1.
Transferring data using
Audio signal in Android
Sudar Muthu
http://sudarmuthu.com
http://twitter.com/sudarmuthu

2.
Yes you heard it
right
It’s possible

3.
Basic Idea
In any data transmission system, data flows from
Transmitter to Receiver
Transmitter Receiver

4.
Basic Idea
Android Audio Player Plays audio and becomes
Transmitter
Plays audio
Audio Player

5.
Basic Idea
Android Audio Recorder records audio and becomes the
Receiver
Receives Audio
Audio Player

6.
Basic Idea
So now the data (audio) flows between Audio Player
and Audio Recorder
Audio
Audio Player Audio Recorder
Data

7.
Data inside Audio
Sound/Audio is Analog
Your data is Digital (0 or 1)
Data and Audio are combined using Frequency Shift
keying (FSK)
Android has a built in analog to digital Convertor

8.
What is FSK?
http://en.wikipedia.org/wiki/Frequency-shift_keying

9.
Code Sample – Audio
Recorder

10.
Code Sample – Audio
Track

11.
So why would anyone
want to use it?
Zero power transmission
Less battery usage, when compared with WIFI or
Bluetooth
Can work with any audio device
Very simple to plug into your phone

12.
Commercial projects
Process credit cards – http://propay.com
Tata sky – Converts your mobile into a remote
Audio cassette interfaces to mobile

13.
Project Ideas
Communication between multiple audio devices like
your PC, iPod/iPad/iPhone
Hide data inside an audio file
Broadcast data as a music file. Imagine what happens
if your radio station does that
Hook up your Arduino and control robots (and that’s
what got me interested in this ;) )

14.
How to get started?
Things you need
Android Phone
Audio cable (4 pole 3.5 mm)
SoftModem –
http://www.sparkfun.com/products/10331
Any additional device (another phone or even an
Arduino)

15.
Libraries/Projects to
check out
Androino - http://code.google.com/p/androino/
AndroinoTerminal -
http://code.google.com/p/androino/wiki/AndroinoTer
minal
Arms22 - http://code.google.com/p/arms22/

16.
Demo

17.
Thank You
Sudar Muthu
http://sudarmuthu.com
http://github.com/sudar
http://twitter.com/sudarmuthu