The aim of these labs is to transmit a simple image from one computer to another with the help of QPSK/4QAM and OFDM.
Our model of a communication channel is a simple plastic bucket containing a PC speaker and a microphone. The bucket introduces all kinds of distortions seen in RF transmission such as reflections, fading, noise and other non-linear effects. Simple multimedia PC speakers and microphones for Skype work well. The worst the better.
The scripts are written in MATLAB/OCTAVE but the coding is C like to emphasise the real-time processing.
The general approach is
We start off with simple binary phase shift keying (BPSK) and then switch to quadrature phase shift keying (QPSK) for the remainder of the tutorial. I introduce step by step the different components of the transmitter and receiver. The pacman is our test image. ;)
OFDM assignment: symbol start detection and transmission via bucket with error correction.