Receiver (radio)
From Free net encyclopedia
In radio terminology, a receiver is an electronic circuit that receives a radio signal from an antenna and decodes the signal for use as sound, pictures, navigational-position information, etc. Radio and radio receiver are often used specifically for receivers whose output consists only of sound, although other types of receivers, such as television receivers, are technically radio receivers as well.
As an appliance, "receiver" refers to a tuner, a preamplifier, and a power amplifier in chassis. Audiophiles will refer to such a device as an integrated receiver, while a single chassis that implements only the receiver function is called a discrete receiver.
A radio receiver is a real world example of a receiver in the information theoretic sense.
Most older receivers also came with a loudspeaker (see photo). Today it is a common component in a high-fidelity or home-theatre system. The receiver is generally the nerve centre of a sophisticated home-theatre system providing selectable inputs for a number of different audio components like turntables, compact-disc players, and tape decks and video components like video-cassette recorders, DVD players, video-game systems, and televisions. With the decline of vinyl discs and magnetic tape recorders, modern receivers tend to omit inputs for turntables and cassette decks. They may provide signal processors to give a more realistic illusion of listening in a concert hall. Digital audio S/PDIF connections are also common today.
Some modern integrated receivers can send audio out to seven loudspeakers and an additional channel for a subwoofer and often include connections for headphones. Receivers vary greatly in price, support stereophonic or surround sound, and a high-quality unit can be relatively inexpensive—$200 US or less. Because modern receivers are purely electronic devices with no moving parts unlike electromechanical devices like turntables and cassette decks, they tend to offer many years of trouble-free service. In recent years, the home theater in a box has become common, which often integrates a surround-capable receiver with a DVD player. The user simply connects it to a television, perhaps other components, and a set of loudspeakers.
Self-powered radios (clockwork radio) with a hand-cranked generator are used in developing nations or as part of an emergency/disaster preparedness kit.