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For loop and Fast Fourrier Transfrom

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Xuan Hiep Dinh
Xuan Hiep Dinh 2017-3-11
关闭： MATLAB Answer Bot 2021-8-20
Dear colleagues, I have a question related to Fast fourier transfrom. I want to calculate the phase and make FFT to draw power spectral density. However when calculate the phase "theta", there was some errors. So sorry because I am new to Matlab. This is my program code. Please help. Thanks so much !
n = 1:32768;
T = 0.2*10^-9; % Sampling period
Fs = 1/T; % Sampling frequency
Fn = Fs/2; % Nyquist frequency
omega = 2*pi*200*10^6; % Carrier frequency
L = 32768; % % Length of signal
t = (0:L-1)*T; % Time vector
x_signal(n) = cos(omega*T*n + 0.1*randn(size(n))); % Additive phase noise (random)
y_signal(n) = sin(omega*T*n + 0.1*randn(size(n))); % Additive phase noise (random)
theta(n) = atan(y_signal(n)/x_signal(n));
f = (theta(n)-theta(n-1))/(2*pi)
Y = fft(f,t);
PSD = Y.*conj(Y); % Power Spectral Density
%Fv = linspace(0, 1, fix(L/2)+1)*Fn; % Frequency Vector
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Xuan Hiep Dinh
Xuan Hiep Dinh 2017-3-12
Thanks for help. However, I need to calculate the phase "theta" before doing fft.
Xuan Hiep Dinh
Xuan Hiep Dinh 2017-3-12
And I am stuck when calculating the frequency.

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