复杂路径低频地波传播相位延迟的高精度快速预测方法研究

项目名称： 复杂路径低频地波传播相位延迟的高精度快速预测方法研究

项目编号： No.61271091

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 无线电电子学、电信技术

项目作者： 席晓莉

作者单位： 西安理工大学

项目金额： 80万元

中文摘要： 传播相位延迟的预测水平是提高低频地波导航/授时精度的关键，FDTD数值方法能够大幅提高预测精度，但是，长距离、大区域复杂路径传播条件下带来了"数值计算误差大、计算速度慢、内存资源占用大、以FDTD作为前向算法反演大地电导率耗时过长"等问题。针对上述问题，本项目开展以下工作：提出一种"低色散FDTD＋PSTD"频域空域结合的数值计算方法以提高数值计算的理论预测精度；采用分段长距离技术结合基于GPU+CPU的并行计算技术以实现内存资源占用和计算时间的大幅度减小；提出一种积分方程方法与数值计算方法联合剥离复杂地形因素影响的高精度大地电导率反演方法；研究大气折射率对传播相位延迟的影响；开展高精度外场试验以实现对理论研究的支撑和验证。本项目的完成将大幅度提高复杂传播路径低频地波相位延迟的理论预测精度和大地电导率反演精度，提高理论预测方法的工程适应性，为提高长波导航/授时的精度提供有力的技术支撑。

中文关键词： 低频；地波传播；低色散数值计算；并行计算技术；大地电导率反演

英文摘要： In a low frequency ground wave navigation system, accurately predicting phase delay is the key in improving the accuracy of positioning, navigation, and timing (PNT). The finite-difference time-domain (FDTD) method has proven to be capable of improving system accuracy dramatically. However, it suffers from very high computational cost especially for long distance complex terrain prediction where using this method as the forward algorithm for ground conductivity inversion is almost impossible. To solve this problem, a combined "low dispersion FDTD pesudo-spectral time-domain PSTD" method is proposed to improve the accuracy therefore reduce cost of the numerical simulation. The memory request and computational time will be reduced significantly by using Segmented Long Path(SLD) technique together with the CPU & GPU based parallel computing techniques. A combined integral equation (IE) and numerical method is proposed to improve the accuracy in the ground conductivity inversion for complex terrain, where the impact of air refraction index on the phase delay will be taken into account. Field tests will be carried out for verification purpose. This investigation will significantly improve the accuracy of both phase delay prediction and ground conductivity inversion in low frequency ground wave propagation system, an

英文关键词： Low Frequency；Propagation of Ground Wave；Numerical Computation；Parallel Computing Technique；Ground Conductivity Inversion