共查询到19条相似文献，搜索用时 78 毫秒
1.
针对单频GPS接收机受电离层影响较大的特点，从定性的角度比较、分析了两种常用经验电离层模型的使用特点和改正精度。利用4个IGS测站的多天GPS实测数据，采用单点定位的方法，从定量的角度，研究了两种常用经验电离层模型应用于单频GPS用户定位时的改正效果，为单频GPS用户修正电离层延迟，选择合适的电离层模型提供了参考性建议。 相似文献
2.
本文根据区域电离层延迟模型的原理与方法，利用载波相位、伪距两种GPS观测值建立了区域VTEC电离层模型，并利用地壳网络观测数据对模型的精度进行了检核。 相似文献
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利用GPS研究电离层延迟及电子浓度变化规律 总被引：3，自引：0，他引：3
电离层是大气层的重要组成部分，电离层对GPS观测信号的折射影响，是GPS测量中最严重最棘手的误差源之一，精确修正电离层折射影响和反演电离层结构，一直是GPS研究和应用中的热点问题，一方面，为提高（特别是单频）GPS测量精度，需研究精确的电离层折射改正模型或其它有效方法；另一方面，利用各类GPS网络所拥有的大量高精度的GPS观测资料可有效提取电离层变化信息，深入了解电离层精细结构、变化规律及其对无线电信号干扰机制，实现对电离层灾害性突发事件的探测和预报，近年来，结合理论研究和实际应用的需要，我们在这领域作了以下几方面的工作：（1）研究如何利用单台双频CPS接收机的观测信息确定电离层延迟改正模型，为小范围的单频用户服务；（2）研究如何建立较大区域的电离层格网模型，进而初步设想利用中国地壳运动观测网络深入研究我国领域的电离层的电子浓度变化规律；（3）研究单频用户如何更好地利用电离层延迟改正信息；（4）研究如何利用GPS网络系统监测电离层的异常活动。 相似文献
4.
用双频GPS观测值建立小区域电离层延迟模型研究 总被引：19，自引：4，他引：19
介绍了用双频GPS伪距观测值建立区域性电离层模型的基本原理和方法。模型的初步结果表明，该电离层模型建立后，可为性病区域的广大单频用户提供在天顶方向优于0．4m精度的电离层延迟改正量，且具有30min以内天顶方向优于0．4m的预报精度。 相似文献
5.
电离层闪烁造成GPS接收机测距误差增大、以致强闪烁条件下的频繁周跳和卫星信号失锁,集成闪烁仿真功能的GPS信号模拟器能够为接收机抗闪烁算法研究和性能测试提供必要的信号源。首先设计了基于AJ-Stanford模型和Cornell模型的电离层闪烁仿真软件,可以灵活配置闪烁时间、数据更新周期以及各模型参数,从而得到闪烁影响下的GPS信号幅度衰落及相位波动序列;然后开发了集成电离层闪烁仿真功能的数字中频GPS信号模拟器,该模拟器作为抗闪烁研究平台工具,可以灵活调整闪烁卫星号、模型及相关参数、开始时间和持续时间;其设计正确性通过实验室自研的软件GPS接收机得到了验证。 相似文献
6.
3种GPS+BDS组合PPP模型比较与分析 总被引：1，自引：1，他引：0
无电离层组合和非组合模型是GNSS精密单点定位(PPP)常用的两种函数模型。本文通过详细分析PPP的两种函数模型各类参数间的相关特性,建立了参数独立的函数模型。对非组合PPP模型的电离层参数引入虚拟观测方程进行约束,有效提高了PPP的收敛速度。最后,从定位精度和收敛时间两方面分析不同函数模型的GPS单系统和GPS+BDS组合PPP静态、模拟动态定位效果。结果表明:GPS单系统和GPS+BDS组合PPP定位精度相当,静态的无电离层组合与非组合PPP均可达到厘米至毫米级精度,动态PPP精度的平面优于3cm,高程优于5cm;无电离层组合PPP收敛时间优于非组合的PPP,电离层加权非组合PPP的收敛时间最短。动态定位中,电离层加权模型相比于无电离层组合模型,可减少约15%的收敛时间,相比于非组合模型,可减少约34%。 相似文献
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GPS现代化后电离层折射误差高阶项的三频改正方法 总被引：13，自引：1，他引：13
研究了电离层对GPS观测信号的主要影响及电离层折射误差模型,总结了电离层双频改正模型。针对GPS现代化中增加的第三频率,系统推导了三个频率的电离层改正模型及相位观测值无电离层组合(LC组合)模型。该模型将电离层折射误差模型改正至二阶项,可进一步提高GPS定位精度,同时,为GPS定位中其他误差的改正及分离、周跳的探测等提供了有力的技术手段。 相似文献
9.
地基GPS区域电离层多项式模型与硬件延迟统一解算分析 总被引：3，自引：0，他引：3
探讨了利用区域地基GPS双频精码数据建立单层电离层多项式模型中,多项式系数、组合硬件延迟统一平差的数据处理方法.数据分析表明,GPS卫星短弧段的天空视图对电离层多项式建模的影响较大,由此估计的组合硬件延迟解不稳定,电离层模型也存在系统误差,边际效应明显;分段常数的全天电离层延迟多项式建模的数据处理方法可以有效地削弱短时弧段建模的影响,获取一致性、稳定性更好的组合硬件延迟. 相似文献
10.
利用码和载波相位观测值半和线性组合可以消除电离层一阶误差的特性,讨论了基于UofC消电离层组合的GPS/GLONASS精密单点定位的数学模型。UofC模型对两个频率上的模糊度参数分别进行估计,为进一步获得模糊度参数的整数解提供了便利。利用IGS跟踪站的GPS/GLONASS观测数据对UofC模型和传统的在两个频率码观测值间进行消电离层组合的模型进行了比较,统计结果表明,UofC模型与传统模型相比在平面位置定位精度上略有提高,但总体上差别不大。 相似文献
11.
Single layer ionosphere models are frequently used for ionospheric modeling and estimation using GPS measurements from a network of GPS reference stations. However, the accuracies of single layer models are inherently constrained by the assumption that the ionospheric electrons are concentrated in a thin shell located at an altitude of about 350 km above Earths surface. This assumption is only an approximation to the physical truth because the electrons are distributed in the entire ionosphere region approximately from 50 to 1,000 km. To provide instantaneous ionospheric corrections for the real-time GPS positioning applications, the ionospheric corrections need to be predicted in advance to eliminate the latency caused by the correction computation. This paper will investigate ionospheric total electron content (TEC) predictions using a multiple-layer tomographic method for ionospheric modeling over a local area GPS reference network. The data analysis focuses on the accuracy evaluation of short-term (5 min in this study) TEC predictions. The results have indicated that the obtainable TEC prediction accuracy is at a level of about 2.8 TECU in the zenith direction and 95% of the total electron content can be recovered using the proposed tomography-based ionosphere model. 相似文献
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Patricia Doherty joins the regular contributors of this column to discuss the correlation between measurements of solar 10.7
cm radio flux and ionospheric range delay effects on GPS. Mrs. Doherty has extensive experience in the analysis of ionospheric
range delays from worldwide systems and in the utilization and development of analytical and theoretical models of the Earth's
ionosphere.
Ionospheric range delay effects on GPS and other satellite ranging systems are directly proportional to the Total Electron
Content (TEC) encountered along slant paths from a satellite to a ground location. TEC is a highly variable and complex parameer
that is a function of geographic location, local time, season, geomagnetic activity, and solar activity. When insufficiently
accounted for, ionospheric TEC can seriously limit the performance of satellite ranging applications. Since the ionosphere
is a dispersive medium, dual-frequency Global Positoning System (GPS) users can make automatic corrections for ionospheric
range delay by computing the apparent difference in the time delays between the two signals. Single-frequency GPS users must
depend on alternate methods to account for the ionospheric range delay. Various models of the ionosphere have been used to
provide estimates of ionospheric range delay. These models range from the GPS system's simple eight-coefficient algorithm
designed to correct for approximately 50% rms of the TEC, to state-of-the-art models derived from physical first principles,
which can correct for up to 70 to 80% rms of the TEC but at a much greater computational cost.
In an effort to improve corrections for the day-to-day variability of the ionosphere, some attempts have been made to predict
the TEC by using the daily values of solar 10.7 cm radio flux (F10,7). The purpose of this article is to show that this type of prediction is not useful due to irregular, and sometimes very
poor, correlation between daily values of TEC and F10.7. Long-term measurements of solar radio flux, however, have been shown to be well correlated with monthly mean TEC, as well
as with the critical frequency of the inonospheric F2 region (foF2), which is proportional to the electron density at the
peak of the ionospheric F2 region. ? 2000 John Wiley & Sons, Inc. 相似文献
13.
论电离层对GPS定位的影响 总被引：13，自引：2，他引：11
电离层是ＧＰＳ定位的主要误差源。本文论述电离层的特征和折射系数,以及电离层的下列影响：电离层码群延、电离层载波相位超前、电离层多普勒频移、振幅闪烁、电离层相位闪烁效应、磁暴对ＧＰＳ定位测量的影响、电离层对差分ＧＰＳ的影响和ＧＰＳ接收机的电离层改正。 相似文献
14.
不同Klobuchar模型参数的性能比较 总被引：3，自引：1，他引：2
对于GPS单频用户而言,电离层延迟是最重要的误差来源之一。GPS系统使用Klobuchar模型对电离层延迟进行改正,其改正数从370组常数中选取。目前全球分布的GPS测站可以获得高精度的全球电离层监测结果,GPS为什么不发播采用实测数据计算得到的Klobuchar模型参数呢？本文针对这一问题进行分析。首先对欧洲定轨中心CODE提供的全球电离层图GIM预报COPG电离层进行精度评估,然后根据COPG电离层进行Klobuchar模型参数拟合并利用IGS提供的事后高精度电离层图进行精度分析,最后将不同的电离层模型参数应用于单点定位以评估其对单频用户的影响。分析结果表明：受8参数的Klobuchar模型本身结构限制,采用全球实测数据计算的电离层模型参数与导航电文中发播的电离层模型精度相当,为55%左右。而仅采用地磁纬度45oS以北的数据拟合得到的模型参数,其电离层改正精度有明显提升,可达65%左右,但其对单频用户定位精度改善不明显。本文研究结果为我国全球电离层建模提供参考。 相似文献
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16.
针对电离层单层模型无法满足单频用户定位精度要求的问题,该文建立了区域电离层斜路径模型和单星多项式函数模型。基于河北省区域CORS站的实验结果表明:该文建立的区域电离层模型的拟合精度比CODE中心的格网电离层模型提高了近80%。并将其应用于北斗、GPS单频伪距单点定位,得出北斗的单点定位高程和平面定位精度分别优于3和2m,GPS的单点定位高程和平面定位精度分别优于1.5和1m;相对于CODE,GPS和北斗在平面及高程方向的定位精度均提高了50%左右。结果证明,采用斜路径电离层模型和多项式函数模型,可以较好地反映区域电离层的精细结构。 相似文献
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结合我国探月项目卫星VLBI测轨资料分析中的实际需求讨论了两个问题：一是在S、X波段时延测量精度均为1ns情况下，电离层延迟改正所能够达到的精度；二是在飞行器VLBI测轨过程中，不能确保S、X波段双频观测情况下获取电离层时延改正的可能途径，包括借助于相关电离层模型、利用常规VLB1历史观测资料积累、借助于局域GPS观测网和IGS网单站GPS测量以及借助于专门设计的单站GPS测量等。最后对电离层VLB1和GPS技术实测结果进行了比较和问题分析。 相似文献
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Application of the TaiWan Ionospheric Model to single-frequency ionospheric delay corrections for GPS positioning 总被引：2，自引：2，他引：0
The performance of a three-dimensional ionospheric electron density model derived from FormoSat3/COSMIC GPS Radio Occultation measurements, called the TaiWan Ionosphere Model (TWIM), in removing the ionospheric delays in single-frequency pseudorange observations is presented. Positioning results using TWIM have been compared with positioning results using other ionospheric models, such as the Klobuchar (KLOB) and the global ionospheric model (GIM). C/A code pseudoranges have been observed at three International GPS Service reference stations that are representative of mid-latitude (BOR1 and IRKJ) and low-latitude (TWTF) regions of the ionosphere. The observations took place during 27 geomagnetically quiet days from April 2010 to October 2011. We perform separate solutions using the TWIM, KLOB, GIM ionospheric models and carry out a solution applying no ionospheric correction at all. We compute the daily mean horizontal errors (DMEAN) and the daily RMS (DRMS) for these solutions with respect to the published reference station coordinates. It has demonstrated that TEC maps generate using the TWIM exhibit a detailed structure of the ionosphere, particularly at low-latitude region, whereas the Klobuchar and the GIM only provide the basic diurnal and geographic features of the ionosphere. Also, it is shown that even for lower satellite elevations, the TWIM provides better positioning than the Klobuchar and GIM models. Specifically, using TWIM, the difference of the uncorrected solution (no ionospheric correction), and the other solutions, relative to the uncorrected solution, is 45 % for the mean horizontal error (DMEAN) and 42 % for the horizontal root-mean-square error (DRMS). Using Klobuchar and GIM, the percent for DMEAN only reaches to about 12 % and 3 %, while the values for the DRMS are only 12 and 4 %, respectively. In the vertical direction, all models have a percentage of about 99 and 70 % for the mean vertical error (VMEAN) and vertical root-mean-square error (VRMS), respectively. These percentages show the greater impact of TWIM on the ionospheric correction compared to the other models. In at least 40 % of the observed days and across all stations, TWIM has the smallest DMEAN, VMEAN, DRMS, and VRMS daily values. These values reach 100 % at station TWTF. This shows the overall performance of TWIM is better than the Klobuchar and GIM. 相似文献