GNSS多径信号模型及测高方法

提出利用全球导航卫星系统反射信号的干涉方法（GNSS-IR）进行测高。深入分析全球导航卫星系统反射信号的多径信号模型（GNSS-MR），在此基础上提出单天线测高模型，旨在获取多径信号信噪比（SNR）频率信息，从而反演出高度信息。Lomb-Scargle（LS）谱分析方法是单天线测高模型中常用的频率提取方法；提出了基于解析模型拟合的方法对多径信号信噪比数据提取频率，同样可以准确获取频率信息，从而反演出天线到地面的高度。在此基础上，讨论了单天线测高的最大测量高度和接收机需要满足的最小输出率。由实验数据分析得出：传统LS谱分析方法和拟合法在反演效果最优时，即LS谱分析方法在高度角上限为17°时，均方根误差为0.028 75 m；拟合法在高度角上限为21°时，均方根误差为0.024 85 m。通过比较不同高度角上限的均方根误差，可以获得最优化的高度反演条件，同时也表明了拟合法的可行性。

GNSS multipath signal model and altimetry method

The method of global navigation satellite system-interferometric reflection (GNSS-IR)was de-veloped to realize the altimetry.The model of global navigation satellite system-multipath reflection (GNSS-MR)was analyzed in depth.A single antenna height measurement model was proposed to obtain the signal-to-noise ratio (SNR)and frequency information of multipath signals,so as to reverse the height information.The Lomb-Scargle (LS)periodogram is a commonly used extraction method of the height measurement model of single antenna.In this paper,a new method based on analytic model fitting method was proposed and the fre-quency information can be acquired accurately for the SNR of the multipath signals.Thus the height of antenna to ground was reversed.On this basis,the maximum measurement height and the minimum output rate re-quired by the receiver were discussed.From the analysis of experimental data,it can be concluded that when the best results of inversion are obtained,that is,as for LS periodogram,when the upper limit of elevation an-gle reaches to 1 7°,the RMSE is 0.028 75 m;as for the fitting method,when the upper limit reaches to 21°, the RMSE is 0.024 85 m.By comparing the RMSE of different upper limit of elevation angle,the best condi-tion of height inversion can be retrieved.And it can also prove the practicability of the fitting method.