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.
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.