电离层延迟变化自模型化的载波相位平滑伪距算法

传统的单频载波相位平滑伪距算法因受到电离层延迟变化的影响,容易出现平滑结果发散和精度下降的问题,而现有的解决方案对精度提高有限或需要外部精密电离层改正数据的支持。本文研究了电离层的变化规律并建立回归模型,在此基础上提出了一种自模型化电离层延迟变化的单频载波相位平滑伪距算法。此算法利用伪距和载波观测量中含有的电离层延迟信息进行电离层延迟建模,从平滑伪距中扣除了历元间电离层延迟变化值,有效避免了平滑伪距的发散问题。利用自编软件GNSSer实现了电离层自模型化的载波平滑伪距算法,并采用静态与动态实测观测数据进行了定位试验和精度分析。算例结果表明:①长时段常规Hatch滤波受电离层影响非常严重;②自模型化电离层延迟可达厘米级的精度,在30 min窗口内,使用线性移动开窗拟合法效果最佳;③自模型化电离层改正可以有效消除平滑伪距电离层影响,随着时段窗口的增加,精度没有降低;④利用本文提出的算法进行逐历元单频平滑伪距单点定位,在静态与动态的NEU方向都达到了亚分米级别的定位精度,其中,动态定位测试中水平和高程方向精度为6.25和10.4 cm,比原始伪距分别提高了5.4倍和3.3倍。

An improved carrier phase smoothing pseudorange algorithm with self-modeling of ionospheric delay variation

The traditional single-frequency carrier phase smoothing pseudo-range algorithm is prone to divergence and precision degradation due to the influence of ionospheric delay. However, the existing solutions have limited accuracy improvement or need external data support. In this paper, the regularity of ionospheric variation is studied and a regressive model is established. On this basis, a self-modelling algorithm for single-frequency carrier phase smoothing pseudorange with ionospheric delay variation is proposed. The algorithm uses the ionospheric delay information contained in the pseudo-range and carrier observations to model the ionospheric delay, and deducts the ionospheric delay variation between epochs from the smooth pseudo-range, thus effectively avoiding the divergence of the smooth pseudo-range. Carrier smoothing pseudo-range algorithm of ionospheric self-modeling is realized by using GNSSer software. Static and dynamic observation data are used to carry out positioning experiment and precision analysis. The example shows that:① the long period regular Hatch filtering is seriously affected by the ionosphere; ② the precision of the self-modelling ionospheric delay can reach centimeter level, and the linear moving window fitting method is the best in the 30-minute window; ③ self-modeling ionospheric correction can effectively eliminate the influence of smooth pseudo-range ionosphere. With the increase of time window, the precision does not decrease; ④ the proposed algorithm is used for epoch-by-epoch single-frequency smoothing pseudo-range single-point positioning, and the positioning accuracy reaches sub-decimeter level in both static and dynamic NEU directions. In the dynamic positioning test, the horizontal and elevation direction accuracy is 6.25 cm and 10.4 cm, which are 5.4 times and 3.3 times higher than the original pseudo-range respectively.