1987 Fiscal Year Final Research Report Summary
Theoretical Research on the Effects of Atmospheric and Ionospheric Turbulence on Space Communication
| Project/Area Number |
61550244
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子通信系統工学
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| Research Institution | Kyushu University |
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Principal Investigator |
TATEIBA Mitsuo Faculty of Engineering, Kyushu University, Associate Professor, 工学部, 助教授 (40037924)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDOMI Kuniaki Faculty of Engineering, Kyushu University, Research Associate, 工学部, 助手 (30150501)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Received Power Reduction / Pulse Distortion / Turbulent Media / Wave Propagation / Satellite Channel / Line-of-Sight Communication / 不均質乱流の影響 |
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| Research Abstract |
This project is theoretically to solve the following three subjects: (1)numerical estimates of received power reduction due to the atmospheric and ionospheric turbulence, (2)clarification of the mechanism of the reduction, and (3)analysis of waveform distortion of pulses propagated through the turbuence. The research is based on the multiple scattering analysis in inhomogeneous turbulent media, which has been developed by Tateiba.
The first and second subjects were satisfactorily solved by using the coherence function of wave beams propagated through the turbulence. In general, the power reduction is given as the sum of the antenna gain loss and the scattering loss. For example, in the down-link transmission of satellite communication, the power loss is nearly equal to the antenna gain loss caused by the decrease of spatial coherence of the received wave. The loss evaluated here is reasonable as compared with the experimental data. In the up-link transmission, the power loss is almost the scattering loss named after the following phenomenon: The average spot-size of the received beams more expands through the scattering due to the turbulence and the intesity of the beam becomes smaller on the aperture. The difference of the loss mechanism depends chiefly on the inhomogeneity of the turbulence.
The third subject was attacked by using an analytic method and a computer simulation. Analytic solutions of the two-frequency moment equation in a strong scattering region were given for the plane and spherical waves, and pulse-waveform distortion was shown in the model of satellite communication. Some numerical data were given on the defects of the model of plane-wave pulse propagation in practical space communication. When C- and X-bands are used for satellite communication, the pulse-waveform distortion due to the turbulence can be neglected even for high bit-rate transmission. The computer simulation is now being studied.
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