共查询到20条相似文献，搜索用时 31 毫秒
1.
We investigate daily and sub-daily non-tidal oceanic and atmospheric loading (NTOAL) in the Australian region and put an upper bound on potential site motion examining the effects of tropical cyclone Yasi that crossed the Australian coast in January/February 2011. The dynamic nature of the ocean is important, particularly for northern Australia where the long-term scatter due to daily and sub-daily oceanic changes increases by 20–55 % compared to that estimated using the inverted barometer (IB) assumption. Correcting the daily Global Positioning System (GPS) time series for NTOAL employing either a dynamic ocean model or the IB assumption leads to a reduction of up to 52 % in the weighted scatter of daily coordinate estimates. Differences between the approaches are obscured by seasonal variations in the GPS precision along the northern coast. Two compensating signals during the cyclone require modelling at high spatial and temporal resolution: uplift induced by the atmospheric depression, and subsidence induced by storm surge. The latter dominates ( \(>\) 135 %) the combined net effect that reaches a maximum of 14 mm, and 10 mm near the closest GPS site TOW2. Here, 96 % of the displacement is reached within 15 h due to the rapid transit of cyclones and the quasi-linear nature of the coastline. Consequently, estimating sub-daily NTOAL is necessary to properly account for such a signal that can be 3.5 times larger than its daily-averaged value. We were unable to detect the deformation signal in 2-hourly GPS processing and show that seasonal noise in the Austral summer dominates and precludes GPS detection of the cyclone-related subsidence. 相似文献
2.
Multi-technique space geodetic analysis software has been developed which allows to combine data on the observation level. In addition to local tie information, site-wise common parameters, i.e., troposphere and clocks, can be estimated with this software. Thus, it will be discussed how common parameters have to be estimated and where biases/offsets need to be taken into account. To test such a novel concept, Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) data from the CONT11 campaign are being utilized. Since the VLBI baselines of this campaign extend over several thousands of kilometers, GPS data are processed in precise-point positioning mode and satellite orbits and clocks are kept fixed to the IGS final products. From the obtained results, it can be shown that the combination of space geodetic data on the observation level leads to a consistent improvement of station position repeatability as well as nuisance parameters like troposphere estimates. Furthermore, estimation of common parameters (troposphere or clocks) at co-located sites helps to improve the solution further and derive an utmost physically consistent model of the concerned parameters. 相似文献
3.
Benjamin W. Remondi 《Journal of Geodesy》1985,59(4):361-377
After removing the modulation from the Global Positioning System (GPS) signal (L 1 orL 2) a pure carrier signal remains. Suppose this carrier is continuously and precisely tracked by aGPS receiver. Furthermore, suppose the phase of the carrier is periodically measured and recorded (nearly simultaneously at two or more locations) with respect to receiver oscillators having the same nominal frequency as theGPS carrier. This paper first considers alternative modeling and processing approaches to these observational data for static operations. Then an approach to dynamic relative positioning using triple differences is presented. This approach should lend itself to performing centimeter accuracy relative surveys in seconds rather than hours. An approach to fixing cycle slips, automatically, is included. 相似文献
4.
Dennis G. Milbert 《Journal of Geodesy》1985,59(1):71-80
A technique for processing correlated observations suitable for large, sparse, least-squares adjustments is reviewed. Correlated coordinate differences derived from the Global Positioning System are used as illustrative examples. However, the methods examined are suitable for all types of correlated observations. The computation of variances of residuals, redundancy numbers, and marginally detectable errors is considered for sparse systems. 相似文献
5.
6.
Patrick J. Fell 《Journal of Geodesy》1980,54(4):564-574
Geodetic positioning accuracies obtained from range, integrated Doppler and double differenced interferometric phase observations
from a constellation of twenty-four Global Positioning System satellites are presented. It is demonstrated that GPS range
and Doppler observations will provide sufficient accuracy for the estimation of geodetic coordinates. However the instability
of the receiver atomic oscillator will limit the usefulness of these observations in providing rapid first-order baseline
determination. Interferometric phase measurements twice differenced to eliminate clock error appear as an alternate procedure
for providing such accuracies. 相似文献
7.
Jaume Sanz J. Miguel Juan Adrià Rovira-Garcia Guillermo González-Casado 《GPS Solutions》2017,21(4):1549-1561
8.
GPS-RTK作为全球定位系统(GPS)测量技术提高定位精度的一种方法得到了大力推广和广泛应用。现今,北斗卫星导航系统(BDS)已建成区域导航星座,并具备了导航定位服务能力,且已正式提供连续无源定位、导航、授时等服务。但由于BDS单星座定位存在一些不足,导致了定位精度偏低,因此多频多系统融合定位导航研究成为了一个技术新热点。文中通过介绍RTK技术,引入了GPS+BDS双系统下RTK的应用思路,并指出RTK技术在地理信息采集系统中的优势以及实际应用中应注意的问题,为类似工程应用提供一定的参考价值。 相似文献
9.
Weixing Zhang Yidong Lou Shengfeng Gu Chuang Shi Jennifer S. Haase Jingnan Liu 《GPS Solutions》2016,20(4):665-676
We present the joint estimation model for Global Positioning System/BeiDou Navigation Satellite System (GPS/BDS) real-time clocks and present the initial satellite clock solutions determined from 106 stations of the international GNSS service multi-GNSS experiment and the BeiDou experimental tracking stations networks for 1 month in December, 2012. The model is shown to be efficient enough to have no practical computational limit for producing 1-Hz clock updates for real-time applications. The estimated clocks were assessed through the comparison with final clock products and the analysis of post-fit residuals. Using the estimated clocks and corresponding orbit products (GPS ultra-rapid-predicted and BDS final orbits), the root-mean-square (RMS) values of coordinate differences from ground truth values are around 1 and 2–3 cm for GPS-only and BDS-only daily mean static precise point positioning (PPP) solutions, respectively. Accuracy of GPS/BDS combined static PPP solutions falls in between that of GPS-only and BDS-only PPP results, with RMS values approximately 1–2 cm in all three components. For static sites, processed in the kinematic PPP mode, the daily RMS values are normally within 4 and 6 cm after convergence for GPS-only and BDS-only results, respectively. In contrast, the combined GPS/BDS kinematic PPP solutions show higher accuracy and shorter convergence time. Additionally, the BDS-only kinematic PPP solutions using clock products derived from the proposed joint estimation model were superior compared to those computed using the single-system estimation model. 相似文献
10.
GPS空间位置精度因子模糊分析 总被引：2，自引：0，他引：2
高精度测量是GPS的重要特性，但由于各种因素的存在，所有GPS测量信息都存在着一定的误差，这说明GPS的读数并不能准确代表目标的真实位置。本文提出一种为提高GPS测量精度的模糊分析，比较本方法与简单的点平均，并提供了在S／A存在与不存在不同时间的真实试验数据，证明了本方法能比简单的点平均提供更精确的位置信息。 相似文献
11.
GPS与GSM在定位业务中的应用 总被引：1，自引：0，他引：1
对全球定位系统GPS（Global Positioning System)全球移动网络GSM（Global System Mobile)及AGPS（辅助GPS）技术在GSM网络定位业务中的应用进行了介绍，并给出了定位业务的几个典型应用。 相似文献
12.
基于时空系统统一的北斗与GPS融合定位 总被引：1，自引：0，他引：1
我国的北斗卫星导航定位系统目前已经发射9颗“北斗”卫星,北斗区域卫星导航系统的基本系统已建设完成,正开展星地联调和测试评估工作,已经具备我国范围内的初步三维定位导航能力。本文研究了Beidou和GPS的时间系统/坐标系统的统一、卫星广播星历与卫星位置计算,以及二者的高精度定位算法,并实现了Beidou和GPS载波相位的数据融合和高精度联合定位,最后通过2011年9月29日的实测数据和处理结果证明了本文方法的正确性,同时为北斗二号系统的调试提供相关试验与结果。 相似文献
13.
在传统多系统非差非组合精密单点定位（precise point positioning，PPP）模型中，电离层延迟会吸收部分接收机码硬件延迟，其估计值可能为负数。提出了一种估计接收机差分码偏差（differential code bias，DCB）参数的GPS（Global Positioning System）/BDS（BeiDou Navigation Satellite System）非组合PPP模型，将每个系统第1个频率上的接收机码硬件延迟约束为零，对接收机DCB进行参数估计，达到了分离电离层延迟和接收机码硬件延迟的目的，降低了接收机钟差和电离层延迟的相关程度。利用4个多星座实验（multi-GNSS experiment，MGEX）跟踪站的GPS/BDS数据进行了静态和动态PPP试验，结果表明，与不估计DCB参数的PPP模型相比，采用估计DCB参数PPP模型后，静态模式下定位精度和收敛速度平均提高了29.3%和29.8%，动态模式下定位精度和收敛速度平均提高了15.7%和21.6%。 相似文献
14.
GPS Solutions - The tropospheric delay is an important error source in the Global Positioning System (GPS) positioning and navigation applications. Although most of the tropospheric delays can be... 相似文献
15.
一种基于交叉证认技术的自适应小波变换及其在削减GPS多路径误差中的应用 总被引：2，自引：1，他引：1
多路径效应影响是目前限制GPS定位精度进一步提高的瓶颈。提出用交叉证认技术自动识别小波分解的信号层,再通过小波重构实现降噪和信号提取,并将该方法应用于GPS多路径误差的削减中。对模拟数据和实际GPS观测资料的分析表明,该方法能合理分离不同噪声水平下资料序列中的信号和噪声;当噪声水平小于信号振幅的一半时,能成功分离资料序列中的高频信号。同时,运用该方法得到的多路径改正模型和GPS多路径效应的重复性,可有效地削弱多路径效应的影响,提高GPS定位精度。 相似文献
16.
信号衍射和多路径效应是限制GPS定位精度进一步提高的瓶颈,观测中两者往往同时存在。衍射效应具有不完全重复的特性,为了研究多路径重复性并使其不受信号衍射的影响,本文提出先应用SIGMA-Δ信噪比加权模型削弱信号衍射的影响,再运用改进恒星时滤波法分析多路径重复性。实验观测资料分析表明,SIGMA-Δ模型能有效削弱衍射信号对定位结果影响,并且保留主要的多路径信号;而改进恒星时滤波法能适应测站周围多路径环境的变化,从而最大限度地削减多路径误差。两者组合比传统的恒星时滤波更能有效提高GPS的动态定位精度。 相似文献
17.
通过全球导航卫星（GNSS）系统获取对流层天顶延迟对于气象和电波折射修正具有重要应用价值。利用自主研发的静态精密单点定位软件CRPPP,基于国际GNSS地球动力学服务局（IGS）发布的北斗系统（BDS）精密星历和精密钟差,给出了BDS估算天顶延迟结果。以IGS发布的全球定位系统（GPS）结果为参考对比,BDS估算天顶延迟结果平均偏差优于5mm,均方根误差（rms）优于2．3cm．同时,给出了西沙地区GPS与BDS估计结果,结果表明：利用北斗系统估计的对流层天顶延迟精度与GPS相当。 相似文献
18.
世纪之交的全球定位系统及其应用 总被引：32，自引：1，他引：31
综合介绍了全球定位系统（ＧＰＳ）,包括它的卫星系统和接收机,近期和今后的发展情况。评述了ＧＰＳ在各方面的重要应用,包括地基ＧＰＳ的动态和静态应用。重点介绍了当前ＧＰＳ应用的前沿,即空基和星基ＧＰＳ的应用。最后推荐了国际地球动力学ＧＰＳ服务（ＩＧＳ）的内容和产品,并对我国ＧＰＳ综合服务系统提出了建议。 相似文献
19.
全球定位系统(Global Positioning System,简称GPS)是美国从20世纪70年代开始研制的用于军事部门的新一代卫星导航与定位系统,历时20年,耗资200多亿美元,分三阶段研制,陆续投入使用,并于1994年全面建成.GPS是以卫星为基础的无线电卫星导航定位系统,它具有全能性、全球性、全天候、连续性和实时性的精密三维导航与定位功能.而且具有良好的抗干扰性和保密性.因此,GPS技术率先在大地测量、工程测量、航空摄影测量、海洋测量、城市测量等测绘领域得到了应用. 相似文献
20.
与全球定位系统（global positioning system,GPS）不同,北斗区域卫星导航系统（BeiDou navigation satellite system,BDS）采用了5颗地球静止轨道卫星、5颗倾斜地球同步轨道卫星和4颗中圆轨道卫星的混合星座,星座分布不均匀。特殊星座决定了不同纬度地区用户的可见卫星数量和观测几何结构存在明显差异,用户的导航定位性能存在明显的纬度效应。分别从理论模型和实际观测两个方面对不同纬度地区用户的可见卫星数目、观测几何结构和导航定位性能进行较全面分析,使用了多家厂商的接收机,在不同纬度地区进行了GPS、BDS以及两系统融合定位试验。结果表明,BDS定位性能存在明显的纬度效应,即定位精度随纬度升高而降低;GPS导航定位性能没有明显的纬度效应;BDS/GPS数据融合可以减弱纬度效应,提高导航定位服务的精度和可靠性。 相似文献