The second edition of this widely praised book offers a comprehensive introduction to GPS: the system, signals, receivers, measurements, and algorithms for estimation of position, velocity, and time. It is intended as a textbook for a senior- or graduate-level engineering course and a self-study guide for practicing engineers.The book is divided into four parts. Part I introduces the basic framework for a global navigation satellite system, including coordinate frames, time references, and satellite orbits, and provides an overview of GPS, GLONASS, and Galileo. Part II describes the fruits of GPS: estimation of position, velocity, and time. Part III discusses the ingenious structure of the GPS signals. Part IV introduces the signal processing steps required to extract the necessary measurements from these signals, and explores the challenges posed by signal blockage and RFI.