Italy
3. Navigation Technology Satellite – 3: A Vanguard for Space-based Position, Navigation, and Timing
Joanna Hinks, Air Force Research Laboratory, Space Vehicles Directorate; David Chapman, ExoAnalytics Solutions, Inc.; Jon Anderson, Canyon Consulting
4. Single Differenced Doppler Positioning with Low Earth Orbit Signals of Opportunity and Angle of Arrival Estimation
Sterling Thompson, Scott Martin, and David Bevly, Auburn University
5. Terrestrial Precise Positioning System Using Carrier Phase from Burst Signals and Optically Distributed Time and Frequency Reference
Han Dun, Christian C. J. M. Tiberius, Cherif Diouf, Geoscience and Remote Sensing, Delft University of Technology, Delft University of Technology, The Netherlands; Gerard J. M. Janssen, Circuits and Systems, Delft University of Technology, The Netherlands
6. Trusted Radionavigation via Two-Way Ranging
Sami Ruponen, Tapio Suihko, Juha Zidbeck, VTT Technical Research Centre of Finland; Ondrej Daniel, Tatjana Petkovic, Huld; Gianluca Caparra, Lionel Ries, European Space Agency, Netherlands
ITM Session

Session Chairs:

Dr. Sabrina Ugazio
Ohio University
Ajay Vemuru
Spirent Communications, UK

1. A High Performance Easily Configurable Satnav SDR for Advanced Algorithm Development and Rapid Capability Deployment
Sanjeev Gunawardena, Air Force Institute of Technology
2. An Improved Frequency Domain Interference Suppressor for DBT Processing of High Order BOC Signals
Zhenyu Tian, Xiaowei Cui, Gang Liu, Department of Electronic Engineering, Tsinghua University, China; Mingquan Lu, Department of Electronic Engineering, and Beijing National Research Center for Information Science and Technology, Tsinghua University, China
3. Cooperative Vector Processing of GPS Signals
Tanner M. Watts and Scott M. Martin, Auburn University
4. Multi-Band Antenna Array Geometry Impact on Array Interpolation
Marco Marinho, Halmstad University, Sweden; Per Gustafson, Gutec AB, Sweden; Felix Antreich, Aeronautics Technology Institute, Brazil; Stefano Caizzone, German Aerospace Agency, Germany; Alexey Vinel, Halmstad University, Sweden
5. Signal Quality Monitoring Spoofing Identification Methods for GNSS Vector Tracking Structure
Xinran Zhang, Hong Li, Chun Yang, Mingquan Lu, Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Tsinghua University, China; China Academy of Engineering Physics, China
ITM Session

Session Chairs:

Dr. Ningchao Wang
Hampton University
Dr. Larry Sparks
Jet Propulsion Laboratory

1. A Risk Assessment of Geomagnetic Conditions Impact on GPS Positioning Accuracy Degradation in Tropical Regions Using Dst Index
Nenad Sikirica, Krapina University of Applied Sciences, Croatia; Franc Dimc, Faculty of Maritime Studies and Transport, University of Ljubljana, Slovenia; Oliver Jukic, Virovitica College, Croatia; Teodor B Iliev, University of Ruse, Bulgaria; Darko Spoljar, Faculty of Engineering, University of Rijeka, Croatia; Renato Filjar, Faculty of Engineering, University of Rijeka, and Krapina University of Applied Sciences, Croatia
2. Assessment of Ionospheric Correction Behavior for Use with Precise Point Positioning (PPP)
Todd Walter and Juan Blanch, Stanford University; Lance de Groot and Laura Norman, Hexagon, Canada
3. Bobcat-1, the Ohio University CubeSat: Preliminary Data Analysis
Kevin Croissant, Gregory Jenkins, Ryan McKnight, Brian C. Peters, Sabrina Ugazio and Frank van Graas, Ohio University
4. Machine Learning-based Investigation of Feature Importance for High-latitude Ionospheric Scintillation Forecasting
Alexis J. Wu, Canyon Crest Academy; Yunxiang Liu, University of Colorado Boulder, Boulder
5. Measuring Small- and Medium-Scale TEC Spatial Variations and Irregularities from Ground-Based GNSS Observations
Xiaoqing Pi, Shadi Oveisgharan, Ekaterina Tymofyeyeva, Heresh Fattahi, Paul Rosen, and Vardan Akopian, Jet Propulsion Laboratory, California Institute of Technology
6. Reporting Pre-Sunset Scintillation on GNSS Frequencies over Arabian Peninsula
M. M. Shaikh and I. Fernini, Space Weather and Ionosphere Laboratory, Sharjah Academy for Astronomy, Space Sciences and Technology, University of Sharjah, Sharjah, UAE
ITM Session

Session Chairs:

Dr. Mihaela-Simona Circiu
German Aerospace Center DLR, Germany
Dr. Steven Langel
The MITRE Corporation

1. An Overview of the Proposed Mode N System in the Context of Alternative Position, Navigation, and Timing (APNT) Development
Brandon Weaver, Gianluca Zampieri, Okuary Osechas, German Aerospace Center (DLR), Germany
2. A Rényi Divergence Based Approach to Fault Detection and Exclusion for Tightly Coupled GNSS/INS System
Changwei Chen and Solmaz S. Kia, University of California, Irvine
3. Antenna Group Delay Variation Bias Effect on Advanced RAIM
Eugene Bang, Mihaela-Simona Circiu, Stefano Caizzone and Markus Rippl, German Aerospace Center (DLR), Germany
4. Gaussian Bounding Improvements and an Analysis of the Bias-sigma Tradeoff for GNSS Integrity
Juan Blanch, Xinwei Liu, and Todd Walter, Stanford University
5. Final Results on Airborne Multipath Models for Dualconstellation Dual-frequency Aviation Applications
Mihaela-Simona Circiu, Stefano Caizzone, Christoph Enneking, Friederike Fohlmeister, Markus Rippl, Michael Meurer, German Aerospace Center, Germany; Michael Felux, ZHAW; Ioana Gulie, David Rüegg, Airbus Defence and Space; Joseph Griggs, Collins Aerospace; Rémy Lazzerini, Florent Hagemann, Francois Tranchet, Airbus Operation SAS; Pierre Bouniol, Thales Avionics; Matteo Sgammini, Joint Research Center of the European Commission
6. On The Impact Of Temporal Variation On GNSS Position Error Models
Syed Ali Kazim, COSYS-LEOST, Univ. Gustave Eiffel, France; Nourdine Aït Tmazirte, IRT Railenium, France; Juliette Marais, COSYS-LEOST, Univ. Gustave Eiffel, France
7. Sigma-Z: A New Parametric and Constrained-by-Design GNSS Observation Weighting Model for Land Applications
Nourdine Ait Tmazirte, Institut de Recherche Technologique Railenium, France; Syed Ali Kazim, Juliette Marais, COSYS-LEOST, Univ Gustave Eiffel, IFSTTAR, Univ Lille, France; Maan El Badaoui El Najjar, CRIStAL - Centre de Recherche en Informatique Signal et Automatique de Lille - Univ. Lille, CNRS, UMR, France
ITM Session

Session Chairs:

Dr. Melania Susi
European Commission JRC, Italy
Dr. Li-Ta Hsu
Hong Kong Polytechnic University, China

1. A Testbench with Increased Accuracy for the Calibration of Inertial Navigation Systems and Inertial Sensors
Bernard Vau, Mehdi Bussutil, Joachin Honthaas, Colin Stevens, Ixblue, France
2. Accurate Covariance Estimation for Pose Data from Iterative Closest Point Algorithm
Rick H. Yuan, Clark N. Taylor, Scott L. Nykl, Air Force Institute of Technology
3. Calibration of Fixed-Wing UAV Aerodynamic Coefficients with Photogrammetry for VDM-based Navigation
Gabriel Laupré and Jan Skaloud, Geodetic Engineering Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland
4. New SLAM Fusion Algorithm based on Lidar/IMU Sensors
Ping Jiang, Hang Guo, Hepeng Wang, School of Information Engineering, Nanchang University, China; Min Yu, College of Computer Information and Engineering, Jiangxi Normal University, China; Jian Xiong, School of Information Engineering, Nanchang University, China
PTTI Session

Session Chairs:

Travis Driskell
The Aerospace Corporation
Gregory Weaver
Johns Hopkins University/APL

1. A Comparison of Relativistic Impacts on Satellite Timekeeping for Various Orbits
Edward A. LeMaster, Lockheed Martin Space
2. Code-and-carrier-phase based Two-Way Satellite Time and Frequency Transfer (TWSTFT) Experiment Between INRiM, LNE-SYRTE and PTB
Tung Thanh Thai, Ilaria Sesia, Istituto Nazionale di Ricerca Metrologica, Italy; Joseph Achkar, Baptiste Chupin, Giovanni Daniele Rovera, LNE-SYRTE, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, France; Dirk Piester, Physikalisch-Technische Bundesanstalt, Germany; Miho Fujieda, Tadahiro Gotoh, Ryo Tabuchi, National Institute of Information and Communications Technology, Japan
3. Pulsars as Next Generation Grid Timing Sources
Peter Fuhr, Oak Ridge National Laboratory
4. Timing Requirements Analysis for Particle Physics and Astrophysics: A Metrological Point of View
G. Cerretto, D. Calonico, E. Cantoni, F. Levi, A. Mura, M. Sellone, Istituto Nazionale di Ricerca Metrologica (INRIM), Italy; I. Gnesi, Centro Ricerche Enrico Fermi, Italy
PTTI Session

Session Chairs:

Dr. Fabrizio Giorgetta
Dr. Jeff Sherman

1. Active Bidirectional Precise Time Transmission Outside the Telecommunication Bands Over 200 km of Single Mode Fiber
Josef Vojtech, Ondrej Havlis, Martin Slapak, Jan Kundrat, Sarbojeet Bhowmick, Vladimir Smotlacha, Radek Velc, Lada Altmannova, Tomas Horvath, Michal Hazlinsky, Tomas Pecka,Vaclav Kubernat CESNET z.s.p.o., Czech Republic; Martin Cizek, Jan Hrabina, Vaclav Hucl, Lenka Pravdova, Ondrej Cip, Institute of Scientific Instruments, Czech Academy of Sciences, Czech Republic
2. A Resilient National Timing Architecture Securing Today’s Systems, Enabling Tomorrow’s
Marc Weiss, Marc Weiss Consulting; Patrick Diamond, Position, Navigation and Timing Advisory Board; Dana A. Goward, Resilient Navigation and Timing Foundation
3. The NIST Special Calibration Test, Preliminary Results and Future Plans
Monty Johnson, OPNT and Judah Levine, NIST
4. Precise Frequency Transfer with Broadband Transportable VLBI Stations
Mamoru Sekido, National Institute of Information and Communications Technology (NICT), Japan; Marco Pizzocaro, Istituto Nazionale di Ricerca Metrologica (INRIM), Italy; Kazuhiro Takefuji, NICT & Japan Aerospace Exploration Agency (JAXA), Japan; Hideki Ujihara, Hidekazu Hachisu, Nils Nemitz, Masanori Tsutsumi, NICT, Japan; Tetsuro Kondo, NICT, Japan and Chinese Academy of Sciences, Shanghai Astronomical Observatory, China; Eiji Kawai, Ryuichi Ichikawa, Kunitaka Namba, Yoshihiro Okamoto, Rumi Takahashi, Junichi Komuro, NICT, Japan; Cecilia Clivati, Istituto Nazionale di Ricerca Metrologica (INRIM), Italy; Filippo Bregolin, INRIM, Italy and Toptica Photonics AG, Germany; Piero Barbieri, Alberto Mura, Elena Cantoni, Giancarlo Cerretto, Filippo Levi, INRIM, Italy; Giuseppe Maccaferri, Mauro Roma, Claudio Bortolotti, Monia Negusini, Istituto Nazionale di Astrofisica (INAF), Istituto di Radioastronomia (IRA), Italy; Roberto Ricci, INRIM and IRA, Italy; Giampaolo Zacchiroli, Juri Roda, IRA, Italy; Julia Leute, Bureau International des Poids et Mesures (BIPM), and LNE-SYRTE, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, France; Gérard Petit, BIPM, France; Federico Perini, IRA, Italy; Davide Calonico, INRIM, Italy; and Tetsuya Ido, NICT, Japan
5. GNSS Calibrations for Difficult Environments
Carsten Rieck, RISE, Kenneth Jaldehag, RISE, Sweden
PTTI Session

Session Chairs:

Dr. Giancarlo Cerretto
INRIM, Italy
Francine Vannicola
Naval Research Laboratory

1. Update on UTC(ESTC) Generation and Monitoring
Pierre Waller, Cedric Plantard, Andrea Samperi, European Space Research and Technology Centre – ESA/ESTEC, The Netherlands
2. Time and Frequency Activities at the JHU Applied Physics Laboratory
Mihran Miranian, Olukayode K. Okusaga, Richard A. Dragonette, Sarah Withee, JHU/Applied Physics Laboratory
3. Continuous UTC: Preliminary Steps in Russian State Service for Time and Frequency
I. Blinov, N. Kosheliaevsky, and A. Naumov, VNIIFTRI Department of Metrology for Time and Space, Russia
4. Overall Activities of Time and Frequency Metrology in NICT
T. Ido, K. Matsubara, H. Saito, R. Ichikawa, M. Kumagai and M. Sekido, NICT, Japan
5. The First Months of Fully Automated Generation of the Italian Time Scale UTC(IT)
V. Formichella, G. Signorile, T. T. Thai, A. Perucca, F. Fiasca, E. Cantoni, M. Sellone, A. Mura, I. Sesia and F. Levi, Quantum Metrology and Nano Technologies Division, INRiM, Torino, Italy
6. Building a Resilient Enhanced Time Scale Infrastructure for the UK: National Timing Centre Programme Overview
John Davis, Kathryn Burrows, Hannah Collingwood, Setnam Shemar, Peter Whibberley, Simon Ashford, Ali Ashkhasi, Belinda Eglin, Rob Foot, Richard Hendricks, Elizabeth Laier English, Conway Langham, Adam Parsons, Krzysztof Szymaniec, Josh Whale, Andrew Wilson, Leon Lobo and Helen Margolis, National Physical Laboratory, UK
PTTI Session

Session Chairs:

Dr. Valerio Formichella
INRIM, Italy
Dr. Demetrios Matsakis

1. Allan Deviation of Atomic Clock Frequency-Corrections: A New Tool for Characterizing Clock Disturbances
Daphna G. Enzer, David W. Murphy, Eric A. Burt, Jet Propulsion Laboratory, California Institute of Technology
3. Testing the Robustness of a Time Scale Algorithm by Using Simulated Optical Clock Data
Valerio Formichella, Quantum Metrology and Nano Technologies Division, INRiM, Italy; Lorenzo Galleani, Department of Electronics and Telecommunications, Politecnico di Torino, Italy; Giovanna Signorile, Quantum Metrology and Nano Technologies Division, INRiM, Italy; Ilaria Sesia, Quantum Metrology and Nano Technologies Division, INRiM, Italy
4. Clock Ensembling to Mitigate GNSS Atomic Clock Frequency Jumps
Kathryn Oleksak and James Camparo, The Aerospace Corporation
5. Comparison of Extensions of the Three-Cornered Hat and Groslambert Covariance Algorithms for Estimating N-Oscillator Ensemble-Relative Time Stability
James Schatzman, Augustus Aerospace Co.
6. On the Uncertainties in UTC-UTC(k): Simulating UTC Generation
Demetrios Matsakis, Masterclock, Inc.