电离层闪烁对GNSS信号影响的相位屏仿真方法

建立了利用相位屏模型实现的全球导航卫星系统(Global Navigation Satellite System, GNSS)闪烁仿真方法.仿真包括随机相位屏的产生和抛物波方程求解.相位屏产生中，通过将零均值的Gauss白噪声通过特定滤波器(根据闪烁功率谱密度函数设计)的方法产生二维随机相位分布；抛物波方程求解中，通过分步法求解抛物波方程获得接收机处的卫星信号复振幅.上述过程考虑了信号倾斜传播路径、不均匀体特征参量等因素, 这些因素可由实测数据估计获得.利用中国低纬地区典型闪烁事件期间的GNSS观测数据提取闪烁相关参量, 并用于闪烁仿真.从信号强度时间序列、幅度相位统计特性、谱特征等多个方面, 对仿真和实测结果进行比较.结果表明, 建立的GNSS信号闪烁仿真方法可以有效复现电离层闪烁影响下的GNSS信号, 仿真信号符合理论变化规律, 且与实测数据结果具有一致性.由此表明了建立的GNSS信号闪烁仿真方法的有效性.

Simulating the impacts of ionospheric scintillation on GNSS signals with phase screen method

A phase screen model based Global Navigation Satellite System (GNSS) scintillation simulation is developed for predicting the impacts of ionospheric scintillation on GNSS signals. The method consists of the phase screen generation and solution of parabolic wave equation (PWE). The 2-D realization of spatial phase fluctuation is realized by passing a normally distributed, zero-mean random sequence through a special designed filter based on the power spectral density (PSD) function. The parabolic wave equation is solved using the split step technique to compute the complex amplitude reaching the receiver antenna. It accounts for the oblique propagation of the GNSS signals and the characteristic parameters of scintillation-producing irregularities, all of which determine the strength of scintillation and could be retrieved from measurements. Ionospheric scintillation impacts on GNSS signals is simulated with the parameters for observation from low-latitude areas in China. Comparison is also conducted from various aspects with the simulated signal and that of field observation, including the amplitude variation, statistics characteristics of intensity and phase, spectral analysis of signal time sequence. It demonstrates that GNSS scintillation simulation can reproduce the scintillation impacted GNSS signals, and the outputs are consistent with the theory analysis and the field data analysis, which show the validity of the GNSS scintillation sinmulation.