台湾集集大地震断层非均匀滑动分布的反演

利用台湾1999集集大地震前后GPS测量获得的地表位移数据,反演断层面上的非均匀滑动分布.反演中采用二次样条函数作为滑动分布的基函数,通过引入阿卡克贝叶斯准则,获得了反演问题的惟一解.反演得到的地表位移与实测位移的差在几个厘米,较好地解释了观测到的GPS位移.另一方面,用反演结果计算得到的地表形变场同INSAR得到的地表实测位移场较相近.     

欧洲ACE+掩星观测计划

最近，欧洲制定了一个新的ACE^ 掩星观测计划。它由4颗小卫星组成，分布在2个轨道面上。星载接收机可以分别接收GPS和Galileo(伽利略)导航星座信号，进行掩星观测。此外，4颗小卫星中的两颗卫星，携带X和K波段的发射机，另外两颗携带接收机，他们之间也进行掩星观测，测量电波振幅变化，独立反演对流层大气温度和水汽。计划创新之处在于，它以前所未有的技术和测量精度获得全球大量的电离层和中性大气的气象场资料。本文介绍ACE^ 计划观测内容、卫星载荷、地面观测设备的数据处理技术，也给出该计划的应用前景。     

空间大地测量的最新进展(一)

现代大地测量的进展主要是空间大地测量的进展 ,而空间大地测量的进展以 GPS的进展最为突出。因此 ,本刊曾在 2 0 0 0年 4期和 2 0 0 1年 1期连载了 GPS的最新进展。现陆续介绍现代空间大地测量最新进展的全貌 ,包括 :1.空间大地测量最新进展的概况 ;2 .甚长基线干涉测量 (VL BI)的最新进展 ;3.激光测月 (L L R)和激光测卫 (SL R)的最新进展 ;4.卫星雷达测高的最新进展 ;5 .合成孔径雷达干涉测量 (INSAR)的最新进展 ;6 .由卫星集成的多普勒和无线电定位系统 (DORIS)的最新进展等     

GPS网的模拟优化设计

对GPS网与常规控制网的优化设计进行比较与分析，给出了GPS网平差及优化设计的数学模型，并对一个实例采用模拟法对一，三阶段进行了优化设计，得出了一些结论。     

The use of GPS arrays in detecting shock-acoustic waves generated during rocket launchings

This paper is concerned with the parameters of shock-acoustic waves (SAW) generated during rocket launchings. We have developed the interferometric method for determining SAW parameters (including angular characteristics of the wave vector, and the SAW phase velocity, as well as the direction towards the source) using GPS-arrays. Contrary to the conventional radio-probing techniques, the proposed method provides an estimate of SAW parameters without a priori information about the site and time of a rocket launching. The application of the method is illustrated by a case study of ionospheric effects from launchings of rockets PROTON, SOYUZ and SPACE SHUTTLE from Baikonur and Kennedy Space Center cosmodromes in 1998–2000. In spite of a difference of rocket characteristics, the ionospheric response for all launchings had the character of an N-wave corresponding to the form of a shock wave. The SAW period T is 270–360 s, and the amplitude exceeds the standard deviation of total electron content background fluctuations in this range of periods under quiet and moderate geomagnetic conditions by factors of 2–5 as a minimum. The angle of elevation of the SAW wave vector varies from 30° to 60°, and the SAW phase velocity (900–1200 m/s) approaches the sound velocity at heights of the ionospheric F-region maximum. The position of the SAW source, inferred by neglecting refraction corrections, corresponds to the segment of the rockets path at a distance no less than 200–900 km from the launch pad, and to the rocket flying altitude no less than 100 km. Our data are consistent with the existing view that SAW are generated during a nearly horizontal flight of the rocket with its engine in operation in the acceleration segment of the path at 100–130 km altitudes in the lower atmosphere.     

4颗卫星情况的几何优化法修正

在GPS定位与导航中,用户可以通过选择至少4颗可见卫星的观测,得到测站位置和站钟差信息,卫星相对于测站的几何关系直接影响到定位和导航的精度,考虑用4颗卫星进行定位,在当前有一定的现实意义,在KihaLra等人工作的基础上对四面体的性质进行了深入讨论,推导了4颗可见卫星构成四面体体积的计算公式,实例分析证明该计算公式更合理、更精确。     

GPS变形监测的SSDM方法的理论与实践

全球定位技术已广泛应用于监测各种建构物的变形,本文根据高精度GPS变形监测的特点,从六个方面综合性地介绍了SSDM(似单差方法)的理论与实践。第一部分介绍了SSDM方法产生的背景,第二部分给出了其基本数学模型。第三部分分析了SSDM方法的误差来源和控制措施,第四部分介绍了采用SSDM方法进行变形监测的监测方案,第五部分简单介绍了采用SSDM方法开发的软件。最后一部分,对SSDM方法的一些重要结论进行总结。本文中,某些论据以参考文献形式给出。     

GPS全球定位系统的改进与发展

随着电子技术与计算机技术的发展，GPS全球定位系统得到了进一步的发展与完善。GPS在全球各领域广泛应用的同时，也成为美军战斗艘能发挥不可或缺的利器。本文在分析美军现有GPS系统本身存在的脆弱性以及所面临挑战的基础上，从GPS系统卫星、接收机、地面站、编码等五个方面着重讨论了美军对现有GPS系统的改进与发展情况，最后简单介绍了美军第三代全球定位系统（GPSⅢ）的发展趋势。     

单站GPS遥感水汽含量范围的确定及结果分析

随着GPS技术的日益成熟和研究的不断深入,GPS的定位精度得到了大幅度的提高,为其在测绘、交通、林业资源、石油勘探、精细农业等行业的应用提供了更广阔的空间。GPS气象学(GPS/Meteorology简称GPS/MET)的诞生改善了原有大气监测技术的局限性,极大的提高了气象监测的时空分辨率,但是在将这项技术由试验阶段向推广普及应用的过程中,单站地基GPS监测的有效范围以及水汽解的精度一直为广大气象学家们所忽略,本文在对以往GPS气象数据收集和整理的基础上,根据理论计算和实际验算,得出了一些有益的结论。     

Detection of station coordinate discontinuities within the Italian GPS Fiducial Network

The Detection Identification Adaptation (DIA) procedure was applied to the coordinate time-series of some permanent GPS stations belonging to the Italian GPS Fiducial Network (IGFN), of the Italian Space Agency (ASI), to detect discontinuities and to reject outliers. The daily solutions of the stations of Cagliari, Genoa, Medicina, Noto, Turin, Perugia and Venice were computed for the period 1997.0–2003.0 using Bernese GPS software v.4.2. The data were interpolated using a model with a linear term and an annual periodic term. The parameters were estimated by least squares. The DIA procedure was organized to automatically detect discontinuities and outliers. Approximately, 70% of the discontinuities present in the coordinate time-series were identified and their magnitudes were estimated. The identified discontinuities are basically caused by equipment replacement and reference frame changes, but in a few cases the reason is still unknown. With regard to the outliers, roughly 6% of the data were rejected. These data were considered outliers on the base of the level of significance and of the power of the test adopted in this work. Except for the stations of Perugia and Venice, the estimated coordinates agree with ITRF2000 values at the 10 mm level, and the estimated velocities are within a few mm/year of the ITRF2000 values.