1. Earth’s Ionosphere and Electromagnetic Signal Propagation

This chapter provides a comprehensive overview of the Earth’s ionosphere and its influence on electromagnetic signal propagation, particularly focusing on Global Navigation Satellite System (GNSS) signals in the L- and S-bands. The chapter begins by examining the structure and dynamics of the Earth’s atmosphere, discussing various models and their real-world applications in atmospheric research. It delves into the intricacies of spread-spectrum signals, analyzing signal structures and generation, with a detailed look at main global positioning system (GPS), GLObal NAvigation Satellite System (GLONASS), Galileo, and BeiDou signals. The propagation of electromagnetic waves is explored through the lens of Maxwell’s equations, highlighting the impact of the troposphere and ionosphere on GNSS signals. This section includes in-depth discussions on different tropospheric delay models and algorithms. The chapter culminates with a thorough analysis of ionospheric models, including single- and multi-layer models, grid models, and a study of ionospheric irregularities. Additionally, this chapter introduces the further development of the scintillation split-beam model, developed by the author. It also examines the potential of strange attractor codes as an alternative to currently used GNSS codes, which are based on traditional and memory code approaches. This exploration provides new insights into the evolving landscape of GNSS signal processing and ionospheric modeling.