qrtone-android
QRTone demo application
This demo of the QRTone library (https://github.com/Ifsttar/qrtone) is an android offline chat application.
It uses only the microphone and speaker to communicate with other Android phones.
Advantages of data transfer via sound:
- Intermediate solution between QRCode and BlueTooth technology
- Low energy consumption and no electromagnetic waves emitted
- No user intervention is required (no device pairing)
- A single message can be sent to an unlimited number of devices.
How it works ?
The data transmission method is similar to the first Internet modems except that it is adapted to the disturbances caused by acoustic propagation.
Here a spectrogram of a sequence:
Top source signal, bottom recorded audio in real situation
Listen to QRTone:
QRTone contain a forward correction code in order to reconstruct loss tones.