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A Calibration of Timing Accuracy in NIST Cyber-Physical Systems Testbed

Published

Author(s)

Marc A. Weiss, Ya-Shian Li-Baboud, Dhananjay Anand, Paul A. Boynton, Kevin Gerard Brady, Martin Burns

Abstract

We report results from a project to calibrate timing in the NIST CPS and Smart Grid Testbeds. We measured clock synchronization accuracy and stability as well as latencies for potential experiments in the testbeds. We determined calibrations of GPS receivers to UTC(NIST) with an uncertainty of 16 ns. However, an anomaly occurred coincident with a power shutdown leaves us with a total uncertainty of receiver calibrations against UTC(NIST) of 100 ns. Synchronization at testbed locations relative to an IEEE 1588 Precision Time Protocol (PTP) grandmaster was found to have a mean offset of 36 ns ± 4 ns from the grandmaster, through two transparent clocks. Finally, we measured the time error relative to the grandmaster of an embedded device attached to a switch without PTP support with a mean offset of 50 s ± 10 s, and at 8 ms ± 500 s for timestamping at the GPIO. We report the methodology used, as well as some of challenges encountered and solutions developed in the process.
Proceedings Title
Proceedings of the IEEE Symposium on Precision Clock Synchronization for Measurement, Control, and
Communication
Conference Dates
September 30-October 5, 2018
Conference Location
Geneva, CH
Conference Title
International IEEE Symposium on Precision Clock Synchronization for Measurement, Control, and
Communication

Keywords

Timing characterization, Cyber-Physical Systems, Internet of Things, testbeds

Citation

Weiss, M. , Li-Baboud, Y. , Anand, D. , Boynton, P. , Brady, K. and Burns, M. (2018), A Calibration of Timing Accuracy in NIST Cyber-Physical Systems Testbed, Proceedings of the IEEE Symposium on Precision Clock Synchronization for Measurement, Control, and Communication, Geneva, CH, [online], https://doi.org/10.1109/ISPCS.2018.8543081 (Accessed January 18, 2022)
Created October 2, 2018, Updated October 12, 2021