Study On GNSS Signal Characteristic And Its Impact On Location Results In Electromagnetic Environment

The GNSS system is widely used in all walks of life because of its high precision,all-weather,high efficiency,multi-function,easy operation,no need to look through the station,and can provide three-dimensional coordinates.Navigation and positioning in traffic,automated deformation monitoring in large projects,precision agriculture,driverless technology,etc.With the development of economy and society,the electromagnetic environment is becoming more and more complex,such as: high-speed railway contact network,high-voltage transmission lines,etc.What is the impact of GNSS positioning results under strong electromagnetic environment? For this reason,this paper conducts experimental research on the influence of electromagnetic field on GNSS positioning,and explores the temporal and spatial distribution characteristics of GNSS positioning results in electromagnetic environment.The main research contents and work are as follows:1.The components of navigation signals of GNSS system are introduced,the indicators of quality inspection of original observations and its checking principle are discussed.The reliability of the quality inspection software of relevant observations is verified by the measured data.The multipath observation points are compared.Compared with the good observation conditions,the quality of the original observations decreases significantly,and can also be used to compare and analyze the quality of the point observations in the electromagnetic environment.2.The spatial distribution of electromagnetic field and radio interference intensity in the high-voltage transmission line is described.At the theoretical level,the possible influence on the carrier phase observation in the electromagnetic environment is analyzed,and the experimental scheme is proposed to verify.3.By changing the corresponding observation data obtained from the distance between the station and the different voltage and high voltage transmission lines,the observation data between different stations in the same observation period shows that the distance between the high-voltage lines decreases with multipath effect,signal-to-noise ratio and cycle-to-hop ratio.There is a trend of variation,and the range of influence of different voltage transmission lines is also different,and the range of influence increases with the increase of voltage.And because of the electromagnetic wave center frequency,the L1 link is affected less than the L2 link.4.Considering the single-difference residuals,it is very convenient to analyze the observation error characteristics of a single satellite.The deformation monitoring system(ADMAS)developed by the Southwest Jiaotong University Satellite Navigation and Positioning Research Center is used to solve the observation points in the electromagnetic environment and the GNSS outside the electromagnetic environment.The base station constitutes a short baseline,outputs the single difference residual value of each satellite,design experiments,accurately measures the positional relationship between the high voltage line and the measuring station,and combines the altitude angular azimuth to analyze the satellite signal passing through the power line area and the non-passing time period.The residual value is found to be reflected in the residual value when the signal passes through the 220 KV transmission line area,but the magnitude is small enough to be ignored.5.Based on the network RTK service software VENUS2.0 developed by the center,the network RTK positioning experiment was carried out and various softwares were used to solve static observation data in different voltage environments.It was found that the 35 KV and 220 KV high voltage transmission line areas failed to affect the GNSS positioning accuracy.After being processed by GNSS positioning service software,In the common electromagnetic environment,GNSS can still achieve high-precision positioning.The electromagnetic field generated by the high-speed rail contact network with lower rated voltage is less enough to affect the normal operation of the GNSS system.The GNSS positioning is applied to the high-speed rail positioning without worrying about the electromagnetic influence generated by the contact net.