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基于延时相乘及其改进算法的DS/FH信号率线检测
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作者 张磊 孟凡计 +1 位作者 胡建平 王玉文 《电讯技术》 北大核心 2012年第3期338-341,共4页
针对DS/FH(直扩/跳频)混合扩频信号截获和参数估计问题,提出了一种基于延时相乘结合自适应滤波和分段自相关的新方法。该算法首先将输入信号进行自适应滤波以提高信噪比,滤波后送入延时相乘器,最后将乘积后数据分段进行自相关,通过分析... 针对DS/FH(直扩/跳频)混合扩频信号截获和参数估计问题,提出了一种基于延时相乘结合自适应滤波和分段自相关的新方法。该算法首先将输入信号进行自适应滤波以提高信噪比,滤波后送入延时相乘器,最后将乘积后数据分段进行自相关,通过分析谱图即可检测DS/FH混合扩频信号的码速率谱线。计算机仿真显示,改进的算法不但能适应低信噪比(-20 dB)条件下DS/FH混合扩频信号的检测,而且同时能够实现对码速率的估计。该方法所用算法简单,适合采用硬件设计实现,且如果是合作目标信号,搜索时间短,实时性强。 展开更多
关键词 DS/FH混合扩频 信号检测 延时相乘 分段自相关 自适应LMS滤波器
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Spatial disparities of regional forest land change based on ESDA and GIS at the county level in Beijing-Tianjin-Hebei area 被引量:10
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作者 Hualin XIE Chih-Chun KUNG Yuluan ZHAO 《Frontiers of Earth Science》 SCIE CAS CSCD 2012年第4期445-452,共8页
Forest land is the essential and important natural resource that provides strong support for human survival and development. Research on forest land changes at the county level about its characteristics, rules, and sp... Forest land is the essential and important natural resource that provides strong support for human survival and development. Research on forest land changes at the county level about its characteristics, rules, and spatial patterns is, therefore, important for regional resource protection and the sustainable development of the social economy. In this study we selected the GIS and Geoda software package to explore the spatial disparities of forest land changes at the Beijing-Tianjin-Hebei area county level, based on the global and local spatial autocorrelation analyses of exploratory spatial data. The results show that: 1) during 1985-2000, the global spatial autocorrelation of forest land change is significant in the study area. The global Moran's I value is 0.3122 for the entire time period and indicates significant positive spatial correlation (p 〈 0.05). Moran's I value of forest land change decreases from 0.3084 at the time stage I to 0.3024 at the time stage II; 2) the spatial clustering characteristics of forest land changes appear on the whole in Beijing- Tianjin-Hebei area. Moran's 1 value decreases from the time stage I to time stage II, which means that trend of spatial clustering of forest land change is weakened in the Beijing-Tianjin-Hebei area; 3) the grid map of the local Moran's I for each county reflects local spatial homo- geneity of forest land change, which means that spatial clustering about regions of high value and low value is especially significant. The regions with "High-High" correlation are mainly located in the north hilly area. However, the regions with "Low-Low" correlation were distributed in the middle of the study area. Therefore, protection strategies and concrete measures should be put in place for each regional cluster in the study area. 展开更多
关键词 correlation land use change forest land spatial auto- ESDA GIS Beijing-Tianjin-Hebei area
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