Imaging of Ionospheric Electron Density Profile Over the Visakhapatnam Region for GPS Precise Position Applications

The electron density profile of the Ionosphere is one of the extreme interests of the Radio navigation and positioning communities. For Global Positioning System users in particular, the unknown distribution of electrons in the ionosphere is the single largest natural error source in the position fix. The GPS navigation solution is significantly affected by the refraction of the GPS signal in atmosphere. This refraction of the ionosphere causes an error of 10-30m. This refraction of the GPS signal in the atmosphere especially in ionosphere is due to the presence of electrons. With the aid of local differential corrections this error term may be eliminated. However, it is better to provide the user with real-time representation of the user-local ionosphere in order to provide the GPS signal correction at the receiver. This real time representation of the local ionosphere electron density can be achieved by several models such as spherical harmonic analysis, Tomography, International Reference Ionosphere etc. In this paper, using Spherical Harmonic analysis, Image of the electron density profile of the atmosphere is estimated over the Visakhapatnam (Lat: 17042‟00‟‟ N and Long: 83018‟00‟‟) region for the entire day of 13th January 2013. Along with electron density profile, Total Electron Content of the entire day of 13th January 2013 is also estimated and analyzed.