Frequency Shift property of FFT

Question

Juan Heusser Killing 2019-5-26

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/464028-frequency-shift-property-of-fft

回答： Sk Group 2021-10-27

Hello,

I am trying to implement DSB modulation in Matlab, but I am having trouble with the frequency shift of the original signal, and how to visualize it.

This is what I have so far, but I can´t visualize the frequency shift.

clc, clear all, close all;
load('data2.mat');
load('data1.mat');
data1=data1(23001:24000,1);
data2=data2(23001:24000,1);
hold on
[m n]=size(data1);
t=[1:m]*2*pi/m;
for j=1:m
    exp_vect(j)=exp(-1i*16e3*t(j)); %Construct freq. shift vector
end
f_data1=highpass(data1,0.01); %Eliminate very low frequencies (freq 0)
f_data2=highpass(data2,0.01);
t_data1=hilbert(f_data1); %Hilbert filter of first signal
t_data2=data2-hilbert(f_data2); %Hilbert filter of second signal
fft_data1 = fft(f_data1);
hf_data1=t_data1.*exp_vect;
ffthf_data1=fft(hf_data1);
plot(abs(fftshift(fft_data1)));
plot(abs(fftshift(ffthf_data1)));