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Our most commonly asked radio questions are:
 How does a radio work?
 What is the difference between AM radio and FM radio?
 What is unacceptable language for radio and television?
 What is Obscene Speech?
 Why do all FM radio stations end in an odd number?
 How does my pager work?
image of radioHow does a radio work?
Radio signals are made up of two kinds of waves: “audio” (or sound) waves represent the sounds being sent to the audience and radio frequency waves travel with these sound waves to "carry" them to radios in homes and car, for example. All waves have three parts: a wavelength, an amplitude and a frequency. Each of these parts can be changed to carry information.
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AM and FM radio waves What is the difference between AM radio and FM radio?
AM stands for “amplitude modulation” – a type of signal. With AM, the amplitude of the combined audio frequency and radio frequency waves varies to match the audio signal. AM radio can develop problems with interference. This makes it hard to hear the radio show. Interference can be caused by many sources. For example, sparks discharge when a car is started, in electric motors in all sorts of electrical appliances, and even lightning. All of these things can produce interference to AM radio. As you can see, there is a lot of background noise that changes the amplitude of the radio wave signal. This creates the random crackling noises call static.
FM stands for “frequency modulation”- a type of radio transmission, the frequency of the combined waves change to reproduce the audio signal. For example, higher frequency is associated with the peak amplitude in the audio wave. FM waves do not have a problem with interference because the noise background does not modify the radio wave frequency. In addition FM waves give better sound reproduction.

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What is unacceptable language for radio and television?
It is a violation of federal law to broadcast obscene programming at any time. It is also a violation of federal law to broadcast indecent programming during certain hours. Congress has given the Federal Communications Commission (FCC) the responsibility for administratively enforcing the law that governs these types of broadcasts. The Commission may revoke a station license, impose a monetary forfeiture, or issue a warning, for the broadcast of obscene or indecent material. www.fcc.gov/cgb/consumerfacts/obscene.html
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people swearing and fighting What is Obscene Speech?
Obscene speech is not protected by the First Amendment and cannot be broadcast at any time. To be obscene, material must meet a three-prong test: (1) an average person, applying contemporary community standards, must find that the material, as a whole, appeals to the prurient interest; (2) the material must depict or describe, in a patently offensive way, sexual conduct specifically defined by applicable law; and (3) the material, taken as a whole, must lack serious literary, artistic, political, or scientific value.
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Why do all FM radio stations end in an odd number?
FM radio stations all transmit in a band between 88 megahertz (millions of cycles per second) and 108 megahertz. The band is divided into 100 channels, each 200 kHz (0.2 MHz) wide. The center frequency is located at 1/2 the bandwidth of the FM Channel, or 100 kHz (0.1 MHz) up from the lower end of the channel. For example, the center frequency for Channel 201 (the first FM channel) is 88.0 MHz + 0.1 MHz = 88.1 MHz. So there can be a station at 88.1 megahertz, 88.3 megahertz, 88.5 megahertz, and so on. The 200-kilohertz spacing, and the fact that they center on odd numbers is completely arbitrary and was decided by the FCC. In Europe, the FM stations are spaced 100 kilohertz apart instead of 200 kilohertz apart, and they can end on even or odd numbers.
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image of pagerHow does my pager work?
A pager is like a FM radio that is tuned to one frequency. (The FCC assigns each paging company specific radio frequencies on which to broadcast their paging signals.) Your pager will "listen" for a unique code within this paging signal. When the code reaches you and your pager "hears" its signal, it decodes it and displays the numeric or word message for you. The frequency of a pager is not within the broadcast bands, and cannot be heard on a regular radio.
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On April 3, 1973, Martin Cooper made the first cellular phone call.



last reviewed/updated on 03/27/08 

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