共查询到20条相似文献，搜索用时 15 毫秒
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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
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用LAMBDA改进算法固定GPS整周模糊度 总被引：1，自引：0，他引：1
介绍了LAMBDA算法原理，结合国土资源调查的工程实践，对常规的LAMBDA方法作了两点改进，即扩大超椭球的体积En和以点位的先验信息检验坐标解算结果。实测数据分析表明，两点改进均能有效地提高基线解算的可靠性，具有一定的理论价值。 相似文献
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The LAMBDA method that was proposed by Teunissen is introduced. Then, on the basis of both the back-sequential conditional LS technique and the upper-triangular Cholesky decomposition, another form for LAMBDA method is proposed. This new form for LAMBDA method has the same principle and calculation speed as the traditional LAMBDA method. 相似文献
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Another form for LAMBDA method 总被引：2，自引：0，他引：2
ZHOUYangmei LIUJingnan 《地球空间信息科学学报》2003,6(3):66-70
The LAMBDA method that was proposed by Teunissen is in-troduced. Then, on the basis of both the back-sequential conditional LS technique and the upper-triangular Cholesky decomposition, another form for LAMBDA method is proposed.This new form for LAMBDA method has the same principle and calculation speed as the traditional LAMBDA method. 相似文献
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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
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附有基线长度约束的单频数据单历元LAMBDA方法整周模糊度确定 总被引：10，自引：2，他引：10
针对某些GPS动态定位中基线长度精确已知的特性，提出了附有基线长度约束的LAMBDA方法，同时在实践中使用两步搜索，对LAMBDA方法进行了优化。实测数据处理结果表明，该方法对LAMBDA方法的改进效果较为显著，能在基线长度已知条件下较高成功率地确定单频单历元数据的整周模糊度。 相似文献
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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
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GPS单历元定位的阻尼LAMBDA算法 总被引：10，自引：0，他引：10
结合Teunissen提出的LAMBDA方法和阻尼最小二乘估计的原理 ,提出了一种新的单历元算法 ,即阻尼LAMBDA方法 相似文献
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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
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On the GPS widelane and its decorrelating property 总被引：2，自引：1，他引：2
P. J. G. Teunissen 《Journal of Geodesy》1997,71(9):577-587
In this contribution we consider the popular widelaning technique from the viewpoint of ambiguity decorrelation. It enables
us to cast the technique into the framework of the least-squares ambiguity decorrelation adjustment (LAMBDA) and to analyse
its relative merits. In doing so, we will provide answers to the following three questions. Does the widelane decorrelate?
Does it explicitly appear in the automated transformation step of the LAMBDA method? Can one do better than the widelane?
It is shown that all three questions can be answered in the affirmative. This holds true for the ionosphere-fixed case, the
ionosphere-float case, as well as for the ionosphere-weighted case.
Received: 11 November 1996 / Accepted: 23 April 1997 相似文献
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The Indian Regional Navigation Satellite System (IRNSS) has recently (May 2016) reached its full operational capability. In this contribution, we provide the very first L5 attitude determination analyses of the fully operational IRNSS as a standalone system and also in combination with the fully operational GPS Block IIF along with the corresponding ambiguity resolution results. Our analyses are carried out for both a linear array of two antennas and a planar array of three antennas at Curtin University, Perth, Australia. We study the noise characteristics (carrier-to-noise density, measurement precision, time correlation), the integer ambiguity resolution performance (LAMBDA, MC-LAMBDA) and the attitude determination performance (ambiguity float and ambiguity fixed). A prerequisite for precise and fast IRNSS attitude determination is the successful resolution of the double-differenced integer carrier-phase ambiguities. In this contribution, we will compare the performance of the unconstrained and the multivariate-constrained LAMBDA method. It is therefore also shown what improvements are achieved when the known body geometry of the antenna array is rigorously incorporated into the ambiguity objective function. As our ambiguity-fixed outcomes show consistency between empirical and formal results, we also formally assess the precise attitude determination performance for several locations within the IRNSS service area. 相似文献
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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
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Lingyong Huang Zhiping Lu Guojun Zhai Yongzhong Ouyang Motao Huang Xiuping Lu Taiqi Wu Kaifeng Li 《GPS Solutions》2016,20(4):761-769
Triple-frequency global navigation satellite systems allow the introduction of additional linear observation combinations. We define two geometry-free phase combinations and one geometry-free pseudorange minus phase linear combination to detect and correct cycle slip in real time. At first, the optimal BDS (BeiDou System) triple-frequency geometry-free phase combinations are selected for cycle slip detection. Then, a detailed analysis of the cycle slip detection is performed by examining whether some special cycle slip groups cannot be discovered by the selected combinations. Since there still remain some cycle slip groups undetectable by the two geometry-free phase combinations, we add a pseudorange minus phase linear combination which is linearly independent with these two phase combinations, to be sure that all the cycle slips can be detected. After that, an effective decorrelation search based on LAMBDA and least squares minimum principle is applied to calculate and determine the cycle slips. The method has been tested on triple-frequency undifferenced BDS data coming from a benign observation environment. Results show that the proposed method is able to detect and repair all the small cycle slips in the three carriers. 相似文献
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Partial integer decorrelation: optimum trade-off between variance reduction and bias amplification 总被引：2，自引：2，他引：0
Different techniques have been developed for determining carrier phase ambiguities, ranging from float approximations to the
efficient solution of the integer least square problem by the LAMBDA method. The focus so far was on double-differenced measurements.
Practical implementations of the LAMBDA method lead to a residual probability of wrong fixing of the order one percent. For
safety critical applications, this probability had to be reduced by eight orders of magnitude, which could be achieved by
linear multi-frequency code–carrier combinations. Scenarios with single or no differences include biases due to orbit errors,
satellite clock offsets, as well as residual code and phase biases. For this case, a linear combination of Galileo E1 and
E5 code and carrier phase measurements with a wavelength of 3.285 m and a noise level of a few centimeters is derived. This
ionosphere-free combination preserves the orbit and clock errors, and suppresses the E1 code multipath by 12.6 dB. Since integer
decorrelation transformations, as used in the LAMBDA method, inflate biases, the number of such transformations must be limited,
and applied in a judicious order. With a Galileo type constellation, this leads to a vertical standard deviation of ca. 20 cm,
while keeping the probability of wrong fixing extremely low for code biases of 10 cm, and phase biases of 0.1 cycle, combined
in a worst case. 相似文献