一种Galileo五频周跳探测与修复新方法

A new method of Galileo five frequency cycle slip detection and repair

提出联合四组无几何相位组合和一组无几何伪距相位组合探测Galileo五频周跳,针对上述组合修复周跳过程中遇到的法方程病态性问题,提出一种基于条件数最小原则优选组合系数的策略。首先,按照波长较长、电离层延迟放大系数和周跳探测量标准差较小的标准选出部分适合的周跳探测组合,这些组合均满足有良好的周跳探测性能,之后依据条件数最小原则优选出最终的组合系数。该策略优势在于不仅顾及了周跳探测精度的需要,又降低了周跳修复时法方程病态性对周跳估值的影响。然后,引入LAMBDA算法进行Galileo五频周跳修复,重点研究了LAMBDA算法中ratio值设置问题。最后,利用实测数据进行验证,对比直接取整结合取整概率公式方法,设置四组实验方案。实验结果表明所提算法选取的周跳探测组合具有较高的周跳探测精度,能够有效探测各类周跳,联合周跳探测成功率达到100%。LAMBDA算法有着较高的周跳修复成功率和可靠性,同等情况下大幅优于直接取整方法。该算法关键在于ratio值阈值的选取,同时需要顾及修复的漏判率和误判率等,结合实验结果,建议设置ratio值阈值为2。

Four groups of geometry-free phase combinations and one group of geometry-free pseudo range phase combinations are combined to detect Galileo five-frequency cycle slips.Considering the ill conditioned problem of normal equation in cycle slip repair,a strategy based on the principle of minimum condition number is proposed to optimize the combination coefficient.Firstly,some suitable cycle slip detection combinations are selected according to the criteria of longer wavelength,smaller ionospheric delay amplification coefficient and smaller standard deviation.These combinations have great cycle-slip detection performance.Then,the optimal combination is selected according to the principle of minimum condition number.The advantage of the proposed method is that it not only considers the need for cycle slip detection sensitivity and accuracy,but also considers the influence of the ill condition of the normal equation on cycle slip estimation.Then the LAMBDA algorithm is introduced to repair Galileo five-frequency cycle slips.The ratio threshold in the LAMBDA algorithm is mainly discussed and four groups of schemes are set.The experimental results show that the cycle-slip detection combination selected by the proposed algorithm has high-sensitivity and can effectively detect simulated cycle slips,and the cycle-slip detection success rate is 100%.LAMBDA algorithm has a high cycle-slip repair success rate and reliability,which is significantly better than the rounding method under the same condition.The key of the algorithm lies in the selection of the ratio threshold,which needs to take into account the missing rate,the false rate of repair and repair success rate.Combined with the experimental results,the threshold of the ratio is suggested to 2.