Ultrasonic communication with consumer devices

On Thursday, November 17, 2016 at 1:06:08 PM UTC+13, ne...@everymundo.com wrote:
> > Could you use a Bode plot please, those intensity things mean nothing unless there is statistical varying data of some sort like speech
> 
> Maybe I'm misunderstanding, but wouldn't that only show frequency response, and not details like if one device could be heard above background noise of other devices? Frequency response on its own doesn't seem that important, as long as it does extend to 20k and there is a good SNR between the high frequency signal and the background.
> 
> Wouldn't a show playing on Netflix in the background, or the signal generated by Google Tone be a suitable statistical varying data? And wouldn't a Bode plot be different based on the broadcasting device, the listening device and the room?
> 
> (not being sarcastic in case it reads that way, sincerely asking)
> Thanks

Then you need a 3D bode plot if the plot changes with time. You can use a spectogram I suppose if you must

sort of unrelated but interesting and cool:

https://quiet.github.io/quiet-blog/2016/03/30/quiet-profile-lab-build-modem-learn-dsp.html


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On Monday, November 28, 2016 at 6:28:16 PM UTC-5, spetcavich wrote:
> sort of unrelated but interesting and cool:
> 
> https://quiet.github.io/quiet-blog/2016/03/30/quiet-profile-lab-build-modem-learn-dsp.html
> 
> 
> ---------------------------------------
> Posted through http://www.DSPRelated.com

Interesting indeed, but very unclear :-)

What kind of speaker is to be used at 19 KHz ? Most speakers won't do.
The doc says the cable mode profile provides at least 40 kbps  - this is above the theoretical limit of 33 kbps for analog transmission over copper wire at some distance (analog modem).
Otherwise its a purely digital link - should be much higher speed and no need for all that DA/AD dsp