The first edition of Satellite Communications was published in 1986, with the second edition following in 2003. There have been many changes in the 33 years since the first edition appeared, with a complete transition from analog to digital communication systems. The launch of satellites, once the province of government agencies, is now a thriving commercial business. By the time this third edition reaches the market, a number of private citizens will have entered the lower reaches of space as tourists. Analog transmission techniques have been replaced by digital modulation and digital signal processing. Spinner satellites have virtually disappeared, replaced by a much wider range of satellites from cubesats with mass less than 1 kg to large GEO satellites with mass exceeding 6000 kg. While distribution of television programming remains the largest sector of commercial satellite communications, earning approximately half of the worldwide revenue from satellite communication systems, low earth orbit constellations of satellites for internet access are set to challenge that dominance.
Satellite communication systems have made a very significant contribution to world economics and society. An international telephone call that cost US$1 per minute in 1960 could be dialed for less than US$0.02 per minute in 2000. Taking account of infla- tion, the cost of communications has been reduced by a factor of more than 1000, a claim that very few other services can make. Access to the internet will become avail- able to 3 billion people in countries that lack a terrestrial communication system as new constellations of LEO satellites are launched. Global satellite navigation systems help motorists to find their way to their destination and make travel by ships and aircraft safer. Two way television links via satellite enable news from anywhere in the world to be available 24 hours a day. Fiber optic systems have contributed significantly to these achievements, but satellite systems provide service wherever there is a need to broadcast to many locations. These contributions to quality of life have been made possible by the efforts of thousands of telecommunications engineers who design, produce, and main- tain the systems that allow us to communicate with almost anyone, anywhere. Rarely do these engineers receive credit from the general public for these achievements.