共查询到20条相似文献，搜索用时 31 毫秒
1.
精密单点定位（PPP）一般基于非差GPS观测值,其中相位观测所含的初始相位偏差（Initial Phase Biases, IPBs）与整周模糊度不可分离,故各类PPP估值均为模糊度浮点解。目前,借助区域或全球GPS网分离卫星IPBs,改正PPP相位观测值,可实现PPP整周模糊度解算,进而提高各类估值精度,显著缩短收敛时间。常用算法包括：分解卫星钟差（分解钟差法）和非整相位偏差（非整偏差法）估计方法。本文从GPS原始观测值入手,推导了卫星IPBs估计的满秩函数模型,以此为基础对两种算法的特点及实施进行了对比分析。研究表明：分解钟差法是一种观测信息的最优利用,且与传统的卫星钟差估计方法具有较优的一致性,但未利用卫星IPBs较为稳定的有利约束;非整偏差法对组合观测值之间的相关性未加考虑,进而是一种次优估计,其实时性实施较差,且较依赖于高精度的码观测值。文中的新模型可有效克服上述两种算法的不足,便于施加部分参数的合理时变性约束,以提高卫星IPBs估计的可靠性。 相似文献
2.
David Underwood 《GPS Solutions》1999,3(2):48-52
The use of the Global Positioning System (GPS) for position and attitude determination has been exploited for many years.
In these systems, it was required that multiple antennas maintained phase lock to common view satellites for long periods
of time in order to determine integer ambiguities. The challenge to overcome with the ballistic space probe is the high rotational
spin of this particular rocket. The antennas, mounted on the outside skin of the rocket, are in full view of each satellite
only for a fraction of a second before the rocket core eclipses them as it rotates. The antennas rarely see common satellites.
This article describes as system that overcomes these obstacles and provides position, acceleration, attitude, and rotation
rate. The approach uses a two-antenna system. One antenna is mounted either side of the rocket facing out. A hybrid tracking
channel combines signals from both antennas to overcome the signal blockage due to the rocket core as well as to defeat the
effect on the tracking channel due to the spin. The amplitude and phase of the spin rotation signature from each satellite
is extracted from the dual antenna data and used to compute the attitude and spin rate of the vehicle. ? 1999 John Wiley &
Sons, Inc. 相似文献
3.
单频GPS快速定位方程是严重病态的,应用最小二乘原理得到的模糊度浮点解大大偏离其准确值,应用LAMBDA方法难以正确地固定模糊度。本文将GPS载波相位双差观测量在不同的小波空间和尺度空间进行分解和重构,去除高频测量噪声,可减小测量噪声对GPS快速定位中病态方程解的影响,提高模糊度浮点解的精度,缩小模糊度搜索空间。实验表明,对于GPS短基线,仅利用1min左右的单频载波观测数据,经过基于haar、db4、coif4和sym4小波的5尺度小波变换后,可获得较准确的模糊度浮点解,应用LAMBDA法可正确地固定模糊度,达到厘米级定位精度。 相似文献
4.
在对GPS／GLONASS组合定位的周跳探测和修复方法进行深入研究的基础上，论述了适合于两种数据联合解算的GPS／GLONASS模糊度迭代处理方法及相应的基于FARA方法的整周模糊度固定方法。在现有BERNESE Ver4.0GSP数据处理软件的基础上，增加及改进了其中的若干模块，从而研制出组合定位系统高精度数据处理软件，并进行了试验计算。结果表明，所开发的组合定位系统数据处理软件内、外符合精度均达到mm级，证明了这种高精度相对定位理论、方法、软件的正确性和可行性。 相似文献
5.
Cycle slip detection and repair is an important issue in the GPS data processing. Different methods have been developed to detect and repair cycle slips on undifferenced , single- or double-differenced observations. The issue is still crucial for high-precision GPS positioning, especially for the undifferenced GPS observations. A method is proposed to fix cycle slips based on the generalized likelihood ratio (GLR) test. The method has a good performance on cycle slip fixing of undifferenced carrier phase observations on individual frequencies, either on L1 or on L2, without making a linear combination among the observables. The functional model is a piecewise cubic curve fitted to a number of consecutive data using the least squares cubic spline approximation (LS-CSA). For fixing the cycle slips, an integer estimation technique is employed to determine the integer values from the float solution. The performance of the proposed method is then compared with the existing two methods using simulated data. The results on a few GPS data sets with sampling rate of 1 Hz or higher confirm that this method can detect and correct all simulated cycle slips regardless of the size of the cycle slip or the satellite elevation angle. The efficacy of the method is then investigated on the GPS data sets with lower sampling rates of 5, 10, and 30 s. The results indicate that the proposed method always performs the best for the data sets considered. This is thus an appropriate method for cycle slip detection and repair of single-frequency GPS observations. 相似文献
6.
由星载GPS双差相位数据进行CHAMP卫星动力学定轨 总被引：1，自引：0，他引：1
为了确定CHAMP卫星的轨道，由星载GPS数据和IGS跟踪站的GPS数据构造星地相位双差观测量，利用EOP、SGO、时间等数据，对GPS数据进行预处理，包括钟差改正、模糊度解算和周跳探测、卫星姿态改正、天线偏差和相位中心改正等，采用CHAMP卫星受力摄动模型，根据动力学原理，对CHAMP卫星进行实际定轨。与德国GFZ定轨结果PSO相比，本方法定轨结果径向精度为0．2857m。对于1d的重叠轨道，径向轨道差异的RMS为0．0958m。对于轨道端点比较，径向轨道差异平均为0．0666m。 相似文献
7.
Double-differenced (DD) ambiguities between overlapping frequencies from different GNSS constellations can be fixed to integers if the associated differential inter-system biases (DISBs) are well known. In this case, only one common pivot satellite is sufficient for inter-system ambiguity resolution. This will be beneficial to ambiguity resolution (AR) and real-time kinematic (RTK) positioning especially when only a few satellites are observed. However, for GPS and current operational BDS-2, there are no overlapping frequencies. Due to the influence of different frequencies, the inter-system DD ambiguities still cannot be fixed to integers even if the DISBs are precisely known. In this contribution, we present an inter-system differencing model for combined GPS and BDS single-frequency RTK positioning through real-time estimation of DISBs. The stability of GPS L1 and BDS B1 DISBs is analyzed with different receiver types. Along with parameterization and using the short-term stability of DISBs, the DD ambiguities between GPS and BDS pivot satellites and the between-receiver single-difference ambiguity of the GPS pivot satellite can be estimable jointly with the differential phase DISB term from epoch to epoch. Then the inter-system differencing model can benefit from the near time-constant DISB parameters and thus has better multi-epoch positioning performance than the classical intra-system differencing model. The combined GPS and BDS single-frequency RTK positioning performance is evaluated with various simulated satellite visibilities. It will be shown that compared with the classical intra-system differencing model, the proposed model can effectively improve the positioning accuracy and reliability, especially for severely obstructed situations with only a few satellites observed. 相似文献
8.
Results are presented for Michibiki, the first satellite of Japan’s Quasi-Zenith Satellite System. Measurements for the analysis
have been collected with five GNSS tracking stations in the service area of QZSS, which track five of the six signals transmitted
by the satellite. The analysis discusses the carrier-to-noise density ratio as measured by the receiver for the different
signals. Pseudorange noise and multipath are evaluated with dual-frequency and triple-frequency combinations. QZSS uses two
separate antennas for signal transmission, which allows the determination of the yaw orientation of the spacecraft. Yaw angle
estimation results for an attitude mode switch from yaw-steering to orbit-normal orientation are presented. Estimates of differential
code biases between QZSS and GPS observations are shown in the analysis of the orbit determination results for Michibiki.
The estimated orbits are compared with the broadcast ephemerides, and their accuracy is assessed with overlap comparisons. 相似文献
9.
GPS三频非差观测数据周跳的自动探测与改正研究 总被引：5，自引：2，他引：3
在GPS三频非差观测数据的处理中,由于伪距噪声的影响,利用原始的伪距和载波相位观测数据估计的模糊度误差比较大,不能用于探测和改正周跳。对原始观测数据进行平滑或适当的组合处理,可降低观测噪声的影响。因此,本文选择合适的经过平滑或组合处理后的观测数据作为探测周跳的检验量,探测并改正单个频点上的周跳。在分析了一般周跳的特点并在研究双频周跳自动探测与改正方法基础上,提出了选取检验量的四条基本原则。最后,依此原则选取了三个观测值组合作为周跳检验量,利用该组检验量实现三频非差观测数据周跳的自动探测与改正。 相似文献
10.
11.
当GPS、GALILEO卫星运行至与太阳、地球近似共线时,卫星很难维持名义姿态,将出现一段时间的偏航姿态异常。本文基于不同分析中心所提供的精密轨道和钟差产品,在卫星偏航姿态异常时期,设计不同姿态改正策略,选取全球分布的7个MGEX站10 d实测数据,分析了GPS、GALILEO卫星的天线相位中心改正、相位缠绕改正对观测值残差及动态PPP定位结果的影响。研究表明,在卫星偏航姿态异常时期,采用名义偏航姿态对GPS、GALILEO卫星观测值残差的影响可分别达到8和11 cm,在此期间,GPS/GALILEO卫星采用模型偏航姿态,与采用名义偏航姿态相比,动态PPP的E、N、U 3个方向的定位精度可分别提高13.30%、15.77%和12.98%,相较于剔除卫星策略,采用模型偏航姿态的动态PPP定位精度在E、N、U方向可分别提高5.399%、4.430%、5.992%。 相似文献
12.
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
13.
GPS伪距观测量由于不存在周跳和整周模糊度的问题,可用来实现动态导航定位,但受到多路径效应影响较为严重,定位精度较低。本文以BJFS站为例,计算了伪距多路径效应,首次大量采用单历元数据,以球谐函数的形式建立了伪距多路径效应、高度角和方位角间的函数模型。建模过程中用截断奇异值分解方法解决了单历元数据引起的的病态问题,求得了模型的最小二乘解。在伪距观测数据中加入模型计算的伪距多路径效应改正,用Bernese软件的动态单点定位功能进行伪距单点定位。对BJFS站的伪距动态定位结果进行统计分析,结果表明单点定位精度得到了改善。 相似文献
14.
GPS天线相位中心变化及测试 总被引：4，自引：1，他引：3
对GPS天线相位中心随卫星变化的情况及减小和消除天线相位中心误差的方法进行了阐述 ,并详细介绍了对两种型号GPS天线相位中心变化进行比较和测试的结果 相似文献
15.
Precise orbit determination of the Sentinel-3A altimetry satellite using ambiguity-fixed GPS carrier phase observations 总被引：1，自引：0，他引：1
The Sentinel-3 mission takes routine measurements of sea surface heights and depends crucially on accurate and precise knowledge of the spacecraft. Orbit determination with a targeted uncertainty of less than 2 cm in radial direction is supported through an onboard Global Positioning System (GPS) receiver, a Doppler Orbitography and Radiopositioning Integrated by Satellite instrument, and a complementary laser retroreflector for satellite laser ranging. Within this study, the potential of ambiguity fixing for GPS-only precise orbit determination (POD) of the Sentinel-3 spacecraft is assessed. A refined strategy for carrier phase generation out of low-level measurements is employed to cope with half-cycle ambiguities in the tracking of the Sentinel-3 GPS receiver that have so far inhibited ambiguity-fixed POD solutions. Rather than explicitly fixing double-difference phase ambiguities with respect to a network of terrestrial reference stations, a single-receiver ambiguity resolution concept is employed that builds on dedicated GPS orbit, clock, and wide-lane bias products provided by the CNES/CLS (Centre National d’Études Spatiales/Collecte Localisation Satellites) analysis center of the International GNSS Service. Compared to float ambiguity solutions, a notably improved precision can be inferred from laser ranging residuals. These decrease from roughly 9 mm down to 5 mm standard deviation for high-grade stations on average over low and high elevations. Furthermore, the ambiguity-fixed orbits offer a substantially improved cross-track accuracy and help to identify lateral offsets in the GPS antenna or center-of-mass (CoM) location. With respect to altimetry, the improved orbit precision also benefits the global consistency of sea surface measurements. However, modeling of the absolute height continues to rely on proper dynamical models for the spacecraft motion as well as ground calibrations for the relative position of the altimeter reference point and the CoM. 相似文献
16.
Cycle slip detection and repair for undifferenced GPS observations under high ionospheric activity 总被引：3，自引：3，他引：0
We develop a new approach for cycle slip detection and repair under high ionospheric activity using undifferenced dual-frequency GPS carrier phase observations. A forward and backward moving window averaging (FBMWA) algorithm and a second-order, time-difference phase ionospheric residual (STPIR) algorithm are integrated to jointly detect and repair cycle slips. The FBMWA algorithm is proposed to detect cycle slips from the widelane ambiguity of Melbourne–Wübbena linear combination observable. The FBMWA algorithm has the advantage of reducing the noise level of widelane ambiguities, even if the GPS data are observed under rapid ionospheric variations. Thus, the detection of slips of one cycle becomes possible. The STPIR algorithm can better remove the trend component of ionospheric variations compared to the normally used first-order, time-difference phase ionospheric residual method. The combination of STPIR and FBMWA algorithms can uniquely determine the cycle slips at both GPS L 1 and L 2 frequencies. The proposed approach has been tested using data collected under different levels of ionospheric activities with simulated cycle slips. The results indicate that this approach is effective even under active ionospheric conditions. 相似文献
17.
论文介绍了GPS/GLONASS组合静态相位相对定位模型,将GLONASS双差观测方程的模糊度参数表示成参考卫星的单差模糊度和双差模糊度参数;用误差分析法证明了单差模糊度按实参数估计不影响基线解算精度,而GLONASS双差模糊度必须按整参数进行解算;用Helmert方差分量估计确定GPS和GLONASS观测值的合理权比。实际观测数据处理结果表明：GPS/GLONASS组合定位较单一系统解算的基线精度均有提高,尤其比GLONASS单系统的解算精度有显著提高,比GPS单系统的精度也有适当提高,其中单历元基线解算精度约提高了10%,当单一系统的可用卫星数少于4颗时,GPS/GLONASS组合定位更具有应用价值。 相似文献
18.
导航卫星自主定轨的算法研究及模拟结果 总被引：5，自引：2，他引：5
讨论了利用卫星-卫星间的距离观测值建立导航卫星系统自主定轨的数学方法，并用GPS星座模拟星间观测值，采用滤波算法计算卫星的状态参数。模拟结果表明，在空间测距精度一定的情况下，自主定轨精度能高于GPS广播星历，因而能较精确地维持卫星系统的坐标框架。 相似文献
19.
The global positioning system (GPS) model is distinctive in the way that the unknown parameters are not only real-valued,
the baseline coordinates, but also integers, the phase ambiguities. The GPS model therefore leads to a mixed integer–real-valued
estimation problem. Common solutions are the float solution, which ignores the ambiguities being integers, or the fixed solution,
where the ambiguities are estimated as integers and then are fixed. Confidence regions, so-called HPD (highest posterior density)
regions, for the GPS baselines are derived by Bayesian statistics. They take care of the integer character of the phase ambiguities
but still consider them as unknown parameters. Estimating these confidence regions leads to a numerical integration problem
which is solved by Monte Carlo methods. This is computationally expensive so that approximations of the confidence regions
are also developed. In an example it is shown that for a high confidence level the confidence region consists of more than
one region.
Received: 1 February 2001 / Accepted: 18 July 2001 相似文献
20.
This paper presents a new strategy for GPS carrier phase data processing. The classic approach generally consists of three steps: a float solution, a search for integer ambiguities, and a fixed solution. The new approach is based on certain properties of ambiguity function method and ensures the condition of integer ambiguities without the necessity of the additional step of the integer search. The ambiguities are not computed explicitly, although the condition of “integerness” of the ambiguities is ensured in the results through the least squares adjustment with condition equations in the functional model. An appropriate function for the condition equations is proposed and presented. The presented methodology, modified ambiguity function approach, currently uses a cascade adjustment with successive linear combinations of L1 and L2 carrier phase observations to ensure a correct solution. This paper presents the new methodology and compares it to the three-stage classic approach which includes ambiguity search. A numerical example is provided for 25 km baseline surveyed with dual-frequency receivers. All tests were performed using an in-house developed GINPOS software and it has been shown that the positioning results from both approaches are equivalent. It has also been proved that the new approach is robust to adverse effects of cycle slips. In our opinion, the proposed approach may be successfully used for carrier phase GPS data processing in geodetic applications. 相似文献