1. School of Earth and Ocean Sciences, University of Victoria 1 , Victoria, British Columbia V8W 2Y2, Canada
2. JASCO Applied Sciences (Deutschland) GmbH 2 , 24223 Schwentinental, Germany
3. Electrical and Computer Engineering Department, Portland State University 3 , Portland, Oregon 97201, USA chapman@uvic.ca , michael.ainslie@Jasco.com , siderius@pdx.edu