The Naked Scientists

The Naked Scientists Forum

Author Topic: Can I bounce a special frequency off a sound wave?  (Read 3161 times)

Offline hernan

  • First timers
  • *
  • Posts: 2
    • View Profile
Am I able to send out "special frequencies" that reflect back from any frequency (20Hz-20K) in the air?
So for example, I'm thinking about a sonar satellite sending out radio frequencies that are targeting any
audible sound in a room and reflecting back to provide data like, position, frequency, direction etc.
Is this physically possible?
« Last Edit: 22/11/2010 19:42:40 by chris »


 

Offline hernan

  • First timers
  • *
  • Posts: 2
    • View Profile
Re: Can I bounce a special frequency off a sound wave?
« Reply #1 on: 17/11/2010 18:57:41 »
This is a diagram of my question. Can the blue circle representing an object be an actual sound wave?

  (if the image is not visible, it's also attached)
 

Offline graham.d

  • Neilep Level Member
  • ******
  • Posts: 2208
    • View Profile
Re: Can I bounce a special frequency off a sound wave?
« Reply #2 on: 19/11/2010 13:13:01 »
Hi Hernan. There are so many issues with what you are describing I'm not sure where to start.
1. Sound waves will not generally reflect other sound waves
2. A satellite, being in space, cannot send sound waves but I note you have it sending radio waves which is OK. I'm not sure what you mean by these radio waves "targetting" sounds in a room. The radio waves would not be reflected (at least not very much) by sound waves.

What is possible, and has been used, is to plant about a room objects which have conductive shapes on them tuned to a particular radio frequency. By designing these shapes correctly (and they can easily be disguised as part of a piece of art, trophy, lampstand etc) they can be made to resonate when excited by a radio wave (usually in the microwave region). Being in the room they will also vibrate when sound waves fall on them. The resulting mix of the sound and the resonating "aerial" can then be detected by a nearby radio receiver and the room effectively bugged without the use of any active circuitry being present. This technique was used by the British Intelligence services (and probably others) many years ago.
 

Offline yor_on

  • Naked Science Forum GOD!
  • *******
  • Posts: 11993
  • Thanked: 4 times
  • (Ah, yes:) *a table is always good to hide under*
    • View Profile
Can I bounce a special frequency off a sound wave?
« Reply #3 on: 06/12/2010 18:22:23 »
Very nice Graham.

Maybe one can ask it this way, is it possible to let a wave bounce of something and later decode the difference made to the 'original' as 'speech/information'?

It seems possible, maybe?
==

Nah, it would be to much information, and from too many diverse sources too maybe. Depend on how you directed it, but if you already had tested it on the room then, letting waves bounce of all of it and used that as a 'original' from which you would compare a new set of waves later, to see if speech would make a difference? I don't know if that's possible though??
« Last Edit: 06/12/2010 18:38:11 by yor_on »
 

The Naked Scientists Forum

Can I bounce a special frequency off a sound wave?
« Reply #3 on: 06/12/2010 18:22:23 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums