北斗三号新信号B2a和B2（B2a+b）质量分析及星座几何性能评估

在最新的能接收到北斗三号新信号B2a及B2（B2a+b）的MGEX测站数据基础上，分析BDS-3信号的载噪比、多路径及卫星的三维位置精度因子（PDOP）。结果表明，与GPS相比，BDS的载噪比B2（B2a+b）>B2a≈L5>B3≈B2b>B1≈L1>L2，多路径误差B2(B2a+b)相似文献   

微塑料在海洋中的分布、生态效应及载体作用

微塑料通常被定义为最大尺寸小于5 mm的塑料碎片.受人类活动的影响,微塑料在海洋环境中广泛存在,引起了人们对其潜在影响的关注.由于粒径较小,微塑料可以通过多种途径进入水生生物体内,沿着食物链迁移、传递,影响海洋生态系统的健康与稳定.在海洋中长期停留的微塑料会吸附环境中的重金属、有机污染物和微生物等,加剧微塑料对海洋生物的毒性作用.本文综述了海洋环境中微塑料的污染特征,微塑料对海洋生物行为、生理等的影响,以及微塑料与微生物、其他污染物的相互作用和复合效应,并对微塑料对海洋环境及生物影响的研究进行了展望.     

青藏高原水系沉积物地球化学衰减模式与区域地球化学勘查对策

文章主要涉及青藏高原干旱荒漠、半干旱草原、高寒草甸等三个景观区。风力搬运的影响遍及整个干旱荒漠和半干旱草原景观区,使其疏松覆盖层中的本域地球化学模式受到不同程度的干扰和变型。干旱荒漠区中水系沉积物的地球化学性质受到风成沙和黄土的双重稀释。高寒草甸区,化学风化作用加强,基本上无外域物质干扰。 考虑技术可能和经济合理两个因素,提出现有交通状况下的区域地球化学勘查对策。     

GPS周跳探测的两种方法研究

在GPS定位中,有时需要测站的高精度坐标,为此模糊度的解算和周跳的探测与修复成为关键问题,在周跳探测中,特别是小周跳的探测成为当今的热点问题。本文中利用接收机的双频观测值进行周跳的探测研究,通过实例分析,证明这两种方法可行。     

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GPS载波相位测量定位设备的设计与实现

介绍了一种GPS载波相位测量定位设备的设计方案和原理.该设备由MCS-51单片机,摩托罗拉VP 6PS 0EM板,高速CMOS电路,非易失存储器和A/D转换器等组成.该设备具有测 量精度高、能耗低、体积小、重量轻、操作灵活简便、抗干扰能力强、能自动记录长时间测量数据等特点.     

电离层高阶项延迟对GPS载波相位观测值及基线的影响

为研究电离层高阶项延迟及其影响,采用IGS提供的实测数据与产品,结合具体实验讨论地磁模型、TEC数据模式、GPS频率及测站分布等对电离层高阶项延迟的影响,分析不同TEC获取方式与地磁模型处理模式下的电离层高阶项延迟对基线的影响.实验表明,利用不同方式获取的TEC是影响电离层高阶项延迟的关键因素,其对载波相位观测值的影响...     

无人机遥感众创时代

当代科技发展降低了无人机和遥感器的准入门槛。大众参与为无人机遥感领域注入了巨大的创造力,触发了无人机遥感创新发展的爆发式增长。当前,无人机已成为普适化和平民化的科学手段,无人机遥感数据在众多领域和部门呈现出取代通航遥感和卫星遥感数据的趋势。本文首先对无人机遥感所处的时代特征及其展现的科技特色进行了分析与归纳,然后列举了无人机遥感在抗震救灾、岛礁测绘、极地科考、精准农田管理等领域开展的典型应用,最后从无人机发展所致遥感数据供应结构性调整、无人机遥感地理学研究推动、遥感无人机试验场地布局等方面进行了展望。特别地,针对无人机遥感应用量大面广、数据分布多源异构等特点,本文提出了无人机遥感数据航母的概念。     

Preliminary assessment of the navigation and positioning performance of BeiDou regional navigation satellite system

BeiDou regional navigation satellite system(BDS)also called BeiDou-2 has been in full operation since December 27,2012.It consists of 14 satellites,including 5 satellites in Geostationary Orbit(GEO),5 satellites in Inclined Geosynchronous Orbit(IGSO),and 4 satellites in Medium Earth Orbit(MEO).In this paper,its basic navigation and positioning performance are evaluated preliminarily by the real data collected in Beijing,including satellite visibility,Position Dilution of Precision(PDOP)value,the precision of code and carrier phase measurements,the accuracy of single point positioning and differential positioning and ambiguity resolution(AR)performance,which are also compared with those of GPS.It is shown that the precision of BDS code and carrier phase measurements are about 33 cm and 2 mm,respectively,which are comparable to those of GPS,and the accuracy of BDS single point positioning has satisfied the design requirement.The real-time kinematic positioning is also feasible by BDS alone in the opening condition,since its fixed rate and reliability of single-epoch dual-frequency AR is comparable to those of GPS.The accuracy of BDS carrier phase differential positioning is better than 1 cm for a very short baseline of 4.2 m and 3 cm for a short baseline of 8.2 km,which is on the same level with that of GPS.For the combined BDS and GPS,the fixed rate and reliability of single-epoch AR and the positioning accuracy are improved significantly.The accuracy of BDS/GPS carrier phase differential positioning is about 35 and 20%better than that of GPS for two short baseline tests in this study.The accuracy of BDS code differential positioning is better than 2.5 m.However it is worse than that of GPS,which may result from large code multipath errors of BDS GEO satellite measurements.