GPS多路径重复性试验研究

Abstract

信号衍射和多路径效应是限制GPS定位精度进一步提高的瓶颈,观测中两者往往同时存在。衍射效应具有不完全重复的特性,为了研究多路径重复性并使其不受信号衍射的影响,本文提出先应用SIGMA-Δ信噪比加权模型削弱信号衍射的影响,再运用改进恒星时滤波法分析多路径重复性。实验观测资料分析表明,SIGMA-Δ模型能有效削弱衍射信号对定位结果影响,并且保留主要的多路径信号;而改进恒星时滤波法能适应测站周围多路径环境的变化,从而最大限度地削减多路径误差。两者组合比传统的恒星时滤波更能有效提高GPS的动态定位精度。 Signal diffraction and multipath disturbance are bottleneck problems that limit accuracy of Global Positioning System(GPS) positioning,both of which tend to exist simultaneously.However,the day-to-day repeatability of signal diffraction is not obvious.To take advantage of the day-to-day repeating property of GPS multipath signals and make it not affected by diffraction effects,this paper used the stochastic SIGMA-Δ model to reduce the effects of signal diffraction and then applied the modified sidereal filtering to analyze the multipath repeatability.Experiments with real GPS observations showed that the SIGMA-Δ model could achieve a balance between reducing the diffraction effects and keeping the main multipath signals.The modified sidereal filtering used time-varying and site-dependent shifts to fully mitigate the multipath errors.It was shown that integrating the two techniques was more effective in improving the dynamic GPS accuracy than the traditional sidereal filtering.