Re: Real-time sound cyphering algorithm

From: Jan Panteltje (pNaonStpealmtje_at_yahoo.com)
Date: 05/26/05

  • Next message: Joseph Ashwood: "Re: Real-time sound cyphering algorithm" 
    Date: Thu, 26 May 2005 18:47:51 GMT

    On a sunny day (Thu, 26 May 2005 07:49:39 -0400) it happened "John E.
    Hadstate" <jh113355@hotmail.com> wrote in
    <_Gile.32334$J25.13956@bignews6.bellsouth.net>:

    >
    >"Astier Anisse" <astier@ece.fr> wrote in message
    >news:slrnd9ba6s.pv5.astier@gandalf.ece.fr...
    >>
    >> I can't use any modem, because the purpose is to send the
    >> sound
    >> through the air.
    >>
    >
    >When you say "send the sound through the air", do you mean,
    >"transmit it over a radio" or do you literally mean "amplify
    >it and play it through a speaker"?
    >
    >If "transmit over a radio", you can still use a modem,
    >though maybe not an off-the-shelf modem.
    If 'through the air' you have more bandwidth :-)
    You could use a fake channel in the audio range, and an
    other channel, for example AM modulated, at 30 kHz.

    An other interesting experiment that I want to try some day is
    use a 40kHz power oscillator, a diode ring modulator, generate one double
    sideband signal and one carrier tone (with directional speakers).
    Normal audio amp output should be enough to drive a ring modulator
    via a transformer.

    Then where the sound crosses (that location both transducers point to)
    demodulation will happen if there is a non linear medium (like your ear
    \ head).

    I think somebody is already selling this as 'speaker less' Hi Fi, using
    very small ultrasound speakers.
    Maybe it is patented.

  • Next message: Joseph Ashwood: "Re: Real-time sound cyphering algorithm"

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