The Long-Term Timing Performance of Satellite Time and Location Receivers Utilizing Signals from Low Earth Orbit Satellites

Published

January 25, 2024

Author(s)

Andrew Novick, Peter Johnson

Abstract

We present the long-term timing accuracy of STL receivers by validating their performance against UTC(NIST), the timing reference at the National Institute of Standards and Technology (NIST), for a duration of 100 days. STL is a mature timing and location service provided by Satelles that is fully operational today and is available anywhere in the world. This paper is focused on the STL timing solution and measuring its long-term stability and accuracy. The data show that an STL receiver with an oven-controlled crystal (OCXO) or a rubidium (Rb) oscillator provides an extremely stable timing solution and maintains an average offset near 0 nanoseconds (ns) to UTC(NIST) after calibration. An STL receiver with a Rb oscillator was able to maintain a Maximum Time Interval Error (MTIE) less than 80 nanoseconds to UTC(NIST) over a period of 66 days, only increasing by another 10 ns by 100 days for an MTIE of 90 ns at 100 days duration. Since the timing variation of these receivers is very balanced around the average and the average error is close the zero, the maximum error from UTC(NIST) at any point for the 100 days will be about one half of the MTIE value or less than 50 ns for the STL receiver with a Rb oscillator. The Time Stability (TDEV) of the STL receiver with a rubidium oscillator is less than 8 ns for all tau values and the stability (ADEV) is below 2 × 10-13 at one day continuing to average down, reaching below 1 × 10-14 at eight days. These results show that an STL receiver can maintain a highly accurate and stable timing solution for long durations in scenarios where Global Navigation Satellite Systems (GNSS) signals cannot be received at a user's location. It should also be noted that all the timing measurements done with these four STL receivers at NIST and Satelles were done using Iridium-only antennas (no GPS band) for the duration of all the testing.

Proceedings Title

ION 2024 Precise Time and Time Interval Systems and Applications Meeting Proceedings

Conference Dates

January 23-25, 2024

Conference Location

Long Beach, CA, US

Conference Title

Precise Time and Time Interval Meeting

Pub Type

Conferences

Download Paper

Local Download

Keywords

satellite, low earth orbit, GNSS, GPS, time

Citation

Novick, A. and Johnson, P. (2024), The Long-Term Timing Performance of Satellite Time and Location Receivers Utilizing Signals from Low Earth Orbit Satellites, ION 2024 Precise Time and Time Interval Systems and Applications Meeting Proceedings, Long Beach, CA, US, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957334 (Accessed November 20, 2024)