数字锁相环matlab仿真代码

数字锁相环的Matlab仿真代码如下：

%% Parameters
fs = 1e6; % Sampling frequency
fc = 10e3; % Carrier frequency
fd = 500; % Input frequency
N = 10000; % Number of samples

f_out = zeros(1, N); % Output frequency
phase_out = zeros(1, N); % Output phase
error_out = zeros(1, N); % Phase error
loop_filter_out = zeros(1, N); % Loop filter output

%% Loop filter parameters
Kp = 1;
Ki = 1;
Kd = 1;
Tf = 1/(2*pi*fc);
Nf = Tf*fs;

%% Loop variables
phase = 0;
freq = fc;
K1 = Kp+Ki/Nf+Kd*Nf;
K2 = -Kp-2*Kd*Nf;
K3 = Kd*Nf;
integ = 0;
prev_err = 0;

%% Loop
for n = 1:N
    % Generate input signal
    x = cos(2*pi*fc*(n-1)/fs+pi/3)+cos(2*pi*fd*(n-1)/fs);
    
    % Multiply by local oscillator
    y = x.*cos(2*pi*fc*(n-1)/fs+phase);
    
    % Lowpass filter
    ylp = lowpass(y, fd, fs);
    
    % Hilbert transform
    yht = hilbert(ylp);
    
    % Phase detector
    err = angle(yht);
    
    % Loop filter
    integ = integ+Ki/Nf*err+Kd*Nf*(err-prev_err);
    loop_filter_out(n) = Kp*err+integ;
    
    % Voltage controlled oscillator
    freq = fc+loop_filter_out(n);
    phase = phase+2*pi*freq/fs;
    
    % Output frequency
    f_out(n) = freq;
    
    % Output phase
    phase_out(n) = phase;
    
    % Output phase error
    error_out(n) = err;
    
    % Save previous error
    prev_err = err;
end

%% Plot results
t = (0:N-1)/fs;
figure;
subplot(4,1,1); plot(t, f_out/1e3); xlabel('Time (s)'); ylabel('Frequency (kHz)'); title('Output frequency');
subplot(4,1,2); plot(t, phase_out); xlabel('Time (s)'); ylabel('Phase (rad)'); title('Output phase');
subplot(4,1,3); plot(t, error_out); xlabel('Time (s)'); ylabel('Error (rad)'); title('Phase error');
subplot(4,1,4); plot(t, loop_filter_out); xlabel('Time (s)'); ylabel('Output (V)'); title('Loop filter output');

注意，此代码仅用于演示数字锁相环的工作原理和效果。实际应用中，需要根据具体的系统要求进行参数调整和优化。