دانلود کتاب اثرات تروپوسفر و یونوسفر بر سیستم های ماهواره ای ناوبری جهانی

Global Navigation Satellite Systems (GNSS) have a range of applications that include not only navigation, but also mapping and surveying, satellite orbit determination, and a precisely synchronized global time reference. This book is focused on the atmospheric effects which impact the propagation of the signals transmitted from GNSS satellites in orbit to receivers on the ground. The book also covers various predictive models which seek to quantify such effects. In order to fully appreciate the limitations imposed by atmospheric propagation effects on GNSS performance and the design considerations that aim to address these effects, the first two chapters of this book provide an overview of GNSS. Chapter 1 introduces the Global Positioning System (GPS) in the role of an exemplary GNSS. System-level design and logistics of GPS are presented as a concrete example of how a typical GNSS operates. In particular, this chapter discusses the roles of the three major segments of the GPS system and a discussion of the GPS communication system, including the carrier frequencies and modulation scheme, ranging codes, and the so-called navigation message (i.e. the data modulated onto the GPS signal). Chapter 2 broadens the focus to include allmodern GNSS signals, and discusses the fundamentals of GNSS positioning. There are several ways to determine the position and velocity of a GNSS receiver based on the signals it receives from a GNSS constellation. Three main quantities, known as GNSS observables – pseudorange, carrier phase, and Doppler shift – are used in positioning and this chapter touches upon each of them. Each GNSS observable is modeled in a straightforward fashion, which makes mathematical analysis simple, but inaccurate – at least without error correction. Various sources of error, from atmospheric to relativistic effects, contribute some error to GNSS positioning. The most important of these effects, as well as common mitigation techniques, are discussed in this chapter. Finally, a derivation of GNSS positioning using pseudorange is presented, building upon the earlier concepts in the chapter.