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In radio communications, a radio receiver (commonly called a ''radio'') is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves (electromagnetic waves) and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation. The information produced by the receiver may be in the form of sound (an audio signal), images (a video signal) or data (a digital signal).〔(Radio-Electronics, ''Radio Receiver Technology'' )〕 A radio receiver may be a separate piece of electronic equipment, or an electronic circuit within another device. Devices that contain radio receivers include television sets, radar equipment, two-way radios, cell phones, wireless computer networks, GPS navigation devices, satellite dishes, radio telescopes, bluetooth enabled devices, garage door openers, and baby monitors. In consumer electronics, the terms ''radio'' and ''radio receiver'' are often used specifically for receivers designed to reproduce the audio (sound) signals transmitted by radio broadcasting stations, historically the first mass-market commercial radio application. ==Types of radio receivers== Various types of radio receivers may include: *Consumer audio and high fidelity audio receivers and AV receivers used by home stereo listeners and audio and home theatre system enthusiasts as well as audiophiles. *Communications receivers, used as a component of a radio communication link, characterized by high stability and reliability of performance. *Simple crystal radio receivers, also known as a crystal set, which operate using the power received from radio waves. *Satellite television receivers, used to receive television programming from communication satellites in geosynchronous orbit. *Specialized-use receivers such as telemetry receivers that allow the remote measurement and reporting of information. *Measuring receivers or measurement receivers are calibrated laboratory-grade devices that are used to measure the signal strength of broadcasting stations, the electromagnetic interference radiation emitted by electrical products, as well as to calibrate RF attenuators and signal generators. *Scanners are specialized receivers that can automatically scan two or more discrete frequencies, stopping when they find a signal on one of them and then continuing to scan other frequencies when the initial transmission ceases. They are mainly used for monitoring VHF and UHF radio systems. *Internet radio devices 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Radio receiver」の詳細全文を読む スポンサード リンク
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