Precision Timing with LEO Satellite Time and Location Signals

Austin M. Smith and David M. Bevly

Abstract: The work presented in this paper aims to assess the accuracy, stability, and convergence rates of static receiver timing solutions from low-Earth orbit (LEO) Satellite Time and Location (STL) signals. The motivation for this work lies in the wide range of industries that rely on nanosecond-level timing precision. Traditional means of satellite-based timing, such as Global Navigation Satellite Systems (GNSS), prove to be vulnerable under various conditions, compromising their accuracy. The STL signals from the Iridium satellite constellation are received at a much higher signal power, rendering them more resilient to these interferences. Two tests were conducted in this study. For Test 1, two scenarios were considered. The first scenario assumes a known, static antenna position, where the receiver clock bias and drift were estimated with an Extended Kalman Filter (EKF). The second scenario assumes an unknown, static antenna position, where a 3-dimensional Earth-Centered, Earth-Fixed (ECEF) position, clock bias and clock drift were estimated with a Recursive Least Squares (RLS) Solution. The algorithms were implemented with live-sky STL data collected with a newly-released, commercially-available Jackson Labs STL-2600 receiver with a Rubidium clock input. For Test 2, a time interval difference test between the Jackson Labs receiver 1-PPS output and a GNSS 1-PPS reference. In each of the tests, the long-term timing accuracy was determined to be within 205 nanoseconds, with sub-nanosecond per second drift. The results for Test 1 include time state estimate plots, filter covariance convergence, and error statistics. The results for Test 2 include pre- and post-settling time difference plots and error statistics.
Published in: Proceedings of the 54th Annual Precise Time and Time Interval Systems and Applications Meeting
January 23 - 26, 2023
Hyatt Regency Long Beach
Long Beach, California
Pages: 197 - 206
Cite this article: Smith, Austin M., Bevly, David M., "Precision Timing with LEO Satellite Time and Location Signals," Proceedings of the 54th Annual Precise Time and Time Interval Systems and Applications Meeting, Long Beach, California, January 2023, pp. 197-206.
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