Timescale Development for GNSS Applications

Michael J. Coleman and Ronald L. Beard

Abstract: The US Naval Research Laboratory (NRL) has been active in the development of clock ensembling technology over the past decades that has become part of a number of vital GNSS projects and services throughout the US and international community. Some of the efforts include: algorithms and systems for local realization of Coordinated Universal Time designated UTC(k), that designates the site performing the realization; participation in the upgrade of the Global Positioning System (GPS) system time, known as GPS Time (GPST); the initial implementation of a coherent geophysical reference time known as IGS Time (IGST) and its later upgrade; support in the IGS clock product working group’s maintenance of IGST and its viability for the geophysical community; and development of various Department of Defense (DoD) capabilities for the dissemination and transfer of precise time. This paper will cover the major algorithm components that compute and maintain a robust and stable time reference for the most stringent applications mentioned here. These components include: automatic adaptation of clock spectral density parameters to real-time data feed; automated alert and response to adapt to clock anomalies with a latency of hours (dependent upon break severity); and, reduction of measurement weight in response to large clock measurement residuals. Both real and simulated data have been used to validate the timescale algorithm and its products for reliable and robust usage in these environments.
Published in: Proceedings of the ION 2019 Pacific PNT Meeting
April 8 - 11, 2019
Hilton Waikiki Beach
Honolulu, Hawaii
Pages: 304 - 317
Cite this article: Coleman, Michael J., Beard, Ronald L., "Timescale Development for GNSS Applications," Proceedings of the ION 2019 Pacific PNT Meeting, Honolulu, Hawaii, April 2019, pp. 304-317.
https://doi.org/10.33012/2019.16779
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