| Project/Area Number |
06405008
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
広領域
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| Research Institution | Waseda University |
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Principal Investigator |
KOMATSU Shinichi (1997) Waseda University, Dep. Science & Engineering, Professor, 理工学部, 教授 (00087446)
山田 勝美 (1996) 早稲田大学, 理工学総合研究センター, 教授 (30063316)
大師堂 経明 (1994-1995) 早稲田大学, 教育学部, 教授 (10112989)
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| Co-Investigator(Kenkyū-buntansha) |
OHBA Ichiro 早稲田大学, 理工学部, 教授 (10063695)
AIZAWA Yohji 早稲田大学, 理工学部, 教授 (70088855)
OHARA Hirayoshi 早稲田大学・理工学部 (40063367)
YAMADA Masami Waseda University, Dep. Science & Engineering, Professor, 理工学総合研究センター, 名誉教授 (30063316)
小松 進一 早稲田大学, 理工学部, 教授 (00087446)
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| Project Period (FY) |
1994 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥34,600,000 (Direct Cost: ¥34,600,000)
Fiscal Year 1997: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1996: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1995: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 1994: ¥22,400,000 (Direct Cost: ¥22,400,000)
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| Keywords | Interterometer / FFT / Transient Radio Source / Nyquist rate / Engodicity / トランジェント電波源 / ディジタル信号処理 / FFT / 低雑音アンプ / HEMT / 干渉計 / 高エネルギー天体物理学 |
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| Research Abstract |
64 element radio interferometer developed for these six years has achieved three times higher sensitivity than before with new HEMT receivers. It is monitoring transient radio sources like Cyg X-3, and watching gamma-ray quasars and rapidly varying BL Lac objects. The interferometer has made it possible to get radio images at Nyquist rate for the first time in the world.
All radio interferometers currently used in the world are Fourier synthesis (indirect imaging interferometer), which could make fine radio maps. The method developed by Cambridge University is optimized to get fine images with less number of antenas, using Wiener-Khinchin theorem. It requires ergodicity(time average = ensamble mean) in received signals.
Since signals from the astronomical radio sources usually do not change rapidly, and the ergodicity is satisfied. However signals from pulsars or comunication are non-ergodic, so Fourier synthesis is inapropiate to search pulsars.
Direct imaging interferometer developed by Waseda University transforms the spatially received waves to the directional amplitudes using spatial FFT processing, in which cordinate representation is related to momentum representation by Fourier transform. Comunication signals could also be processed by this processor, and it is usefull in the fields of simultaneous and multi-directionai comunications. We have got a patent of the procesor.
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