Earth rotation parameter estimation by GPS observations

The methods of Earth rotation parameter (ERP) estimation based on IGS SINEX file of GPS solution are discussed in detail. There are two different ways to estimate ERP: one is the parameter transformation method, and the other is direct adjustment method with restrictive conditions. By comparing the estimated results with independent copyright program to IERS results, the residual systemic error can be found in estimated ERP with GPS observations.     

基于SINEX文件的ERP参数估计

利用IGS所发布的对GPS全球站处理后形成的单天解SINEX文件,通过参数转换和附有限制条件的间接平差两种不同的思路,详细推导了ERP参数的估计方法。并给出了利用自编程序估计的结果与IERS所发布的结果的比较,发现单纯利用GPS观测结果进行ERP参数的估计可能存在残留的系统性偏差。     

同时估计电离层延迟的单频精密单点定位方法

提出一种基于单频码和相位观测量的单频精密单点定位方法,将每个观测量的电离层延迟量与接收机钟差、对流层天顶延迟、接收机位置、相位模糊度一起作为未知参数。采用约化参数的平方根信息滤波与平滑算法进行参数解算。该方法适用于实时定位和事后处理,且不需要外部的电离层模型。采用全球分布的32个IGS监测站16 d实测数据进行静态解算试验,结果表明E、N、U方向的RMS分别为0.023 m、0.018 m、0.059 m;基于一组机载GPS数据进行动态解算试验,得到E、N、U方向的RMS(与载波相位动态相对定位结果比较)分别为0.168 m、0.151 m、0.172 m。     

GPS高程转换的模型参数优选与稳健估计

在进行GPS高程拟合时,如果所用函数模型中未知参数个数不恰当,或者随机模型中采用了一个不合理的权阵,都将导致所建数学模型和客观实际存在较大偏差,而影响最终的拟合精度。文中研究了GPS高程拟合时对所建立的数学模型进行参数优化选择和稳健估计,计算数据表明该方法比常规方法在精度上有所提高。     

序贯静态点定位的原理与实现

介绍了利用参数消去法对GPS伪距点定位方程进行约化,结合序贯静态参数平差进行了定位解算,提高了单历元的计算精度。     

计算转换参数提高手持式GPS接收机定位精度的方法与探讨

通过在矿区施测的静态GPS控制测量,根据实际不同的坐标系工程用图需要,在矿区内均匀选择三个以上公共点的两套坐标,探讨对手持式GPS接收机求取其转换参数的方法,采用五参数转换法,求出转换参数,然后在手持GPS接受机上设置五参数来提高定位精度.     

应用Jones—TryonKalman滤波器对在轨GPSRb钟进行状态监测

针对用于石英钟和GPS主控站原子钟状态监测的Jones—TryonKalman滤波器,尝试把其引入到在轨GPSRb钟状态监测中去,结合哈达玛方差分析了其过程噪声和观测噪声协方差矩阵的确定方法,并讨论了滤波初值的选取,从而得到一个适合在轨GPSRb钟状态监测的滤波器。算例表明,这种Jones—TryonKal—man滤波器可以较好地监测在轨GPSRb钟的状态。     

病态模型参数估计在整周模糊度解算中的应用

介绍了病态模型参数估计方法,并将其应用于GPS快速动态定位整周模糊度的解算,实现了模糊度初值的快速准确求解。     

应用选权拟合法建立单历元伪距和载波相位双差模型

本文根据选权拟合法的一个重要性质:只要被约束的那部分参数估值无偏,其余的参数估值也无偏;该性质说明利用选权拟合进行参数估计的结果是条件无偏的。这个不同于一般正则化解的重要特性可以建立单历元伪距和载波相位双差模型,并通过实例验证了该方法的可行性。     

长江口航道GPS控制网数据处理与应用分析

介绍了应用GPS技术布设长江口航道GPS控制网,采用了七参数转换方法,实现了WGS-84至1954北京坐标系之间的转换,进行了相应的应用分析.     

利用地面气象观测资料确定对流层加权平均温度

地基GPS气象学的核心思想是通过垂直方向上GPS信号的湿分量延时确定出可降水分 ,而这两个物理量之间的转换必须使用对流层加权平均温度。本文首先讨论了上述转换估计中加权平均温度的几种逼近方式及其容许误差 ,然后利用香港地区的地面和高空气象资料 ,采用逐步回归分析方法 ,建立了适合香港地区的对流层加权平均温度计算公式 ,通过数据分析表明 ,这个公式有效地消除了在香港地区使用Bevis经验公式引起的系统误差 ,较好地满足了地基GPS气象应用中实时性和高精度的要求。本研究也充分表明 ,在地基GPS气象研究中 ,应该利用本地区的气象资料来确定适合本地区的估计对流层加权平均温度的经验公式。     

IGS Earth Rotation Parameters

Since its official start in January 1994, the International GPS Service (IGS) has been distributing, as part of its product combination, two distinct Earth rotation parameter (ERP) series: the IGS Rapid series and the IGS Final series. Initially, the IGS Rapid ERP values were interpolations of the International Earth Rotation Service (IERS) Bulletin A, whereas the IGS Final ERP series was based on the IERS Bulletin B. Since June 1996, the IGS has been generating its own Final ERP series consistent with the IGS combined orbit products and based on weighted means of individual IGS analysis center (AC) solutions. At first, only the polar motion (PM) coordinates and their rates were combined. Length of Day (LOD) and Universal Time (UT) solutions, also based on separate weighted mean combinations, followed in March 1997. Currently, the IGS Rapid and Final combinations are produced and made available within 17 hours and 11 days, respectively, after the last observation. Both IGS and the best AC series are consistent and precise at the 0.1-milliarcsecond (mas) level for PM and at about 30 μs for LOD. Biases in some AC solutions may exceed these consistency levels. Comparisons of both IGS ERP series with external standards, such as the IERS multitechnique Bulletins and atmospheric angular momentum series, confirm the estimated precisions. ? 1999 John Wiley & Sons, Inc.     

DETERMINATION OF WEIGHTED MEAN TROPOSPHERIC TEMPERATURE USING GROUND METEOROLOGICAL MEASUREMENTS

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Determination of weighted mean tropospheric temperature using ground meteorological measurements

The weighted mean tropospheric temperature is a critical parameter in the conversion of wet zenith delay to precipitable water vapor in GPS Meteorology. This parameter can not be calculated from the radiosonde data in real time through the conventional methods. In this study, we first discuss the admissible error of weighted mean temperature to enable the accuracy of the conversion better than 1 mm, then summarize the performance of some of the existing methods. An empirical formula is established that satisfies the real-time requirement in GPS meteorology using Sequential Regression Analysis method. It is shown that this real-time formula as compared with other empirical methods is more accurate for local applications.     

实时动态GPS测量转换参数求解分析

随着GPS测量技术的不断进步，目前动态GPS技术，特别是实时动态载波相位差分（RTK）技术，已成为GPS测量技术发展中的一个新的突破。但由于GPS测量采用WGS-84坐标系统，而我国目前所采用的坐标系统为1954北京坐标系（或1980国家大地坐标系、地方坐标系统等），高程基准为1956年青岛黄海高程系（或1985国家高程基准），所以GPS—RTK测量时必须先求解转换参数，以便于测量成果的应用。转换参数的求解是RTK测量的基础，转换参数的精确程度是影响RTK测量精度的关键因素。     

GPS网参数约束平差法研究

简要介绍了参数约束平差的模型,与常规平差方法比较,参数约束平差数据处理简单,易于程序实现,以一GPS网为算例,用参数约束平差法获得了经典自由网平差、秩亏自由网平差、符合网平差的结果。     

Analysis of the first year of Earth rotation parameters with a sub-daily resolution gained at the CODE processing center of the IGS

 The solutions of the CODE Analysis Center submitted to the IGS, the International Global Position System (GPS) Service for Geodynamics, are based on three days of observation of about 80–100 stations of the IGS network. The Earth rotation parameters (ERPs) are assumed to vary linearly over the three days with respect to an a priori model. Continuity at the day boundaries as well as the continuity of the first derivatives are enforced by constraints. Since early April 1995 CODE has calculated a new ERP series with an increased time resolution of 2 hours. Again continuity is enforced at the 2-hours-interval boundaries. The analysis method is described, particularly how to deal with retrograde diurnal terms in the ERP series which may not be estimated with satellite geodetic methods. The results obtained from the first year of data covered by the time series (time interval from 4 April 1995 to 30 June 1996) are also discussed. The series is relatively homogeneous in the sense of the used orbit model and the a priori model for the ERPs. The largest source of excitation at daily and sub-daily periods is likely to be the effect of the ocean tides. There is good agreement between the present results and Topex/Poseidon ocean tide models, as well as with models based on Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data. Non-oceanic periodic variations are also observed in the series. Their origin is most probably a consequence of the GPS solution strategy; other possible sources are the atmospheric tides. Received: 13 July 1999 / Accepted: 21 March 2000     

七参数的高程转换精度的分析

GPS七参数转换的高程精度到底是个什么概念?本文首先谈了GPS测高和七参数的原理,然后根据三个实例分析了采用七参数进行高程转换的精度,得到结论:GPS七参数的高程转换在一定测区内可以达到五等水准的精度;检验合格后,GPS七参数转换的高程数据可以满足图根控制精度的要求。     

带参数GPS水准拟合实现跨河高程传递

为了解决在特大桥隧工程建设中远距离高程基准传递的难题,介绍带高程基准参数的GPS水准拟合方法,给出拟合函数、计算公式及精度估算公式.通过3个大跨度桥梁高程控制的计算实例验证方法的可靠性,证明方法能同时获得局部似大地水准面模型和高程基准参数,解算高程基准参数的精度优于公路桥位勘测设计规程中桥梁高程控制测量的限差要求.     

GPS-RTK点校正方法的对比分析

首先介绍了GPS—RTK技术及其工作原理，然后在点校正实验的基础上，重点介绍GPS—RTK的三种常规校正方法：单点校正，多点校正和参数校正的原理与对比实验，通过实验数据探讨了三种校正方法的精度。对比分析，认为多点校正和参数校正均优于单点校正。