Radio (wireless communication and broadcasting)
Radio is the transmission and reception of information by electromagnetic waves. It enables broadcasting, two-way communication, navigation and remote control across many frequency bands.
Overview
Radio is a method of sending information through space using electromagnetic waves at frequencies typically from a few kilohertz up to many gigahertz. The basic components are a transmitter that encodes and radiates a signal and a receiver that detects and decodes it; many devices combine both functions as a transceiver. When a single transmitted signal is intended for many listeners it is called a broadcast. Radio carries a wide range of content, from spoken words and music to data and control instructions.
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How radio works
At the simplest level a transmitter converts information—voice, music or digital data—into variations of a carrier wave. These variations may be in the wave's amplitude, frequency or phase; common early methods were AM (amplitude modulation) and FM (frequency modulation). An antenna launches the modulated carrier into space as electromagnetic signals, which travel at nearly the speed of light. A receiver's antenna captures a portion of that energy and electronics extract the original information, which is then converted back into sound, images or data. Some modern systems also use digital modulation techniques that pack data more efficiently and resist interference.
History and development
Discoveries in the late 19th and early 20th centuries showed that oscillating electric currents produce waves that travel through space; engineers and inventors then developed ways to generate, amplify and detect those waves for communication. Early radio was used for ship-to-shore telegraphy, later expanding into public broadcasting, two-way mobile communication and, eventually, digital wireless services. Television used radio-frequency techniques to carry picture and sound signals as well; see television for the related technology.
Common uses and examples
- Broadcasting: AM and FM radio stations transmit news, music and talk programs to the public.
- Two-way communication: walkie-talkies, amateur (ham) radio and marine/aviation radios allow real-time exchanges.
- Navigation and timing: systems such as beacons and satellite navigation rely on radio signals to provide location and clock information.
- Control and telemetry: remote control of model aircraft, keyless entry for cars, and telemetry links for satellites use radio links; see radio control.
- Wireless data: Wi‑Fi, Bluetooth and cellular networks also use radio-frequency communications to carry digital data.
Regulation, bands and distinctions
Radio spectrum is a finite resource managed by national and international regulators to prevent interference and to assign bands for particular services. Frequencies are grouped into bands—longwave, mediumwave, shortwave, VHF, UHF and microwave—each with different propagation characteristics. Long wavelengths can travel far by following the Earth's surface or reflecting off the ionosphere; higher frequencies often require line-of-sight but support higher data rates. Modern distinctions include analog versus digital modulation, narrowband voice channels versus wideband data channels, and licensed versus unlicensed spectrum.
Notable facts and practical considerations
Radio waves are ubiquitous in daily life and are the backbone of many modern systems. Sound and audio programs are commonly carried by radio; for an explanation of audio transmission see sound-related techniques. Different modulation schemes and engineering choices balance range, fidelity, robustness and spectrum efficiency. For introductory and technical references consult overview pages on electromagnetic theory and radio practice: information about radio and related standards are available from educational and regulatory sources.
Radio technology continues to evolve: digital broadcasting, software-defined radios, and cognitive radio techniques allow more flexible use of spectrum and more robust services. For further background and practical guides, explore the linked resources and introductory materials on wireless communication and broadcasting.
Language
Historically, the terms "radio", "Rundfunk" and "broadcasting" competed at the beginning of broadcasting in Germany. In 1924, "broadcasting" was written in brackets after "Rundfunk" in letters from Austrian authorities. The Reichspostverwaltung in Berlin rejected the buzzword "radio". Radio, they said, was nothing more than a beam. At that time, the Reichspost acted as a guardian of language. For example, it banned the words "poste restante" and "recommanded letter" from its correspondence. So their vote against the word radio carried weight.
In common German it means the radio, derived from the radio set. In Central and Northern Germany it is always a neuter. In Southern Germany, Austrian German and Swiss High German, the radio is also common, derived from the radio apparatus.
Furthermore, both in German-speaking countries and in global usage, the word "radio" denotes a radio or radio station or a chain of stations such as Radio Bremen, Swiss Radio and Television or Radio Canada International. The short form "radio" is always neuter in this meaning, unless a compound noun is formed that requires otherwise (such as "the radio station").
Classification as a radio receiver
In Germany, a radio is a radio receiver within the meaning of the German Interstate Broadcasting Treaty, i.e. a 'technical device which is suitable for the wireless or wire-bound, non-time-delayed listening or viewing or recording of radio broadcasts (radio and television)'.
Questions and answers
Q: What is radio?
A: Radio is a way to send electromagnetic signals over a long distance, to deliver information from one place to another.
Q: What is a transmitter?
A: A transmitter is a machine that sends radio signals.
Q: What is a receiver?
A: A receiver, also known as an antenna, is a machine that "picks up" radio signals.
Q: What is a transceiver?
A: A transceiver is a machine that performs both the functions of a transmitter and a receiver.
Q: What is a broadcast?
A: When radio signals are sent out to many receivers at the same time, it is called a broadcast.
Q: How is sound sent through radio?
A: Sound can be sent through radio, sometimes through Frequency Modulation (FM) or Amplitude Modulation (AM).
Q: What are some examples of things that can be controlled using radio signals?
A: Airplanes and cars are examples of things that can be controlled using radio signals.
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AlegsaOnline.com Radio (wireless communication and broadcasting) Leandro Alegsa
URL: https://en.alegsaonline.com/art/80765