Study On GNSS Signal Dust Influence Analysis And Sand Sensing Method

With the development and application of GNSS technology,higher requirements for GNSS signal interference elimination are put forward.GNSS signals will pass through the ionosphere and troposphere when propagating in atmospheric space.Due to the ionization characteristics of ionospheric,the phase,polarization and propagation time of GNSS signal are greatly affected.In the troposphere,GNSS signals are affected by the weather environment such as haze,dust and moisture in the near-surface aerosol,which scatter the signals and lead to attenuation and delay.The scattering field of locally charged spherical sand particles is derived based on Rayleigh scattering theory and Mie scattering theory,and the applicability of the two theories are discussed.Based on the single scattering theory,the theoretical solution of multiple scattering of sand particle system is generalized.Combining the two theories,the physical model and method which can be used to solve the multiple scattering effect of charged sand particle in sandstorm is established.On the basis of scattering model,the relationship between visibility and dust concentration is introduced to illustrate the extent of attenuation affected by dust scattering.The propagation of GNSS signals in space through different mediums,namely the ionosphere and troposphere,is studied.Based on the analysis of the ionospheric distribution and signal transmission model,the delay and attenuation caused by the ionospheric signal were eliminated,and the troposphere delay model containing floating dust was constructed by referring to the existing model.This study provides a hypothesis for the equivalent refraction phenomenon of path bending.That is,when sandstorms occur,the aerosol dielectric constant is changed due to the sand particles in the air,and the signal propagation speed is changed.According to Fermat’s theorem,the atmospheric refraction index is also changed,resulting in additional delay.Based on the tropospheric delay model and the meteorological data in Shaanxi province,a new refractive index correction model with tropospheric wet delay as unknown parameter is proposed.Based on the elimination of tropospheric attenuation,the reflectance of GNSS signals reflected from desert surface was studied.The emissivity changes with different surface water content and sand-soil ratio are discussed.In the AIEM model,the emissivity of1.4GHz GNSS signal with two polarization forms changes in the horizontal altitude Angle.Effect of surface roughness on inversion accuracy;The observation and inversion results of desert measurement parameters are obtained.In the AIEM model,the emissivity of1.4GHz GNSS signal with two polarization forms changes in the horizontal altitude Angle.The physical structure of sandy land,the measurement and observation parameters of desert are obtained.