- Joined
- Sep 22, 2007
- Messages
- 977
- Points
- 0
The whole laser thing about transferring information as well as the youtube video is an example of modulation. In the two cases mentioned the laser frequency acts as a carrier wave while the data is superimposed on this wave. The same happens with the audio device. They are using an ultrasonic waveform as the carrier wave and superimposing audio in the human hearing range onto the carrier. My suspicion about the audio is that they have developed a slick waveguide for the ultrasonic wave to give it directionality.
Now once you are modulating a signal you have all kinds of possibilities. Many of them are in daily use. You can start multiplexing signals onto the carrier using various algorithms such as TDMA, FDMA, CDMA, DWDM and a whole host of other methods. Modulation and multiplexing is used in every modern communications device from DSL, to cellular systems, from computer bus architecture to satellite communication.
Finally, what the OP was originally talking about was a sound device designed for crowd control that emits an ultrasonic wave at 180-200 db. You cant hear it but you can feel it (resonance) just from the amplitude of the wave.
I believe they are now using microwaves to achieve somewhat the same effect as the audio crowd control device. The microwaves penetrate just the top layers of the skin where the temperature receptors are and induce a sensation of heat and burning although the microwaves are doing neither.
Now once you are modulating a signal you have all kinds of possibilities. Many of them are in daily use. You can start multiplexing signals onto the carrier using various algorithms such as TDMA, FDMA, CDMA, DWDM and a whole host of other methods. Modulation and multiplexing is used in every modern communications device from DSL, to cellular systems, from computer bus architecture to satellite communication.
Finally, what the OP was originally talking about was a sound device designed for crowd control that emits an ultrasonic wave at 180-200 db. You cant hear it but you can feel it (resonance) just from the amplitude of the wave.
I believe they are now using microwaves to achieve somewhat the same effect as the audio crowd control device. The microwaves penetrate just the top layers of the skin where the temperature receptors are and induce a sensation of heat and burning although the microwaves are doing neither.