Preprints
https://doi.org/10.5194/gi-2020-47
https://doi.org/10.5194/gi-2020-47

  18 Jan 2021

18 Jan 2021

Review status: this preprint is currently under review for the journal GI.

The Impact and Resolution of the GPS Week Number Rollover of April 2019 on Autonomous Geophysical Instrument Platforms

Shane Coyle1, C. Robert Clauer1,2, Michael D. Hartinger3, Zhonghua Xu1,2, and Yuxiang Peng1 Shane Coyle et al.
  • 1Virginia Polytechnic Institute and State University, Blacksburg VA, US
  • 2National Institute of Aerospace, Hampton VA, US
  • 3Space Science Institute, Boulder CO, US

Abstract. Instrument platforms the world over often rely on GPS or similar satellite constellations for accurate timekeeping and synchronization. This reliance can create problems when the timekeeping counter aboard a satellite overflows and begin a new epoch. Due to the rarity of these events (19.6 years for GPS), software designers may be unaware of such circumstance, or may choose to ignore it for development complexity considerations. Although it is impossible to predict every fault that may occur in a complicated system, there are a few best practices that can allow for graceful fault recovery and restorative action. These guiding principles are especially pertinent for instrument platforms operating in space or in remote locations like Antarctica, where restorative maintenance is both difficult and expensive. In this work, we describe how these principles apply to a communications failure on Autonomous Adaptive Low-Power Instrument Platforms (AAL-PIP) deployed in Antarctica. In particular, we describe how code execution patterns were subtly altered after the GPS week number rollover of April 2019, how this led to Iridium satellite communications and data collection failures, and how communications and data collection were ultimately restored. Finally, we offer some core tenets of instrument platform design as guidance for future development.

Shane Coyle et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gi-2020-47', Anonymous Referee #1, 05 Apr 2021
    • AC1: 'Reply on RC1', Shane Coyle, 02 May 2021
  • RC2: 'Comment on gi-2020-47', Anonymous Referee #2, 14 Apr 2021

Shane Coyle et al.

Shane Coyle et al.

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Short summary
Global satellite navigation systems are commonly used for timing and synchronization of instrument platforms. These system clocks periodically roll over from limitations in discrete counter math. Due to the rarity of these events (19.6 years for GPS), special consideration must be given to designing instruments intended for use in hard to reach locations like the Antarctic Plateau. A few best practices are presented to prevent total system failure from unexpected subsystem faults.