Precise Time and Time Interval (PTTI)

PTTI Pre-Conference Tutorials

The following pre-conference tutorials will be offered on January 21:

• Fundamentals of time and its measurement
• Time transfer protocols
• Microwave oscillators
• Optical oscillators
• Optical transmission

PTTI Keynote Address

The Redefinition of the SI Second
Dr. Elisa Felicitas Arias, SYRTE/Paris Observatory, France

PTTI Session Topics

Countering Jamming and Spoofing on GNSS Timing Services
Timing systems depending on GNSS signals are at the core of numerous critical infrastructure systems, including the electric power grid, telecommunication systems, financial and stock exchanges, and digital TV broadcasting. This session will focus on techniques to counter spoofing and jamming of GNSS receivers that provide accurate time to these critical infrastructure systems. A number of developments are under way in academia and industry to counter this threat by making GNSS receivers more resilient and robust: the techniques being investigated rely on improved hardware and robust software algorithms, designed with the aim of improving the resiliency of timing products against all forms of intentional and unintentional failures.
Co-chairs:
Dr. Edoardo Detoma, LJT & Associates, Italy
Michael Lombardi, NIST

GNSS/RNSS Time and Frequency Transfer and Emergent Timing Technologies
Advances and improvements in the growing number of GNSS and RNSS systems have expanded the options for performing time and frequency transfer and changed the complexity of the analysis. Submissions in the areas of time and frequency transfer that utilize any of the GNSS/RNSS systems, multi-GNSS techniques, as well as cutting-edge developments in timing are encouraged. Suggested topics include, but are not limited to, research on more robust infrastructures to master timing in GNSS systems, PPP-like services from GNSS to timing users, comparison of authenticated time provisioning using GNSS to authenticated time provisioning through industry or other organizations, timing for space exploration, and other future needs.
Co-chairs:
Dr. Joerg Hahn, ESA, The Netherlands
Katarzyna Oldak, USNO

Network Synchronization Technologies for High-end Science and Robust Critical Infrastructure
Commercial time and frequency transfer methods such as NTP, PTP and White Rabbit offer a range of synchronization performances for both industry and high-end science. When combined with atomic clocks, these methods can offer scalable and traceable distributed time, which is needed for critical infrastructure as a robust alternative to GNSS.
Co-chairs:
Dr. Elizabeth Laier English, National Physical Laboratory, UK
John Clark, Masterclock

Optical Clocks and Possible Scenario Towards the Redefinition of the Second
Optical atomic clocks have recently surpassed the performance of the current primary frequency standards — the caesium fountains — in both accuracy and stability by more than an order of magnitude. This makes optical clocks not only powerful for the fundamental research but also for realizing the redefinition of the SI unit of second. This session presents the recent advances in the development of the optical clocks as well as their applications aiming for the redefinition of the SI second. The suitable topics relevant to optical clocks include, but not limited to, the possible implementations of a new SI second, improvement on the stability and reliability, development of the transportable optical clocks, remote frequency comparisons, and timescales based on the optical clocks, etc.
Co-chairs:
Dr. Bin Jian, National Research Council, Canada
Dr. Tetsuya Ido, NICT, Japan

Present and Future Clocks for Ground and Space Applications
This session will consider applications of both present and future clocks (e.g., atomic, MEMs, etc.) to space systems, which implies both the ground and space aspects of system timekeeping.
Co-chairs:
Dr. James Camparo, The Aerospace Corporation
Jamie Mitchell, Microchip

Space-based Time and Frequency Transfer – Established and Emerging
One-way time and frequency transfer from GNSS is the dominant global method for military, civilian, and critical national infrastructure. However, because of the increasing potential for adverse action to deny or deceive GNSS signals, an emerging range of complementary and alternative space-based systems, both two-way and one-way, are under development. Several of these emerging time and frequency systems take advantage of the new thrust in massively proliferated low-earth orbit (LEO) space architectures, while some look to still utilize higher orbits. This session will present talks discussing this evolving state of space-based time and frequency transfer.
Co-chairs:
Travis Driskell, The Aerospace Corporation
Gregory Weaver, Johns Hopkins University/APL

Terrestrial Time and Frequency Transfer
Without the benefit of space-borne assets like GNSS for common-view observation or geo-stationary satellites for signal relay, time and frequency transfer requires a terrestrial exchange of physical signals. We focus on high-performance techniques involving networks, optical signals over free-space or fiber optics, free-space microwave and mm-wave links.
Co-chairs:
Dr. Fabrizio Giorgetta, NIST
Dr. Jeff Sherman, NIST

Time and Frequency Activities and Updates from NMIs and International Organizations
The opportunity for Time and Frequency Laboratories, including those operated by National Metrology Institutes (NMIs), military, scientific and academic organizations, to highlight their current and future PTTI activities. Topics to include UTC(k) generation and performance, time dissemination, time services, calibrations and specific PTTI measurements supporting a wide range of scientific activities.
Co-chairs:
Dr. Giancarlo Cerretto, INRIM, Italy
Francine Vannicola, Naval Research Laboratory

Time Scales and Algorithms
Independent and steered time scales are generated by GNSS, laboratories, networks, and others. The advent of optical frequency standards at the high-accuracy and high-precision end, and SWAP-optimized clocks at the opposite end, is adding new demands and constraints to the algorithms. We solicit papers on any aspect of time scales and related algorithms.
Co-chairs:
Dr. Valerio Formichella, INRIM, Italy
Dr. Demetrios Matsakis, Masterclock

International Technical Meeting (ITM)

ITM Keynote Address

COVID-19 Contact Tracing/Exposure Notification
Google Representative, Invited

ITM Sessions

GNSS and Security: Interference, Jamming, and Spoofing
Techniques to make GNSS more robust to spoofing, jamming, and inter-ference in general, through signal processing, complementary PNT, or other means. Applications in robust positioning and secure time transfer. Threat modeling, assessment and mitigation. Integrity and continuity implications of security measures. Analysis of GNSS disruption events.
Co-chairs:
Fabian Rothmaier, Stanford University
Barbara Clark, Federal Aviation Administration

GNSS Integrity and Augmentation
Fault monitoring, fault exclusion, protection level algorithms and requirements for receiver-based integrity, ground-based, space-based and aircraft-based augmentation. Challenges in the provision of integrity in multi-frequency/multi-constellation services. Applications include navigation for aviation, automotive, rail, maritime and other transportation applications.
Co-chairs:
Dr. Jinsil Lee, KAIST, South Korea
Dr. Michael Felux, zurich University of Applied Sciences, Switzerland

Navigation in GNSS Challenged Environments
Navigation in GNSS-denied/challenged environments. Sensing, perception, and map building in ground vehicle operations. Guidance, navigation, and control (GNC) systems for autonomous or semi-autonomous vehicles. Sensing for visual interfaces of driver-assistance systems. Requirements for ground vehicle GNC systems. Validation and verification of ground vehicle GNC systems. Algorithms and tools for global path planning and local obstacle avoidance.
Co-chairs:
Dr. Boubeker Belabbas, Bosch, Germany
Dr. Victoria Kropp, BMW, Germany

Navigation of Unmanned Aerial Vehicles and Other Autonomous Systems
Advanced positioning and navigation algorithms for novel sensors, sensor fusion, and signals of opportunity. Algorithms and methods for high-performance applications using low-cost sensors. Derivation of multi-sensor system navigation performance requirements. New approaches for dealing with delayed and out-of-sequence measurements. Sensor fault detection and exclusion.
Co-chairs:
Dr. Jiwon Seo, Yonsei University, South Korea
Sriramya Bhamidipati, University of Illinois at Urbana-Champaign

Precise GNSS Positioning
New algorithms and methods for improving Precise Point Positioning (PPP), Real-Time Kinematic (RTK) and other precise positioning techniques (e.g., PPP-RTK, network-RTK). Multi-constellation solutions using single-/multi-frequency high-cost and low-cost receivers/antennas, including smartphones. PPP with Integer Ambiguity Resolution (IAR). Methods and algorithms for reliable outlier detection. Estimation of corrections relevant for PPP-RTK (or PPP-IAR), such as fractional phase biases, satellite orbits and clocks, atmospheric delays and differential code biases. Interoperability of correction services with different user equipment.
Co-chairs:
Dr. Sandra Verhagen, Delft University of Technology, The Netherlands
Dr. Erin Kahr, Hexagon, Canada

Radionavigation Beyond Medium Earth Orbit GNSS
Going beyond signals from Medium Earth Orbit (MEO) GNSS, this session examines alternate and novel radionavigation signals and techniques to support their use. These signals include cellular and communications satellite signals (e.g., low Earth orbit (LEO) Mega Constellations). Navigational aids include terrestrial ultra-wideband (UWB) technologies, modern Wi-Fi protocols, near-field communication (NFC) devices, and emerging LEO-based satellite time and location services. Combining these sources to demonstrate positioning, navigation, and timing (PNT) accuracy, integrity, and robustness. Space navigation.
Co-chairs:
Dr. Zak Kassas, University of California Irvine
Dr. Tyler Reid, Xona Space Systems

Receiver Design, Signal Processing, and Antennas
GNSS receiver signal processing techniques, especially for operations in challenging environments like indoor, urban canyons, foliage, scintillation or high-dynamics. Improved acquisition and tracking sensitivity, robustness and accuracy. Mitigation of multipath and NLOS signals. Use of multiple GNSS signals including new GNSS signals. Antenna design and evaluation.
Co-chairs:
Dr. Sabrina Ugazio, Ohio University
Ajay Vemuru, Spirent Communications, UK

Remote Sensing, Atmospheric Effects, and Space Weather
Modeling of ionospheric and tropospheric effects on navigation. Use of GNSS in atmospheric and space weather science. Scientific applications of GNSS. Forecasting, now-casting.
Co-chairs:
Dr. Ningchao Wang, Hampton University
Dr. Larry Sparks, Jet Propulsion Laboratory

Safety-critical Applications of GNSS and Other Sensors
Navigation system design and analysis for safety-critical applications of GNSS and other sensors. Topics include: integrity monitoring for filtered solutions, antenna and receiver hardware, data collection and analysis techniques including sorting and clustering, and development of statistical models for measurement and process noise for use in safety-critical navigation algorithms.
Co-chairs:
Dr. Mihaela-Simona Circiu, German Aerospace Center DLR, Germany
Dr. Steven Langel, The MITRE Corporation

Sensor Fusion
Fusion of measurements from multiple sensors, data, and information sources. Estimation theory, algorithms, data processing techniques, test methods, and results of new implementations integrating diverse sensors such as GNSS, inertial sensors, odometers, magnetometers, radar, LiDAR, cameras, barometers, maps, signals of opportunity, infrared, ultrasound sensors, etc. Topics of interest include context-awareness based integration, collaborative approaches such as methods enabled by connected vehicle and infrastructure aided methods, etc.
Co-chairs:
Dr. Melania Susi, European Commission JRC, Italy
Dr. Li-Ta Hsu, Hong Kong Polytechnic University, China