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Radio, in which parameter is the information?

  1. Mar 19, 2006 #1
    When I listen to radio, then I know that the radio gets the information from electromagnetic radio waves. But in which parameter is the information of the song/news/output/whatever included?

    It can't be amplitude, since amplitude decreases with distance of obstruction, and the data most people receive is relatively identical.

    it can't be frequency/wavelength, since every channel has a constant frequency assigned to.
  2. jcsd
  3. Mar 19, 2006 #2
  4. Mar 20, 2006 #3


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    Staff: Mentor

    In the USA, each FM channel actually spans a frequency range of 0.2 MHz. For example, a station that broadcasts at 90.1 MHz actually uses frequencies between 90.0 and 90.2 MHz.


    The diagram on that page has a typographical error. FM Channel 202 should be labeled as 88.3 MHz.
    Last edited by a moderator: Apr 22, 2017
  5. Mar 20, 2006 #4


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    Gold Member

    AM = amplitude modulation
    FM = frequency modulation

    Remember that the radio freq is a carrier wave. This means that the (AM)680kHz wave or (FM)107.1 MHz wave is modulated to provide a much lower normal humans range signal riding on top.

    FM = the frequency of the carrier is modulated to carry sounds in the normal human range
    AM = the amplitude of the carrier is modulated to carry sounds in the normal human range
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