@article{oai:nipr.repo.nii.ac.jp:00001265,
 author = {Igi, Seiji and Aikyo, Kazuhiro and Nishizaki, Ryo and Ogata, Takanobu and Maruyama, Takashi and Hirasawa, Takeo},
 journal = {Memoirs of National Institute of Polar Research. Special issue},
 month = {Sep},
 note = {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.},
 pages = {140--154},
 title = {Efficient coding and resonance spike identification for topside ionogram processing},
 volume = {22},
 year = {1982}
}