Introduction
Two developments in the nineteenth and twentieth century changed the way people lived: the automobile and telecommunications. Prior to the widespread availability of personal automobiles, individuals had to travel on foot, by bicycle, or on horseback. Trains provided faster travel between cities, but most people's lives were centered on their home town and immediate surroundings. A journey of 100 miles was a major expedition for most people, and the easy mobility that we all take for granted in the twentyfirst century was unknown. Before the telegraph and telephone came into widespread use, all communication was face to face, or in writing. If you wanted to talk to someone, you had to travel to meet with that person, and travel was slow and arduous. If you wanted to send information, it had to be written down and the papers hand-carried to their destination.
Telecommunication systems have now made it possible to communicate with virtually anyone at any time. Early telegraph and telephone systems used copper wire to carry signals over the earth's surface and across oceans, and high-frequency (HF) radio made possible intercontinental telephone links.
The development and installation of optical fibers and optical transmission techniques has greatly. increased the capacity of terrestrial and oceanic links. Artificial earth satellites have been used in commu- nication systems for more than 50 years and have become an essential part of the world's telecommu- nication infrastructure. Satellites allow people to receive hundreds of television channels in their homes, either by receiving direct broadcast satellite television (DBS-TV) signals, or via cable TV from a satellite distribution center. Virtually all cable TV systems collect their signals from satellites that distribute television programming nationwide. Access to the Internet via satellite from areas that are not served by cable is also available, providing many people in rural areas with much faster service than can be achieved over telephone lines.