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Dog whistles and cell phones.

Discussion in 'Electronic Basics' started by Gunluvver2, Dec 9, 2003.

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  1. Gunluvver2

    Gunluvver2 Guest

    If a dog whistle is blown near a cell phone could a dog in the area of a
    receiving cell phone hear the ultrasonic sound from the cell phone? I know it
    is a crazy question but I read this in a mystery story I read recently. Can
    ultra sound be transmitted over cell phones or regular phones and heard on the
    other end or registered on instruments that detect ultrasound?
    TIA
    DL
     
  2. No. Wired telephone networks use narrow bandpass filtering on the signals,
    the maximumj frequency they can transmit is around 5kHz I think. I imagine
    cellphones are not much different, and even if they are building a phone
    network to transmit inaudibly high pitched signals would just be stupid,
    don't you agree? Capability to transmit higher frequencies means wider
    bandwidth means more expense and complexity with no real benefits to the
    cell company or customer.

    So no.
     
  3. Gunluvver2

    Gunluvver2 Guest

    No. Wired telephone networks use narrow bandpass filtering on the signals,

    Thank you for the answer. I suspected that might be the case but since I know
    absolutely Zilch about electronics I wasn't sure. I guess the author of that
    story knew just about as much as I do. But it did make for a good story.
    DL
     
  4. Extremely unlikely. I would say that the author of that mystery
    story didn't do their homework.

    The typical telephone passband for voice, no matter if it's wired,
    wireless, or two tin cans and a string, has been spec'd for decades at
    300-3000Hz. Anything above that top end gets sharply attenuated.



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  5. Steve

    Steve Guest

    voice communications bandwidth is generally accepted to be 300Hz to
    3.4kHz.

    Dog whistles range from 5kHz to 12kHz or thereabouts. Not quite
    ultrasound. Apparently some believe dogs can hear up to 65kHz!
     
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