Research On GPS Signal-to-noise Ratio For Sea Level Change Monitoring

Sea level change directly affect the global weather and long-term climate evolution,which is a concerned important problem in environmental science.At the same time,sea level change is also an important content of geodynamics,dynamic geodetic survey and marine survey.It is related to the unity of global elevation datum and an important research content of modern space geodetic technology.With the deepening of GNSS(Global Navigation Satellite System)research and application,GNSS-MR(Global Navigation Satellite System Multipath Reflectometry)based on Multipath inversion technique is used for monitoring surface environmental(vegetation,soil moisture,snow depth,sea level,volcano,etc.)and has become a new means of remote sensing.Based on the relationship between GPS multipath and SNR,this paper studies the theory and method of GPS-MR technology to monitor the water surface change.The regional mean sea level is obtained by the GPS-MR technique and verify the feasibility of GPS SNR to monitor sea level changes.The main research contents and innovations are as follows:1.The causes of GPS multipath generation,the characteristics of time and space,and the influence on GPS antenna design are explored,and the polarization mode of GPS reflected signal and the reflection coefficient of reflection surface are studied.The concept of GPS SNR is given,and the characteristics and influencing factors of SNR sequence are analyzed.Based on this,the relationship between GPS multipath effect and signal to noise ratio is analyzed in detail.It is pointed out that The SNR in low altitude is seriously affected by multipath,so the GPS multipath also directly affects the change of GPS signal-to-noise ratio.Therefore,the surface environment parameters of reflector can be obtained through the SNR spectrum analysis,2.The basic principle of tide detection based on GNSS-MR technique is studied.The characteristics of the GNSS reflection signal reflected by different media are studied,and the criterion of the vertical reflection distance obtained by the LSP spectrum analysis is put forward.The area range of GNSS-MR is analyzed by the Fresnel reflection area.3.The function model of water level detection by GPS-MR technique based on SNR observation is studied.The selection of SNR residual sequence and the selection of effective satellite arc are discussed.The criteria for determining whether the vertical reflection high obtained by LSP spectrum analysis is valid is proposed and The range of sea level in GNSS station is analyzed by the theory of Fresnel reflector zone theory.In this paper,GPS-MR technique is used to invert the change of water level in the lake surface and the sea level.The validity of GPS-MR technology applied to water level monitoring is verified.In the lake and the sea inversion accuracy of different reasons.It is proved that the shore-based CORS(Continuously Operating Reference Stations)can be used as a supplement to the tide gauge.4.The basic theory of regional mean sea level acquisition is introduced.The method of obtaining regional mean sea level by GPS-MR is studied.It is proved that GPS-MR in mean sea level is highly accurate after compared with the tide gauge.So the technology can play the potential application value of shore-based CORS in the field of monitoring sea level change.