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Quietnet: Chat client that works over near-ultrasonic sound

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Re: Quietnet: Chat client that works over near-ultrasonic sound

#31

Post by Torgo »

jared314 wrote: post #28
slowmover wrote: post #10

Earlier quoted context omitted.

Interestingly, some early wireless TV remotes used sound this way. The battery-free remotes would strike a tone when a button was pressed, and carefully tuned forks in the TV set would resonate in response, triggering the remote function. http://www.tvhistory.tv/1957_Zentih_Ad-Remote1.JPG

There are also reasons they stopped using it in the first place[1]: Some problems with this method were that the receiver could be triggered accidentally by naturally occurring noises, and some people could hear the piercing ultrasonic signals. There was an incident in which a toy xylophone changed the channels on such sets because some of the overtones from the xylophone matched the remote's ultrasonic frequency. Wh…

I don't see why DTMF https://en.wikipedia.org/wiki/Dual-tone_multi-frequency_sign... couldn't have solved this pretty easily without adding too much complexity. I've seen those remotes before and they usually only had about three buttons on them. Still pointless, but I think this would have worked.

Re: Quietnet: Chat client that works over near-ultrasonic sound

#32

Post by Raphmedia »

solox3 wrote: post #21

In case anyone else is as daft as I was, this will not work for everyone in an everybody-wears-headphones environment.

You can make software use different speakers and other your headphones. iTunes has this in it's interface even (mac anyway).

Re: Quietnet: Chat client that works over near-ultrasonic sound

#33

Post by samolang »

STRML wrote: post #11
brownbat wrote: post #2

I'm glad people are realizing that radio waves aren't the only ways to send signals around a room. I really want someone to make a wireless, powerless keyboard where every key's click is tuned to a slightly different sound. Keylogging by acoustic emanations is a well researched technique, I just think it could be a feature if we made the keyboard right. https://www.schneier.com/blog/archives/2005/09/snooping_on_t...

Would be great, until you had more than one in a room - what a mess that would be.

Are there limitations on the number of possible sounds? If not, each keyboard could use a unique set of sounds.

Re: Quietnet: Chat client that works over near-ultrasonic sound

#34

Post by GrantS »

songzme wrote: post #12

Can this be accomplished on mobile devices? This could be a clever trick to implement interesting multiplayer games on train rides, airplanes, where wifi is not available. From a quick research, it seems that iPhones are not able to play ultrasonic sound: "iPhone 4s is rated for 20Hz - 20,000Hz, which means it cannot generate ultrasonic frequencies." - http://stackoverflow.com/questions/10034346/ios-how-to-produ...

Not ultra-sonic but this app sends photos from iPhone to iPhone using the speaker and microphone.

https://itunes.apple.com/us/app/acoustic-picture-transmitter...

Fun to play around with and think of the possibilities of using sensors in unintended ways.

Re: Quietnet: Chat client that works over near-ultrasonic sound

#35

Post by dsl »

samolang wrote: post #33
STRML wrote: post #11

Earlier quoted context omitted.

Would be great, until you had more than one in a room - what a mess that would be.

Are there limitations on the number of possible sounds? If not, each keyboard could use a unique set of sounds.

There is no limit on the number of sounds if you want every keyboard to cost as much as a handmade finely tuned professional musical instrument.

Re: Quietnet: Chat client that works over near-ultrasonic sound

#36

Post by tmp123415 »

namecast wrote: post #8
GotAnyMegadeth wrote: post #6

Earlier quoted context omitted.

Until you get crumbs under the keys... EDIT: "a wireless, powerless keyboard where every key's click is tuned to a slightly different sound" hang on, like a piano?

Heh, I just visualized my laptop keyboard transposed onto an 88 key piano, and then tried to imagine what a typical vim session would sound like on it...

This must be done.

Re: Quietnet: Chat client that works over near-ultrasonic sound

#37

Post by sliverstorm »

samolang wrote: post #33
STRML wrote: post #11

Earlier quoted context omitted.

Would be great, until you had more than one in a room - what a mess that would be.

Are there limitations on the number of possible sounds? If not, each keyboard could use a unique set of sounds.

No, but the more sounds you use, the more precise everything has to be. Just think of a machine that recognizes blue, red, and yellow as compared to a machine that recognizes all 24-bit colors. Aside from everything else, how on earth would you calibrate the sensor?

Re: Quietnet: Chat client that works over near-ultrasonic sound

#38

Post by [deleted] »

GrantS wrote: post #34
songzme wrote: post #12

Can this be accomplished on mobile devices? This could be a clever trick to implement interesting multiplayer games on train rides, airplanes, where wifi is not available. From a quick research, it seems that iPhones are not able to play ultrasonic sound: "iPhone 4s is rated for 20Hz - 20,000Hz, which means it cannot generate ultrasonic frequencies." - http://stackoverflow.com/questions/10034346/ios-how-to-produ...

Not ultra-sonic but this app sends photos from iPhone to iPhone using the speaker and microphone. https://itunes.apple.com/us/app/acoustic-picture-transmitter... Fun to play around with and think of the possibilities of using sensors in unintended ways.

[deleted]

Re: Quietnet: Chat client that works over near-ultrasonic sound

#39

Post by samolang »

sliverstorm wrote: post #37
samolang wrote: post #33

Earlier quoted context omitted.

Are there limitations on the number of possible sounds? If not, each keyboard could use a unique set of sounds.

No, but the more sounds you use, the more precise everything has to be. Just think of a machine that recognizes blue, red, and yellow as compared to a machine that recognizes all 24-bit colors. Aside from everything else, how on earth would you calibrate the sensor?

You could do something like keep the frequency offset between keys constant for all keyboards, but add some way of shifting the frequency of all of the keys by the same amount. It seems feasible to me, but I have no expertise in the area. The difficulty could prohibit an infinite set of configurations, but it could easily allow for a small set of configurations for cases when a few keyboards are in close proximity.
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