Study on ionospheric delay in GPS standard positioning service

Recently, GPS standard positioning system (SPS) has been spreading rapidly for its confidence and usefulness, and now it is used in various situations. However application of GPS SPS is restricted because of its accuracy. It is known that the ionospheric delay affects accuracy of positioning. Since prediction of the ionospheric delay is difficult, it is not easy to improve the accuracy of GPS SPS. We investigated time course of ionospheric delay, and elevation dependence through the experiment and simulation. We improved 4 meters in the height measurement of GPS better than previous system by using Klobuchar model compared with the experiment.