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1.
The Indian Regional Navigation Satellite System (IRNSS) has recently (May 2016) become fully operational. In this contribution, for the fully operational IRNSS as a stand-alone system and also in combination with GPS, we provide a first assessment of L5 integer ambiguity resolution and positioning performance. While our empirical analyses are based on the data collected by two JAVAD receivers at Curtin University, Perth, Australia, our formal analyses are carried out for various onshore locations within the IRNSS service area. We study the noise characteristics (carrier-to-noise density, measurement precision, time correlation), the integer ambiguity resolution performance (success rates and ambiguity dilution of precision), and the positioning performance (ambiguity float and ambiguity fixed). The results show that our empirical outcomes are consistent with their formal counterparts and that the GPS L5-data have a lower noise level than that of IRNSS L5-data, particularly in case of the code data. The underlying model in our assessments varies from stand-alone IRNSS (L5) to IRNSS \(+\) GPS (L5), from unconstrained to height-constrained and from kinematic to static. Significant improvements in ambiguity resolution and positioning performance are achievable upon integrating L5-data of IRNSS with GPS. 相似文献
2.
The Indian Regional Navigation Satellite System (IRNSS), which is being developed for positioning services in and around India, is the latest addition to the global family of satellite-based navigation systems. As IRNSS only shares the L5-frequency with GPS, the European Galileo, and the Japanese Quasi-Zenith Satellite System (QZSS), it has at least at present a limited interoperability with the existing systems. Noting that the L5-frequency capability is under development even for GPS, this contribution assesses the interoperability of the IRNSS L5-signal with the GPS, Galileo, and QZSS L5/E5a-signals for positioning and navigation using real data collected in Perth, Australia. First, the noise characteristic of the IRNSS L5-signal and its comparison with that of the GPS, Galileo, and QZSS L1/E1- and L5/E5a-signals is presented. Then, the L5-observables of combined systems (formed from IRNSS, GPS, Galileo, and QZSS) are assessed for real-time kinematic positioning using the standard LAMBDA method and for instantaneous attitude determination using the constrained LAMBDA method. The results show that the IRNSS L5-signal has comparable noise characteristics as that of the other L5/E5a-signals. For single-frequency carrier phase-based positioning and navigation, the results show better ambiguity resolution performance of L5/E5a-only processing than that of L1/E1-only processing. 相似文献
3.
Testing of a new single-frequency GNSS carrier phase attitude determination method: land,ship and aircraft experiments 总被引：4，自引：1，他引：3
Global navigation satellite system (GNSS) ambiguity resolution is the process of resolving the unknown cycle ambiguities of
the carrier phase data as integers. The sole purpose of ambiguity resolution is to use the integer ambiguity constraints as
a means of improving significantly on the precision of the remaining GNSS model parameters. In this contribution, we consider
the problem of ambiguity resolution for GNSS attitude determination. We analyse the performance of a new ambiguity resolution
method for GNSS attitude determination. As it will be shown, this method provides a numerically efficient, highly reliable
and robust solution of the nonlinearly constrained integer least-squares GNSS compass estimators. The analyses have been done
by means of a unique set of extensive experimental tests, using simulated as well as actual GNSS data and using receivers
of different manufacturers and type as well as different platforms. The executed field tests cover two static land experiments,
one in the Netherlands and one in Australia, and two dynamic experiments, a low-dynamics vessel experiment and high-dynamics
aircraft experiment. In our analyses, we focus on stand-alone, unaided, single-frequency, single-epoch attitude determination,
as this is the most challenging case of GNSS compass processing. 相似文献
4.
The affine constrained GNSS attitude model and its multivariate integer least-squares solution 总被引：1，自引：1，他引：0
P. J. G. Teunissen 《Journal of Geodesy》2012,86(7):547-563
A new global navigation satellite system (GNSS) carrier-phase attitude model and its solution are introduced in this contribution. This affine-constrained GNSS attitude model has the advantage that it avoids the computational complexity of the orthonormality-constrained GNSS attitude model, while it still has a significantly improved ambiguity resolution performance over its unconstrained counterpart. The functional and stochastic model is formulated in multivariate form, for one-, two- and three-dimensional antenna arrays, tracking GNSS signals on an arbitrary number of frequencies with two or more antennas. The stochastic model includes the capability to capture variations in the antenna-quality within the array. The multivariate integer least-squares solution of the model parameters is given and the model’s ambiguity success-rate is analysed by means of the ambiguity dilution of precision (ADOP). A general closed-form expression for the affine-constrained ADOP is derived, thus providing an easy-to-use and insightful rule-of-thumb for the ambiguity resolution capabilities of the affine constrained GNSS attitude model. 相似文献
5.
下三角Cholesky分解的整数高斯变换算法 总被引：1，自引：0，他引：1
针对全球导航卫星系统(GNSS)载波相位测量中,基于整数最小二乘估计准则解算整周模糊度问题。目前以LAMBDA降相关算法和Lenstra-Lenstra-Lovász(LLL)为代表的规约算法应用最为广泛。由于不同算法采用的模糊度方差-协方差阵的分解方式不同,导致难以合理地进行不同算法性能的比较。该文通过分析LAMBDA算法的降相关特点,从理论上推出基于下三角Cholesky分解多维情形下的整数高斯变换的降相关条件及相应公式,并与分解方式不同的LAMBDA和LLL算法作了对比。实验结果表明,降相关采用的分解方式将会直接影响计算复杂度和解算性能,因此该文推导的整数高斯变换算法便于今后基于下三角Cholesky分解的降相关算法间的合理比较。 相似文献
6.
Integer least-squares theory for the GNSS compass 总被引：7，自引：2，他引：5
P. J. G. Teunissen 《Journal of Geodesy》2010,84(7):433-447
Global navigation satellite system (GNSS) carrier phase integer ambiguity resolution is the key to high-precision positioning
and attitude determination. In this contribution, we develop new integer least-squares (ILS) theory for the GNSS compass model,
together with efficient integer search strategies. It extends current unconstrained ILS theory to the nonlinearly constrained
case, an extension that is particularly suited for precise attitude determination. As opposed to current practice, our method
does proper justice to the a priori given information. The nonlinear baseline constraint is fully integrated into the ambiguity
objective function, thereby receiving a proper weighting in its minimization and providing guidance for the integer search.
Different search strategies are developed to compute exact and approximate solutions of the nonlinear constrained ILS problem.
Their applicability depends on the strength of the GNSS model and on the length of the baseline. Two of the presented search
strategies, a global and a local one, are based on the use of an ellipsoidal search space. This has the advantage that standard
methods can be applied. The global ellipsoidal search strategy is applicable to GNSS models of sufficient strength, while
the local ellipsoidal search strategy is applicable to models for which the baseline lengths are not too small. We also develop
search strategies for the most challenging case, namely when the curvature of the non-ellipsoidal ambiguity search space needs
to be taken into account. Two such strategies are presented, an approximate one and a rigorous, somewhat more complex, one.
The approximate one is applicable when the fixed baseline variance matrix is close to diagonal. Both methods make use of a
search and shrink strategy. The rigorous solution is efficiently obtained by means of a search and shrink strategy that uses
non-quadratic, but easy-to-evaluate, bounding functions of the ambiguity objective function. The theory presented is generally
valid and it is not restricted to any particular GNSS or combination of GNSSs. Its general applicability also applies to the
measurement scenarios (e.g. single-epoch vs. multi-epoch, or single-frequency vs. multi-frequency). In particular it is applicable
to the most challenging case of unaided, single frequency, single epoch GNSS attitude determination. The success rate performance
of the different methods is also illustrated. 相似文献
7.
GNSS antenna array-aided CORS ambiguity resolution 总被引：1，自引：1，他引：0
Array-aided precise point positioning is a measurement concept that uses GNSS data, from multiple antennas in an array of known geometry, to realize improved GNSS parameter estimation proposed by Teunissen (IEEE Trans Signal Process 60:2870–2881, 2012). In this contribution, the benefits of array-aided CORS ambiguity resolution are explored. The mathematical model is formulated to show how the platform-array data can be reduced and how the variance matrix of the between-platform ambiguities can profit from the increased precision of the reduced platform data. The ambiguity resolution performance will be demonstrated for varying scenarios using simulation. We consider single-, dual- and triple-frequency scenarios of geometry-based and geometry-free models for different number of antennas and different standard deviations of the ionosphere-weighted constraints. The performances of both full and partial ambiguity resolution (PAR) are presented for these different scenarios. As the study shows, when full advantage is taken of the array antennas, both full and partial ambiguity resolution can be significantly improved, in some important cases even enabling instantaneous ambiguity resolution. PAR widelaning and its suboptimal character are hereby also illustrated. 相似文献
8.
Single-Epoch Ambiguity Resolution for Real-Time GPS Attitude Determination with the Aid of One-Dimensional Optical Fiber Gyro 总被引：9，自引：0，他引：9
High-accuracy real-time GPS-based attitude determination requires that integer ambiguities be resolved very quickly so that
the attitude angles can be output with minimum delay. This article describes an attitude determination algorithm that can
resolve integer ambiguities instantaneously, relative to one antenna of a multi-antenna array configuration. The carrier phase
and pseudorange observations are used with fixed baseline length constraints and fiberoptic gyro data. Real-time stochastic
model improvement using empirical elevation-dependent standard deviation function and an estimated scale factor are a feature
of this algorithm. Integer ambiguity search using the LAMBDA method, sophisticated validation criteria, and an adaptive procedure
has also been implemented within the software. An experiment was carried out using four Leica dual-frequency GPS receivers
(but only the L1 carrier phase and pseudorange data were used) and a low-cost fiberoptic on a car. The results indicate that
integer ambiguities can be resolved on a single-epoch basis with a 98.9% success rate. ? 1999 John Wiley & Sons, Inc. 相似文献
9.
Since its introduction in 1993, the LAMBDA method has found widespread use across the world. The method has been employed
in many geodetic and navigation applications, with lots of satisfied users. Independent tests show that it is considered the
best method for integer carrier phase ambiguity resolution available. But every now and then we still notice some misunderstandings
concerning the principles and potential of the method. In this contribution we will briefly summarize the principles underlying
the LAMBDA method, go into some of the frequently asked questions on the LAMBDA method and try to clarify some of the existing
misunderstandings.
Electronic Publication 相似文献
10.
本文提出了一种改进LAMBDA方法:在确定Z变换后的模糊度时,改变以往对所有历元的模糊度全部进行搜索的做法,而是通过设置合理的条件,将搜索与直接归整有效地结合起来,从而减少了模糊度的解算时间,提高了解的效率。文章最后利用实测GPS数据验证了改进效果。 相似文献
11.
Integer aperture bootstrapping: a new GNSS ambiguity estimator with controllable fail-rate 总被引：1，自引：0，他引：1
P.J.G. Teunissen 《Journal of Geodesy》2005,79(6-7):389-397
In this contribution, we introduce a new bootstrap-based method for Global Navigation Satellite System (GNSS) carrier-phase ambiguity resolution. Integer bootstrapping is known to be one of the simplest methods for integer ambiguity estimation with close-to-optimal performance. Its outcome is easy to compute due to the absence of an integer search, and its performance is close to optimal if the decorrelating Z-transformation of the LAMBDA method is used. Moreover, the bootstrapped estimator is presently the only integer estimator for which an exact and easy-to-compute expression of its fail-rate can be given. A possible disadvantage is, however, that the user has only a limited control over the fail-rate. Once the underlying mathematical model is given, the user has no freedom left in changing the value of the fail-rate. Here, we present an ambiguity estimator for which the user is given additional freedom. For this purpose, use is made of the class of integer aperture estimators as introduced in Teunissen (2003). This class is larger than the class of integer estimators. Integer aperture estimators are of a hybrid nature and can have integer outcomes as well as non-integer outcomes. The new estimator is referred to as integer aperture bootstrapping. This new estimator has all the advantages known from integer bootstrapping with the additional advantage that its fail-rate can be controlled by the user. This is made possible by giving the user the freedom over the aperture of the pull-in region. We also give an exact and easy-to-compute expression for its controllable fail-rate. 相似文献
12.
采用方向余弦矩阵描述姿态,建立GPS/陀螺组合姿态确定系统模型,由矩阵Kalman滤波方法解算整周模糊度的浮点解,然后再利用MCLambda方法得到整周模糊度固定解。仿真实验结果表明,附加方向余弦矩阵约束的Kalman滤波方法可以有效地提高整周模糊度浮点解的精度,使得整周模糊度的固定成功率和效率均得到提高,尤其是在GPS观测条件较差的情况下。 相似文献
13.
14.
Christian Tiberius Thomas Pany Bernd Eissfeller Peter Joosten Sandra Verhagen 《GPS Solutions》2002,6(1-2):96-99
In this short contribution it is demonstrated how integer carrier phase cycle ambiguity resolution will perform in near future,
when the US GPS gets modernized and the European Galileo becomes operational. The capability of ambiguity resolution is analyzed
in the context of precise differential positioning over short, medium and long distances. Starting from dual-frequency operation
with GPS at present, particularly augmenting the number of satellites turns out to have beneficial consequences on the capability
of correctly resolving the ambiguities. With a 'double' constellation, on short baselines, the confidence of the integer ambiguity
solution increases to a level of 0.99999999 or beyond.
Electronic Publication 相似文献
15.
根据GNSS不同频率间整周模糊度的约束关系,提出一种基于多频整周模糊度间关系约束的模糊度新算法(dual-frequency integer relationship constrained ambiguity resolution,FirCAR)。FirCAR可快速动态解算出高高度角卫星的整周模糊度,将已经固定的整周模糊度视为高精度的伪距观测值应用到下一步的浮点解重算中。结合模糊度搜索算法,如LAMBDA,在模糊度搜索方面的高效性,根据重算后的浮点解进一步解算其他未固定的模糊度解。模糊度固定成功后,即可实现OTF(on the fly)快速定位。实测数据表明,FirCAR算法在静态和动态观测条件下,模糊度初始化所用的平均观测历元数分别为1.04和1.10。与常规的模糊度搜索算法的对比试验表明,结合FirCAR算法模糊度固定所用的观测历元数分别减少了39%和18%。 相似文献
16.
Performance analysis of triple-frequency ambiguity resolution with BeiDou observations 总被引：5，自引：1，他引：4
We investigate triple-frequency ambiguity resolution performance using real BeiDou data. We test four ambiguity resolution (AR) methods which are applicable to triple-frequency observations. These are least squares ambiguity decorrelation adjustment (LAMBDA), GF-TCAR (geometry-free three-carrier ambiguity resolution), GB-TCAR (geometry-based three-carrier ambiguity resolution) and GIF-TCAR (three-carrier ambiguity resolution based on the geometry-free and ionospheric-free combination). A comparison between LAMBDA, GF-TCAR and GB-TCAR was conducted over three short baselines and two medium baselines. The results indicated that LAMBDA is optimal in both short baseline and medium baseline cases. However, the performances of GB-TCAR and LAMBDA differ slightly for short baselines. Compared with GF-TCAR, which uses the geometry-free model, the GB-TCAR using the geometry-based model improves the AR performance significantly. Compared with dual-frequency observations, the LAMBDA AR results show a significant improvement when using triple-frequency observations over short baselines. The performance of GIF-TCAR is evaluated using multi-epoch observations. The results indicated that multi-path errors on carrier phases will have a significant influence on GIF-TCAR AR results, which leads to different GIF-TCAR AR performance for different type of satellites. For GEO (Geostationary Orbit) satellites, the ambiguities can barely be correctly fixed because the multi-path errors on carrier phases are very systematic. For IGSO (Inclined Geosynchronous Orbit) and MEO (Medium Earth Orbit) satellites, when the elevation cutoff angle is set as 30°, several tens to several hundreds of epochs are needed for correctly fixing the narrow lane ambiguities. The comparison of positioning performance between dual-frequency observations and triple-frequency observations was also conducted. The results indicated that a minor improvement can be achieved by using triple-frequency observations compared with using dual-frequency observations. 相似文献
17.
The least-squares ambiguity Decorrelation (LAMBDA) method has been widely used in GNSS for fixing integer ambiguities. It
can also solve any integer least squares (ILS) problem arising from other applications. For real time applications with high
dimensions, the computational speed is crucial. A modified LAMBDA (MLAMBDA) method is presented. Several strategies are proposed
to reduce the computational complexity of the LAMBDA method. Numerical simulations show that MLAMBDA is (much) faster than
LAMBDA. The relations between the LAMBDA method and some relevant methods in the information theory literature are pointed
out when we introduce its main procedures. 相似文献
18.
Precise GRACE baseline determination using GPS 总被引：13，自引：1，他引：13
Precision relative navigation is an essential aspect of spacecraft formation flying missions, both from an operational and a scientific point of view. When using GPS as a relative distance sensor, dual-frequency receivers are required for high accuracy at large inter-satellite separations. This allows for a correction of the relative ionospheric path delay and enables double difference integer ambiguity resolution. Although kinematic relative positioning techniques demonstrate promising results for hardware-in-the-loop simulations, they were found to lack an adequate robustness in real-world applications. To overcome this limitation, an extended Kalman Filter modeling the relative spacecraft dynamics has been developed. The filter processes single difference GPS pseudorange and carrier phase observations to estimate the relative position and velocity along with empirical accelerations and carrier phase ambiguities. In parallel, double difference carrier phase ambiguities are resolved on both frequencies using the least square ambiguity decorrelation adjustment (LAMBDA) method in order to fully exploit the inherent measurement accuracy. The combination of reduced dynamic filtering with the LAMBDA method results in smooth relative position estimates as well as fast and reliable ambiguity resolution. The proposed method has been validated with data from the gravity recovery and climate experiment (GRACE) mission. For an 11-day data arc, the resulting solution matches the GRACE K-Band Ranging System measurements with an accuracy of 1 mm, whereby 83% of the double difference ambiguities are resolved. 相似文献
19.
基于整周模糊度概率特性的有效性检验 总被引：1，自引：0，他引：1
准确确定载波相位整周模糊度是快速高精度GPS定位的关键,已有的检验GPS整周模糊度有效性的方法几乎均是基于其为非随机常量建立的,因而都存在一定的缺陷。本文在研究整周模糊度概率特性的基础上,提出一种基于LABMBAD算法的整周模糊度概率分布函数的检验方法。实际演算表明该方法简单有效,统计概念明确。 相似文献
20.
GPS载波相位观测值作为高精度观测量在姿态测量中得到广泛应用。姿态测量系统中,基线长度可以通过提前量测精确求得。作为约束条件,可以用于模糊度搜索,提高模糊度搜索效率和准确度。本文介绍了传统的LAMBDA方法,且在此基础上提出了附有基线长度约束的LAMBDA搜索方法,并比较了两者的搜索效率。 相似文献