Show HN: I made a tool to communicate data using the PC speaker

Re:Show HN: I made a tool to communicate data using the PC s... by ggerganov on Wednesday April 21, 2021 @02:11PM (#26893352)

Hi HN,

r2t2 is a command-line tool for transmitting data through sound using the PC speaker on the motherboard. The name of the tool is a reference to the R2-D2 robot from Star Wars :)

In short, you type some message and it gets FSK modulated and transmitted via sound through the PC speaker. Note that this is the speaker/buzzer that you connect to the motherboard and not the regular speakers that you connect to the sound card.

I also made a simple web page that listens to the sound emitted by r2t2 and decodes the received messages. The page can be used by simply opening it on your phone and placing the phone near a computer/device that emits data with r2t2.

I made this tool mostly for fun, but I think it might have some useful applications too. The advantage of this type of communication is that the hardware is very cheap (~$1/speaker), does not require a sound card and the software is very simple and does not use any 3rd-party audio libraries.

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Re:Show HN: I made a tool to communicate data using the PC s... by bityard on Wednesday April 21, 2021 @05:31PM (#26895701)

My google-fu is failing me because all I'm getting is blogspam, but I could have swore that some higher-end washing machines had a feature where when they broke down, they would emit some kind of diagnostic noise. Not just the standard series of beeps, but complex digital data. When you called in for warranty support or repair, they would guide you though pushing some buttons on the machine, the machine makes the noise, it goes through the phone, and the call center person on the other end could decode it. Or a repair tech on-prem could presumably decode it with an app on their phone.

Also, ham radio operators are doing some amazing things with audio-encoded data. You can send a message halfway around the world with just a few watts and a person with a computer on the other end can received and decode it, even if the signal itself is _below the noise floor_. Of course, the tradeoff is time: it takes a few minutes to transmit the small amount of data required to make a contact.

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Re:Show HN: I made a tool to communicate data using the PC s... by Madrigal on Wednesday April 21, 2021 @05:43PM (#26895832)

You're probably thinking of LG Smart Diagnosis https://www.lg.com/us/support/help-library/smart-diagnosis-f...

Video on how it looks like https://youtu.be/Q_fTfGJFK2A?t=68

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Re:Show HN: I made a tool to communicate data using the PC s... by tdeck on Wednesday April 21, 2021 @06:27PM (#26896231)

Wow it sounds like RTTY (radioteletype):

https://m.youtube.com/watch?v=wzkAeopX7P0

I suppose there are only so many ways to modulate a data signal.

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Re:Show HN: I made a tool to communicate data using the PC s... by nereye on Wednesday April 21, 2021 @10:00PM (#26897869)

There are a few hundreds listed at https://www.sigidwiki.com/wiki/Signal_Identification_Guide.

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Re:Show HN: I made a tool to communicate data using the PC s... by jhgb on Wednesday April 21, 2021 @03:09PM (#26894112)

Receive Resources Through Tones?

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Re:Show HN: I made a tool to communicate data using the PC s... by nicbou on Wednesday April 21, 2021 @06:25PM (#26896210)

It's an interesting project. I couldn't think of a use case for it but the one in a readme was a good example.

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Re:Show HN: I made a tool to communicate data using the PC s... by frombody on Thursday April 22, 2021 @01:57AM (#26899231)

This is a modem. (modulator/demodulator)

Once upon a time transferring digital data over analog channels brought us fax machines and dial-up internet.

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Re:Show HN: I made a tool to communicate data using the PC s... by fogihujy on Thursday April 22, 2021 @04:11AM (#26900142)

Also, packet radio, and semi-related, the good old IrDA ports in computers and PDA's in the late 90's/early 00's.

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Re:Show HN: I made a tool to communicate data using the PC s... by SwiftyBug on Wednesday April 21, 2021 @02:52PM (#26893935)

Very cool! What are some of the useful applications you thought for this concept?

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Re:Show HN: I made a tool to communicate data using the PC s... by ggerganov on Wednesday April 21, 2021 @03:03PM (#26894041)

I imagine a use case where you have headless devices (servers, raspberry pis, etc.) that are not connected to the internet. These devices can be measuring something through a sensor and periodically reporting the measured value using sound through the speaker. When you go near the device of interest, you take your phone and "listen" to the emitted value to see what was the last measurement.

The advantage of this is that it is a very cheap way of adding such communication channel to your device.

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Re:Show HN: I made a tool to communicate data using the PC s... by jonah-archive on Wednesday April 21, 2021 @05:05PM (#26895442)

at one point the iPod bootloader was extracted by playing it aloud: http://www.ipodlinux.org/stories/piezo/

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Re:Show HN: I made a tool to communicate data using the PC s... by fpopa on Wednesday April 21, 2021 @05:17PM (#26895557)

Well done, great demo!

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Re:Show HN: I made a tool to communicate data using the PC s... by TedDoesntTalk on Wednesday April 21, 2021 @04:24PM (#26894966)

Amazing work!

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