Field Geophysics – Sampling and Aliasing Theory and Examples

Lawrence Braile

Earth and Atmospheric Sciences, Purdue University

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Initial Publication Date: December 8, 2011

Summary

Collecting geosciences data in the field involves sampling in time and space. Sampling includes theoretical limitation and the possibility of aliasing which has severe effects on sampled data. The concepts are applicable to spatial sampling and geological data. The discussion is most appropriate for classroom or computer laboratory use prior to field data collection.

Geophysics | College Upper (15-16), Graduate/Professional

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Context

Audience

Geological and geophysical data analysis. Upper level undergraduate or graduate course.

Skills and concepts that students must have mastered

Computer programming, some understanding of time series analysis and Fourier series or Fourier transforms.

How the activity is situated in the course

Stand alone discussion, early in course on data analysis.

Goals

Content/concepts goals for this activity

Understanding of limitations of sampled data and illustrations of the effects of improper sampling in time and space.

Higher order thinking skills goals for this activity

Fundamentals of sampling theory, examples of Fourier analysis.

Other skills goals for this activity

Develop time series analysis skills.

Description of the activity/assignment

Collecting geosciences data in the field involves sampling in time and space. Sampling includes theoretical limitation and the possibility of aliasing which has severe effects on sampled data. The material presented here focuses on geophysical data and time domain sampling. The concepts are applicable to spatial sampling and geological data. Examples of time series analysis and Fourier analysis are included. The discussion is most appropriate for classroom or computer laboratory use prior to field data collection.