3 ms·
Difficulty level, probably. I'd love to see both and also one that can survive over GSM audio (is that even possible?)
by voltagex_ 10y ago
Difficulty level, probably. I'd love to see both and also one that can survive over GSM audio (is that even possible?)
- jleahy 10y agoGSM is definitely possible, but you'd struggle to get more than 2kbit/second (and that'd be over a good connection). You'd probably need FEC to pull it off.
- noselasd 10y agoThere's dialup over GSM. Though those modems does this by piping data through a software modem and then onto the GSM channel, however it requests a clear channel, so no transcoding is done by the network or the phone (the lossy GSM codecs arn't suitable for this) GPRS made that pretty much obsolete though.
- kalleboo 10y agoThe feature for getting a pure data channel was called CSD https://en.wikipedia.org/wiki/Circuit_Switched_Data https://en.wikipedia.org/wiki/Circuit_Switched_Data
- huehehue 10y agoI built a similar internet-over-voice system for a hackathon a couple of years ago. A mobile app started a call, sent a URL over the line via DTMF tones, the server fetched the page, converted each response character to a frequency, saved it all as a sound file, and played it back over the line. The app would listen to the call, decode the sound via FFT and display the resultant data as a web page. I found decent results by increasing the pitch variance between notes. The interesting thing about GSM/low-quality audio is that, since quality is known, it might be possible to account for it in a more specific way. The idea was to provide a means of internet access on a device with no mobile data plan. Of course, the worst case scenario is just sending everything as DTMF tones, but getting a tweet out would take like an hour