CENS Technical Seminar Series

Recovering Temporal Integrity with Data Driven Time Synchronization

Slides

Invited Speaker: Martin Lukac, UCLA
Date: December 5, 2008
Time: 1:00 PM - 2:00 PM
Venue: Boelter Hall 4760

Abstract

Data driven time synchronization provides synchronization across sensors by using underlying characteristics of data collected by an embedded sensing system. We apply the concept of data driven time synchronization through a seismic deployment consisting of 100 seismic sensors to repair data that was not time synchronized correctly. This deployment used GPS for time synchronization but due to system faults common to environmental sensing systems, data was collected with large time offsets. In seismic deployments, offset data is often never used but we show that data driven time synchronization can recover the synchronization and make the data usable again. To implement data driven time synchronization to repair the time offsets we use microseisms as the underlying characteristics. Microseisms are waves that travel through the earth's crust and are independent of the seismic events used for the study of the earth's structure. We have developed a model of microseism propagation through a linear seismic array and use the model to obtain time correction shifts. By simulating time offsets in real data which does not have offsets, we determined that this method is able to repair the offset to less than 0.2 seconds. Our ongoing work attempts to refine the model to correct the offsets to 0.05 seconds and evaluate how errors in the correction affect seismic results such as event location. Data driven time synchronization may be applicable to other high data rate embedded sensing applications such as acoustic source localization.

Biography

Martin Lukac is a Ph.D. student in Computer Science at University of California Los Angeles. He received his B.S. from Haverford College and his M.S. from UCLA. He joined CENS in the Fall of 2004 and from his first days has been working with the CENS seismic group.