Date of Award

5-1-2000

Document Type

Thesis (Undergraduate)

Department or Program

Department of Computer Science

First Advisor

Dan Rockmore

Abstract

HF radio transmissions propagate long distances by reflecting off the ionosphere. At high latitudes radio propagation is strongly affected by the northern lights (aurora borealis), which causes ionization at low altitudes and hence the absorption of radio waves. Models of this process are still in a primitive state. A simulation of radio wave propagation was created in order to test Foppiano and Bradley's empirical model of auroral absorption. The simulation attempts to predict the net absorption of signals at a receiver by simulating a large number of transmitters, even though the exact sources of the signals are unknown. Although the simulation takes into account auroral and nonauroral absorption as well as other sources of path loss, the analysis focuses on the nighttime aurora. An intelligent search algorithm is used in order to efficiently adjust the model to best fit the data. The output of the simulation is qualitatively and quantitatively compared to signal levels observed with HF radio receivers located in northern Canada. The analysis allows us to develop alternative models of auroral absorption which account for the level of geomagnetic activity, and these are compared to the standard Foppiano and Bradley model.

Comments

Originally posted in the Dartmouth College Computer Science Technical Report Series, number TR2000-368.

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