Total electron content obtained by using the global positioning system

A procedure is introduced to obtain the balance of measurements of differential group delays and differential carrier phase lead characteristics, both phenomena being due to the ionospheric total electron content (TEC) along the ray path from a Global Positioning System (GPS) satellite. It has been demonstrated that utilizing the measurement of both pseudorange and carrier phase recorded by genetic GPS receivers, the precision of the vertical TEC derived when the anti-spoofing (AS) is on can be as good as that derived when it is off. Combining the data of a network of four GPS receivers, a TEC map is reconstructed which can be employed to examine the ionospheric latitude/longitude structure and dynamics in the Taiwan area.