Research On Regional Ionospheric Delays Model Based On GPS Observations

Ionospheric delay is the main error source of the GNSS in navigation, positioning and time transferring , it is a focus for people to influence the electromagnetic signal about ionospheric refraction delay, and also an emphasis to explore ionospheric physical reason and scout ionospheric disturbance. By measuring the changes in the time it takes for the GPS signals to arrive at the receiver as they travel through Earth's atmosphere, the people can derive some information about the Earth's ionosphere. So, the primary content of paper is as follows:1. The paper introduces the basic knowledge of ionospheric study by GPS, including ionospheric basic knowledge, the history and present of ionospheric study. And this paper described the data processing methods of getting ionospheric delay using dual-frequency observation of GPS. It described the method to deduct the hardware delay from TEC, introduced the ionosphere single layer model and Klobuchar model, VTEC polynomial model(POLY), Grid model, generalized trigonometric series function(GTSF) model, low degree and order spherical harmonic function(TSF) model etc. And then it introduce the way of how to make use of dual-frequency observations to set up ionosphere model in local area.2.By using the data, which is obtained from Hefei comprehensive service system of satellite positioning at on 5 Nov 2007, ionospheric delay model of VTEC polynomial model in small area is set up. And this paper analyzes the influence about parametre of this model to the precision. Finally summarize this paper, and put forward certain following research proposals.