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Measurement and simulation of clock errors from resource-constrained embedded systems.

Collett, M A; Matthews, C E; Esward, T J; Whibberley, P B (2010) Measurement and simulation of clock errors from resource-constrained embedded systems. Meas. Sci. Technol., 21 (7). 075203

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Abstract

Resource-constrained embedded systems such as wireless sensor networks are becoming increasingly sought-after for a range of critical sensing applications. Hardware for such systems is typically developed as a general tool, intended for research and flexibility. These systems often have unexpected limitations and sources of error when being implemented for specific applications. We investigate via measurement and simulation the output of the onboard clock of a Crossbow MICAz testbed, comprising a quartz oscillator accessed via a combination of hardware and software. We show that the clock output available to the user suffers a number of instabilities and errors. Using a simple software simulation of the system based upon a series of nested loops, we identify the source of each component of the error, finding that there is a 7.5x10-6 probability that a given oscillation from the governing crystal will be miscounted, resulting in frequency jitter over a 60 micro-Hz range.

Item Type: Article
Keywords: Wireless Sensor Network, Synchronisation, Clock, Embedded, Monte Carlo
Subjects: Time and Frequency
Mathematics and Scientific Computing
Time and Frequency > Time
Mathematics and Scientific Computing > Modelling
Electromagnetics > Wireless Communications
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/4674

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