Investigation of Ionospheric Total Electron Content (TEC) During Summer Months for Ionosphere Modeling in Indian Region Using Dual-Frequency NavIC System Sharat Chandra Bhardwaj, Anurag Vidyarthi, B. S. Jassal, and A. K. Shukla Abstract When signals from satellites propagate through the ionosphere, a delay is introduced due to the presence of Total Electron Content (TEC) between trans- mitter and receiver. The generation of TEC in the ionosphere is primarily dependent on solar activity (Diurnal and Seasonal). The ionospheric delay can cause a major degradation in the positional accuracy of the satellite navigation system. For the esti- mation of ionospheric delay, slant TEC (STEC) along the path between satellite and receiver is needed. For a single-frequency user, a modeled ionospheric vertical TEC (VTEC) at Ionospheric Pierce Point (IPP) is converted into STEC for delay estima- tion. However, the behavior of TEC is highly dynamic in low-latitude and equatorial regions (Indian region), and thus conventional ionospheric model introduces addi- tional error in positioning. The NavIC (Navigation with Indian Constellation) system geostationary satellite constellation is uniquely capable of the investigation of iono- spheric TEC, and it can facilitate for ionospheric modeling applications. This paper deals with estimating of accurate STEC and VTEC using dual-frequency NavIC code and carrier measurements, and investigation of its temporal variation for modeling applications. Keywords Total Electron Content (TEC) · STEC · VTEC · Ionospheric delay · NavIC · Ionospheric modeling S. C. Bhardwaj (B ) · A. Vidyarthi · B. S. Jassal Propogation Research Laboratory, Department of Electronics and Communication, Graphic Era (Deemed to be University), Dehradun, India e-mail: bhardwaj.sharat@gmail.com A. Vidyarthi e-mail: dr.anuragvidyarthi@ieee.org B. S. Jassal e-mail: bsjassal@yahoo.co.in A. K. Shukla Space Applications Center, Indian Space Research Organization, Ahmedabad, India e-mail: ashish@sac.isro.gov.in © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021 D. Gupta et al. (eds.), International Conference on Innovative Computing and Communications, Advances in Intelligent Systems and Computing 1166, https://doi.org/10.1007/978-981-15-5148-2_8 83