| Summary: | Approved for public release; distribution unlimited. === The dissertation discusses High Frequency (HF) radio sources. It consolidates data from all available, published HF spectrum surveys. The author conducted a new HF survey using detection of new energy events. The first cumulative probability distribution function for the amplitude of detected non-broadcast HF signals is developed, and the distribution is log-normal. HF receiver site performance quantification is possible using the HF signal distributions. Site performance degradation results from noise, interference, and signal path attenuation. Noise examples are presented in a 3-D format of time, frequency, and amplitude. Graphs are presented that allow estimation of the percentage of HF non-broadcast signals lost as a function of noise and interference levels. Limitations of HF search receivers using analog-to-digital converters as the receiver front-end are discussed. Derived bounds on AD converter performance show that today's digital technology does not provide enough dynamic range, sensitivity, or sampling rate. Alternative dynamic range extension methods are examined. A new method of dynamic range extension by removing the strongest signals present is presented. Greater receiver sensitivity results from changing the HF signal environment seen by the AD converter. The new method uses a phase-tracking network and signal reconstruction techniques.
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