Matlab code for a simple Phase lock loop(PLL)

[yksdsu]

phase locked loop matlab

hai buddies,
I am providing a simple phase lock loop implementation in matlab.. Try this, I have simulated a long back... I will try provide you the theory of phase lock loop in the time being..

 

[power-testing]

Your code is close but had a few errors. Here is the working code.
close all;
clear all;
reg1 =0;
reg2 =0;
reg3 = 0;

eta =sqrt(2)/2;
theta =2*pi*1/100;
Kp = [(4*eta*theta)/(1+2*eta*theta+theta^2)];
Ki = [(4*theta^2)/(1+2*eta*theta+theta^2)];
d_phi_1 = 1/20;
n_data = 100;

for nn =1:n_data
phi1= reg1 +d_phi_1;
phi1_reg(nn) = phi1;

s1 =exp(j*2*pi*reg1);
s2 =exp(j*2*pi*reg2);

s1_reg(nn) =s1;
s2_reg(nn) =s2;

t =s1*conj(s2);
phi_error =atan(imag(t)/real(t))/(2*pi);
phi_error_reg(nn) = phi_error;
sum1 =Kp*phi_error + phi_error*Ki+reg3;

reg1_reg(nn) =reg1;
reg2_reg(nn) = reg2;
reg1 =phi1;

reg2=reg2+sum1;
reg3 =reg3+phi_error*Ki;
phi2_reg(nn) =reg2;
end

figure(1)
plot(phi1_reg);
hold on
plot(phi2_reg,'r');
hold off;
grid on;
title('phase plot');
xlabel('Samples');
ylabel('Phase');


figure(2)

plot(phi_error_reg);
title('phase Error of phase detector');
grid on;
xlabel('samples');
ylabel('Phase error(degrees)');


figure(3)
plot(real(s1_reg));
hold on;
plot(real(s2_reg),'r');
hold off;
grid on;
title('Input signal & Output signal of VCO');
xlabel('Samples');
ylabel('Amplitude');
axis([0 n_data -1.1 1.1]);

 

[YaraFayyad]

Thank you .

 

[Anushka Heshan]

Re: phase locked loop matlab

Hi, I tried to model PLL in SIMULINK, Since there is no component available for phase detector in SIMULINK I couldn't build the model. I have found that a Mixer can be used instead of a phase detector. Yet I couldn't get an output. Appreciate it very much if you can help me on this. Thanks!

 

[bk20091884]

Your code is close but had a few errors. Here is the working code.
close all;
clear all;
reg1 =0;
reg2 =0;
reg3 = 0;

eta =sqrt(2)/2;
theta =2*pi*1/100;
Kp = [(4*eta*theta)/(1+2*eta*theta+theta^2)];
Ki = [(4*theta^2)/(1+2*eta*theta+theta^2)];
d_phi_1 = 1/20;
n_data = 100;

for nn =1:n_data
phi1= reg1 +d_phi_1;
phi1_reg(nn) = phi1;

s1 =exp(j*2*pi*reg1);
s2 =exp(j*2*pi*reg2);

s1_reg(nn) =s1;
s2_reg(nn) =s2;

t =s1*conj(s2);
phi_error =atan(imag(t)/real(t))/(2*pi);
phi_error_reg(nn) = phi_error;
sum1 =Kp*phi_error + phi_error*Ki+reg3;

reg1_reg(nn) =reg1;
reg2_reg(nn) = reg2;
reg1 =phi1;

reg2=reg2+sum1;
reg3 =reg3+phi_error*Ki;
phi2_reg(nn) =reg2;
end

figure(1)
plot(phi1_reg);
hold on
plot(phi2_reg,'r');
hold off;
grid on;
title('phase plot');
xlabel('Samples');
ylabel('Phase');


figure(2)

plot(phi_error_reg);
title('phase Error of phase detector');
grid on;
xlabel('samples');
ylabel('Phase error(degrees)');


figure(3)
plot(real(s1_reg));
hold on;
plot(real(s2_reg),'r');
hold off;
grid on;
title('Input signal & Output signal of VCO');
xlabel('Samples');
ylabel('Amplitude');
axis([0 n_data -1.1 1.1]);

Hello, I read your code but I don't understand about Kp and Ki. Could you tell me more about that. And you use d_phi_1 = 1/20, therefore phi1 will linear (not suitable with real).Thank you so much!

 

[qsj8362234]

Kp and Ki are two parameters about second-order filter.
you can find the ralation between KP Ki and aquisition bandwidth in gardner's book