Radio station

A radio station is a set of equipment necessary to carry on communication via radio waves. Generally, it is a receiver and/or transmitter, an antenna, and some smaller additional equipment necessary to operate them. Radio stations play a vital role in communication technology as they are heavily relied on to transfer data and information across the world.

More broadly, the definition of a radio station includes the aforementioned equipment and a building in which it is installed. Such a station may include several "radio stations" defined above (i.e. several sets of receivers and/or transmitters installed in one building but functioning independently, and several antennas installed on a field next to the building). This definition of a radio station is more often referred to as a transmitter site, transmitter station, transmission facility or transmitting station. An example of this definition is Bethany Relay Station of the Voice of America which had seven broadcast transmitters and could broadcast up to seven independent programs (even produced by different broadcasters) simultaneously, as well as several communications transmitters and receivers.

Radio broadcasting

Radio broadcasting is a unidirectional wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both. Audio broadcasting also can be done via cable radio, local wire television networks, satellite radio, and internet radio via streaming media on the Internet. The signal types can be either analog audio or digital audio.

In 2009, there were 3,494 radio broadcasting stations in the United States.

History

The earliest radio stations were simply radiotelegraphy systems and did not carry audio. For audio broadcasts to be possible electronic detection and amplification devices had to be incorporated.

The thermionic valve was invented in 1904 by the English physicist John Ambrose Fleming. He developed a device he called an "oscillation valve" (because it passes current in only one direction). The heated filament, or cathode, was capable of thermionic emission of electrons that would flow to the plate (or anode) when it was at a higher voltage. Electrons, however, could not pass in the reverse direction because the plate was not heated and thus not capable of thermionic emission of electrons. Later known as the Fleming valve, it could be used as a rectifier of alternating current and as a radio wave detector. This greatly improved the crystal set which rectified the radio signal using an early solid-state diode based on a crystal and a so-called cat's whisker. However, what was still required was an amplifier.

Radio

Radio is the use of radio waves is to carry information, such as sound, by systematically modulating some property 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 vice versa. An antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual stations 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 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.

Track

Track or Tracks may refer to:

Electronics and computing

Entertainment

Hip hop

Hip hop or hip-hop is a sub-cultural movement that formed during the early 1970s by African-American and Puerto Rican youths residing in the South Bronx in New York City. It became popular outside of the African-American community in the late 1980s and by the 2000s became the most listened-to musical genre in the world. It is characterized by four distinct elements, all of which represent the different manifestations of the culture: rap music (oral), turntablism or DJing (aural), b-boying (physical) and graffiti art (visual). Even while it continues to develop globally in myriad styles, these four foundational elements provide coherence to hip hop culture. The term is often used in a restrictive fashion as synonymous only with the oral practice of rap music.

The origin of the hip hop culture stems from the block parties of the Ghetto Brothers, when they plugged in the amplifiers for their instruments and speakers into the lampposts on 163rd Street and Prospect Avenue and used music to break down racial barriers, and from DJ Kool Herc at 1520 Sedgwick Avenue, where Herc mixed samples of existing records with his own shouts to the crowd and dancers. Kool Herc is credited as the "father" of hip hop. DJ Afrika Bambaataa of the hip hop collective Zulu Nation outlined the pillars of hip hop culture, to which he coined the terms: MCing or "Emceein", DJing or "Deejayin", B-boying and graffiti writing or "Aerosol Writin".