引用本文: 徐宗秋, 张鸿洋, 徐彦田, 李军, 杨南南, 石帅. 一种BDS非差非组合PPP中电离层功率谱密度估计方法[J]. 武汉大学学报 ( 信息科学版).
XU Zongqiu, ZHANG Hongyang, XU Yantian, LI Jun, YANG Nannan, SHI Shuai. A Method for Estimating Ionospheric Power Spectral Density in BDS Undifferenced and Uncombined PPP[J]. Geomatics and Information Science of Wuhan University.
 Citation: XU Zongqiu, ZHANG Hongyang, XU Yantian, LI Jun, YANG Nannan, SHI Shuai. A Method for Estimating Ionospheric Power Spectral Density in BDS Undifferenced and Uncombined PPP[J]. Geomatics and Information Science of Wuhan University.

## A Method for Estimating Ionospheric Power Spectral Density in BDS Undifferenced and Uncombined PPP

• 摘要: 无电离层组合模型和非差非组合模型是PPP定位中最常用的两种函数模型，非差非组合模型中电离层误差常被描述为随机游走，随机游走过程中的功率谱密度成为决定PPP定位性能的主要因素，采用经验值功率谱密度的方法没有考虑电离层小尺度变化。本文在非差非组合模型基础上，分析电离层时间相关性信息，在电离层差分时间间隔较小时观测噪声较大甚至淹没电离层的变化，为此，本文通过平滑去噪的方法削弱观测值噪声的影响，实时确定电离层功率谱密度，对非差非组合模型中的电离层延迟参数进行合理的约束，从而改善定位性能。通过对12个测站10天的BDS数据进行不同电离层模型下的解算，结果表明：相对于传统无电离层组合PPP模型，本文方法在收敛时间上缩短8%左右，水平方向精度相当，垂直方向定位精度提高28%左右。相较于功率谱密度采用经验值方法，本文方法在收敛时间上缩短9%左右，水平方向精度相当，垂直方向定位精度提高28%左右。

Abstract: The ionosphere-free(IF)model and the undifferenced and uncombined(UDUC)model are the two most commonly used functional models in precise point positioning(PPP). In the UDUC model, the ionospheric error is often described as random walk parameter, and the power spectral density(PSD) in the process of random walk becomes the main factor determining the positioning performance of PPP. The method of determining the PSD by the empirical value can not show the small scale variation of the ionosphere. In this paper, based on the UDUC model, the time correlation information of the ionosphere is analyzed. When the difference time interval of the ionosphere is small, the observation noise is large and it will submerge the changes of the ionosphere. Hence, this paper uses the smooth denoising method to weaken the influence of the observation noise, determine the ionospheric PSD in real time, and reasonably constrain the ionospheric delay parameters in the UDUC model, so as to improve the positioning performance. The experiment was carried out through 10 days BDS observations come from 12 stations under different ionospheric models, the results show that compared with the traditional IF model, the convergence time of the method proposed in this paper is shortened by 8%, the horizontal direction accuracy is equivalent, and the vertical direction positioning accuracy is improved by about 28%. Compared with the empirical value PSD method, the convergence time of the method proposed in this paper is shortened by about 9%, the horizontal direction accuracy is equivalent, and the vertical direction positioning accuracy is improved by about 28%.

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