Consumer Electronics

CHAPTER 37

TELECOMMUNICATION SYSTEMS

Telecommunications is defined as the technology concerned with communicating at a distance. The first requirement is for the original form of energy (human voice, music, or a telegraph signal) to be converted into electrical form to produce an electronic information signal. This is achieved by a suitable transducer, a device that converts energy from one form to another. In a telephone system, the transmitted signals are replicas of the speech waveforms. Digital signals consist of discrete pulses of voltage or current which represent the information to be processed. Digital voltages can vary only in discrete steps; normally only two voltage levels are used, so that two-state devices can be employed. A ...