共查询到20条相似文献，搜索用时 31 毫秒
1.
The network-based approach to kinematic GPS positioning significantly increases the distance, over which carrier-phase ambiguity
resolution can be performed. This can be achieved either by introducing geometric conditions based on the fixed reference
locations, and/or through the use of reference network data to estimate the corrections to GPS observations that can be broadcast
to the users. The Multi Purpose GPS Processing Software (MPGPS) developed at The Ohio State University uses the multiple reference
station approach for wide area and regional differential kinematic GPS positioning. The primary processing algorithm uses
the weighted free-net (WFN) approach with the distance-dependent weighting scheme to derive optimal estimates of the user
coordinates and realistic accuracy measures. The WFN approach, combined with the single epoch (instantaneous) ambiguity resolution
algorithm is presented here as one approach to real-time kinematic (RTK) GPS. Since for baselines exceeding ~100 km, the instantaneous
ambiguity resolution may not always be possible due to the increasing observation noise and insufficient number of observations
to verify the integer selection, an alternative approach, based on a single- (or multiple-) baseline solution, supported by
a double-difference (DD) ionospheric delay propagated from the previous epoch is also presented. In this approach, some data
accumulation, supported by the network-derived atmospheric corrections, is required at the beginning of the rover data processing
to obtain the integer ambiguities; after this initialization period, the processing switches to the instantaneous RTK positioning
mode. This paper presents a discussion on the effects of the network geometry, station separation and the data reduction technique
on the final quality and reliability of the rover positioning solution. A 24-h data set of August 31, 2003, collected by the
Ohio Continuously Operating Reference Station (CORS) network was processed by both techniques under different network geometry
and reference station separation. Various solutions, such as (1) single-baseline solution for varying base-rover separation,
(2) multi-baseline solution with medium-range base separation (over 100 km), and (3) multi-baseline solution with long-range
base separation (up to 377 km), were obtained and compared for accuracy and consistency. The horizontal positioning accuracy
achieved in these tests, expressed as the difference between the estimated coordinates and the known rover coordinates, is
at the sub-decimeter level for the first approach, and at the centimeter-level for the second method, for baselines over 100 km.
In the vertical coordinate, decimeter- and sub-decimeter levels were achieved for the two approaches, respectively. Even though
all the results presented here were obtained in post-processing, both algorithms are suitable for real-time applications. 相似文献
2.
The network-based GPS technique provides a broad spectrum of corrections to support RTK (real-time kinematic) surveying and
geodetic applications. The most important among them are the ionospheric corrections generated in the reference network. The
accuracy of these corrections depends upon the ionospheric conditions and may not always be sufficient to support ambiguity
resolution (AR), and hence accurate GPS positioning. This paper presents the analyses of the network-derived ionospheric correction
accuracy under extremely varying – quiet and stormy – geomagnetic and ionospheric conditions. In addition, the influence of
the correction accuracy on the instantaneous (single-epoch) and on-the-fly (OTF) AR in long-range RTK GPS positioning is investigated,
and the results, based on post-processed GPS data, are provided. The network used here to generate the ionospheric corrections
consists of three permanent stations selected from the Ohio Continuously Operating Reference Stations (CORS) network. The
average separation between the reference stations was ∼200 km and the test baseline was 121 km long. The results show that,
during the severe ionospheric storm, the correction accuracy deteriorates to the point when the instantaneous AR is no longer
possible, and the OTF AR requires much more time to fix the integers. The analyses presented here also outline the importance
of the correct selection of the stochastic constraints in the rover solution applied to the network-derived ionospheric corrections. 相似文献
3.
Quality assessment of GPS rapid static positioning with weighted ionospheric parameters in generalized least squares 总被引：3，自引：2，他引：1
Pawel Wielgosz 《GPS Solutions》2011,15(2):89-99
Precise GPS positioning requires the processing of carrier-phase observations and fixing integer ambiguities. With increasing
distance between receivers, ambiguity fixing becomes more difficult because ionospheric and tropospheric effects do not cancel
sufficiently in double differencing. A popular procedure in static positioning is to increase the length of the observing
session and/or to apply atmospheric (ionospheric) models and corrections. We investigate the methodology for GPS rapid static
positioning that requires just a few minutes of dual-frequency GPS observations for medium-length baselines. Ionospheric corrections
are not required, but the ionospheric delays are treated as pseudo-observations having a priori values and respective weights.
The tropospheric delays are reduced by using well-established troposphere models, and satellite orbital and clock errors are
eliminated by using IGS rapid products. Several numerical tests based on actual GPS data are presented. It is shown that the
proposed methodology is suitable for rapid static positioning within 50–70 km from the closest reference network station and
that centimeter-level precision in positioning is feasible when using just 1 min of dual-frequency GPS data. 相似文献
4.
基于区域参考站网的网络实时动态定位(real-time kinematic,RTK)方法是实现全球定位系统(global positioning system,GPS)、北斗卫星导航系统(BeiDou satellite navigation system,BDS)高精度定位的主要手段。研究了一种长距离GPS/BDS双系统网络RTK方法,首先采用长距离参考站网GPS/BDS多频观测数据确定宽巷整周模糊度,利用引入大气误差参数的参数估计模型解算GPS/BDS双差载波相位整周模糊度;然后按照长距离参考站网观测误差特性的不同,分类处理参考站观测误差,利用误差内插法计算流动站观测误差,以改正流动站GPS/BDS双系统载波相位观测值的观测误差;最后使用流动站多频载波相位整周模糊度解算方法确定GPS/BDS载波相位整周模糊度并解算位置参数。使用长距离连续运行参考站(continuously operating reference stations,CORS)网的实测数据进行实验,结果表明,该方法能够利用长距离GPS/BDS参考站网实现流动站的厘米级定位。 相似文献
5.
Currently, the GNSS computing modes are of two classes: network-based data processing and user receiver-based processing. A GNSS reference receiver station essentially contributes raw measurement data in either the RINEX file format or as real-time data streams in the RTCM format. Very little computation is carried out by the reference station. The existing network-based processing modes, regardless of whether they are executed in real-time or post-processed modes, are centralised or sequential. This paper describes a distributed GNSS computing framework that incorporates three GNSS modes: reference station-based, user receiver-based and network-based data processing. Raw data streams from each GNSS reference receiver station are processed in a distributed manner, i.e., either at the station itself or at a hosting data server/processor, to generate station-based solutions, or reference receiver-specific parameters. These may include precise receiver clock, zenith tropospheric delay, differential code biases, ambiguity parameters, ionospheric delays, as well as line-of-sight information such as azimuth and elevation angles. Covariance information for estimated parameters may also be optionally provided. In such a mode the nearby precise point positioning (PPP) or real-time kinematic (RTK) users can directly use the corrections from all or some of the stations for real-time precise positioning via a data server. At the user receiver, PPP and RTK techniques are unified under the same observation models, and the distinction is how the user receiver software deals with corrections from the reference station solutions and the ambiguity estimation in the observation equations. Numerical tests demonstrate good convergence behaviour for differential code bias and ambiguity estimates derived individually with single reference stations. With station-based solutions from three reference stations within distances of 22–103 km the user receiver positioning results, with various schemes, show an accuracy improvement of the proposed station-augmented PPP and ambiguity-fixed PPP solutions with respect to the standard float PPP solutions without station augmentation and ambiguity resolutions. Overall, the proposed reference station-based GNSS computing mode can support PPP and RTK positioning services as a simpler alternative to the existing network-based RTK or regionally augmented PPP systems. 相似文献
6.
GNSS区域参考站网可为大范围PPP和RTK终端用户提供快速精密定位服务,然而不同技术体制下的误差影响因素及服务模式不同,服务端数据处理方法及终端定位性能也会有所差异。本文在实现参考站非差模糊度固定的基础上,给出了基于区域参考站网的PPP及RTK一体化服务方法,并对两种技术体制的终端定位效果进行了全面评估。采用西北某省站间距约100 km的CORS站网数据进行试验分析,结果表明,采用区域参考站网解算的整数钟/UPD产品进行PPP固定解动态定位时精度较高,水平方向RMS可达0.5 cm,区域大气改正数可以显著提升定位终端的初始化速度,对于PPP和RTK,60.0%和87.7%的时段单历元即可得到固定解。需要注意的是,基于VRS模式的RTK定位等价于大气强约束,在大气建模精度较差时定位精度会显著下降,而采用虚拟大气约束的PPP-RTK定位精度几乎不受影响。 相似文献
7.
This paper presents a data processing strategy for GPS kinematic Positioning by using a GPS active network to model the GPS errors in double difference observable.Firstly,the double difference residuals are estimated between the reference stations in the active network.Then the errors at a user station are predicted as the network corrctions to user measurements,based on the location of the user,Finally conventional kinematic positioning algorithms can be applied to determine the position of the user station.As an example,continuous 24-hour GPS data in March 2001 has been processed by this method.It clearly demonstrates that,after applying these corrections to a user within the network,both the success rate for ambiguity resolution and the positioning accuracy have been significantly improved. 相似文献
8.
9.
GPS/VRS 卫星定位服务网络建设与精度评定 总被引：13，自引：0，他引：13
虚拟参考站技术是近几年发展起来的,集Internet、无线通讯、计算机网络和GPS于一体的卫星定位技术。成都虚拟参考站卫星定位服务系统的建设,在设计上可满足全天候地向大成都地区用户提供厘米级实时动态定位服务。为了对该系统的实际定位精度进行客观的评价,从2 0 0 4年7月开展,历时两个月,全面完成了成都虚拟参考站卫星定位服务系统的精度评定工作,结果表明:在网内,水平方向上的精度可达2 .5cm ,垂直方向上的精度为4 . 5cm ,精度分布均匀;在网外,未模型化的距离相关误差的残余逐步增大,特别是距离网络中心大于1 2 0km以上时,定位精度开始衰减,为分米级。 相似文献
10.
基于GPS技术的滑坡动态变形监测试验结果与分析 总被引：2，自引：0，他引：2
结合某类滑坡的大型物理模型试验,在滑坡体上布设了若干监测点,并用GPS单历元定位技术和RTK技术对该滑坡体进行了连续实时监测。通过对该滑坡从开始滑动至产生破坏全过程监测数据的处理与分析,以及将GPS监测结果与全站仪三维监测结果的对比,发现在观测条件较好和基线较短时,基于Track模块GPS单历元定位技术监测滑坡变形的平面精度在5mm左右,高程精度约为9mm;RTK定位技术的平面精度在11mm左右,高程精度约为17mm;而用小波变换等方法进行滤波后的精度还会更高。 相似文献
11.
12.
13.
14.
An Overview of Multi-Reference Station Methods for cm-Level Positioning 总被引：11，自引：2，他引：11
Over the past few years, a significant amount of research has been conducted on the formulation of carrier phase corrections
in order to enhance ambiguity resolution and to increase the distances over which precise positioning can be achieved. Recently
the use of a network of multiple GPS reference stations for generating carrier phase-based corrections has emerged with great
promise for use in real-time environments. However, little research has been conducted on the distribution of these corrections
to potential GPS users located within, and surrounding, the network coverage area. This is an integral part of real-time kinematic
DGPS, and it must be adequately addressed before a practical realization of the multireference station concept is implemented.
The focus of this paper is to present a comprehensive summary of some of the multiple reference station methods, with specific
attention directed toward the correction generation and dissemination processes. More specifically, the various multi-reference
station methodologies have been categorized according to their underlying correction generation framework, but will be discussed
in terms of the correction dissemination options presented by the various authors. The for main categories of methods investigated
in this paper are: (a) partial derivative algorithms, (b) linear interpolation algorithms, (c) condition adjustment algorithms,
and (d) virtual reference station methodologies. ? 2001 John Wiley & Sons, Inc. 相似文献
15.
基于GPS基准网的GPS快速静态定位及动态定位方法 总被引：3，自引：0，他引：3
介绍基于GPS基准网进行GSP快速静态定位和动态定位的原理和方法。通过计算基准网改正数及其空间分布，利用内插方法求出用户站的模型误差改正数，不仅可以提高GPS整周模糊度的可靠性，而且能够大大改善GPS测量的精度。利用香港GPS基准网2001年3月的实测数据进行了解算，发现地区在该时间段内受强电离层活动的影响，采用常规GPS测量方法很难确定整周模糊度。利用传统的快速静态定位方法对香港GPS基准网其中一条边（9.2km）24h的观测数据按每15min计算，模糊度确定的准确率仅为45％。采用基准网内插改正数后，仅利用L1的观测数据模糊度确定的准确率提高到100％。点位精度平面位置由2cm提高到5mm，高程精度由4cm提高到3cm。 相似文献
16.
随着GPS现代化的发展以及中国北斗二代的实施,GPS／BDS组合导航系统在各个行业领域和亚太地区各个国家得到日益广泛的应用,国际海运事业无线电技术委员会（RTCM）增加了北斗卫星导航系统（BDS）星历电文并支持BDS载波相位差分应用使得北斗的地基增强系统在各行业中的应用更加重要。本文介绍相对定位基本模型,单基站实时运态（RTK）与多基站RTK基本原理以及虚拟参考站（VRS）定位方法,通过采集GPS／BDS观测值,分析单基站RTK与多基站定位结果。结果表明,若流动站与基准站距离较短,多基站与单基站定位精度均能得到厘米级定位结果;在流动站与基准站距离较长时,GPS／BDS双频多基站RTK的定位精度能达到厘米级定位结果,可用性强。 相似文献
17.
基于DREAMNET的GPS/BDS/GLONASS多系统网络RTK定位性能分析 总被引：1，自引：1，他引：0
随着BDS系统完成亚太地区组网、GLONASS系统再次实现满星座部署以及GPS系统的现代化,多系统集成已逐步成为网络RTK技术的发展趋势。本文结合笔者所在课题组自主研发的网络RTK数据处理系统DREAMNET,对不同卫星系统组合模式下的定位精度进行比较分析。试验结果表明,GPS/BDS/GLONASS网络RTK和GPS/BDS网络RTK的定位精度最高,GPS、BDS单系统网络RTK次之。此外,随着高度角的增加,GPS单系统网络RTK的可用性显著降低,而GPS/BDS/GLONASS网络RTK在高度角为40°时依然可以在99.84%的时间里提供水平精度0.01 m、高程精度0.025 m的定位服务。最后,对15 d的定位结果进行统计,包括不依赖GPS系统的BDS和BDS/GLONASS在内的6种组合方式皆可达到水平0.01 m、高程0.025 m的定位精度,其中GPS/BDS/GLONASS网络RTK则可以得到水平0.006 m、高程0.015 m的定位精度,证明DREAMNET的定位精度和稳定性完全可以满足测绘作业的需要。 相似文献
18.
With the advances in the field of GPS positioning and the global densification of permanent GPS tracking stations, it is now
possible to determine at the highest level of accuracy the transformation parameters connecting various international terrestrial
reference frame (ITRF) realizations. As a by-product of these refinements, not only the seven usual parameters of the similarity
transformations between frames are available, but also their rates, all given at some epoch t
k
. This paper introduces rigorous matrix equations to estimate variance–covariance matrices for transformed coordinates at
any epoch t based on a stochastic model that takes into consideration all a priori information of the parameters involved at epoch t
k
, and the coordinates and velocities at the reference frame initial epoch t
0. The results of this investigation suggest that in order to attain maximum accuracy, the agencies determining the 14-parameter
transformations between reference frames should also publish their full variance–covariance matrix.
Electronic Publication 相似文献
19.
Time-relative positioning makes use of observations taken at two different epochs and stations with a single global positioning
system (GPS) receiver to determine the position of the unknown station with respect to the known station. The limitation of
this method is the degradation over time of the positioning accuracy due to the temporal variation of GPS errors (ionospheric
delay, satellite clock corrections, satellite ephemerides, and tropospheric delay). The impact of these errors is significantly
reduced by adding to the one-way move from the known to the unknown station, a back move to the known station. A loop misclosure
is computed from the coordinates obtained at the known station at the beginning and at the end of the loop, and is used to
correct the coordinates of the unknown station. The field tests, presented in this paper, show that using the loop misclosure
corrections, time-relative positioning accuracy can be improved by about 60% when using single frequency data, and by about
40% with dual frequency data. For a 4-min processing interval (an 8-min loop) and a 95% probability level, errors remain under
20 cm for the horizontal components and 36 cm for the vertical component with single frequency data; and under 11 cm for the
horizontal components and 29 cm for the vertical component with dual frequency data. 相似文献
20.
探讨了精密单点定位的基本原理、处理方法、所涉及的误差改正及数据处理中的一些关键技术;采用直接内插IGS卫星精密星历的方法代替利用IGS跟踪站进行轨道精化方法计算卫星轨道参数,对现有精密单点定位计算方法进行了简化,使之更具有实用性。最后利用自主研发的精密非差单点定位软件计算和分析了实测数据。计算结果表明,经过大约15 min的初始化后,非差相位单历元的定位结果精确度在X,Y,Z方向上均优于20 cm。 相似文献