INTRODUCTION

Communication -- the exchange of information from one point to another -- has existed since the dawn of human life, but the growth of science and technology over the last two centuries removed the "locational disadvantage" that once made long-distance exchange slow or impossible. The communication industry is one of the oldest and largest in the world: the telegraph arrived in 1844, the telephone in 1876, and radio in 1887, and the pioneering work of scientists such as J.C. Bose, G. Marconi and Alexander Graham Bell drove leaps and bounds of progress through the late nineteenth century, developing long-distance transmission in ever-shorter times. The twentieth century then layered on the demands of speed and secure data transfer, and today the Global Positioning System (GPS), satellite links, mobile networks and optical communication touch almost every economic sector with significant productivity gains. This unit builds up electronic communication from the ground: the need for and types of modulation; the elements of a communication system; bandwidth and antenna size; how electromagnetic waves actually propagate through space (ground wave, sky wave and space wave); satellite communication; fibre-optic communication; RADAR; mobile communication; the Internet; GPS; and, finally, how all of this technology is applied in fields as different as fishing, mining and agriculture.