% EE3150 Communication Systems Lab
% Experiment 7 Design of a Communication System
% E.Cura

diary myproject.txt
SSN=input('Enter your Student I.D. number (SSN, without dashes):');

ms=SSN-100*floor(SSN/100);
SSN=(SSN-ms)/100;
ms1=SSN-100*floor(SSN/100);
SSN=(SSN-ms1)/100;
ms2=SSN-100*floor(SSN/100);
SSN=(SSN-ms2)/100;
ms3=SSN-100*floor(SSN/100);

% Selection of modulation scheme
if ms<=50,
    disp(' 1) Modulation method: DSB with coherent demodulation');
    C=5;
else
    disp(' 1) Modulation method: AM with envelope detection');
    disp('    Modulation index m = 0.5');
    C=13;
end

% Selection of bandwidth for the LPFs
fc=ms1/10+2;
s=sprintf(' 2) Cutoff frequency for LPFs, fc = %1.1f kHz',fc);
disp(s);

% Selection of frequency for the modulating signal
fx=round(sqrt(fc)*10)/10;
s=sprintf(' 3) Message frequency,         fx = %1.1f kHz',fx);
disp(s);


% Selection of carrier frequency
fs=round(ms2/10)*fx*C;
while (fs<200)&(ms>50),
    fs=2*fs+fx;
end
while (fs<50)&(ms<=50),
    fs=2*fs+fx;
end
s=sprintf(' 4) Carrier frequency,         fs = %1.1f kHz',fs);
disp(s);


% Selection of gain for output filter
if ms3<=25, K=1; end
if (ms3>25)&(ms3<=50), K=2; end
if (ms3>50)&(ms3<=75), K=3; end
if (ms3>75)&(ms3<=99), K=4; end
s=sprintf(' 5) Gain for active LPF,       K = %d dB',K);
disp(s);
diary off