1991 Fiscal Year Final Research Report Summary
Optimum Digital Modulation/Demodulation Techniques for Mobile Satellite Communications Systems
| Project/Area Number |
02452150
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 | Osaka University |
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Principal Investigator |
MORINAGA Norihiko Osaka University, Faculty of Engineering, Professor, 工学部, 教授 (30029102)
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| Co-Investigator(Kenkyū-buntansha) |
KATAYAMA Masaaki Osaka Universitu, Computation Center, Associate Professor, 大型計算機センター, 講師 (60185816)
HARA Shinsuke Osaka University, Faculty of Engineering, Assistant Professor, 工学部, 助手 (80228618)
TSUKAMOTO Katsutoshi Osaka University, Faculty of Engineering, Assistant Professor, 工学部, 助手 (10207342)
KOMAKI Shozo Osaka University, Faculty of Engineering, Associate Professor, 工学部, 助教授
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| Project Period (FY) |
1990 – 1991
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| Keywords | Mobile satellite communications systems / Modulation / demodulation and coding techniques / Doppler shift / Low Earth Orbiting satellites / Kalman algorithm / Inter-satellite communication link / Polarization modulation / optical coherent detection system / Optical heterodyne spatial tracking system |
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| Research Abstract |
(1) A summary of the trends of digital modulation/demodulation and coding techniques. for mobile satellite communications systems has been provided. In LEO (Low Fmfl Orbiting) satellites symm, reduction of mobile station size introduces the degradation of transmission performance, since the received signal power decreases. Moreover, the detection performance is mwh affected by Doppler frequency shift associated with the rapid motion of LEO satellite. Then, it is necessary to investigate the AFG/PLL circuit which can rapidly track the fluctuation of carrier frequency by Doppler shift.
(2) A novel phase and frequency estimator which works as an AFC/PLL circuit in coherent detection systems has been proposed. Ibis estimator operation is based on Kalman algorithm which estimates the first and second derivatives of the carrier frequency. so that it can estimate and track the carrier phase accurately. The coherent detection system with the proposed estimator recieves good bit error rate performance in both an additive Gaussian noise channel with Doppler frequency shift and a Rician fading channel.
(3) Transmission techniques in inter-satellite comomication link are key technologies in order to construct worldwide mobile satellite communications systems using LED satellites. A polarization modulation/optical coherent detection system has been proposed. atid the performance of the proposed system has been evaluated. Also, an optical heterodyne spatial tracking system has been proposed.
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