BDS/GPS组合单点定位与伪距双差算法分析

文章介绍了BDS/GPS组合系统伪距单点定位与伪距双差的数学模型与算法,讨论了BDS/GPS组合系统的时空基准统一以及伪距双差定权模型的问题。最后为了验证模型与算法的可靠性和可行性,利用安徽理工大学校园内坐标已知的GPS观测点进行数据采集,利用自编程序进行数据处理。结果表明BDS/GPS组合系统伪距双差较伪距单点定位精度有较大的提升,单点定位精度可以达到5m以内,伪距双差可达2m以内。     

BDS/GPS/GLONASS融合网格伪距差分定位性能分析

为了充分利用全球导航卫星系统资源,最大限度发挥北斗卫星导航系统的优势,向用户提供高精度、高可靠性和稳定性更好的服务,该文对BDS/GPS/GLONASS 3系统融合网格伪距差分定位性能进行了分析。运用该文阐述方法的原理进行实验分析,结果表明,3系统融合网格伪距差分定位较其他方案具有更高的定位精度、解算成功率,可见卫星数大幅度提高,可靠性和稳定性更优。     

GPS／BDS／GLONASS组合伪距单点定位性能测试与分析

本文以高山峡谷地区以及城市建筑群区域GNSS卫星受山体及建筑物遮挡的实际问题为出发点,通过选取不同的卫星方位角模拟不同遮挡环境,研究GPS／BDS、GPS／GLONAS和GPS／BDS／GLONASS组合系统伪距单点定位模型对于单GPS、单BDS系统在不同遮挡环境下的定位精度和三维导航可用性等方面的改善情况。结果表明,组合系统相对于单系统,增加了可见卫星数,降低了PDOP值,当观测条件不佳时,可以很好地改善定位精度和提高三维导航可用性。      

BDS/GPS组合伪距单点定位性能分析与评价

随着北斗系统全球组网即将完成,该系统将逐步具备全球导航定位能力。详细介绍在多种卫星导航系统并存的背景下,北斗和GPS组合单点定位基本原理以及数学模型的建立。利用实测数据分别对BDS、GPS和BDS+GPS三种定位模式下单点定位性能进行分析研究。计算结果表明,BDS+GPS双模式相对于BDS或GPS单系统定位精度更高,稳定性更好。     

GPS伪距改正及精密动态单点定位精度分析

给出了GPS伪距定位在动态模式下的改正模型：对流层折射延迟、电离层延迟改正、地球自转改正、相对论效应改正、卫星天线和接收机天线改正、固体潮改正。并针对单频GPS接收机进行动态伪距定位的试验，分析了各项改正对GPS伪距定位的精度影响及综合改正后的精度分析。     

不同截止高度角GPS/BDS组合伪距差分定位性能分析

针对在不同截止卫星高度角时,GPS,BDS,GPS/BDS系统间伪距差分定位精度的差异,文中对多系统融合伪距差分定位的数学模型方法进行研究。以香港CORS站6.9km和34.0km的两条基线为例,在截止卫星高度角10°、20°、30°、40°的情况下,进行GPS,BDS,GPS/BDS伪距差分基线解算。结果表明,与34.0km基线相比,6.9km基线伪距差分定位具有更高的精度,在不同截止高度角下,GPS/BDS组合系统在E,N,U方向的定位精度都优于单GPS,BDS系统,且定位结果更加稳定,特别在截止高度角为40°的极端条件下,GPS/BDS组合伪距差分定位精度仍能达到m级左右。     

BDS/GPS实时动态网络伪距差分定位

针对基于单基准站的伪距差分定位方法中,随着流动站与基准站距离的增加,大气误差相关性减弱,定位精度将会降低的问题,该文采用网络伪距差分方法,利用网络将多个基准站的伪距改正数实时传输给流动站,并内插流动站改正数,提高定位精度的同时扩大差分范围。实验表明,该方法提高了常规伪距定位精度,实现了实时分米级定位,可满足大多数用户的导航定位需求。     

BDS/GPS组合相位平滑伪距差分定位研究

为提高卫星实时定位的精度,利用载波相位测距精度高,伪距测距可实时解算的优势,并兼顾多卫星可有效提高定位几何精度。本文采用BDS/GPS组合相位平滑伪距差分定位理论,应用于导航系统实时位置解算,试验表明BDS/GPS组合相位平滑伪距差分定位可有效改善伪距差分定位的精度,满足了高精度动态实时定位的需求。     

GEO对BDS伪距单点定位影响分析

BDS星座构成不同于其他导航定位系统,GEO卫星的独特性将会增加我国BDS定位的优势,因此,本文选取多个MGEX跟踪站数据,分析了GEO卫星对BDS系统B1I和B3I单频伪距单点定位精度的影响。实验结果表明,GEO卫星能明显改善BDS卫星可用性,使BDS卫星可见数有明显增加,使PDOP值有明显降低,同时GEO卫星能有效提升BDS伪距单点定位精度,使伪距单点定位精度提升都在分米级,水平定位精度提升量在13%以上,高程定位精度提升量在10%以内。     

定位解算中的伪距的地球自转改正

地球同步卫星定位是利用三球交会原理精确解算用户位置参数的定位方式。定位的精度体现为解算结果的位置精度,它受到多方面因素的影响。定位解算所需的主要源是用户观测量（伪距）,因此伪距的精度直接影响了定位的精度。在观测到的伪距中包含了多项误差,而地球自转的影响是其中一项主要的误来源,必须加以修正。在实际的定位解算中,伪距的误差将会给定位结果带来相同量级的位置误差。本文详细讨论了地球同点卫星定位中的地球自转     

GLONASS pseudorange inter-channel biases and their effects on combined GPS/GLONASS precise point positioning

Combined GPS/GLONASS precise point positioning (PPP) can obtain a more precise and reliable position than GPS PPP. However, because of frequency division multiple access, GLONASS carrier phase and pseudorange observations suffer from inter-channel biases (ICBs) which will influence the accuracy and convergence speed of combined GPS/GLONASS PPP. With clear understanding of the characteristics of carrier phase ICBs, we estimated undifferenced GLONASS pseudorange ICBs for 133 receivers from five manufacturers and analyzed their characteristics. In general, pseudorange ICBs corresponding to the same firmware have strong correlations. The ICB values of two receivers with the same firmware may be different because of different antenna types, and their differences are closely related to frequency. Pseudorange ICBs should be provided for each satellite to obtain more precise ICBs as the pseudorange ICBs may vary even on the same frequency. For the solutions of standard point positioning (SPP), after pseudorange ICB calibration, the mean root mean square (RMS) improvements of GLONASS SPP reach up to 57, 48, and 53 % for the East, North, and Up components, while combined GPS/GLONASS SPP reach up to 27, 17, and 23 %, respectively. The combined GPS/GLONASS PPP after pseudorange ICB calibration evidently improved the convergence speed, and the mean RMS of PPP improved by almost 50 % during the convergence period.     

GPS/BDS组合系统伪距单点定位模型精度分析

合理确定观测值权阵对于应用GPS/BDS组合系统提高单点定位的精度和稳定性十分重要.文章对GPS/BDS常用的几种定权模型等权模型、高度角随机模型、基于Helmert验后方差估计模型、顾及PDOP值的定权模型等进行了实验与分析.结果表明:基于Helmert的定权方法精度最高,进一步对其观测值的分类根据高度角进行改进并利用PDOP值的选星思想后,模型精度再次提高.研究结果可以为提高GPS/BDS组合系统伪距单点定位的精度提供参考.     

GLONASS pseudorange inter-channel biases considerations when jointly estimating GPS and GLONASS clock offset

GLONASS clock offset estimation is affected by the inter-channel biases (ICBs) caused by frequency division multiple access technique. The effect of ICBs on joint GPS/GLONASS clock offset estimation is analyzed. An efficient approach for joint estimation of GPS/GLONASS satellite clock offset is applied to the generation of 30-s clock offset products. During the estimation, the following three ICB handling strategies were tested: calculating ICBs for each GLONASS signal channel, calculating ICBs for each GLONASS satellite and neglecting ICBs. The behavior of ICBs under different strategies was statistically stable. Subsequently, the clock offset products using different ICB strategies were evaluated. The evaluation shows that consideration of the ICB is important when estimating the clock offset. Furthermore, estimating one ICB for each GLONASS satellite is better than estimating one for each GLONASS signal channel because, with the former strategy, the clock offset products behave more smoothly and have higher accuracy compared with products from the International GNSS Service Analysis Center. In addition, precise point positioning, using clock offsets based on one ICB for each GLONASS satellite, has the highest positioning accuracy.     

Impact of GLONASS pseudorange inter-channel biases on satellite clock corrections

GLONASS carrier phase and pseudorange observations suffer from inter-channel biases (ICBs) because of frequency division multiple access (FDMA). Therefore, we analyze the effect of GLONASS pseudorange inter-channel biases on the GLONASS clock corrections. Different Analysis Centers (AC) eliminate the impact of GLONASS pseudorange ICBs in different ways. This leads to significant differences in the satellite and AC-specific offsets in the GLONASS clock corrections. Satellite and AC-specific offset differences are strongly correlated with frequency. Furthermore, the GLONASS pseudorange ICBs also leads to day-boundary jumps in the GLONASS clock corrections for the same analysis center between adjacent days. This in turn will influence the accuracy of the combined GPS/GLONASS precise point positioning (PPP) at the day-boundary. To solve these problems, a GNSS clock correction combination method based on the Kalman filter is proposed. During the combination, the AC-specific offsets and the satellite and AC-specific offsets can be estimated. The test results show the feasibility and effectiveness of the proposed clock combination method. The combined clock corrections can effectively weaken the influence of clock day-boundary jumps on combined GPS/GLONASS kinematic PPP. Furthermore, these combined clock corrections can improve the accuracy of the combined GPS/GLONASS static PPP single-day solutions when compared to the accuracy of each analysis center alone.     

GPS/BDS/GLONASS双频RTK定位算法研究

针对GLONASS采用频分多址技术导致双差观测方程中双差模糊度失去整周特性的问题,提出了一种基于站间单差模糊度分别求解的方法,并结合附加模糊度参数的卡尔曼滤波模型,实现了GPS/BDS/GLONASS组合RTK定位。通过自编RTK程序对GPS、BDS与GLONASS双频实测短基线数据进行测试,并对比分析其他RTK模式下的稳定性与定位精度。结果表明,GLONASS单频和双频定位的模糊度固定率分别为99.8%、99.7%,其定位精度与BDS、GPS相差不大。在单频或双频RTK定位中,双系统、三系统组合定位的稳定性和定位精度明显高于单系统,其中三系统组合定位的稳定性最好,精度最高。随着频率增加,初始化时间明显减少,为实现单历元获得固定解提供了可能性。     

An enhanced calibration method of GLONASS inter-channel bias for GNSS RTK

A user of heterogeneous GPS and GLONASS receiver pairs in differential positioning mode will experience ambiguity fixing challenges due to the presence of inter-channel biases. These biases cannot be canceled by differencing GLONASS observations, whether pseudorange or carrier phase. Fortunately, pre-calibration of GLONASS pseudorange and carrier phase observations can make ambiguity fixing for GPS/GLONASS positioning much easier. We propose an effective algorithm that transforms an RTK (real-time kinematic) solution in a mixed receiver baseline from a float to a fixed ambiguity solution. Carrier phase and code inter-channel biases are estimated from a zero baseline. Then, GLONASS both carrier phase and code observations are corrected accordingly. The results show that a mixed baseline can be transformed from a float (~100 %) to a fixed (more than 92 %) solution.     

Helmert方差分量估计在GPS/GLONASS/BDS/Galileo组合精密单点定位权比确定中的应用CSCD

多星座组合定位可以提升导航定位性能,但不同星座观测量组合时需要考虑合适的随机模型.传统方法是根据经验直接设定各系统的等价权重,但会导致随机模型确定不精确,从而影响组合系统的性能提升.将Helmert方差分量估计方法应用于GPS/GLONASS/BDS/Galileo组合精密单点定位(PPP)中,以自适应确定各系统间权比.采用国际GNSS服务(IGS)MGEX(Multi-GNSS Experiment)观测网的10个测站一周的观测数据进行静态和仿动态试验.结果表明:采用Helmert方差分量估计定权方法可显著提高GPS/GLONASS/BDS/Galileo组合PPP的收敛速度,与等权定权方案比较,静态模式下平均提高52%,仿动态模式下平均提高64%.因定位精度主要由载波相位观测值精度和误差修正水平决定,在静态和仿动态测试中Helmert方差分量估计方法对定位精度没有明显改善.     

地磁暴对北斗用户伪距定位的影响分析

地磁暴是近地空间经常发生的一种自然现象.发生磁暴时,电离层会发生明显的波动,导致电离层模型改正精度下降,进而影响单频用户定位解算结果.利用哈尔滨、北京、三亚三个地区的观测结果,计算了2017年4月地磁暴发生前后的电离层变化,并分别解算了双频模式、单频基本导航模式和单频增强模式下的伪距定位结果,对比了不同模式定位结果的差异.发现在地磁暴期间,双频定位结果最好,单频增强模式的结果稍逊于双频结果,两种模式一般优于单频基本导航模式.     

基于卡尔曼滤波方法的BDS动态伪距差分定位算法研究

针对北斗卫星导航系统(BDS)最小二乘伪距差分方法定位精度及稳定性不足的问题,提出了一种基于卡尔曼滤波方法的伪距差分算法,并进行了静态以及人行慢动态两种条件下的实验.对实测数据结果的处理分析表明,卡尔曼滤波方法在静态条件下,东、北、高三个方向精度分别提升55%、23%、48%.在动态条件下,东、北、高三个方向精度分别提升71%、49%、33%.