Remote sensing and its kindred technologies, such as geographic information systems (GIS), the Global Positioning System (GPS) etc. have a pervasive impact on the conduct of sciences, government and business alike. This book is designed to be primarily used in two ways: as a textbook in a very specialized field of remote sensing and a reference for the burgeoning number of practitioners who use space science and associated information of technology in the field of radio signal reception from terrestrial sources and the subsequent analysis as well as some popular applications involved in the process of cloud computing in their work. We have strongly emphasized radio signal data acquisition and analysis under different behaviors of the terrestrial sources, while retaining basic information about earlier sensors and methods from which one may also gather a vast amount of archival data exist, which may be considered increasingly valuable as a source for studies of long?term change.