How I get all frequency in FFT result?

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I have a sine signal with many frewuency. I should get the frequency from FFT result.
Please let me know your suggestion.
I should generate the Fc values in frequencies element.
Fs = 5e4;
t = (0:Fs-1)*1/Fs; % Time vector
Datapoints = Fs;
Fc1 = 30:6/Fs:33; %(b-a)*2
Fc2 = sort(Fc1,'descend');
Fc = [Fc1 Fc2];
% % Select Variable amplitude
A1 = [1:64/Fs:9 3:96/Fs:15 5:24/Fs:8 2:16/Fs:4];
A2 = [2:48/Fs:8 4:24/Fs:7 1:32/Fs:5 3:24/Fs:6];
A = [A1 A2];
for i=1:length(t)
a_HZ = 2*pi*Fc(i)*t; % Set Frequency
sys(i) = A(i)*sin(a_HZ(i)); % FFT Output, A(i) Amplitude and a_HZ(i) is the changes in frequency
h = rand(1,4); % Random unknown system
r = filter(h,1,sys); % Input passed trought system(h)
y = awgn(r,30); % FFT Output Plus the random noise, white Gaussian noise to signal with SNR% Fourier Transformation
NFFT = Fs; % Next power of 2 from length of y
Y = fft(y,NFFT)/Fs;
fs= Fs/1;
[B,IX] = sort(2*abs(Y(1:NFFT))); %order the amplitudes
Amplitudes=(B) %find all amplitudes above the BFloor
Frequencies=Fc(IX) %frequency of the peaks

Accepted Answer

Swetha Polemoni
Swetha Polemoni on 3 Nov 2020
As per my understanding , you want to all the frequcies available in the signal after it is being filtered out.
In the last but one line of your code "Amplitudes=(B) %find all amplitudes above the BFloor" , you haven't set any threshold for the amplitude.
This one line code would work for getting frequencies whose corresponding amplitudes greater than the threshold you set.
Refer "this" for better understanding.

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