Publication Date

2015

Document Type

Thesis

Committee Members

Steven Fiorino (Committee Member), Ernest Hauser (Committee Chair), Douglas Petkie (Committee Member)

Degree Name

Master of Science (MS)

Abstract

This thesis investigates how well ground vibrations can be detected at ladar or radar wavelengths and how the atmosphere may impact the observation of such activity. First understanding atmospheric hindrances at each of these wavelengths is helpful to prioritize by those yielding best transmission results. A prerequisite to the outdoor field experiment performed for this study involves analyzing atmospheric effects characterization at six probable wavelengths using the Laser Environmental Effects Definition and Reference tool (LEEDR) developed by the Air Force Institute of Technology's (AFIT) Center for Directed Energy (CDE). These wavelengths, selected from the shortwave infrared and microwave portions of the electromagnetic (EM) spectrum, are assessed to determine which provides optimal path transmission results allowing a sensor platform at an altitude of 1525 meters to sense induced ground vibrations. Selecting an altitude just above the typical atmospheric boundary layer (BL) allows further investigation of precipitation and cloud impacts on potential path transmission. The objective of performing the outdoor field experiment is to induce surface vibrations tracked by a 12 channel geophone spread linked to a seismograph at various locations along a horizontal path to determine if the signal can be detected by a 35 GHz radar. The contributory goal of this research is to realize new ways of monitoring otherwise invisible illegal or terrorist-like activities for the security of this nation. Additionally, the use of LEEDR could allow the atmospheric effects measured in the microwave part of the spectrum to be scaled for various platform altitudes and applied for atmospheric correction in other parts of the spectrum such as the visible, near-infrared, infrared, or submillimeter ranges. Experimental results indicate a 35 GHz radar is optimal and capable of detecting ground vibrations across short ranges when using a retro-reflector. How well seismic activity can be detected and the impacts of estimating atmospheric transmission in various weather conditions is presented and discussed.

Page Count

83

Department or Program

Department of Earth and Environmental Sciences


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