Study And Application Of The Ionosphere Modeling Based On GNSS System

The ionospheric delay error is a major error source of the GNSS system. The ionospheric delay can cause the carrier phase signal advanced movement and cause the pseudorange signal delayed movement. The error caused by the ionospheric delay can reach several meters to dozens of meters. It is especially important for single frequency GNSS users to correct the ionospheric delay errors. Because of the complicated structure of the ionosphere, application of the multi-GNSS system can improve the reliability of the ionospheric study on global and regional scale. The influence factors of the global and regional ground based ionosphere modeling are mainly studied in this paper. The main contents of the research are as follows:1. Study on global ionosphere modeling. In this part, the ionosphere modeling strategies were studied. The differences of ionosphere modeling between the use of single GPS system and the use of GPS+GLONASS system were analyzed. And the influence factors of the two strategies were analyzed.2. Study on regional ionosphere modeling. In this part, the ionosphere modeling of three different regions was studied. And the effect of the station number was studied.3. Design and implementation of the ionosphere interpolation software. According to the acquirement of the ionosphere analysis, the ionosphere interpolation software was designed and implemented.4. Ionosphere anomalies analysed before the Nepal 4.25 earthquake. Studies and analysises were taken to the ionosphere anomal changes before the earthquake.According to the study of this paper, the differences of the ionosphere modeling between the use of single GPS system and the use of GPS+GLONASS system are minor. And the GPS+GLONASS results are more closely to the CODE results. The accuracy of the two strategies is about 2 TECU compared to CODE results. According to the study of the regional ionosphere modeling, the station number has an effect on the ionosphere modeling. The accuracy of the ionosphere modeling improves as the station number increases and finally tends to be steady.