A recent project me and Gal Grinblat were embarked on, consist of making a locking-mechanism where the password is being transferred as musical notes.

Think about it,

You type your password on the keyboard, right? click ‘Enter’ and good to go.

Pretty dull, right?!

So why not translate those keyboard strokes into sound and silence,
and then a microphone on the other side listen to what you’re transmitting and reacquire the password from those signals!

Sounds like some James Bond type stuff!

Here is the final result:

Note the melody playing at the end indicates that the password been inserted correctly.

However, for the sake of simplicity (we had only few days for a proof of concept) we used one note (i.e. on frequency) rather than a handful more.

Since the project involves a keyboard, microphone and speakers, we had to implement it in hardware, so we used the DE-2 Altera board and programmed everything using QuartusII in VHDL.

A High Level View of the whole system


The most interesting parts where the transmitter(TX) receiver (RX)

In-order to compare the inputted signal, we used Autocorellation, where we delayed the input signal by 3 cycles and then took 300 samples and calculated the Auto-correlation value with the current signal.

Here is another high-level view of the modules




It was FUN seeing it working accordingly!