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AM and FM frequencies

  1. May 15, 2012 #1
    Hello, looking at the attached graph of noise voltage to frequency, I am trying to understand (from a noise point of view) why AM and FM broadcasts at the frequencies they do ?

    Can anyone offer any suggestions please ?

    Thank you.

    Attached Files:

    Last edited: May 15, 2012
  2. jcsd
  3. May 16, 2012 #2


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  4. May 16, 2012 #3


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    Staff: Mentor

    Everything is a compromise. AM frequencies were probably chosen to exploit the extended over the horizon range provided by bending and reflections, while keeping to a manageable antenna size.
  5. May 17, 2012 #4
    FM has a better signal to noise ratio, so it looks like it is in a place with higher noise (to make use of its resilience toward noise -- it would be a waste to use it between 1k to 10M). AM seems situated in the dip since it isn't particularly resilient against noise.
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