Modelling a Digital Communication System using Matlab

I modelled the digital communication system by a simple script. In first, if you haven't installed Matlab in your system yet, you can see my article about installation of matlab on Linux.
A digital telephone converts an analog signal(our voice) to a digital signal before transmission. While the analog signal takes on real number values, the digital signal takes on only a finite set of integer values. We can model these implementation effects and save memory by storing the digital as an integer data type rather than as type double. I did this by writing the script in the following. When I run I got the pics showing the script is nicely working in the below of the script..

%% ====== Sources ======</div> <div> % Load sampled (discretized time) analog sources</div> <div> % with double values between -1 and +1.</div> <div> load phonecalls</div> <div> % See and hear both sources together.</div> <div> % Note source clipping at -1 and +1.</div> <div> plot(source1,'r')</div> <div> hold on</div> <div> plot(source2,'b')</div> <div> ylabel('DOUBLE Values')</div> <div> title('{\bf Analog Sources}')</div> <div> legend('Source 1','Source 2')</div> <div> soundsc([source1,source2],Fs) % Stereo</div> <div> pause(4)</div> <div> %% ====== Source coding (quantization) ======</div> <div> % Digital signals (discretized values) with scaled</div> <div> % and quantized int8 values between -128 and 127.</div> <div> sig1 = int8(128*source1);</div> <div> sig2 = int8(128*source2);</div> <div> % See and hear both signals together.</div> <div> % Clipped values at -1 and +1 in the sources</div> <div> % saturate in the signals at -128 and 127.</div> <div> figure</div> <div> plot(sig1,'r.')</div> <div> hold on</div> <div> plot(sig2,'b.')</div> <div> ylabel('INT8 Values')</div> <div> title('{\bf Digital Signals}')</div> <div> legend('Signal 1','Signal 2')</div> <div> soundsc([double(sig1),double(sig2)],Fs) % Stereo</div> </div> <div> ------</div> <div> <div> As you see from the script I plotted the analog sources and the digital signals seperately. The</div> <div> plot are shown in Figures. Any other necessary explanations is in the comments in the</div> <div> script.</div> <div> I want to speak about some functions and commands these are we used in the script above.</div> <div> load: load workspace variables from disk.</div> </div> <div> <div> soundsc: Scale data and play as sound.</div> <div> pause: Halt execution temporarily.</div> <div> int8: Stored integer value of fi object as built-in int8

See the pics below:

Read More