Ala Ghordlo

Date of Award


Document Type


Degree Name

Master of Science


Department of Electrical and Computer Engineering

First Advisor

Gerald C. Gerace, PhD


This research expanded Low Probability of Intercept (LPI) communications analysis in two areas. First, multimode communication was included to account for ground to ground and air to ground links in addition to the standard air to air links traditionally used in LPI analysis. The propagation equations for the three modes of interest were derived and included in LPI analytic models in the form of a mode quality factor to account for multimode LPI scenarios. This new quality factor was used in studying several communication and interception link combinations. Variations due to differences between the communication and interception modes were presented graphically. Second, atmospheric conditions were included to account for atmospheric attenuation. Previously, both links were assumed to be under the same atmospheric conditions. This assumption limits LPI analysis to scenarios where the receiver and interceptor are located close to each other. Therefore, the atmospheric quality factor had to be expanded to include scenarios where the communication link and the interception link are experiencing different and possibly fluctuating atmospheric conditions. The atmospheric propagation losses were accounted for by using the Liebe atmospheric propagation model to estimate atmospheric attenuation in dB/km for any practical atmospheric conditions. The atmospheric quality factor was then applied to the analysis of various scenarios for communication and interception links under similar and different atmospheric conditions. The results were represented graphically emphasizing the changes in LPI quality due to atmospheric conditions. It was apparent from the simulations, that LPI analysis was greatly enhanced by including the atmospheric quality factor. Finally, using both the mode and the atmospheric quality factors along with all the standard quality factors, a comprehensive LPI analysis was performed for many possible LPI scenarios.

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