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换星换波段接收系统的调整
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作者 谭儒良 《无线电》 1997年第3期14-15,共2页
关键词 卫星电视 换波段 接收
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卫星电视换星/换不皮段传送后地面接收系统重新调整要点
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作者 谭儒良 《无线电与电视》 1997年第6期48-50,共3页
关键词 卫星电视 星/换波段 传送 地面接收系统
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On temporal-spatial distribution of backscatter coefficients over China determined by TOPEX/Poseidon mission 被引量:6
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作者 GUO JinYun YANG Lei +2 位作者 LIU Xin HWANG CheinWay YANG Hong 《Science China Earth Sciences》 SCIE EI CAS 2012年第12期2068-2083,共16页
This paper deals with the backscatter coefficients known as sigma0 at Ku band and C band based on the GDR-M (Merged Geophysical Data Record) of TOPEX/Poseidon (T/P) through Jan.1993 to Dec.2004 over land surface of Ch... This paper deals with the backscatter coefficients known as sigma0 at Ku band and C band based on the GDR-M (Merged Geophysical Data Record) of TOPEX/Poseidon (T/P) through Jan.1993 to Dec.2004 over land surface of China.After smoothing and interpolating the backscatter coefficients for both bands, we achieve the 5′×5′ grid data and the time series of backscatter coefficients in 12 years.The spatial distribution of sigma0 over typical areas (wetland, desert, mountainous area, agriculture base, etc.) of Chinese territory is analyzed and discussed.The fast Fourier transformation (FFT) is used to detect the cycles of seasonal variations of sigma0 time series and gives that the annual period is the major cycle.Meanwhile a semiannual period is also found in some places.We use the least squares method on both periods and find that the amplitude of annual period is obviously greater than that of semi-annual period.The relationship among the anomalousness of time series, variations of environment and climate change, and the serious natural calamity (flood, drought) is also discussed.Data of topography slope extracted from SRTM are used to do correlation analysis with the backscatter coefficients in parts of China to quantify the impact of slope on backscatter coefficients in Ku and C bands, and the results show that they all have a negative correlation but the magnitudes are different in different places with different coverages.Such as the area of Liaoning and Jilin has the maximum correlation -0.56, the Taklimakan Desert has the minimum correlation -0.11, and the other places commonly have correlations in (-0.3, -0.5). 展开更多
关键词 backscatter coefficient satellite altimetry TOPEX/POSEIDON land surface SRTM
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