Ultrasonic communicator!

Discussion in 'General Electronics Chat' started by eman12, Mar 29, 2009.

  1. eman12

    Thread Starter Active Member

    Oct 26, 2007
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    0
    Hi,

    I just want to transmit my voice by a T-type ultrasonic sensor and then let another guy to hear the said voice by another R-type ultrasonic sensor at say 1 to 2 meters away.
    So the receiver consists of a R-ultrasonic sensor and a headphone..

    Can somebody direct me how to do so please?

    I do not know what phrase I should google!?
    Thanks in advance.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    I believe to pull this off, you are going to need to either amplitude modulate the ultransonic tone with your voice or you will need to frequency modulate the ultrasonic tone with your voice.

    Does that sound like what you are looking for?

    The fidelity of such a link may not be as good as you would like it to be. Keep in mind that the frequency of ultrasonics is not conducive to modulation at audio frequencies. At least for audio frequencies above 2KHz or 3KHz.

    hgmjr
     
  3. eman12

    Thread Starter Active Member

    Oct 26, 2007
    41
    0
    Thanks sir for your help.

    Is the modulation the only way to do so?

    I am looking for all options which I can use, then I will choice the best.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Those are the ones that I am aware of. Do you have any ideas you have found from other sources?

    hgmjr
     
  5. eman12

    Thread Starter Active Member

    Oct 26, 2007
    41
    0
    No unfortunately, I have no idea from any other source. This forum is the first one I selected to ask the said question.

    My own idea was to adding or multiplying the 40KHZ signal with that voice. That was the only way I thought of. But I would like to know if there is any other option to go with. hope somebody could help me for other options, otherwise I'll go for modulation
     
  6. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    After additional consideration, I have concluded that the easy approach to implement is amplitude modulation.

    In searching the internet, I encountered a number of patents that addressed the use of ultrasonics as the carrier in an audio transmission scheme. I was unable to view any of them so they did not do me much good.

    I don't know what your technical background is and I would be the last person to discourage you in undertaking such a project. I will saty that this is a challenging project to be sure. Regardless of your background I would get as much information as you can find from as many sources as you can locate so that you will have the greatest likelihood of success.

    hgmjr
     
  7. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    telephone quality used to be about 500Hz-4kHz. Amplitude Modulation would be too difficult, as the range makes very wide swings.

    A good link could only be established for about 30 feet/10meters. Amplitude of the ultrasonic piezos drops off very sharply 1kHz either size of resonance (this also is a block in AM).

    Narrowband FM (acceptable voice quality) could be used, but receiver end would need to add emphasis on low and high frequencies far from center. Phase modulation and Piezos may not get along as well. A digital system wouldn't be able to carry data at a fast enough rate.

    So, you are stuck with narrowband FM (about 2kHz bandwidth)

    A good source of info is what people use for rangefinding/speed/doppler ultrasonic, some of which are not pulse based.
     
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