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1.
Sidereal filtering based on single differences for mitigating GPS multipath effects on short baselines 总被引：5，自引：2，他引：3
Ping Zhong Xiaoli Ding Linguo Yuan Youlin Xu Kenny Kwok Yongqi Chen 《Journal of Geodesy》2010,84(2):145-158
Carrier-phase multipath effects are one of the most significant error sources in precise Global Positioning System (GPS) positioning
applications. A new sidereal filtering algorithm based on single differences is developed to mitigate multipath effects for
short-baseline high-rate GPS applications such as structural deformation monitoring. This method differs from traditional
sidereal filtering in that our method operates on the single differences rather than the coordinates or double differences.
A multipath model for the single differences on the reference day is established for each satellite and is used to remove
multipath errors from observations of subsequent days by taking advantage of the sidereal repeatability of multipath signals.
Using both simulated and real GPS observations, we demonstrate that this method is insensitive to different weighting strategies
used in computing single differences from double differences. Applying the proposed method can reduce the root mean square
(RMS) of positioning noises by 82% on average. Compared to sidereal filtering (in either coordinate or double differences
domain) and aspect repeat time adjustment, this method can further reduce the RMS values by 13 and 7%, respectively. Wavelet
spectra have shown that the proposed method is more effective in mitigating multipath errors of both long and short periods.
This method is also more advantageous in that it is applicable when different GPS satellites are observed on different days. 相似文献
2.
信号衍射和多路径效应是限制GPS定位精度进一步提高的瓶颈,观测中两者往往同时存在。衍射效应具有不完全重复的特性,为了研究多路径重复性并使其不受信号衍射的影响,本文提出先应用SIGMA-Δ信噪比加权模型削弱信号衍射的影响,再运用改进恒星时滤波法分析多路径重复性。实验观测资料分析表明,SIGMA-Δ模型能有效削弱衍射信号对定位结果影响,并且保留主要的多路径信号;而改进恒星时滤波法能适应测站周围多路径环境的变化,从而最大限度地削减多路径误差。两者组合比传统的恒星时滤波更能有效提高GPS的动态定位精度。 相似文献
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Multipath disturbance is one of the most important error sources in high-accuracy global positioning system (GPS) positioning and navigation. A new data filtering method, based on the Vondrak filter and the technique of cross-validation, is developed for separating signals from noise in data series, and applied to mitigate GPS multipath effects in applications such as deformation monitoring. Both simulated data series and real GPS observations are used to test the proposed method. It is shown that the method can be used to successfully separate signals from noise at different noise levels, and for varying signal frequencies as long as the noise level is lower than the magnitude of the signals. A multipath model can be derived, based on the current-day GPS observations, with the proposed method and used to remove multipath errors in subsequent days of GPS observations when taking advantage of the sidereal day-to-day repeating characteristics of GPS multipath signals. Tests have shown that the reduction in the root mean square (RMS) values of the GPS errors ranges from 20% to 40% when the method is applied. 相似文献
4.
一种基于交叉证认技术的自适应小波变换及其在削减GPS多路径误差中的应用 总被引：2，自引：1，他引：1
多路径效应影响是目前限制GPS定位精度进一步提高的瓶颈。提出用交叉证认技术自动识别小波分解的信号层,再通过小波重构实现降噪和信号提取,并将该方法应用于GPS多路径误差的削减中。对模拟数据和实际GPS观测资料的分析表明,该方法能合理分离不同噪声水平下资料序列中的信号和噪声;当噪声水平小于信号振幅的一半时,能成功分离资料序列中的高频信号。同时,运用该方法得到的多路径改正模型和GPS多路径效应的重复性,可有效地削弱多路径效应的影响,提高GPS定位精度。 相似文献
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Adaptive wavelet transform based on cross-validation method and its application to GPS multipath mitigation 总被引：3，自引：2，他引：1
Global positioning system (GPS) multipath disturbance is a bottleneck problem that limits the accuracy of precise GPS positioning
applications. A method based on the technique of cross-validation for automatically identifying wavelet signal layers is developed
and used for separating noise from signals in data series, and applied to mitigate GPS multipath effects. Experiments with
both simulated data series and real GPS observations show that the method is a powerful signal decomposer, which can successfully
separate noise from signals as long as the noise level is lower than about half of the magnitude of the signals. A multipath
correction model is derived based on the proposed method and the sidereal day-to-day repeating property of GPS multipath signals
to remove multipath effects on GPS observations and to improve the quality of the GPS measurements. 相似文献
6.
GPS动态监测中多路径效应的规律性研究 总被引：14，自引：1，他引：14
在分析GPS多路径效应特性的基础上,结合GPS动态变形监测的特点,对连续多天的观测数据解算结果采用滤波与周日位置求差相结合的方法进行数据处理。研究结果表明,多路径误差具有较强的周日重复性,在有效地削弱多路径效应的影响后,GPS动态监测的三维位置精度可以达到mm级,尤其是垂直方向的精度改善明显。 相似文献
7.
HUANG Shengxiang JIN Xiangsheng YANG Baocen 《地球空间信息科学学报》2006,9(2):79-83
IntroductionThere are many factors that affect the precisionand reliability of GPS measuring. Generally, theerror sources can be grouped into the followingthree classes: errors correlated with the satellites(such as ephemeris error, satellite clock error,… 相似文献
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9.
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
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对GPS载波相位测量误差进行了理论分析和试验研究。根据噪声特征以及它们对载波相位测量结果的影响，提出了基于自适应噪声抵消与小波滤波相结合的GPS噪声抑止方法。对具有强相关特性的多路径误差采用自适应噪声抵消方法，而对于不相关的高频噪声则通过合理选择小波分解层数对信号进行分解，对作用闽值后的小波系数进行重构，得到最后的变形信号。实测数据分析表明，该方法能有效地削弱多路径效应及测量随机噪声，较用单一方法对GPS数据进行消噪处理有较大的优越性。 相似文献
11.
变形监测中GPS信号衍射误差的环境建模法 总被引：1，自引：0，他引：1
信号衍射是GPS结构变形监测的重要误差源之一.GPS天线周围的建筑物是常见的信号衍射体.针对在变形监测中观测环境相对固定之特点,提出一种基于环境模型的衍射误差建模算法.若干试验表明所提方法能有效检测并削弱衍射误差对变形监测结果的影响. 相似文献
12.
A new multipath mitigation method based on adaptive thresholding wavelet denoising and double reference shift strategy 总被引：1，自引：0，他引：1
Multipath disturbance is one of the major error sources in high-accuracy positioning for global navigation satellite system (GNSS). Although various methods based on software and hardware strategies have been developed to mitigate this error, they are still limited by different kinds of factors and the effect is not ideal. After analyzing the existing methods, a new single-difference sidereal filtering method, based on adaptive thresholding wavelet denoising and double reference shift strategy (ATDR), is proposed to mitigate multipath effects for static short-baseline GNSS applications. The key idea of the proposed method is the use of both the adaptive thresholding wavelet denoising to extract an accurate multipath correction model from the reference Day and the double reference shift strategy to mitigate multipath for subsequent Day 2 more accurately and efficiently. By applying the introduced adaptive thresholding method, the average improvement rate of the RMS values of the single-difference residuals can reach about 15.82% compared with the constant thresholding method. Moreover, after applying the proposed ATDR method, the 3D positioning precision is improved by about 37.73% for the single epoch mode with 30 s data sampling rate and about 31.22% for the continuous mode with 1 s high sampling rate compared with the original results. Even compared with the constant thresholding single orbital reference (CTSR) method, the improvement percentage is about 33.94% in single epoch mode and about 25.40% in continuous mode for 3D positioning precision, respectively. In conclusion, the results of the two experiments indicate that the proposed ATDR method performs much better than the CTSR method in mitigating multipath for different sampling rates and different processing modes in the measurement domain for GNSS static short-baseline postprocessing applications. 相似文献
13.
GPS变形监测系统中的监测点的观测资料是与时间有关的信号序列,本文研究应用小波分析优化流程,结合苏通大桥GPS变形监测系统获取的监测点数据序列进行分析。结果表明,选择合适的小波基函数,对数据信号进行小波分解与重构,可以有效地从受到强噪声干扰的监测数据序列中提取有用的特征信号,较好解决了传统处理技术对GPS动态观测数据去噪以及特征信息提取的局限性。 相似文献
14.
在利用北斗卫星导航系统（BDS）进行高精度变形监测时,BDS信号产生的多路径效应是影响变形监测数据精度和可靠性的一个不可忽视的误差源. BDS有三种不同的轨道卫星,所形成的多路径误差较为复杂. 基于坐标域的多路径误差使用小波分析(Wavelet)和经验模态分解(EMD)进行原始序列降噪,对降噪后序列使用改进恒星日滤波(ASF)进行多路径误差剔除,两种方法分别对基线精度的E方向改善了38.6％和40.8％,N方向改善了59.1％和61.0％,U方向改善了57.8％和57.9％,EMD对坐标序列的平滑和基线精度改善较优. 相似文献
15.
利用交叉证认的方法,提出一种新的基于EMD滤波去噪方法,并将其应用于GPS多路径效应的研究中。通过模拟实验及实测数据分析表明,该方法能够自适应地选择IMF中的信号层数,削弱随机噪声,合理地分离信号和噪声。利用该滤波方法去噪并建立具有重复性的多路径误差效应改正模型,可有效地削弱多路径效应的影响,进而提高GPS动态变形监测的精度。 相似文献
16.
A new method to mitigate multipath error in single-frequency GPS receiver with wavelet transform 总被引：2，自引：1，他引：1
One of the major errors in high-precision GPS positioning is multipath. Multipath effect modeling and reduction have been a challenging issue in high-accuracy GPS positioning applications due to its special properties. Different methods have been employed to mitigate this error including hardware and software approaches. We reduce C/A code multipath error by adopting an efficient software method which uses wavelet transform as a basic data processing trend. The key idea of the proposed method is using stationary wavelet transform (SWT) in GPS signal data processing. Since we have used SWT, there is complete access to high-frequency and low-frequency terms in both time and frequency domains, and we can apply appropriated procedures to mitigate this error. The multipath error mostly is a low-frequency term. In our proposed method, the double difference (DD) residuals are applied to the SWT to identify the multipath disturbance. The extracted multipath is then used to correct DD observations. Our experiments include three data sets to investigate the proposed method and compare it with existing algorithms. We used simulations for two of these data sets. The results indicate the efficiency of the proposed method over existing algorithms. 相似文献
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Though state-of-the-art dual-frequency receivers are employed in the continuous Global Positioning System (CGPS) arrays, the
CGPS coordinate time series are typically very noisy due to the effects of atmospheric biases, multipath, receiver noise,
and so on, with multipath generally being considered the major noise contributor. An adaptive finite-duration impulse response
filter, based on a least-mean-square algorithm, has been developed to derive a relatively noise-free time series from the
CGPS results. Furthermore, this algorithm is suitable for real-time applications.
Numerical simulation studies indicate that the adaptive filters is a powerful signal decomposer, which can significantly mitigate
multipath effects. By applying the filter to both pseudorange and carrier phase multipath sequences derived from some experimental
GPS data, multipath models have been reliably derived. It is found that the best multipath mitigation strategy is forward
filtering using data on two adjacent days, which reduces the standard deviations of the pseudorange multipath time series
to about one fourth its magnitude before correction and to about half in the case of carrier phase. The filter has been successfully
applied to the pseudorange multipath sequences derived from CGPS data. The benefit of this techniques is that the affected
observable sequences can be corrected, and then these corrected observables can be used to improve the quality of the GPS
coordinate results. ? 2000 John Wiley & Sons, Inc. 相似文献