Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.
Radio systems need a transmitter to modulate (change) some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation (which can be frequency modulation or phase modulation). Radio systems also need an antenna to convert electric currents into radio waves, and radio waves into an electric current. An antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual frequencies to be selected. The electromagnetic wave is intercepted by a tuned receiving antenna. A radio receiver receives its input from an antenna and converts it into a form that is usable for the consumer, such as sound, pictures, digital data, measurement values, navigational positions, etc. Radio frequencies occupy the range from a 3 kHz to 300 GHz, although commercially important uses of radio use only a small part of this spectrum.
Amateur radio or ham radio is a hobby that is practised by over 16,000 licensed users in India.
Licences are granted by the Wireless and Planning and Coordination Wing (WPC), a branch of the Ministry of Communications and Information Technology. In addition, the WPC allocates frequency spectrum in India. The Indian Wireless Telegraphs (Amateur Service) Rules, 1978 lists five licence categories:
To obtain a licence in the first four categories, candidates must pass the Amateur Station Operator's Certificate examination conducted by the WPC. This exam is held monthly in Delhi, Mumbai, Kolkata and Chennai, every two months in Ahmedabad, Nagpur and Hyderabad, and every four months in some smaller cities. The examination consists of two 50-mark written sections: Radio theory and practice, Regulations; and a practical test consisting of a demonstration of Morse code proficiency in sending and receiving. After passing the examination, the candidate must clear a police interview. After clearance, the WPC grants the licence along with the user-chosen call sign. This procedure can take up to one year. This licence is valid for up to five years.
Each licence category has certain privileges allotted to it, including the allotment of frequencies, output power, and the emission modes. This article list the various frequencies allotted to various classes, and the corresponding emission modes and input DC power.
Bakelite radio at the Bakelite Museum, Orchard Mill, Williton, Somerset, UK.
An audio signal (top) may be carried by an AM or FM radio wave.
A Fisher 500 AM/FM hi-fi receiver from 1959.
2008 Pure One Classic digital radio
Radio communication. Information such as sound is converted by a transducer such as a microphone to an electrical signal, which modulates a radio wave sent from a transmitter. A receiver intercepts the radio wave and extracts the information-bearing electronic signal, which is converted back using another transducer such as a speaker.
Degen DE1103, an advanced world mini-receiver with single sideband modulation and dual conversion
BBC Radio 2 is one of the BBC's national radio stations and is the most popular station in the UK. It broadcasts throughout the UK on FM radio between 88 and 91 MHz from its studios in Western House, adjacent to Broadcasting House in central London. Programmes are also relayed on DAB, Sky Digital, Cable TV, Freeview and the Internet.
The station started at 7:00am on September 30, 1967, and succeeded the Light Programme, with some of the Light's music shows transferring to the newly-launched Radio 1. The first show however had actually started at 5.30am (on the Light programme) but continued on with Breakfast Special from Paul Hollingdale as Radio 1 split off.
||Nobody seems to know yet how television is going to affect the radio, movies, love, housekeeping or the church, but it has definitely revived vaudeville.
Fred Allen (born John Florence Sullivan on May 31, 1894 in Cambridge, Massachusetts, died March 17, 1956 in New York City) was an American comedian whose absurdist, pointed radio show (1934-1949) made him one of the most popular and forward-looking humorists in the so-called classic era of American radio.
His best-remembered gag may be his long-running mock feud with friend and fellow comedian Jack Benny. Allen has been considered one of the more accomplished, daring and relevant humorists of his time. A master ad libber, he constantly battled censorship and developed routines the style and substance of which influenced future comic talents. Perhaps more than any of his generation, Fred Allen wielded influence that outlived both his contemporaries and the medium that made him famous.
- Radio December 12, 2006 "...to create, expand, and maintain popflock.com resource articles related to radio, including radio propagation and reception, radio programming, radio personalities, and the business of radio." (Example: Mutual Broadcasting System)
- Amateur Radio August 24, 2006 "...to improve Wikipedia's articles related to Amateur radio, maintain the amateur radio category and its sub-categories for clean organization, and to produce and maintain templates for Amateur radio-related topic identification." (Example: Amateur radio)
- Radio Stations February 15, 2005 "...to coordinate the activities of creating and maintaining articles about radio stations." (Example: Pulse FM Kingborough & Huon)
- Podcasting January 21, 2007 "...to make Wikipedia's knowledge of notable Podcast and podcast-related information as complete as possible." (Example: Podcast)
||Music radio, Old-time radio, Radio comedy, Radio documentary, Radio drama, Top 40
||BBC Radio, Blue Network, Columbia Broadcasting System, Mutual Broadcasting System, National Broadcasting Company, Sirius Satellite Radio, XM Satellite Radio
||Fred Allen, Gracie Allen, Don Ameche, Jack Benny, Edgar Bergen, Jagadish Chandra Bose, George Burns, Ronald Colman, Jim Connors, Frank Conrad, Norman Corwin, Frankie Crocker, Alice Faye, Stan Freberg, Vaughn Harper, Phil Harris, Bob Hope, Hal Jackson, Spike Jones, Hans von Kaltenborn, Kay Kyser, Frances Langford, Guglielmo Marconi, Elizabeth McLeod, J. Carrol Naish, Ozzie Nelson, Arch Oboler, Dorothy Parker, Virginia Payne, Harold Peary, David Sarnoff, Red Skelton, Kate Smith, Howard Stern, Nikola Tesla, Jonathan Toubin, Lurene Tuttle, Rudy Vallée, Fred Waring, Orson Welles
||Abbott and Costello, Amos 'n' Andy, Arch Oboler's Plays, Burns and Allen, Cavalcade of America, CBS Radio Mystery Theater, Dragnet, Duffy's Tavern, Fibber McGee and Molly, The Goldbergs, The Howard Stern Show, Inner Sanctum Mysteries, The Jack Benny Program, Life with Luigi, Lights Out, Lux Radio Theater, Opie and Anthony, The Archers, The Hitchhiker's Guide to the Galaxy, The Phil Harris-Alice Faye Show, Quiz Kids, The Screen Guild Theater, The Shadow, Suspense, Theater Guild on the Air, Twenty Questions, The Whistler, Yours Truly, Johnny Dollar
||Amateur radio, AM broadcasting, FM broadcasting, International broadcasting, Internet Radio, Digital Radio Mondiale, HD Radio, Digital Audio Broadcasting and GNU Radio, Software-defined radio, Transistor radio, Vacuum tube