A comparison of high-latitude ionosphere propagation predicitions from AMBCOM with measured data

Abstract

This thesis examines the performance of SRI's Ambient Communications (AMBCOM) model for high latitude propagation prediction. It is one in a series of studies, conducted at the Naval Postgraduate School, to establish the relative merits of several computer-based propagation prediction models using a standard set of measured data. AMBCOM modeled the propagation path between a transmitter located in the polar cap region and several midlatitude receiver sites. Model predictions were matched to measured data obtained during two high- latitude communication experiments (campaigns). The absolute difference between model signal-to-noise ratio (SNR) and measured SNR was considered as error. Error statistics were accumulated to show the distribution of the error by campaign and frequency. The percentage, by frequency, of matched AMBCOM predictions in reference to total predictions for a given frequency was considered a measure of AMBCOM performance. AMBCOM exhibited small absolute values of average error, i.e., 7-11 dB, and high percentages of matched records. The average error was typically distributed between -20 and +20 dB. Unfortunately, these are only relative measures of model performance. The site antenna and environmental data used to model high latitude campaigns were estimated not measured, and some variation in AMBCOM results may be attributable to poor estimates. The measured data were not designed specifically for model validation, and further comparisons are needed with new measured data.