The Application of Frequency Stability Analysis and the Use of Time Domain Statistics for Clock and Oscillator Performance Assessment	Gregory L. Weaver, Johns Hopkins University/Applied Physics Laboratory
Atomic Clock Technology	Dr. Robert Lutwak, Air Force Research Laboratory and Dr. David R. Scherer, The MITRE Corporation
Timescales and Timekeeping	Dr. Patrizia Tavella, Bureau International des Poids et Mesures
Global Navigation Satellite System (GNSS) Overview with a Focus on Precise Time Disseminations and Standards	Ed Powers, Aerospace Corporation
Distributing Time and Frequency Data: Requirements and Methods	Dr. Judah Levine, US National Institute of Standards and Technology Time and Frequency Division

The Application of Frequency Stability Analysis and the Use of Time Domain Statistics for Clock and Oscillator Performance Assessment

Time: Monday, January 28, 9:00 a.m. - 10:30 a.m.
Room: Regency B

This tutorial will provide the information to unwrap the interpretation of clock and frequency source measurements, clock statistical characterization, and frequency stability analysis to bring about a workable understanding of clock and oscillator performance assessment for the PTTI attendee. The presentations and proceedings of the PTTI generally require an attendee to have a basic working knowledge of performance metrics such as Allan deviation and single-sideband phase noise to discern the extent of contribution to the improvement of the community’s practice.

The tutorial will use NIST Special Publication 1065, Handbook of Frequency Stability Analysis by William J. Riley as a reference, so that subsequently, the user may be familiar with its application and techniques. The tutorial will also inject the work of Victor S. Reinhardt, David A. Howe, and Patrizia Tavella to supplement the material of NIST 1065. The tutorial will demonstrate analysis of measurement data from devices such as the Chip Scale Atomic Clock, GPS disciplined composite clock, and the ultra-stable oscillators on-board the New Horizons spacecraft. The use of these devices is intended to provide illustrative working examples for the identification, characterization, and assessment of both deterministic (systematic) processes and stochastic (noise) properties.

Gregory L. Weaver is a member of the Principle Professional Staff of JHU/APL and works within the RF Engineering Group of the Space Department. He is a technologist with background in the technical and business aspects of the frequency control industry as a senior design engineer, technical manager and marketing strategist.

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Atomic Clock Technology

Time: Monday, January 28, 10:45 a.m. - 12:15 p.m.
Room: Regency B

Atomic frequency standards provide the ultimate source of accuracy and stability for all modern communications, navigation, and time-keeping systems. Commercially-available “Industrial” atomic clocks, including cesium beam frequency standards, rubidium oscillators, and hydrogen masers, are based on technology originally developed in the 1950’s. Since that time, technology evolution and field experience have led to a level of performance and reliability that atomic clocks are now deployed throughout critical infrastructure applications. With the advent of GPS and, consequently, global availability of precision timing, new applications for precision timing have emerged, with ever increasing demands for improved precision, robustness, and portability. In parallel, we are, at present, experiencing a renaissance of atomic timekeeping, as modern techniques of atomic and laser physics have enabled new techniques for confining, interrogating, and exploiting precision atomic timing signals. This tutorial will provide an introduction to existing and emerging atomic clock technologies. The tutorial will focus on mature technologies: rubidium oscillators, cesium beam frequency standards, and hydrogen masers, as well as commercially-available chip-scale atomic clocks. Time permitting, the tutorial will address emerging atomic clock technologies: laser-cooled atoms and atomic fountains, optical-carrier-frequency clocks and optical frequency synthesis, and next-generation high-performance chip-scale clocks.

Dr. Robert Lutwak serves as Senior Technologist for Position, Navigation, and Timing (ST PNT) at the Air Force Research Laboratory in Dayton, OH (AFRL). He received his B.S. in Physics from Miami University in 1988 and his Ph.D. in Atomic and Optical Physics from M.I.T. in 1997.

Dr. David R. Scherer is a Lead Scientist at The MITRE Corporation in the Communications, SIGINT, and PNT Department. Previously, he was a Senior Physicist at Microsemi, where he developed several next-generation atomic clock architectures. He holds a Ph.D. in Optical Sciences from the University of Arizona.

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Timescales and Timekeeping

Time: Monday, January 28, 1:30 p.m. - 2:45 p.m.
Room: Regency B

Realizing a time scale means having at one’s disposal atomic clocks, a measurement system, and the capacity to process data to establish an ensemble time possibly steered on the international reference time UTC. The definition of a reference time scale and the necessary tools, mostly related to the necessary algorithms, will be reviewed and the current realization of UTC at the BIPM will be presented. Time scales and timekeeping are as well of interest for navigation systems: clocks are to be estimated, predicted, and validated as typically carried out in timekeeping laboratories. The tutorial will cover these aspects, also showing the main challenges in this area.

Dr. Patrizia Tavella holds a degree in Physics and a Ph.D. in Metrology. She is Director of the Time Department at the BIPM and was previously a senior scientist with the Italian Metrology Institute, INRIM, Torino, Italy. Her main interests are mathematical and statistical models mostly applied to atomic time scale algorithms.

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Global Navigation Satellite System (GNSS) Overview with a Focus on Precise Time Disseminations and Standards

Time: Monday, January 28, 3:00 p.m. - 4:00 p.m.
Room: Regency B

GPS has provided an operational Position Navigation and Timing (PNT) service for more 25 years, and the vast majority of PNT applications use GPS as its fundamental source for PNT data. GPS operates using very precise synchronized ranging signals, where in general every nanosecond of synchronization error can lead to one foot of navigation error. Because of this exquisite timing synchronization, GPS provides a precise timing service used to support many important user communities ranging from power grid, telecommunication networks, science and the banking industry. Today GPS is no longer the only GNSS system, there are now several other GNSS systems in either operations and/or system development. This tutorial will provide an overview of how GPS operates, discuss the other GNSS systems and the reference standard that underlay each system.

Ed Powers received his BS and MS degrees in Electronic Engineering and Instrumental Science from the University of Arkansas. Previously, he has worked at NRL on GPS clock development and at the USNO as the GPS Operations Division Chief. Ed joined the Aerospace Corp in October 2018 as Senior Project Engineer, GNSS Engineering & Technology.

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Distributing Time and Frequency Data: Requirements and Methods

Time: Monday, January 28, 4:00 p.m. - 5:00 p.m.
Room: Regency B

This course will describe the methods that are used to distribute time and frequency information, with special emphasis on methods that are independent of global navigation satellite systems. The course will illustrate these methods with the requirements of commercial and financial institutions and distributors of electrical power. In addition to the purely technical requirements, additional requirements that result from the need to demonstrate traceability to national standards will also be discussed. The level of accuracy that is required to support these applications is relatively modest from the perspective of the internal time scales of most National Metrology Institutes and timing laboratories, but satisfying the requirements becomes much more challenging when the need for extreme reliability and the limitations of many of the common distribution channels are included. None of the alternative solutions that have been proposed is completely adequate now and all of them will have increasing difficulty satisfying the increasing accuracy requirements in the future.

Dr. Judah Levine is a Fellow of NIST and leader of the Network Synchronization Project in the Time and Frequency Division in Boulder, Colorado. He received his Ph.D. in Physics from New York University in 1966. Dr. Levine is a member of the IEEE and a Fellow of the American Physical Society.

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