Summary: | P(論文) This paper describes an effective coding method to eliminate the redundancy contained in digital ionograms and an algorithm to identify the resonance spikes appearing on topside ionograms. This work is a first step toward automatic profile reduction to obtain ionospheric electron density profiles. Topside sounder data recorded by ISIS-2 satellite are digitized and converted to digital ionograms. A quantitative comparison of data compression techniques, based on the run-length and predictive coding method, is made and leads the conclusion that the modified run-length coding method is most effective and useful from the practical view point. This simulation experiment results in self-consistent determination of characteristic frequencies with good accuracy except for the ionograms with obscure resonance spikes. departmental bulletin paper
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