共查询到18条相似文献,搜索用时 156 毫秒
1.
周跳是影响GPS定位精度的一个重要因素,对周跳的探测与修复一直是个重要问题。首先研究了电离层残差法、宽巷相位减窄巷伪距法两种经典方法的优缺点,提出了一种探测周跳的组合算法。根据周跳的整数特性,利用搜索整数解的思想确定周跳的大小进而修复周跳。经实测数据检验,该算法有效可行,有很强的实用性。 相似文献
2.
3.
高精度位置服务依赖模糊度正确固定的载波相位观测值,而复杂环境的相位周跳和中断给模糊度固定和数据处理带来了巨大挑战。北斗三号系统向全球播发四频和五频信号,为提升周跳处理性能提供了机遇。本文建立了探测多频超宽巷周跳的伪距-相位无几何组合模型,以及探测窄巷周跳的相位-相位无几何组合模型,并以周跳探测成功概率最大为准则确定了多频最优超宽巷和窄巷组合。由于电离层延迟制约了数据中断和电离层变化剧烈情况下的窄巷周跳探测,进而建立了顾及电离层延迟的窄巷周跳探测滤波模型。试验结果表明,对30 s采样间隔,基于无几何组合模型探测周跳的成功率均优于96%;对于3 min的数据中断,基于无几何组合模型的周跳探测成功率仅为70%,但补偿电离层延迟的滤波模型将成功率提升至95%以上。 相似文献
4.
5.
6.
《武汉大学学报(信息科学版)》2016,(3)
针对低高度角双频非差数据测量噪声大、周跳探测容易出现误判和漏判的情况,本文基于电离层残差组合和MW组合进行了周跳探测算法的改进。在电离层残差法的周跳探测中,引入了时间窗口方法,利用周跳检测量的误差分布合理确定判定阈值的大小;在宽巷周跳的探测中,对MW组合方法中的判定条件进行了改进,采用加权递推平滑和时间窗口相结合的方法进行宽巷模糊度的精确估计和精度评价。经IGS站观测数据验证,改进算法取得了较好的周跳探测效果。 相似文献
7.
8.
9.
10.
BDS三频观测条件下可以组合得到具有优良特性的虚拟载波观测量,有利于改善非差观测数据的周跳实时探测与修复。文中提出一种基于BDS三频非差数据的周跳实时探测与修复模型:首先,采用消电离层无几何HMW组合观测量探测和修复EWL周跳;然后,将经过修复的EWL观测量与WL组合消除几何相关项,忽略电离层延迟残差进而确定WL周跳;最后采用经过修复的WL观测量与NL组合形成无几何观测量,并通过优化载波相位组合确定电离层延迟的变化量以探测和计算NL周跳,并通过简单变换得到原始载波观测量的周跳值。通过实测BDS三频数据对模型可行性进行验证分析,结果表明,即使在30s的采样率以及电离层活动活跃条件下,该模型都可有效实时探测和修复各类周跳。 相似文献
11.
In order to incorporate the time smoothness of ionospheric delay to aid the cycle slip detection, an adaptive Kalman filter is developed based on variance component estimation. The correlations between measurements at neighboring epochs are fully considered in developing a filtering algorithm for colored measurement noise. Within this filtering framework, epoch-differenced ionospheric delays are predicted. Using this prediction, the potential cycle slips are repaired for triple-frequency signals of global navigation satellite systems. Cycle slips are repaired in a stepwise manner; i.e., for two extra wide lane combinations firstly and then for the third frequency. In the estimation for the third frequency, a stochastic model is followed in which the correlations between the ionospheric delay prediction errors and the errors in the epoch-differenced phase measurements are considered. The implementing details of the proposed method are tabulated. A real BeiDou Navigation Satellite System data set is used to check the performance of the proposed method. Most cycle slips, no matter trivial or nontrivial, can be estimated in float values with satisfactorily high accuracy and their integer values can hence be correctly obtained by simple rounding. To be more specific, all manually introduced nontrivial cycle slips are correctly repaired. 相似文献
12.
Dezhong Chen Shirong Ye Wei Zhou Yanyan Liu Peng Jiang Weiming Tang Bing Yuan Lewen Zhao 《GPS Solutions》2016,20(3):439-450
The difficulty to detect and repair cycle slip of carrier phase measurements is a key limit for continuously high accuracy of GNSS positioning and navigation services. We propose an automated cycle slip detection and repair method for data preprocessing of a CORS network. The method jointly uses double-differenced (DD) geometry-free (GF) combination and ionospheric-free observation corrected for the computed geometrical distance (IF-OMC) to estimate the cycle slips in dual-frequency observations. The DD GF combination, which is only affected by the ionospheric residual, can be used to detect cycle slips with high reliability except for special pairs such as (77, 60) on GPS L1/L2 frequencies. The detection principle of the IF-OMC observable is such that there is a large discontinuity related to the previous epoch when cycle slips occur at the present epoch. The disadvantages of these two combinations can be overcome employing the proposed detection method. The cycle slip pair (77, 60) has no effect on the GF combination, while a change of 14.65 m is derived from GPS L1/L2 observations using the IF-OMC algorithm. Using pre-determined station coordinates as precise values, we found that the accuracy of the DD IF-OMC combination was 18 mm for a 200-km CORS baseline. Therefore, cycle slips in dual-frequency observations can be correctly and uniquely determined using DD GF and IF-OMC equations. The proposed method was verified by adding simulated cycle slips in observations collected from the CORS network under a quiet ionosphere and shown to be effective. Moreover, the method was assessed with observations made during intense ionospheric activity, which generated extensive cycle slips. The results show that the algorithm can detect and repair all cycle slips apart from two exceptions relating to long data gaps. 相似文献
13.
14.
A new automated cycle slip detection and repair method for a single dual-frequency GPS receiver 总被引:12,自引:2,他引:10
Zhizhao Liu 《Journal of Geodesy》2011,85(3):171-183
This paper develops a new automated cycle slip detection and repair method that is based on only one single dual-frequency
GPS receiver. This method jointly uses the ionospheric total electron contents (TEC) rate (TECR) and Melbourne–Wübbena wide
lane (MWWL) linear combination to uniquely determine the cycle slip on both L1 and L2 frequencies. The cycle slips are inferred
from the information of ionospheric physical TECR and MWWL ambiguity at the current epoch and that at the previous epoch.
The principle of this method is that when there are cycle slips, the MWWL ambiguity will change and the ionospheric TECR will
usually be significantly amplified, the part of artificial TECR (caused by cycle slips) being significantly larger than the
normal physical TECR. The TECR is calculated based on the dual-frequency carrier phase measurements, and it is highly accurate.
We calculate the ionospheric change information (including TECR and TEC acceleration) using the previous epochs (30 epochs
in this study) and use the previous data to predict the TECR for the epoch needing cycle slip detection. If the discrepancy
is larger than our defined threshold 0.15 TECU/s, cycle slips are regarded to exist at that epoch. The key rational of method
is that during a short period (1.0 s in this study) the TECR of physical ionospheric phenomenon will not exceed the threshold.
This new algorithm is tested with eight different datasets (including one spaceborne GPS dataset), and the results show that
the method can detect and correctly repair almost any cycle slips even under very high level of ionospheric activities (with
an average Kp index 7.6 on 31 March 2001). The only exception of a few detected but incorrectly repaired cycle slip is due
to a sudden increased pseudorange error on a single satellite (PRN7) under very active ionosphere on 31 March 2001. This method
requires dual-frequency carrier phase and pseudorange data from only one single GPS receiver. The other requirement is that
the GPS data rate ideally is 1 Hz or higher in order to detect small cycle slips. It is suitable for many applications where
one single receiver is used, e.g. real-time kinematic rover station and precise point positioning. An important feature of
this method is that it performs cycle slip detection and repair on a satellite-by-satellite basis; thus, the cycle slip detection
and repair for each satellite are completely independent and not affected by the data of other satellites. 相似文献
15.
长基线条件下,测站间空间相关性弱,电离层、对流层延迟经过双差并不能很好地消除,致使CIR方法在长基线条件下解算模糊度成功率较低。本文通过BDS三频组合选择长波长、弱电离层组合改进宽巷组合系数,选取(-1,-5,6)代替传统的宽巷组合(0,-1,1),选择弱电离层几何相位组合(4,-5,2)代替传统的窄巷组合(0,0,1),并通过将多频点的伪距观测值和确定了模糊度的宽巷相位观测值线性组合消除电离层延迟一阶项。通过实测数据分析,本文提出的算法能够有效解算超宽巷、宽巷模糊度,提高模糊度解算成功率。 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.
针对载波相位观测值中出现周跳的问题,将TurboEdit算法中的LG组合进行二次历元间差分(STPIR),差分结果可以很好地消除电离层延迟的趋势项影响,而且差分后的组合观测值不受观测数据采样间隔的影响,从而有利于周跳的探测。同时,利用MW组合与STPIR组合实现了周跳的探测与修复。对静态和动态观测数据进行处理的结果表明,将MW与STPIR组合可以更准确地探测与修复周跳。 相似文献
18.
在利用W-M宽巷组合进行周跳初步探测的基础上,加入了新方法进行二次周跳探测。该方法通过利用来自同颗GPS卫星的无电离层影响L3组合相位观测值在相邻历元间的变化量与dm级精度的先验轨道坐标,计算得出星载GPS接收机历元间的钟差变化值。对于存在周跳的载波相位观测值,其计算结果会与同历元其他无周跳观测值解算的钟差变化量存在较大差异。实验结果表明,二次探测可以发现新的周跳并对初步探测结果进行检核。 相似文献