How can you transfer a file from one computer to another via sound card?

Discussion in 'Wireless & RF Design' started by zero_coke, Sep 19, 2011.

  1. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
    Can someone please explain to me the basic steps involved in transferring a file via sound wave and receiving it on the other end and converting it back to a file? Is it like the following:

    File --> convert to binary --> digital to analog converter --> Play the sound file --> receive the sound file via microphone on other computer --> analog to digital converter --> convert from binary to file

    Are these the steps involved?

    Please help!

    Thank you!
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    A 3.5mm stereo - 3.5mm stereo cable should work. Plug the sending end into that sound card output (headphone) and the receiving end to the other sound card's line input. You will need a media player to send the file, and something like Audacity (freeware app) to receive it.

    A thumb drive works for longer distances, should always be error free, and transfer the file (already in binary whether in WAV, MP3, OGG, or whatever) much faster.
  3. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
    No but we have to do this without any wires or anything of that sort. We have to do it in this program called MATLAB too. So this program needs to take a file, convert it to sound, play the file, and then other laptop will hear it using its microphone, convert it back to a file. I just want to know the general steps in taking a file and converting it to sound file. How do you do that? Is it even possible? Can you play it after you've converted it??
  4. MrChips


    Oct 2, 2009
    Cool. Never thought of that but I suppose it can be done. You have to come up with a modulation scheme, like they did with cassette recorders back in the good old days. Google "Kansas City Standard".

    And make a note of the names of the participants at that Byte gathering!
    Last edited: Sep 19, 2011
  5. strantor

    AAC Fanatic!

    Oct 3, 2010
    Beenthere! You've been-wherever, and now you're back! welcome back!
    (sorry for the hijack)
  6. bertus


    Apr 5, 2008

    It is possible but will be very slow.
    Think of the analog modems of the old days.
    Normaly they managed 9600 Bps.
    With a special modulation scheme they managed 56 kBps.

    You can read more about digital modulation schemes here:

  7. debjit625

    Well-Known Member

    Apr 17, 2010
    Wait a second...receiving the digital file using microphone. I don't think it might be possible as in air where the sound will travel will have noise and other sound signals unless of some special areas like recording studio. These signals will be also picked up by the microphone and the original data will mixed up with the noise and other sound signals so you will loose the integrity of the data.

    Anyway I didn’t tried ever, you could give it a try....

    Sound scheme was used long ago to do this kind of stuff not for digital files but for information known as telegraph... it used Morse code which used a high frequency tone for the data elements so noise couldn’t interfered.
    These days I am learning Morse code as planning to get a HAM license ,the sounds are really irritating....

    Good Luck
    Last edited: Sep 20, 2011
  8. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
    Hey guys thanks for all the replies.

    I will read a textfile into the program, split the whole file up into individual characters and apply a tone to each character like how it is in morse code, and then the other laptop will pick it up and record it back into a file. I hope this is possible as this is our project for school and I don't think integrity of data matters much. We just have to show that we can transmit data from one laptop to another via soundcard. Thanks!
  9. lageos

    New Member

    Oct 2, 2011
    PSK can do the tick, some hams sites have source codes for psk medem.
  10. radiohead

    Distinguished Member

    May 28, 2009
    Reminds me of the old magnetic tape that has been obsolete since the 1980s. The sound the microphone will have to pick up will probably be like the handshake burst tones you hear when you call a fax line. It was useful at one time, but advances in technology offer much more efficient and error-free ways of transferring data.
  11. zero_coke

    Thread Starter Active Member

    Apr 22, 2009
    Nevermind, got it.
    Last edited: Oct 11, 2011
  12. panic mode

    Senior Member

    Oct 10, 2011
    read in file, encode it, save as wav, play sound
    on receiving end record the sound, filter, decode, write file.

    this is only proof of concept so data rate is irrelevant.
    you can use FM or PM to reduce interference. PM or PSK is used in digital communication.
    AM can work too but it will be very sensitive to noise.
  13. Adjuster

    Late Member

    Dec 26, 2010