利用GPS进行高精度变形监测的新模型

提出一种GPS变形监测的新模型：用变形后的监测点和基准点上的载波相位观测值组成双差观测值ΔΔ↓φ0‘(含整周模糊度ΔΔ↓N及整周计数ΔΔ↓Int(φ）），用变形前的监测点位置和基准点位置计算的双差值为ΔΔ↓φc,从ΔΔ↓φc和ΔΔ↓φ0‘之差中可求出变形矢量Δμ。如果变形量很小，对该差值的影响远小于1周，则在数据处理时可绕开“周跳的探测与修复”及“整周模糊度的确定”等问题，使数据处理大为简化。该模型还可用于基线向量的精处理。我们用测试软件对实际观测资料进行了大量，计算结果表明本方法的原理及数学模型是正确的。     

论GPS测量中的多径误差

多径误差是小区域(<3000km2)GPS点位测量的主要误差源。论述多径误差的简化模型和4种参数(卫星方位角、卫星高度角、截止高度角和时段长度)对多径误差的影响。     

全球卫星导航系统发展面面观

1 全球卫星导航系统三雄争霸 20世纪70年代,美国和原苏联建立了各自的全球卫星导航定位系统。后来,特别是“冷战”结束后,美国的全球定位系统GPS逐步向民用开放。所谓卫星导航定位市场就是围绕卫星导航定位系统而兴起的产业。由于GPS在全球越来越得到广泛应用,在野外勘探、陆路运输、海上作业及航空航天等诸多行业中占据了重要位置,GPS     

无线扩频技术在碾压GPS实时监控中的应用

分析了无线扩频技术的原理及主要特点,组建了碾压GPS实时监控系统的无线局域网,实现了总控中心和各移动远端的双向无线数据传输及局域网内各节点的资源共享。     

GPS的应用现状和发展前景

1 概述 GPS是现代高新技术实现军民两用的一个成功典范。GPS己逐步演变为一种世界性的高新技术产业,受到人们的普遍注意。GPS原本是美国国防部(DOD)负责研发专门用于军事目的的,可在任何时间全球任何地方提供三维位置、三维速度和时间     

北京城市热岛效应的流动观测和初步研究

采用车载气象观测仪器结合GPS定位、连续数据采集系统的流动观测方法研究了北京城区内不同城市地表覆盖物对城市局地小气候的影响和气象要素分布,发现城市下垫面分布与城市的温度和湿度有密切关系,一般在城市建筑物密集、水体和植被少的区域具有较高的气温和较低的相对湿度,在建筑物稀疏和植被、水体较多的区域则相反。观测结果表明,流动观测方法是对常规气象观测资料的有益补充,也是城市气候观测中的一种有效方法。     

Positive Charge Region in Lower Part of Thunderstorm and Preliminary Breakdown Process of Negative Cloud-to-Ground Lightning

A new lightning locating technology, called Lightning Mapping Array （LMA）, has been developed. The system takes advantage of GPS technology to measure the times of arrival （TOA） of lightning impulsive very high frequency （VHF） radiation events at each remote location. The spatiotemporal development processes of lightning are described in three-dimension by measurement of the system with high time resolution （50 ns） and space precision （50-100 m）. The charge structures in thunderstorm and their relationship with lightning discharge processes are revealed. The temporal and spatial characteristics of preliminary breakdown process involved in negative cloud-to-ground （CG） lightning discharges are analyzed based on the data of lightning VHF radiation events. The effect of positive charge region in lower part of thunderstorm on the occurrence of negative CG lightning discharge is discussed. The results indicate that the preliminary breakdown process with longer duration in negative CG lightning discharges is an intracloud discharge process. It occurs between negative and positive charge regions located in middle and lower parts of thunderstorm respectively. It initiates from the negative charge region and propagates downward. After propagating into the positive charge region, the lightning channel develops horizontally. The characteristics of the preliminary breakdown process are consistent with that of intracloud lightning discharges. The stepped leaders are initiated by the K type breakdown which occurs in the last stage of the preliminary breakdown process and develops downward through the positive charge region. The existence of positive charge region in lower part of thunderstorm results in the occurrence of preliminary breakdown process with longer duration before the return stroke of negative CG lightning discharges.     

GPS接收机检定系统研究

研究GPS接收机检定中各种边长、各种图形组合的优劣或能达到的精度指标,努力寻找最高精度、最优方案以指导检定基线场的建设;研制出一套可操作性强、实用性好、可靠性佳的GPS接收机检定系统软件,以满足GPS接收机检定市场的迫切需求,同时可为GPS连续跟踪站提供基站服务.     

Investigation of ionosphere TEC distribution in China region by GIM model

In this paper, the TEC in China region is calculated by final GIM model and plotted as contour maps, the TEC value calculated from dual frequency GPS measurements（carrier-phase and pseudorange） is used as the reference truth and the TEC values from GIM models are then compared with the reference truth, and the accuracy and performance of GIM model in China region are analyzed and concluded.     

Evaluation of CHAMP satellite orbit with SLR measurements

The technique of Evaluating CHAMP satellite orbit with SLR measurements iS presented. As an independent evaluation of the orbit solution, SLR data observed from January 1 to 16, 2002 are processed to compute the residuals after fixing the GFZ＇s post science orbits solutions. The SLR residuals are computed as the differences of the SLR measurements minus the corresponding distances between the SLR station and the GPS-derived orbit positions. On the basis of the SLR residuals analysis, it is found that the accuracy of GFZ＇ s post science orbits is better than 10 cm and that there is no systematic error in GFZ＇s post science orbits.