Frequency components in a singnal.

  1. Aug 12, 2010 #1
    From a book:

    "The waveform is distorted because of different amounts of attenuation and phase shift suffered by different frequency components of the signal"

    Question:

    If there are different frequency components in a single, how do the ratio channels operate on a single frequency. A channel, for example, operates on the frequency 101. How can this happen when the signal contains components of differing frequencies?

    Thanks.
     
  2. jcsd
  3. Aug 12, 2010 #2
  4. Aug 12, 2010 #3

    berkeman

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    Staff: Mentor

    The channel has some bandwidth, so that gives rise to different frequency components being in even a narrow-band signal.

    The bandwidth of each US FM broadcast radio station is 200kHz, in the band from 87.8 MHz to 108.0 MHz.

    http://en.wikipedia.org/wiki/FM_broadcasting

    .
     
    Last edited: Aug 12, 2010
  5. Aug 12, 2010 #4
    So, when we say ration station 106 (for example), we're talking about the Bandwidth. And Bandwidth means that this station/channel can be captured on all the frequencies in this band, right?
     
  6. Aug 12, 2010 #5
    Another related question: When we say that a certain broadband/DSL connection has a bandwidth of say, 1 Mbps, what does that mean?

    Thanks.
     
  7. Aug 12, 2010 #6

    berkeman

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    No, when you say FM radio station 98.5, that is the channel centered on 98.5MHz, with a bandwidth of 200kHz.
     
  8. Aug 12, 2010 #7

    berkeman

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    That means that the channel has enough bandwidth to support 1 million bits per second being transmitted through it (with an acceptably low bit error rate).
     
  9. Aug 12, 2010 #8
    Thanks.

    I bit confused about this. Does this mean that the channel is best transmitted at 98.5, but it can be transmitted, with a bit low quality, in the range of 200 kHz bandwidth?

    Thanks.
     
  10. Aug 12, 2010 #9

    berkeman

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    No, the transmitted FM signal is centered at 98.5MHz, with signal components (due to the frequency modulation) that extend out +/- 100kHz above and below the center frequency. Check out this info on modulation, and its relation to channel bandwidth:

    http://en.wikipedia.org/wiki/Modulation

    .
     
  11. Aug 12, 2010 #10
    Thanks a lot! It was really helpful! Taking first course in Analogue Communication. :)
     
    Last edited: Aug 12, 2010
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