wenti.m

锁相环的仿真以及含有文本

clc;
close all;
clear all;

Fc = 2100; % Input Reference signal frequency
F0 = 2000; % Center Frequency of NCO
Fs = 40000 ;% Sampling freqency
Ts = 1/Fs; % Sampling duration
t = 0:Ts:150/Fc; % Vector of time samples

sigI = cos(2*pi*Fc*t+pi);
sigQ = sin(2*pi*Fc*t+pi);

% Calculation of PLL parameters
zeta = 0.707; % Damping factor
%Wl = 1*pi; % Lock range defined according to expected
Wl = 800*pi; % Lock range defined according to expected
% input characteristics
Wn = Wl/2/zeta ;% Natural frequency calculated from lock range
%Wn = 80*pi % Natural frequency calculated from lock range
Kd = 1; % Phase detector gain
Ko = 1; % Loop filter gain

% Loop filter constants and lead-lag gain constants calculated
C1=((8*zeta*Wn*Ts)/(4+4*zeta*Wn*Ts+Wn*Wn*Ts*Ts))/(Ko*Kd);
C2=((4*Wn*Wn*Ts*Ts)/(4+4*zeta*Wn*Ts+Wn*Wn*Ts*Ts))/(Ko*Kd);

% Initialization for first cycle of feedback loop
phi = 0; % Output phase of the NCO
theta = 0; % Phase error of the two signals
Uf=0; % Output signal of the loop filter

thetaI = 0; % Error of in-phase signal
thetaQ = 0; % Error in quadrature-phase signal

F1 = 2*pi*F0; % Output frequency of NCO

spll(1)=0; 
% General case phase lock loop
for n = 2:1:length(sigI)

phi(n) = phi(n-1)+F1(n-1)*Ts; % Phase error from current cycle 

thetaI(n) = sigI(n)*cos(phi(n))+sigQ(n)*sin(phi(n));
thetaQ(n) = sigI(n)*sin(phi(n))-sigQ(n)*cos(phi(n));
% theta(n) = atan(-thetaQ(n)/thetaI(n));
%theta(n) = thetaQ(n);
theta(n) = thetaQ(n)*sign(thetaI(n));

spll(n)=spll(n-1)+C2*theta(n);

Uf(n) = C1*theta(n)+spll(n);
F1(n) = 2*pi*(F0+Uf(n));
end 

figure;
plot(theta);

figure;
plot(Uf);