长距离网络RTK参考站间双差模糊度快速解算算法

提出了一种长距离网络RTK参考站间双差整周模糊度快速解算方法,该方法利用双频载波相位模糊度间的线性关系确定宽巷模糊度,然后选取双频载波相位的备选模糊度组合,通过计算参考站间对流层误差和轨道误差等非色散误差,对双频载波相位整周模糊度进行搜索。实验结果表明,此方法能够快速、可靠地解算长距离参考站间的双差整周模糊度。     

联合使用载波相位变化率法和电离层残差法探测和修复周跳

作者针对双频接收机定位的特点,提出了一种综合探测周跳的方法。处理对象是双频载波相位数据,采用的方法是综合利用载波相位变化率和电离层残差来探测周跳。文章介绍了两种方法的数学模型,给出了具体实施步骤,最后用算例验证了方法的可靠性和有效性。     

顾及有色噪声影响的位置域双频载波相位平滑伪距算法

载波平滑伪距技术是一种有效的GNSS数据处理技术，在很多高精度实时定位场合得到了广泛的应用。本文在随机模型中考虑载波相位时间差分观测量中有限冲激响应有色观测噪声的影响，推导出采用递归最小二乘方法的距离域和位置域双频载波相位平滑伪距算法，并利用实测数据验证了新算法的有效性。试验表明，相位平滑伪距能够减小伪距观测值的误差，提高伪距观测量的精度，从而提高定位精度；相对于传统的算法，距离域与位置域滤波的伪距平滑精度均有提高，三维定位误差精度均得到改善；同时表明，载波相位时间差分的有色噪声对平滑效果和定位精度有一定的影响。     

GNSS双频整周关系约束模糊度算法研究

根据GNSS双频载波相位观测值间的特定关系,提出了一种基于双频整周关系约束的模糊度解算方法(FirCAR)。该方法在局部整数范围内可将载波相位的等效波长增长,以利于整周模糊度的快速解算。不同长度的基线数据实验证明了该算法的正确性和有效性,并分析了卫星截止高度角对解算结果的影响。     

BDS网络RTK中距离参考站整周模糊度单历元解算方法

提出了一种BDS网络RTK中距离(50~100 km)参考站间的双频载波相位整周模糊度单历元解算方法。该方法首先利用B1、B2载波相位整周模糊度间的线性关系选取B1、B2载波相位整周模糊度备选值。利用双频载波相位整周模糊度备选值计算双差电离层延迟误差,根据参考站各卫星电离层延迟误差间的空间关系,使用双差电离层延迟误差构建双差电离层延迟误差的线性计算模型。通过双差电离层延迟误差线性计算模型的建立搜索和确定B1、B2载波相位的整周模糊度。经CORS网实测数据试验算例的验证,该方法只需一个历元的观测数据即可确定参考站间双差B1、B2载波相位整周模糊度,且不受周跳影响。     

GPS载波相位观测值中周跳探测与修复的研究

针对GPS载波相位定位中出现的周跳问题,提出一种新的周跳探测方法。基于非差相位观测值线性组合模式,以相位与伪距差法和电离层残差法相结合来探测与修复周跳。通过对同一组无周跳的数据采取人为加入周跳,比较两种周跳探测与修复方法的优缺点,以相位与伪距之差组合为辅助,检查大周跳,用电离层残差组合方法再对双频GPS数据进行进一步的周跳探测和修复。根据实例分析,验证该方法能够快速有效地探测并修复周跳,使双频载波相位法更具有实用性。     

一种基于双频GPS接收机的精确快速相对定位方法

利用GPS载波相位测量可以精确确定两个载体间的相对距离，其核心问题是整周模糊度的快速求解，通过双频数据可以提高模糊度求解的速度。在推导模糊度组合的一般公式的基础上，研究了一种基于双频GPS接收机模糊度快速求解算法。实验证明该方法正确有效。     

BDS参考站三频整周模糊度单历元确定方法

参考站载波相位整周模糊度的准确确定是实现BDS网络RTK定位的关键。本文研究了BDS参考站三频载波相位整周模糊度单历元确定方法。首先推导了参考站三频载波相位整周模糊度之间的多个整数线性关系,根据双频载波相位整周模糊度的整数线性关系,以及B1载波相位整周模糊度备选值,确定B1/B2和B1/B3载波相位整周模糊度的备选组合。然后利用不受误差影响的三频载波相位整周模糊度间整数线性关系,对整周模糊度备选值进行约束和确定。根据大气误差的空间相关性,采用以卫星高度角和方位角为依据的基准卫星选择方法,降低了对流层延迟误差残差对多频载波相位整周模糊度之间线性关系约束能力的影响。试验结果表明,本文方法能够实现参考站三频载波相位整周模糊度的单历元准确确定,且计算效率高,算法简单。     

长距离网络RTK基准站间整周模糊度单历元确定方法

提出一种长距离(100～200km)网络RTK基准站间的整周模糊度单历元确定方法。该方法首先利用载波相位模糊度间的线性约束关系对双差宽巷模糊度进行搜索。为了减小非弥散误差残差对载波相位模糊度解算的影响,采用了一种新的根据高度角重新选择基准卫星的方法。然后根据双差宽巷模糊度选取双频载波相位模糊度的备选组合,利用基准站间非弥散误差残差的计算值对双差载波相位模糊度进行搜索和确定。经试验算例的验证,该方法快速、稳定,不受周跳影响,只需一个历元的观测数据即可确定长距离基准站间的双差整周模糊度。     

一种GPS整周模糊度单历元解算方法

仅利用单历元的载波相位观测值进行整周模糊度解算,观测方程秩亏,给单历元模糊度解算带来很大困难.因此,本文提出一种单历元确定GPS整周模糊度的方法.利用单历元测码伪距观测值和双频载波相位观测值组成双差观测方程,根据方差矩阵对宽巷模糊度进行分组,采用基于LABMDA方法的逐步解算方法来确定双差相位观测值的宽巷模糊度.确定宽...     

Civilian GPS: The Benefits of Three Frequencies

A third civil frequency at 1176.45 MHz will be added to the Global Positioning System (GPS). This new frequency will bring a number of benefits. The aviation user will be one of the prime beneficiaries because the new frequency is in a protected aviation band. Thus, the system will be more robust against interference and jamming. The carrier-phase differential user will also be a prime beneficiary as long as his application has a reasonably short baseline. It is this high accuracy use that is explored in some depth. The process of forming linear combinations of both the code and carrier-phase measurements is studied, and the benefits and problems are explained. ? 2000 John Wiley & Sons, Inc.     

An analytical study on the carrier-phase linear combinations for triple-frequency GNSS

The linear combinations of multi-frequency carrier-phase measurements for Global Navigation Satellite System (GNSS) are greatly beneficial to improving the performance of ambiguity resolution (AR), cycle slip correction as well as precise positioning. In this contribution, the existing definitions of the carrier-phase linear combination are reviewed and the integer property of the resulting ambiguity of the phase linear combinations is examined. The general analytical method for solving the optimal integer linear combinations for all triple-frequency GNSS is presented. Three refined triple-frequency integer combinations solely determined by the frequency values are introduced, which are the ionosphere-free (IF) combination that the Sum of its integer coefficients equal to 0 (IFS0), the geometry-free (GF) combination that the Sum of its integer coefficients equal to 0 (GFS0) and the geometry-free and ionosphere-free (GFIF) combination. Besides, the optimal GF, IF, extra-wide lane and ionosphere-reduced integer combinations for GPS and BDS are solved exhaustively by the presented method. Their potential applications in cycle slip detection, AR as well as precise positioning are discussed. At last, a more straightforward GF and IF AR scheme than the existing method is presented based on the GFIF integer combination.     

基于加权的伪距和历元间相位差分模型GPS单点定位方法

在星载GPS精密定轨或单点定位中,尤其单频接收机的情况下,仅利用相位观测值,由于需要解算模糊度方程通常奇异,仅利用伪距观测资料,由于伪距观测值的噪声影响使得难以实现高精度定位要求。鉴于此,本文讨论了基于加权的伪距和历元间相位差分模型的GPS单点定位方法,该方法既能改善方程奇异性,又无需考虑模糊度因素,能确保观测值的精度。本文分别探讨了伪距观测方程和历元间差分相位观测方程,并给出了联合误差模型,推导了权值的计算公式和参数解算公式,最后基于动态单点定位考虑,探讨了基于加权的伪距和历元间相位差分模型的序贯最小二乘参数解算一般表达式。     

Carrier-phase inter-frequency biases of GLONASS receivers

The frequency division multiplexing of the GLONASS signals causes inter-frequency biases in the receiving equipment. These biases vary considerably for receivers from different manufacturers and thus complicate or prevent carrier-phase ambiguity fixing. Complete and reliable ambiguity fixing requires a priori information of the carrier-phase inter-frequency bias differences of the receivers involved. GLONASS carrier-phase inter-frequency biases were estimated for 133 individual receivers from 9 manufacturers. In general, receivers of the same type and even receivers from the same manufacturer show similar biases, whereas the differences among manufacturers can reach up to 0.2 ns (more than 5 cm) for adjacent frequencies and thus up to 2.4 ns (73 cm) for the complete L1 or L2 frequency bands. A few individual receivers were identified whose inter-frequency biases behave differently as compared to other receivers of the same type or whose biases vary with time.     

Short-term analysis of GNSS clocks

A characterization of the short-term stability of the atomic frequency standards onboard GNSS satellites is presented. Clock performance is evaluated using two different methods. The first method derives the temporal variation of the satellite’s clock from a polynomial fit through 1-way carrier-phase measurements from a receiver directly connected to a high-precision atomic frequency standard. Alternatively, three-way measurements using inter-station single differences of a second satellite from a neighboring station are used if the receiver’s clock stability at the station tracking the satellite of interest is not sufficient. The second method is a Kalman-filter-based clock estimation based on dual-frequency pseudorange and carrier-phase measurements from a small global or regional tracking network. Both methods are introduced and their respective advantages and disadvantages are discussed. The analysis section presents a characterization of GPS, GLONASS, GIOVE, Galileo IOV, QZSS, and COMPASS clocks based on these two methods. Special focus has been set on the frequency standards of new generation satellites like GPS Block IIF, QZSS, and IOV as well as the Chinese COMPASS/BeiDou-2 system. The analysis shows results for the Allan deviation covering averaging intervals from 1 to 1,000 s, which is of special interest for real-time PPP and other high-rate applications like processing of radio-occultation measurements. The clock interpolation errors for different sampling rates are evaluated for different types of clocks and their effect on PPP is discussed.     

A systematic investigation of optimal carrier-phase combinations for modernized triple-frequency GPS

The upcoming modernization of the GPS signals will allow for measurements on an additional third frequency L5 located at 1176.45 MHz. To take advantage of carrier-phase measurements on this new signal, the strategies for integer ambiguity resolution, required for centimeter-level accuracy, may need to be revised. The Least-squares Ambiguity Decorrelation Adjustment method remains perhaps the most powerful tool for finding the best combinations based on a complete decorrelation of the variance–covariance matrix related to the ambiguities. However, the computational load of that method plus the opportunity to comprehensively study the interaction of multiple frequencies suggest a reconsideration of approaches using predefined combinations between frequencies is not out of place. In this paper a systematic investigation is made of all possible triple-frequency geometry-free carrier-phase combinations which retain the integer nature of the ambiguities. The concept of the lane-number is presented to unambiguously describe the wavelength of a particular combination. The propagation of the observation noise and of the ionospheric bias on these combinations is presented. These noise and ionospheric amplification factors are analysed with respect to the resulting wavelength, in an effort to highlight optimal combinations characterized by a long wavelength, low noise and limited ionospheric impact.     

GPS/GLONASS相位差分的数据处理方法

由于GLONASS与GPS在系统上存在差异 ,致使GLONASS的载波相位差分的数据处理与GPS的有明显的不同 ,必须使用特殊的方法。本文给出了GPS、GLONASS及GPS/GLONASS联合相位差分的数学模型和一种数据处理方法 ,并对实测数据进行处理 ,给出了双卫星系统的定位结果及结果分析     

Investigation of ionosphere TEC distribution in China region by GIM model

In this paper, the TEC in China region is calculated by final GIM model and plotted as contour maps, the TEC value calculated from dual frequency GPS measurements（carrier-phase and pseudorange） is used as the reference truth and the TEC values from GIM models are then compared with the reference truth, and the accuracy and performance of GIM model in China region are analyzed and concluded.     

卫星双向载波相位时间频率传递及其误差分析

深入解析了基于码伪距测量的卫星双向时间频率传递(TWSTFT)原理,对其误差进行了分析,其精度主要受码速率的限制,难于满足更高精度要求;文章提出了基于载波相位的卫星双向时间频率传递方法,载波频率高,波长短,从理论上分析了以其作为TWSTFT伪距测量的参数可大幅度提高时间传递的精度;并对TWSTFT载波相位测量存在的误差源进行了初步分析,得出影响最大的因素是转发器误差、电离层误差、多径效应误差及星站相对运动引起的误差,参考GPS载波相位测量中误差消除的方法,对误差的消除方法提出建议。     

Investigation of ionosphere TEC distribution in China region by GIM model

In this paper, the TEC in China region is calculated by final GIM model and plotted as contour maps, the TEC value calculated from dual frequency GPS measurements (carrier-phase and pseudorange) is used as the reference truth and the TEC values from GIM models are then compared with the reference truth, and the accuracy and performance of GIM model in China region are analyzed and concluded.