China, Gps Neutral Atmosphere Zenith Delay The Research And Application

The troposphere ranges from ground level to about 40km in altitude. When GPS signal transmit from the atmosphere to receiver, the signal transmission delay caused by the troposphere can be about 2.3m at the zenith and about 20～25m at lower receiver-to-satellite elevation angles such as 10 degrees. So the troposphere delay is one of the major error sources in GPS/GNSS satellite navigation. For the purposed of application, the character of zenith troposphere delay(ZTD) in the region of China, the evaluate of precision about Hopfield,Saastamoinen and EGNOS tropospheric delay correction model are studied, and the local models of tropospheric delay correction of Chinese S/C tracking station is built in these thesis.The main contents of this thesis as followings:1 In order to study the ZTD of the region of China, the data of 30 stations from 1999 to 2004 obtained from Crustal Motion Observation Network of China(CMONC) are used. The annual, seasonal, monthly, diurnal and the distribution variations are discussed. The studies show that there is a very strong annual variation, the character of which(the swing and the average) is relate to the latitude and height of stations.; seasonal variation is obviously which is max in summer and min in winter; Through the study of monthly average, the ZTD in the south is bigger than in the north and it in the east is bigger than in the west(the major reason is the hypsography of the west is higher than east); The system differences between the day and the night isn't obviously.2 We evaluate the precision about Hopfield,Saastamoinen and EGNOS tropospheric delay correction model using the data of ZTD and meteorology obtained from IGS. The results show that if there is meteorological data, the precision of Saastamoinen model is highest; The precision of EGNOS model is as well as it of Hopfield model and Saastamoinen model. But if there isn't meteorological data (standard meteorological data), the precision of EGNOS model is better than Hopfield model and Saastamoinen model. So EGNOS model is a good choice if there isn't real time meteorological data. We also first discovered that the problem of Hopfield model: it isn't suitable to be used to correct the3 Because of the need of the EC-1,, we build a forecasting model on the basis of EGNOS model with the data obtained from COMOC. And then a real-time model is built on the basis of the forecasting model. The newly established model have been successfully tested and confirmed in ESA lunar orbit SMART-1 VLBI observation experiments.