Posted in: Musicouching by honeybadger1 on February 13th, 2012 | 0 Comments
Radio is a way to send information. It requires no wires or other physical connections. Instead, information travels on electromagnetic waves. Sound is the most familiar radio transmission. But radio can also transmit other types as well.
Communicating by radio involves three steps. First, sound is converted, or changed, into an electrical signal. Second, the signal is transmitted, or sent. Third, something must receive the signal.
Broadcast radio reaches large numbers of people. Programming includes music, news, and talk shows. These programs originate in broadcast studios. Radio stations transmit the broadcasts, which people listen to with radios receivers.
Two-way radios transmit as well as receive. They are vital for dispatching emergency workers. They allow pilots and astronauts to talk with ground controllers. Walkie-talkies are portable two-way radios. Citizens band (CB) radio is a public, two-way radio system. It is popular among truckers.
Radio is also important to the Global Positioning System (GPS). A GPS navigation unit receives radio signals from orbiting satellites. It uses them to calculate location. Radar is yet another inventive use of radio. It detects objects by bouncing radio waves off their surface. The echo reveals the objects’ location. Radio telescopes detect radio waves that occur naturally in space.
Today, many wireless devices employ radio signals. Cellular phones are a prime example. They send and receive signals from cell towers. Cordless phones send and receive signals from desktop bases. Some remote-control devices use radio. Radio can even link computers with devices such as printers.
In the United States the Federal Communications Commission (FCC) regulates the use of radio frequencies. It assigns each radio station a different channel. This reduces interference between signals. AM broadcasts operate from 525 to 1,700 kilohertz. FM stations use 88 to 108 megahertz. Shortwave radios use frequencies in between.
AM and FM refer to two types of radio transmission. The first is amplitude modulation. It involves varying the strength, or amplitude of electromagnetic waves. FM stands for frequency modulation. It involves varying wave frequency.
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Radio receivers pick up electromagnetic waves. Inside the receiver’s antenna, the waves produce electric current. When you tune to a station’s frequency, the radio amplifies its signal. Circuits transform the signal back into sound.
Stereo sound is more realistic. It is recorded with two or more microphones. It is played using two or more speakers. Stereo broadcasting transmits two channels on the same frequency. This is called multiplexing.
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Traditional radio broadcasting uses analog signals. Analog signals are similar, or analogous, to sound waves. In the 1990s, broadcasters began using digital transmission. Digital signals convert sound into binary code. (Binary code consists of 0s and 1s.) In the United States, digital signals are sent on the FM band, alongside analog signals.
Digital broadcasting produces clearer sound. It can also transmit additional information. Examples include text messages. They can tell you what song is playing or alert you to emergencies.
Satellite radio is beamed from orbiting satellites in space to the listener’s receiver. Unlike ordinary broadcast radio, satellite service involves a monthly fee. One advantage it has over traditional radio is its impressively clear reception, regardless of location. Satellite programming has very few, if any, commercials.
