4

I am considering using ultrasound (inaudible) as an option for determining the relative position of 2 mobile devices (which can be either on Android or iOS devices). There will be my app installed on both of these devices. Its users will face each other (with their max. distance being 1,5 m), holding the devices facing each other.

I would like to know whether it could be possible to create an efficient system in which one app would send ultrasound/inaudible signal and other user's app would receive it and determine that this particular user (standing very close) sent it (emitted the sound).

Note: In my case the sound can be audible but the less audible it is, the better (therefore I used the word ultrasound). Battery consumption of such application is not important at this point (though I'll appreciate any information). I only would like to know whether it's possible and how efficient such application would be. I also want to send (if possible) few bytes of information but the system should work also in places where there is some ambient noise.

Can anyone answer such question/share experiences on this topic?

syntagma
  • 23,346
  • 16
  • 78
  • 134
  • Well this does it with just one phone and a wall: http://itunes.apple.com/app/sonar-ruler/id324621243?mt=8 or this for android: https://play.google.com/store/apps/details?id=com.dicon.sonar&hl=en – Justin Paulson Jun 07 '12 at 21:06
  • What is the minimum pulse width that you can generate with your android hardware? Minimum detect distance is related to pulse width. May not be the same for all hardware. – starbolin Jun 07 '12 at 22:13
  • Can you calibrate the system by holding the two devices a known distance apart before you start measurement? – hotpaw2 Jun 08 '12 at 00:31
  • Note that it's never going to be ultrasound - the hardware on consumer devices such as phones is not capable of it - the best you can do is to use a high frequency around say 18 kHz which will be inaudible to most adults but irritating to younger people and various animals, e.g. dogs. – Paul R Jun 08 '12 at 07:24
  • @starbolin I can't provide this data at this point of time (manufacturers may not provide it in general), but I'd would appreciate even general information (e.g. when is the pulse width I'd need to make it work). – syntagma Jun 08 '12 at 13:39
  • @hotpaw2 No - it should work in a given distance (2 meters max), even when the user(s) moves back and forth. – syntagma Jun 08 '12 at 13:42
  • In one milisecond sound will travel 34 cm. Before receiving the return signal the transmitter has to be off and the receiver settled to baseline. I suspect that is the reason the mentioned market device uses two active devices. – starbolin Jun 08 '12 at 17:20
  • Did you get any good solution? Here, I am facing the similar problem. – Md Mahbubur Rahman Mar 02 '15 at 12:44
  • I, too, am curious if you got it to work. I may try implementing something similar, myself, if not. – Erhannis Dec 20 '16 at 22:09

1 Answers1

1

See related question here: Transfering data using ultrasound

I definitely think this would be possible.

As a starting point, I would look at this project and the wikipedia page for their transmission method. You would apply their processing concepts in your software audio processing code.

Community
  • 1
  • 1
Nicolas Renold
  • 557
  • 2
  • 5