The aim of this book is to give a clear and concise exposition of the principles of satellite communications. It is intended for newcomers to the design, provision, operation, management or use of communication satellites and should prove as useful to engineers as to students. Chapter 1 describes the development of communication-satellite systems and outlines the services that they provide. Chapter 2 deals in a simple but practical way with the physics and geometry of the geostationary orbit. Chapter 3 considers the factors which determine the radio-frequency (RF) carrier-to-noise power ratio at the receiving station. Chapter 4 discusses the relation between the RF carrier-to-noise power ratio and the baseband signal-to-noise power ratio in a system using frequency modulation, particular attention being given to television transmissions. Chapter 5 outlines the digital transmission methods used for satellite communication. Chapter 6 is devoted to systems serving moblie stations at sea, in the air and on land. Chapter 7 describes the most important characteristics of earth stations.