全球导航卫星系统反射信号遥感技术(global navigation satellite system reflectometry,GNSS-R)地基功率测量应用中,信号接收天线对于背向同极化和各向交叉极化信号的抑制并不理想.为了分析天线方向性对于目标信号相关功率测量的影响,...全球导航卫星系统反射信号遥感技术(global navigation satellite system reflectometry,GNSS-R)地基功率测量应用中,信号接收天线对于背向同极化和各向交叉极化信号的抑制并不理想.为了分析天线方向性对于目标信号相关功率测量的影响,以右旋圆极化(right hand circular polarized,RHCP)直射信号接收天线和左旋圆极化(left hand circular polarized,LHCP)反射信号接收天线为例,建立了实际天线接收信号的相关功率模型,确定了实际信号相关功率的概率分布以及数字特征,在仿真信号相关功率的数字特征的基础上计算了相关功率的相对偏差和离散系数并进行了分析.结果表明:天线方向性的不理想会造成目标信号相关功率测量误差,RHCP天线方向性仅在低卫星高度角范围内对直射目标信号相关功率测量有较大影响,而LHCP天线方向性在整个卫星高度角变化范围内都对反射目标信号相关功率测量有显著影响.展开更多
A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GIS (Geographical Information System), GPS (Global Positioning Sys...A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GIS (Geographical Information System), GPS (Global Positioning System) and ancillary data were combined by the method which adopts the main idea of classifying images by steps from decision tree method and the hybridized supervised and unsupervised classification. An integration of automatic image interpretation, ancillary materials and expert knowledge was realized. Two subscenes of Landsat 5 Thematic Mapper (TM) images of bands 3, 4 and 5 obtained on December 15, 1992, and January 17, 1999, were used for image processing and spatial data analysis in the study. The overall accuracy of the results of classification reached 90%, which was verified by field check.Results showed that shrimp farm land, urban and traffic land, barren land, bush and agricultural developing area increased in area, mangrove, paddy field, swamp and marsh land, orchard and plantation, and tropical grass land decreased, and the forest land kept almost stable. Ecological analysis on the land use changes showed that more attentions should be paid on the effect of land development on ecological environment in the future land planning and management.展开更多
In this paper, the propagating geometry and the w av eform of the GPS reflected signals are expatiated in detail. Furthermore, the pr inciple and the method of retrieving sea surface wind are presented. In order to te...In this paper, the propagating geometry and the w av eform of the GPS reflected signals are expatiated in detail. Furthermore, the pr inciple and the method of retrieving sea surface wind are presented. In order to test the feasibility of retrieval, the experiment data obtained by NASA in Hurr icane Michael are used. The result shows that the retrieval accuracy of wind spe ed is about 2 m/s.展开更多
文摘全球导航卫星系统反射信号遥感技术(global navigation satellite system reflectometry,GNSS-R)地基功率测量应用中,信号接收天线对于背向同极化和各向交叉极化信号的抑制并不理想.为了分析天线方向性对于目标信号相关功率测量的影响,以右旋圆极化(right hand circular polarized,RHCP)直射信号接收天线和左旋圆极化(left hand circular polarized,LHCP)反射信号接收天线为例,建立了实际天线接收信号的相关功率模型,确定了实际信号相关功率的概率分布以及数字特征,在仿真信号相关功率的数字特征的基础上计算了相关功率的相对偏差和离散系数并进行了分析.结果表明:天线方向性的不理想会造成目标信号相关功率测量误差,RHCP天线方向性仅在低卫星高度角范围内对直射目标信号相关功率测量有较大影响,而LHCP天线方向性在整个卫星高度角变化范围内都对反射目标信号相关功率测量有显著影响.
基金Project supported by the Tingthanathikul Foundation of Thailand, the Provincial Natural Science Foun- dation of Jiangxi (No. 0230025) the Open Research Foundation of Hubei Provincial Key Labaratory of Waterlogged Disaster and Wetland Agriculture (No. H
文摘A comprehensive method of image classification was developed for monitoring land use dynamics in Chanthaburi Province of Tailand. RS (Remote Sensing), GIS (Geographical Information System), GPS (Global Positioning System) and ancillary data were combined by the method which adopts the main idea of classifying images by steps from decision tree method and the hybridized supervised and unsupervised classification. An integration of automatic image interpretation, ancillary materials and expert knowledge was realized. Two subscenes of Landsat 5 Thematic Mapper (TM) images of bands 3, 4 and 5 obtained on December 15, 1992, and January 17, 1999, were used for image processing and spatial data analysis in the study. The overall accuracy of the results of classification reached 90%, which was verified by field check.Results showed that shrimp farm land, urban and traffic land, barren land, bush and agricultural developing area increased in area, mangrove, paddy field, swamp and marsh land, orchard and plantation, and tropical grass land decreased, and the forest land kept almost stable. Ecological analysis on the land use changes showed that more attentions should be paid on the effect of land development on ecological environment in the future land planning and management.
文摘In this paper, the propagating geometry and the w av eform of the GPS reflected signals are expatiated in detail. Furthermore, the pr inciple and the method of retrieving sea surface wind are presented. In order to test the feasibility of retrieval, the experiment data obtained by NASA in Hurr icane Michael are used. The result shows that the retrieval accuracy of wind spe ed is about 2 m/s.
