Modeling the impact of ionosphere composition on GNSS signal in a diurnal cycle

Abstract

Ionospheric layer creates an abrupt change in the state of radio signals as they pass through plasma density irregularity produced by the solar radiations of the sun. These irregularities cause the signals from satellite to be affected by ions and free electrons, resulting in changing the speed and accuracy of pseudorange and carrier phase measurements as well as losing the signal altogether. The Ionospheric composition is separated into three fundamental layers largely known as D, E and F regions. Where D region is the result of a solar flow created 60 to 90 km over the earth's surface. As the degree of ionization depends fundamentally on the sun, this layer disappears at night due to the rearrangement of ions and electrons. Due to the ionization in D layer at day time, a large pseudorange delay is produced and an inaccuracy of up to several meters in the end user position is seen as a result. However, at night when there is no effect of solar radiations, these signals are observed to give a smaller pseudorange delay and fairly good results. In this research paper, we have observed the change in ionospheric delays over a 24 hour period. The data is collected after every 30 minutes throughout this duration and we apply the Klobuchar's ionospheric model to determine the time delay problem by utilizing the eight ionospheric coefficients obtained from the satellite navigation message. The authenticity of pseudorange delay calculation is proved by simulation in this paper.