7 ms·

The alleged ability to communicate over audio, since its very existence is questionable.

by jff 13y ago

ParadisoShlee 13y ago
#BadBIOS might be vapor but #RadBIOS is coming! https://pbs.twimg.com/media/BZpjjcyCUAI48nH.png https://pbs.twimg.com/media/BZpjjcyCUAI48nH.png
logicallee 13y ago
Does nobody here remember modems? You take an old 2400 baud modem that's supposed to work over a crackly telephone line - www.engadget.com/media/2009/05/090527-300baud-01.jpg that's literally how TCP/IP was invented. This stuff - pure, analog audio - went all the way up to 28.8kbps, which was the limit of the line bandwidth. Why not just take those protocols and put them into a speaker and microphone. Why bother writing new protocols? Just start with modem protocols and play with the frequencies. Home Internet connectivity was literally born out of TCP/IP over audio...
- jff 13y ago
  The question is not "can you transmit digital information over audio". That's an obvious yes. The question is, can laptop speakers transmit at ultrasonic frequencies, and can a laptop microphone pick those frequencies up sufficiently to actually communicate. This guy used 17 and 18 kHz as carriers. That is within the hearing range of young people, but a quick experiment shows that either my desktop speakers cannot reproduce 17 kHz, or I have recently become too old to hear 17 kHz.
  - acdha 13y ago
    > The question is, can laptop speakers transmit at ultrasonic frequencies, and can a laptop microphone pick those frequencies up sufficiently to actually communicate. Given two separate examples of running code, the question is really what percentage of laptops can do this. It's possible that some systems have filters but so far I haven't found one.
  - lutusp 13y ago
    > This guy used 17 and 18 kHz as carriers. That is within the hearing range of young people, but a quick experiment shows that either my desktop speakers cannot reproduce 17 kHz, or I have recently become too old to hear 17 kHz. It's easy to find out -- go here: http://arachnoid.com/JSigGen http://arachnoid.com/JSigGen Enter any frequency you want. Chances are if you're over 40, you can't hear 17 KHz. I'm 68 and I can't hear anything over 6 KHz. > ... or I have recently become too old ... It usually takes longer than that. :)
    - guiambros 13y ago
      > Enter any frequency you want. Chances are if you're over 40, you can't hear 17 KHz. (Maybe I should get better speakers...)
      - lutusp 13y ago
        > (Maybe I should get better speakers...) Maybe, but you can test your hearing range more easily by putting on a set of headphones and experimenting with the linked signal generator -- reasonable quality audio headphones should easily be able to exceed your own hearing range on the high end. And chances are typical computer speakers should also be able to exceed a normal hearing range.
  - mistercow 13y ago
    >or I have recently become too old to hear 17 kHz. If you're in your mid-20s (and you're on HN, so you probably are), it's not terribly unlikely that you've recently lost that part of your range. In my experience (back when I was young enough to hear those frequencies), even crappy speakers can usually go up to 20kHz easily. Very low frequencies are another story.
    - ithkuil 13y ago
      do we have a age poll for hn users ?
      - mistercow 13y ago
        I am almost positive that there was one a while back, but I'm having trouble finding it.
- dfc 13y ago
  At the end of its service I had flashed my USRobotics Courier modem from 9600k to 56.6k. That was still audio over POTS.
  - mbell 13y ago
    56.6k speeds required a digital POTS, it transmitted PCM through the digital portions of the network only to become analog at the last moment, from the nearest pole switch to your house. In other words, the modem you were calling had to be 'all digital' and plugged into the telecom network. There wasn't a lot of connection left to 'audio' for these modems, other than their baseband frequency range (0-4khz).
    - dfc 13y ago
      I swear that I used to call another friends BBS that also had a Courier modem hooked up to a POTS line and connect at 56.6k.
      - mbell 13y ago
        That is unlikely, the relevant standard is V.90: http://en.wikipedia.org/wiki/V.90_(recommendation) http://en.wikipedia.org/wiki/V.90_(recommendation) Only downstream was 56.6k PCM, upstream was 33.6k analog-modulated, so two consumer modems hooked together would only be capable of 33.6k. There was a later V.92 standard that improved upstream speed, but is was a bit wonky as it sacrificed download speed to do it, I'm not sure how much it was really used.
    - ChuckMcM 13y ago
      You are mistaken. 56K baud was the 'last' of the POTS modems, and it worked over an unimproved POTS line. Work beyond 56K was not pursued because ISDN was 64K and "imminent" (only to be DSLAMed :-) by ADSL.)
      - mbell 13y ago
        No need to take my word for it, here is the spec: https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.90-199809-I!!PDF-E&type=items https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.90...
- mbell 13y ago
  Communicating through copper wires using electrical signaling at audio frequencies is _very_ different from communicating through air using acoustic waves. Even assuming 'perfect' speakers and microphones you have completely different transmission effects than you have with low frequency electrical signals in copper.
  - rahimnathwani 13y ago
    Didn't some old modems use an acoustic coupler (i.e. a cradle which held the handset)?
    - prof_hobart 13y ago
      Yes, they did. I've still got an old one in a cupboard somewhere.
  - stedaniels 13y ago
    Please do thorough research. Modems were originally, more often than not, used with acoustic couplers.
    - cnvogel 13y ago
      Exactly! And the DIY version of it looked like this: http://commons.wikimedia.org/wiki/File:Akustikkoppler_CCC_Datenklo.jpg http://commons.wikimedia.org/wiki/File:Akustikkoppler_CCC_Da... And it supports 300bps and 1200bps speeds.
    - mbell 13y ago
      It's unclear what difference that makes in the context of my post. The fact remains that the modulation and signaling protocols developed for use in modems were designed within the constraints of electrical transmission across miles of copper wire, not through sounds waves in an unknown acoustical environment. The constraints for the two situations are entirely different. Acoustic couplers are designed to minimize any acoustical impact of their use to avoid the exact acoustical problems you'd have transmitting across a room.
- bnegreve 13y ago
  > Why bother writing new protocols? Just start with modem protocols and play with the frequencies. Technically PPP is a point to point protocol which makes everything easier (no real addressing, no routing and so on). This protocol would be more comparable to wifi.
gscott 13y ago
Furbys have been there, done that. http://robotzsf.blogspot.com/2012/11/furby-2012-hacking.html http://robotzsf.blogspot.com/2012/11/furby-2012-hacking.html

The alleged ability to communicate over audio, since its very existence is questionable.

by jff 13y ago

The alleged ability to communicate over audio, since its very existence is questionable.

#BadBIOS might be vapor but #RadBIOS is coming! https://pbs.twimg.com/media/BZpjjcyCUAI48nH.png https://pbs.twimg.com/media/BZpjjcyCUAI48nH.png

logicallee 13y ago

Does nobody here remember modems? You take an old 2400 baud modem that's supposed to work over a crackly telephone line - www.engadget.com/media/2009/05/090527-300baud-01.jpg that's literally how TCP/IP was invented. This stuff - pure, analog audio - went all the way up to 28.8kbps, which was the limit of the line bandwidth. Why not just take those protocols and put them into a speaker and microphone. Why bother writing new protocols? Just start with modem protocols and play with the frequencies. Home Internet connectivity was literally born out of TCP/IP over audio...

jff 13y ago
The question is not "can you transmit digital information over audio". That's an obvious yes. The question is, can laptop speakers transmit at ultrasonic frequencies, and can a laptop microphone pick those frequencies up sufficiently to actually communicate. This guy used 17 and 18 kHz as carriers. That is within the hearing range of young people, but a quick experiment shows that either my desktop speakers cannot reproduce 17 kHz, or I have recently become too old to hear 17 kHz.
- acdha 13y ago
  > The question is, can laptop speakers transmit at ultrasonic frequencies, and can a laptop microphone pick those frequencies up sufficiently to actually communicate. Given two separate examples of running code, the question is really what percentage of laptops can do this. It's possible that some systems have filters but so far I haven't found one.
- lutusp 13y ago
  > This guy used 17 and 18 kHz as carriers. That is within the hearing range of young people, but a quick experiment shows that either my desktop speakers cannot reproduce 17 kHz, or I have recently become too old to hear 17 kHz. It's easy to find out -- go here: http://arachnoid.com/JSigGen http://arachnoid.com/JSigGen Enter any frequency you want. Chances are if you're over 40, you can't hear 17 KHz. I'm 68 and I can't hear anything over 6 KHz. > ... or I have recently become too old ... It usually takes longer than that. :)
  - guiambros 13y ago
    > Enter any frequency you want. Chances are if you're over 40, you can't hear 17 KHz. (Maybe I should get better speakers...)
    - lutusp 13y ago
      > (Maybe I should get better speakers...) Maybe, but you can test your hearing range more easily by putting on a set of headphones and experimenting with the linked signal generator -- reasonable quality audio headphones should easily be able to exceed your own hearing range on the high end. And chances are typical computer speakers should also be able to exceed a normal hearing range.
- mistercow 13y ago
  >or I have recently become too old to hear 17 kHz. If you're in your mid-20s (and you're on HN, so you probably are), it's not terribly unlikely that you've recently lost that part of your range. In my experience (back when I was young enough to hear those frequencies), even crappy speakers can usually go up to 20kHz easily. Very low frequencies are another story.
  - ithkuil 13y ago
    do we have a age poll for hn users ?
    - mistercow 13y ago
      I am almost positive that there was one a while back, but I'm having trouble finding it.
dfc 13y ago
At the end of its service I had flashed my USRobotics Courier modem from 9600k to 56.6k. That was still audio over POTS.
- mbell 13y ago
  56.6k speeds required a digital POTS, it transmitted PCM through the digital portions of the network only to become analog at the last moment, from the nearest pole switch to your house. In other words, the modem you were calling had to be 'all digital' and plugged into the telecom network. There wasn't a lot of connection left to 'audio' for these modems, other than their baseband frequency range (0-4khz).
  - dfc 13y ago
    I swear that I used to call another friends BBS that also had a Courier modem hooked up to a POTS line and connect at 56.6k.
    - mbell 13y ago
      That is unlikely, the relevant standard is V.90: http://en.wikipedia.org/wiki/V.90_(recommendation) http://en.wikipedia.org/wiki/V.90_(recommendation) Only downstream was 56.6k PCM, upstream was 33.6k analog-modulated, so two consumer modems hooked together would only be capable of 33.6k. There was a later V.92 standard that improved upstream speed, but is was a bit wonky as it sacrificed download speed to do it, I'm not sure how much it was really used.
  - ChuckMcM 13y ago
    You are mistaken. 56K baud was the 'last' of the POTS modems, and it worked over an unimproved POTS line. Work beyond 56K was not pursued because ISDN was 64K and "imminent" (only to be DSLAMed :-) by ADSL.)
    - mbell 13y ago
      No need to take my word for it, here is the spec: https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.90-199809-I!!PDF-E&type=items https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.90...
mbell 13y ago
Communicating through copper wires using electrical signaling at audio frequencies is _very_ different from communicating through air using acoustic waves. Even assuming 'perfect' speakers and microphones you have completely different transmission effects than you have with low frequency electrical signals in copper.
- rahimnathwani 13y ago
  Didn't some old modems use an acoustic coupler (i.e. a cradle which held the handset)?
  - prof_hobart 13y ago
    Yes, they did. I've still got an old one in a cupboard somewhere.
- stedaniels 13y ago
  Please do thorough research. Modems were originally, more often than not, used with acoustic couplers.
  - cnvogel 13y ago
    Exactly! And the DIY version of it looked like this: http://commons.wikimedia.org/wiki/File:Akustikkoppler_CCC_Datenklo.jpg http://commons.wikimedia.org/wiki/File:Akustikkoppler_CCC_Da... And it supports 300bps and 1200bps speeds.
  - mbell 13y ago
    It's unclear what difference that makes in the context of my post. The fact remains that the modulation and signaling protocols developed for use in modems were designed within the constraints of electrical transmission across miles of copper wire, not through sounds waves in an unknown acoustical environment. The constraints for the two situations are entirely different. Acoustic couplers are designed to minimize any acoustical impact of their use to avoid the exact acoustical problems you'd have transmitting across a room.
bnegreve 13y ago
> Why bother writing new protocols? Just start with modem protocols and play with the frequencies. Technically PPP is a point to point protocol which makes everything easier (no real addressing, no routing and so on). This protocol would be more comparable to wifi.

gscott 13y ago

Furbys have been there, done that. http://robotzsf.blogspot.com/2012/11/furby-2012-hacking.html http://robotzsf.blogspot.com/2012/11/furby-2012-hacking.html