共查询到18条相似文献，搜索用时 140 毫秒
1.
利用MP提高GPS单点定位精度的研究 总被引：1，自引：0，他引：1
多路径误差是GPS定位重要的误差源之一,本文利用MP(多径组合观测值)对观测值受到的多路径效应进行定量评价,在GPS伪距单点定位中降低受多路径效应影响的观测值的权重,达到削减多路径误差提高定位精度的目的,最后通过试验验证了此方法的有效性和可靠性。 相似文献
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本文主要从GPS的基本观测方程出发,通过数学分析的方法,在GPS观测值之间建立数学模型,进一步推导了伪距观测值和相位观测值中多路径效应的影响.此外,主要研究了利用相位平滑伪距削弱伪距多路径误差的方法,以及利用小波分析的方法对GPS多路径值序列进行分解和重构,提取出高精度的多路径误差,并通过实验数据分析了几种方法中的多路径效应. 相似文献
3.
主要从GPS的基本观测方程出发,通过数学分析的方法,在GPS观测值之间建立数学模型,进一步分别推导了伪距观测值和相位观测值中多路径效应的影响。此外,主要研究了利用相位平滑伪距削弱伪距多路径误差的方法和利用小波分析的方法对GPS多路径值序列进行分解和重构,提取出高精度的多路径误差,并通过实验数据分析了几种方法中的多路径效应影响。 相似文献
4.
卫星伪距偏差对卫星精密定位的实现及其应用会产生较大的影响,为了探究BDS-3卫星伪距观测值是否存在伪距偏差,正确评价BDS-2和BDS-3各频率信号伪距观测值多路径误差,推导了可以度量多路径及噪声的无几何和无电离层的多路径组合(MP)观测量,并利用全球均匀分布的43个MGEX测站的观测数据,计算分析了多路径误差与卫星高度角的关系,对比分析了BDS-2和BDS-3不同频率信号伪距多路径的特性,统计了多路径误差的均方根,结果表明BDS-3伪距多路径误差明显小于BDS-2,验证了BDS-3卫星伪距观测值中不存在与卫星相关的伪距偏差。 相似文献
5.
北斗星座包含3类卫星,即GEO、IGSO和MEO,GEO卫星高度角变化微小,伪距多路径观测序列系统偏差较明显;IGSO、MEO卫星随多路径序列系统偏差随卫星高度角变化,多路径误差对单个接收机定位结果影响较大.本文针对GEO卫星伪距观测值偏差问题提出了一种基于卡尔曼滤波的修正方法,利用3 d的多路径效应误差观测序列进行拟合后,利用拟合值修正,修正后的GEO卫星多路径观测序列标准差下降了31％. 相似文献
6.
本项研究在双频消除电离层技术的基础上,根据北斗的三频特性,消除观测值中的几何观测量,得到消电离层消几何观测量的组合值,并且对同一地区两个测站同步观测数据的组合值站间单差处理,在伪距观测和载波观测两个方面,分析各类卫星观测值的噪声和多路径误差的相关特征,预估和评定北斗系统的观测质量。结果表明:地球静止轨道卫星观测值主要影响为多路径误差,非地球静止轨道卫星观测值主要影响为观测噪声。 相似文献
7.
在全球导航卫星系统(Global Navigation Satellite System,GNSS)接收机附近的反射、衍射、干扰信号等所造成的多路径效应是影响定位的主要误差来源。信噪比(Signal-Noise Ratio,SNR)的振荡是由多路径信号叠加在直接信号上引起的,基于此原理学者们提出了很多检测和缓解多路径误差的方法。本文通过谱分析的方法对多路径时间序列进行了分析,并研究多路径与信噪比之间的相关性,对基于信噪比检测和缓解多路径误差的方法的适用性进行了说明。实验表明:多路径和信噪比振荡值的时间序列具有显著的相关性,能够利用信噪比观测值削弱多路径影响。 相似文献
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时荣 《测绘与空间地理信息》2015,(8):175-177
多路径误差分析是北斗卫星导航系统性能评估的一项重要内容。本文给出了一种新的计算3频多路径误差的方法,该方法只需对B1和B2载波相位观测值进行处理就能得到3个频率的伪距多路径误差。利用MGEX跟踪站的数据计算了BDS的多路径误差,从GPS和BDS多路径误差比较以及纬度、轨道和频率因素分析了BDS多路径误差的特性,结果表明,BDS多路径误差小于0．5 m,符合质量检查要求,其性能优于GPS卫星系统。 相似文献
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本文基于扩频信号分析了不同多径参数对载波幅度和相位的影响,在低信噪比条件下,使用自适应均衡技术,实时估计多径参数和抑制载波多径。使用实时估计得到的多径参数,重构多径信号,从接受信号中消去多径信号。仿真结果表明,这2种算法均能很好地降低多径对载波的影响,可以有效提高载波相位的测量精度。 相似文献
12.
基于IGS的L2C信号跟踪站数据验证了具有L2C码的卫星的L2载波的信噪比高于没有L2C码的卫星的L2载波的信噪比,L2载波恢复的数据质量更好.针对不同的接收机,对比分析了C/A码和L2C码多路径效应及观测噪声水平,发现对TRIMBLE NETRS接收机,L2C码误差水平明显高于C/A码,与期望结果相反. 相似文献
13.
A new technique for detecting GNSS multipath interference by comparing signal-to-noise (SNR) measurements on three frequencies is presented. Depending on the phase lag of the reflected signal with respect to the direct signal, multipath interference can be either constructive or destructive, with a commensurate effect on the measured SNR. However, as the phase lag is frequency dependent, the SNR is perturbed differently on each frequency. Thus, by differencing SNR measurements on different frequencies and comparing the result with that obtained in a low-multipath environment, multipath can be detected. Using three frequencies makes the process more robust. A three-frequency SNR-based multipath detector has been developed and calibrated using measurements from GPS Block IIF satellites in a low-multipath environment. The new detector has been tested in a range of urban environments and its multipath detection capability verified by showing that the MP observables oscillate when the new detection statistic is above a threshold value determined using data collected in a low-multipath environment. The new detector is also sensitive to diffraction. 相似文献
14.
Multipath on carrier phase measurements is among the major error sources for short baseline positioning. A new method is proposed
to improve the accuracy of the positioning results by mitigating the multipath effects on carrier phase measurements using
the variable length Least Mean Square (VLLMS) adaptive filter. The performance of the filter is analyzed as well as compared
with that of the standard LMS adaptive filter using a set of carrier phase observation data of two consecutive days collected
in a short baseline experiment. Because the two antennas are static, the multipath error is the only dominant component in
the carrier phase double-differenced residuals and indicates a repeated pattern. The numerical results show that both filters
can significantly mitigate the multipath effects in carrier phase double-differenced residuals, and hence improve the positioning
results. Furthermore, the VLLMS filter that reduces up to about 47.4% of the multipath effects on 3D positioning performs
better than the LMS filter that only reduces 22.0%. Both filters are suitable for real-time applications. 相似文献
15.
Wavelet packets based denoising method for measurement domain repeat-time multipath filtering in GPS static high-precision positioning 总被引：1，自引：1，他引：0
Lawrence Lau 《GPS Solutions》2017,21(2):461-474
Repeatable satellite orbits can be used for multipath mitigation in GPS-based deformation monitoring and other high-precision GPS applications that involve continuous observation with static antennas. Multipath signals at a static station repeat when the GPS constellation repeats given the same site environment. Repeat-time multipath filtering techniques need noise reduction methods to remove the white noise in carrier phase measurement residuals in order to retrieve the carrier phase multipath corrections for the next day. We propose a generic and robust three-level wavelet packets based denoising method for repeat-time-based carrier phase multipath filtering in relative positioning; the method does not need tuning to work with different data sets. The proposed denoising method is tested rigorously and compared with two other denoising methods. Three rooftop data sets collected at the University of Nottingham Ningbo China and two data sets collected at three Southern California Integrated GPS Network high-rate stations are used in the performance assessment. Test results of the wavelet packets denoising method are compared with the results of the resistor–capacitor (RC) low-pass filter and the single-level discrete wavelet transform (DWT) denoising method. Multipath mitigation efficiency in carrier phase measurement domain is shown by spectrum analysis of two selected satellites in two data sets. The positioning performance of the repeat-time-based multipath filtering techniques is assessed. The results show that the performance of the three noise reduction techniques is about 1–46 % improvement on positioning accuracy when compared with no multipath filtering. The statistical results show that the wavelet packets based denoising method is always better than the RC filter by 2–4 %, and better than the DWT method by 6–15 %. These results suggest that the proposed wavelet packets based denoising method is better than both the DWT method and the relatively simple RC low-pass filter for noise reduction in multipath filtering. However, the wavelet packets based denoising method is not significantly better than the RC filter. 相似文献
16.
Carrier phase ambiguity resolution on the fly is investigated using two receiver technologies, namely dual-frequency P code and high performance, single frequency, C/A code receivers. Both receiver types were used simultaneously in a series of land kinematic trials. A least-squares search technique is used to find the correct double difference carrier phase ambiguities. Both C/A and single frequency P code technologies are found to be equivalent and capable of resolving the integer ambiguities on the fly using some 30 to 200 seconds of data under benign multipath conditions. Successful ambiguity resolution on the fly results in cm-level accuracy kinematic positioning. The ambiguity resolution time required and success rate are however found to be strongly dependent on the level of carrier phase multipath and, as a consequence, on the error variance assigned to the carrier phase measurements. The use of widelaning with the dual frequency P code results in ambiguity resolution in seconds. The performance of widelaning is also superior in a comparatively high carrier phase multipath environment. 相似文献
17.
Carrier phase multipath is currently one source of unmodeled signals that may bias GPS coordinate time series significantly.
We investigate the effect of simulated carrier phase multipath on time series of several sites covering the period 2002.0–2008.0
and spanning a range of observation geometries. High-, mid-, and low-latitude IGS sites are investigated as well as sites
with significant signal obstructions. We examine the effect of multipath in different sectors of the sky, considering time-constant,
horizontal reflectors at each of 0.1, 0.2, and 1.5 m below the antenna. The differences between a horizontally uniform multipath
source are analyzed, and it is shown that positioning errors are generally larger when unmodeled carrier phase multipath is
azimuthally heterogeneous. Using the adopted multipath model, height biases reach ±1 mm in case of the symmetric multipath
and ±5 mm for the asymmetric multipath but this increases to being ±10 mm in the worst case. In addition to mean bias, low-frequency
variations in the bias also exist, including periodic signals and leading to velocity biases of up to ±0.1 mm/year in the
symmetric case and ±1 mm/year in the asymmetric case over the considered period. In contrast to the generally slowly varying
observation geometry that is typically experienced, we show the effects of an abrupt change in geometry due to receiver/antenna
hardware changes; in the case considered, we see changed pattern of temporal variation in the bias in addition to an instantaneous
offset. 相似文献
18.
Markus Irsigler 《GPS Solutions》2010,14(4):305-317
A well-known effect of multipath propagation is multipath fading that typically causes periodic signal variations. Such signal
variations may become visible in some basic GNSS observables such as the code minus carrier observable, single or double differences
or in C/N
0 time series. The frequency of these variations—also called fading frequency or multipath phase rate—strongly depends on the
multipath environment, i.e. on the actual geometric conditions which can be described by the location of the satellite causing
the multipath signal and the reflector location with respect to the receiving antenna. This paper gives a detailed insight
on the expected multipath phase rates in different multipath environments. Different geometric conditions are analyzed, from
arbitrary reflector positions to the point of dealing with the special case of ground multipath. Fading frequencies are determined
by means of an empirical approach using the characteristics of real satellite passes. The approach results in distributions
of multipath phase rates which are computed for a multitude of possible reflector locations and from which minimum, mean and
maximum multipath phase rates can be derived. 相似文献