Digital Analysis of Geophysical Signals and Waves (DAGSAW)/Filtering

George R. Jiracek

San Diego State University/Department of Geological Sciences

This activity has been reviewed by 3 review processes (view details)

This activity was selected for the Teaching Computation in the Sciences Using MATLAB Peer Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are
- Computational, Quantitative, and Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
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This activity has benefited from input from faculty educators beyond the author through a review and suggestion process. This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.

Initial Publication Date: July 6, 2007 | Reviewed: November 19, 2018 (see revision history: 2 events)

Summary

Filtering is one of the most important steps in geophysical data recording and processing since it is present in all geophysical analysis. Filtering is explained in the Digital Analysis of Geophysical Signals and Waves (DAGSAW) web site using animations in space, time and frequency domains.

Exploration Methods, Gravity, Magnetism/Paleomag, Seismology | College Upper (15-16), Graduate/Professional

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Context

Audience

Used with NSF-sponsored research experiences for undergraduates (REUs), upper division course in geophysics field methods, and an upper division-graduate course in geophysical analysis. Designed for a geophysics course

Skills and concepts that students must have mastered

Undergraduate physics and mathematics through differential and integral calculus. A course in geophysics is desirable but not required.

How the activity is situated in the course

The Digital Analysis of Geophysical Signals and Waves (DAGSAW) web site is used as introductory material at SAGE (Summer of Applied Geophysical Experience) for REU students. It is also used in the sequence of material taught in geophysics field methods and geophysical analysis courses at San Diego State University.

Goals

Content/concepts goals for this activity

Understanding filtering as a continuous and discrete convolution operation in space and time domains, and as a multiplication of complex functions in the frequency domain.

Higher order thinking skills goals for this activity

Filtering as a tool to understand the analysis and modeling of geophysical data. Writing filtering programs with MATLAB.

Other skills goals for this activity

Report writing using actual geophysical data.

Description of the activity/assignment

Students use the concept of filtering as a "black box" input-output operation in either space, time, or frequency domains to develop and use practical geophysical filters such as pass bands, derivatives, integration, and upward/downward continuation of gravity and magnetic geophysical data. Addresses student fear of quantitative aspect and/or inadequate quantitative skills Addresses student misconceptions

Determining whether students have met the goals

Several years of using the attached 25-question quiz given before and after using the Digital Analysis of Geophysical Signals and Waves (DAGSAW) web site during a single morning session with undergraduate students has revealed an improvement of student test scores by an average of ~100%.

More information about assessment tools and techniques.