双频载波相位求差法在周跳探测与修复中的应用

载波相位测量中小周跳的探测与修复一直是高精度GPS定位研究中的热点领域。分析了L1和L2载波相位观测值的关系,通过相邻历元的相位观测值求差来探测周跳,并结合伪距差分约束条件来确定及修复周跳。结合实例分析,证明该方法可以有效地探测并修复周跳,并通过Matlab编程实现了算法的程序化。     

基于电离层残差法探测与修复周跳的特性分析

周跳的探测与修复一直是GPS精密定位数据处理中的一个十分重要的任务。介绍了电离层残差法探测周跳的原理,并通过伪距差分约束法来确定和修复周跳,通过Matlab编制了相应程序,并结合实例分析了其在不同采样率下探测与修复周跳的效果,且得到了一些有益的结论。     

联合M-W组合和电离层残差组合的周跳探测与修复方法

针对电离层残差法和TyrboEdit方法在周跳探测与修复方面的不足,提出了联合利用M-W组合观测值和电离层残差组合观测值进行周跳处理的方法.通过对高采样机载GPS动态测量数据的计算分析,提出的方法可探测出电离层残差法和TurboEdit方法各自不能探测的周跳,同时联合利用两种组合进行周跳偏差的估计,可以得到精确的周跳估...     

一种基于数据质量分析的改进TurboEdit方法

针对TurboEdit方法中Geometry-Free(GF)组合拟合窗口、Melbourne-Wübbena(MW)组合中误差求取窗口过大造成小周跳探测不敏感的问题,通过对观测数据进行质量分析自适应设置GF组合和MW组合窗口,重新构造周跳检测量进行周跳探测,并利用搜索法解决修复失败历元的周跳修复问题。利用GPS和BDS实测双频数据对改进方法进行验证,实验结果表明本方法能准确探测到1周的小周跳,经搜索后周跳修复成功率提高至100%。     

一种双频数据的周跳探测和修复方法的研究

研究了伪距／载波组合和电离层残差探测和修复周跳。利用伪距／载波组合探测和修复6—8周以上的周跳，对修复后的数据进行电离层残差探测，分离发生周跳历元的电离层残差跳变量，得到8周以内的周跳量并修复，实现了30s以内采样间隔任意整周周跳的探测和修复。实验证明此方法是可行的。     

综合利用双频观测值进行周跳的探测与修复

首先对周跳的产生和常用的探测与修复周跳方法作了简要介绍。其次,详细介绍了综合利用双频P码伪距法和载波相位变化率法来探测和修复周跳的方法。通过数据模拟计算分析,检验方法的正确性并得出结论。     

基于STPIR与EWL组合的北斗三频周跳探测与修复

根据电离层残差法在周跳探测与修复中的应用原理,提出了历元间相位电离层残差二次差分的方法,解决了采样间隔较大时,周跳探测与修复的精度受电离层延迟误差制约的问题,提高了周跳探测的精度;在进行周跳修复时,利用超宽巷组合代替B2和B3组合,解决了无法修复不敏感周跳的问题。结果表明,对于采样间隔较大、历元间电离层状态不稳的观测值,该组合方法有效地探测出不足1周的周跳值,并能够有效地修复任意周跳组合。     

基于双频载波和高次差法的周跳探测与修复

采用载波无几何组合和星间单差无电离层组合的历元间高次差作为周跳检验量,因组合观测值中不包含伪距,其理论噪声与波长相比几乎可以忽略。利用两种组合观测值联合进行周跳探测,可避免各自的探测盲点。将两个载波组合联立进行周跳的求解,由于组合噪声较小,直接取整即可求得周跳的大小。提出的方法在一定程度上克服了传统周跳探测与修复算法中,由于引入伪距带来的探测能力不强、修复精度不高等问题。通过对IGS站观测数据模拟周跳探测与修复情况的统计,新提出算法的周跳探测成功率为99%,周跳修复成功率为94%。     

北斗三频非差观测值实时周跳探测与修复

基于三频观测值组合原理,在周跳探测与修复过程中提出了一种新的组合方法,即利用一组伪距/相位组合,一组无几何组合以及一组系数之和为1的几何组合,通过历元间差分,分步求取周跳估值。实验证明,该方法无不敏感周跳,并能够实时有效探测并修复周跳。     

STPIR和MW组合的北斗三频周跳探测与修复

针对载波相位观测值中出现周跳的问题及北斗卫星导航系统全星座播发三频信号的现状,提出一种三频相位电离层残差二阶历元差分(STPIR)的算法,克服了传统电离层残差法受观测数据采样间隔影响较大的问题,联合MW组合观测量进行周跳探测又可避免各自的探测盲区。两种组合观测量均很好地削弱了电离层延迟项的影响,联立方程组进行周跳求解时,直接取整即可得到周跳值。通过北斗三频实测数据验证,提出的组合方法在观测数据采样间隔较大时,可以准确探测出所有周跳,并有效修复。     

Undifferenced Cycle Slip Estimation of Triple-Frequency BeiDou Signals with Ionosphere Prediction

With the rapid development of BeiDou satellite navigation system (BDS), high-quality service has been provided in the Asia-Pacific region currently, which will be extended to the whole world very soon. BDS is the first Global Navigation Satellite System that all satellites broadcast the triple-frequency signals. The triple-frequency signals in theory can improve the cycle slip detection that is one of the preconditions in precise positioning by making use of carrier phase. This paper discusses the development of a cycle slip detection method for undifferenced BDS triple-frequency observations in kinematic scenario. In this method, two geometry-free extra-wide-lane combinations and one geometry-free narrow-lane (NL) combinations are employed. The key is to mitigate the between-epoch ionospheric biases in the geometry-free NL combinations. We propose to predict the ionospheric biases of current epoch by using those from its consecutive foregoing epochs. The method is tested with extensive experiments in varying observation scenarios. The results show that in case of sampling interval as small as 5 s, the between-epoch ionospheric biases can be ignored and the correct cycle slips can be determined. Meanwhile in case of lower sampling frequency, one needs to compensate the ionospheric biases of current epoch by using the predicted ionospheric biases. The presented method can correctly detect all cycle slips even if they are as small as 1 cycle.     

Ambiguity Recovery Using the Triple-Differenced Carrier Phase Type Approach for Long-Range GPS Kinematic Positioning

Precise, long-range GPS kinematic positioning to centimeter accuracy requires that carrier phase ambiguities be resolved correctly during an initialization period, and subsequently to recover the “lost" ambiguities in the event of a cycle slip. Furthermore, to maximize navigational efficiency, ambiguity resolution and carrier phase-based positioning need to be carried out in real-time. Due to the presence of the ionospheric signal delay, satellite orbit errors, and the tropospheric delay, so-called absolute ambiguity resolution “on-the-fly” for long-range applications becomes very difficult, and largely impossible. However, all of these errors exhibit a high degree of spatial and temporal correlation. In the case of short-range ambiguity resolution, because of the high spatial correlation, their effect can be neglected, but their influence will dramatically increase as the baseline length increases. On the other hand, between discrete trajectory epochs, they will still exhibit a large degree of similarity for short time spans. In this article, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive relative ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have slipped when loss-of-lock occurred). Because of the temporal correlation characteristics of the error sources, the cycle slips can be recovered using the proposed methodology. In order to test the performance of this algorithm an experiment involving the precise positioning of an aircraft, over distances ranging from a few hundred meters up to 700 kilometres, was carried out. The results indicate that the proposed technique can successfully resolve relative ambiguities (or cycle slips) over long distances in an efficient manner that can be implemented in real-time.     

Ambiguity Recovery Using the Triple-Differenced Carrier Phase Type Approach for Long-Range GPS Kinematic Positioning

Precise, long-range GPS kinematic positioning to centimeter accuracy requires that carrier phase ambiguities be resolved correctly during an initialization period, and subsequently to recover the “lost" ambiguities in the event of a cycle slip. Furthermore, to maximize navigational efficiency, ambiguity resolution and carrier phase-based positioning need to be carried out in real-time. Due to the presence of the ionospheric signal delay, satellite orbit errors, and the tropospheric delay, so-called absolute ambiguity resolution “on-the-fly” for long-range applications becomes very difficult, and largely impossible. However, all of these errors exhibit a high degree of spatial and temporal correlation. In the case of short-range ambiguity resolution, because of the high spatial correlation, their effect can be neglected, but their influence will dramatically increase as the baseline length increases. On the other hand, between discrete trajectory epochs, they will still exhibit a large degree of similarity for short time spans. In this article, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive relative ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have slipped when loss-of-lock occurred). Because of the temporal correlation characteristics of the error sources, the cycle slips can be recovered using the proposed methodology. In order to test the performance of this algorithm an experiment involving the precise positioning of an aircraft, over distances ranging from a few hundred meters up to 700 kilometres, was carried out. The results indicate that the proposed technique can successfully resolve relative ambiguities (or cycle slips) over long distances in an efficient manner that can be implemented in real-time.     

Improved Method to Detect and Repair Cycle Slip for GNSS Medium–Long Baseline in Real-Time Marine Surveys

Distance-related errors complicate the resolution of real-time ambiguity in medium–long baseline marine surveys. Therefore, detection and recovery of cycle slips in real time is required to ensure high accuracy of global navigation satellite system positioning and navigation in marine surveys. To resolve this, an improved method was presented, where linear combinations of the triple-differenced (TD) between carriers L₁ and L₂ were formed for a wide lane and free ionosphere. To overcome severe ill-conditioned problems of the normal equation, the Tikhonov regularization method was used. The construction of a regularized matrix by combining a priori information of known coordinates of reference stations, followed by the determination of the corresponding regularized parameter are suggested. A float solution was calculated for the TD ambiguity. The search cycle slip (TD integer ambiguity) was obtained using the least-squares ambiguity decorrelation adjustment (LAMBDA) method. Using our method, cycle slips of several reference station baselines with lengths of a few hundred to one thousand kilometers were detected in real time. The results were consistent with professional software, with a success rate of 100%.     

实时GPS精密卫星钟差估计及实时精密单点定位

研究了GPS实时精密卫星钟差的估计方法,并将实时钟差应用于实时精密单点定位。采用自编软件,依据全球均匀分布的IGS参考站实测数据,基于非差消电离层组合载波和伪距观测量实现了GPS实时精密卫星钟差估计。试验结果表明,自主估计的实时卫星钟差与IGS发布的最终精密钟差具有较好一致性,互差优于0.2ns;用于实时精密单点定位,能够获得静态定位1~2cm、仿动态定位厘米级精度。     

精密单点定位技术在海上工程中的应用

结合海上科研工程实践,对GPS精密单点定位模型及数据处理方法进行研究,并采取陆上静动态定位和海上动态定位试验进行了精密单点定位精度统计和分析。结果表明:在超出常规差分定位基线长度限制的广阔海域,采用精密单点定位技术可实现亚米级实时动态定位,为海上高精度实时动态定位应用提供了技术依据。