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Sundial: Using Sunlight to Reconstruct Global Jayant Gupchup
 

Summary: Sundial: Using Sunlight to Reconstruct Global
Timestamps
Jayant Gupchup
Razvan Musaloiu-E.
Alex Szalay
Andreas Terzis
Computer Science Department
Physics and Astronomy Department
Johns Hopkins University
{gupchup,razvanm,terzis}@jhu.edu
szalay@jhu.edu
Abstract. This paper investigates postmortem timestamp reconstruc-
tion in environmental monitoring networks. In the absence of a time-
synchronization protocol, these networks use multiple pairs of (local,
global) timestamps to retroactively estimate the motes' clock drift and
offset and thus reconstruct the measurement time series. We present Sun-
dial, a novel offline algorithm for reconstructing global timestamps that
is robust to unreliable global clock sources. Sundial reconstructs times-
tamps by correlating annual solar patterns with measurements provided
by the motes' inexpensive light sensors. The surprising ability to accu-

  

Source: Amir, Yair - Department of Computer Science, Johns Hopkins University

 

Collections: Computer Technologies and Information Sciences