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1991 Fiscal Year Final Research Report Summary

Development of Direction Finding System for Plasma Waves

Research Project

Project/Area Number 02650242
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field 電子通信系統工学
Research InstitutionThe University of Electro-Communications (1991)
Nagoya University (1990)

Principal Investigator

HAYAKAWA Masashi  The University of Electro-Communications Faculty of Electro-Communications Professor, 電気通信学部, 教授 (80023688)

Co-Investigator(Kenkyū-buntansha) SHIMAKURA Shin  Chiba University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00009721)
Project Period (FY) 1990 – 1991
KeywordsDirection Finding / Magnetospheric VLF waves / Inversion problem / Wave distribution function / Maximum entropy method / Regularization / Generalized cross validation
Research Abstract

We have developed a new ground-based directim finding system for magnetospheric VLF/ELF emissions, which will be of great importance in the study of their generation and propagation mechanisms. This new method enables us to estimate the distribution of wave energy density at the ionospheric base as the inversion problem to the observed data of three possible field canponents (two horizontal magnetic and a vertical electric component) obervable on the ground. The previous methods so far proposed, are of no use for the situations with a very wide distribution at the ionospheric base or with a multiple ducts, and our new method is still effective for these cases. The first wave distribution function. (WDF) method) is based on the concept such that the entropy of the distribution function be maximized. The application of this method to the simulated data consisting of a single and double source, has yielded that this method is able to distinguish between the closely spaced sources. Also, i … More ts application to the actually observed data of whistlers at Yamaoka (geomag. lat. 25゚N) (three field components), has provided us with useful information on the ionospheric transmission mechanism of low-latitude vyhistlers. This maximum entropy method has a few demerits ; (1) The validity of the final WDF is not objective and (2) the computing time is rather long because of its nonlinear estimation. These problems are solved by the combined use of the regularization and generalized cross validation (GCV). This method is found to yield very objective way of estimating the final optimum EWDF especially for a single peaked source. The WDF at the regularization parameter giving the minimum GCV is the optimum on the basis of the simulation experiments. However, we have to think about scmeting for the doubly peaked source, and a method fortthis is the regularization with smaller smoothness, which we would like to study in future. Furthermore, in order to examine the accuracy of our proposed methods, we carried out the three-stationed direction finding measurements, the data from which will be analyzed extensively in future. Less

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Shimakura,S.,K.Ohta & M.Hayakawa: "Wave distribution functions of magnetospheric whistlers at low latitudes" Res.Lett.Atmospheric Electricity. (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shimakura S.,& M.hayakawa: "Wave distribution functions of magnetospheric VLF waves wish multiple field components i The espect of polarization model in the integration hernels on the reconstruction of wave distribution functions" Trans.Inst.Elect.Inform.Comm.Enprs.Japan.Special Issue on Digital Signal Processing. (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hayakawa,M.,K.Ohta & Shimakura,S.: "Direction finding of low-latihrde whistlevs and their propagation" "Environmental & Space Electromagnetics",Ed.K.Kikuchi,Springer-Verlag. 168-171 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hayakawa,M.: "Direction finding of magnetospheric VLF/ELF emissions and their generation mechanism" "Environmental & Space Electromagnetics",Eds H.Kikuchi,Springer-Verlag. 155-167 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 馬場 清英,太田 健次,友松 通,早川 正士: "トウィ-ク変電の波動特性の周波数依存性" 電子情報通信学会論文誌. J74ーBーII. 587-593 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 早川 正士,島倉 信: "トウィ-ク変電を用いた遠距離変電源の高精度方位測定" 電子情報通信学会環境電磁工学研究会特報. EMCJ91ー76. 75-81 (1991)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shimakura, S., K. Ohta, and M. Hayakawa: "Wave distribution functions of magnetosperic whistlers at low latitudes" Res. Lett. Atmospheric Electricity.(1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Shimakura, S. and M. Hayakawa: "Wave distribution functions of magnetospheric vlf waves with multiple field components ; The effect of polarization model in the integration kernels on the reconstruction of wave distribution functions" Trans. Inst. Electr. Inform. Comm. Engrs. Japan, Special Issue on digital signal processing. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hayakawa, M., K. Ohta, and S. Shimakura: "Direction finding of very low latitude whistlers and their propagation," "Environmental and Space Electromagnetics". Springer-Verlag. 168-171 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hayakawa, M.: "Direction finding of magnetospheric vlf/elf emissions and their generation and propagation mechanism" "Environmental and Space Electromagnetics". Springer-Verlag. 155-167 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Baba, K., K. Ohta, T. Tomomatsu and M. Hayakawa: "Frequency dependence of wave characteristics of tweek atmospherics" Trnas. Inst. Electr. Inform. Comm, Engrs. Japan. J74-B-II. 587-593 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hayakawa, M. and S. Shimakura: "High accuracy location of distant sferics by the use of tweeks" Tech. Report, Inst. Electr. Inform. Comm. Engrs. Japan. EMCJ-91-76. 75-81 (1991)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-03-16  

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