% Phase Locked Loop:
close all
% Input Arguments:
t = 0:0.002:2;
A = 10; % Amplitude of Message Signal
wm = 2*pi*20; % Frequency of message signal
fs = 500; % Corresponding Sampling frequency
oi = 2; % phase shift in input
filter_order = 70; % filter order of LPF
wcut = (2*5)/(fs); % Cutoff frequency of LPF
wc = 2*pi*40; % Free Running frequency of VCO
e0 = 10 ; % Initialization for loop with a random
value
c = 1; % Constant multiple of e0
B = 10; % Amplitude of the signal generated by
VCO
% Working:
% u --->(x)---->[ H(s) ]---+--> y
% | |
% ------[ VCO ]<-----
% H(s) = Low Pass loop filter
% VCO = Voltage Controlled Oscillator
% (x) = A multiplier working as a phase detector
% Input Signal:
u=A*sin(wm*t);
w=-250:(2*250)/1000:250;
U=fftshift(abs(fft(u)));
figure, plot(t(1:20),u(1:20)), title('Message
Signal'),xlabel('time'),ylabel('Amplitude')
figure, plot(w(501:1001),U(501:1001)), title('Spectrum of Message
Signal'),xlabel('frequency (Hz)'),ylabel('Amplitude')
a = length(u);
for k=1:1000
% VCO:
wt = wc*t(c*(e0));
v = B*cos(wt);
% for plot of e0:
x(k) = (oi-(c*e0));
y(k) = e0;
% Multiplier:
m0 = u.*v;
% Low Pass Filter:
Filter = fir1(filter_order,wcut,'low');
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