Study the Efficiency and Availability of GLONASS in Total Electron Content Mapping over Egypt

Abstract

Global Navigation Satellite Systems (GNSS) are used for positioning and navigation, so the precision of its observations are crucial. The ionosphere has a significant impact on GNSS observations causing the biggest error. The free electrons in the ionosphere affect the navigation signals having electromagnetic properties. The ionosphere error can be eliminated by calculating Total Electron Content (TEC) using dual frequency receivers. On estimating TEC, a systematic error which is device (satellite and receiver) dependent is found called differential code bias (DCB). This article provides an overview of two GNSS systems: the Global Positioning System (GPS) and the GLObal NAvigation Satellite system (GLONASS). Moreover, data from four regional receivers in Egypt are used to investigate the availability of GPS and GLONASS satellites over Egypt on May 10, 2015 by comparing them with four European International GNSS Services (IGS) stations on the same day. Furthermore, the TEC values are calculated on 2-hour temporal resolution over the 24 hours of the day and validated using IGS TEC products. The results show that GLONASS satellites are covering Egypt efficiently; GLONASS observations compose around 42% of the total number of GNSS observations. The calculated TEC in Egypt are found less than IGS products over the most hours of the day with differences between 0.04 to 9.40 TECU.