How to separate signals with diffrent frequencies
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Srey
le 1 Jan 2015
Commenté : aarthi arunachalam
le 11 Mar 2016
t = linspace(0, 1, 1001);
x=sin(2*pi*t*3) + sin(2*pi*t*6) + sin(2*pi*t*10)+sin(2*pi*t*13)+sin(2*pi*t*20)+sin(2*pi*t*50)+sin(2*pi*t*100)+sin(2*pi*t*200);
% my signal with frequencies 3,6,10,13,20,50,100,200 KHz
sigma=0.1;
y=x+randn(size(x)).*sigma; % adding noise
I filtered the signal using fft.
I want to separate signals.
Eg : from my original signal, I want a signal with frequency range say 3 to 8 KHz, another signal say from 100 to 200 KHz. How can I separate them and display those signals.How can I do this. Anybody Please help me to solve this.?
2 commentaires
aarthi arunachalam
le 11 Mar 2016
i too want to seperate certain frequency range from my original signal. can you help me?
Réponse acceptée
Shoaibur Rahman
le 1 Jan 2015
Add the following lines of code at the bottom of your code (after y=x+randn(size(x)).*sigma;):
ffty = fft(y);
ffty = abs(ffty(1:ceil(length(y)/2)));
ffty(ffty<100)=0;
[~,locs] = findpeaks(ffty);
freqs = (locs-1)/t(end)
signal_1 = sin(2*pi*t*freqs(1))+sin(2*pi*t*freqs(2))+sin(2*pi*t*freqs(3)); % 3-10
signal_2 = sin(2*pi*t*freqs(6))+sin(2*pi*t*freqs(7)); % 50-100
subplot(211), plot(t,signal_1)
subplot(212), plot(t,signal_2)
10 commentaires
Shoaibur Rahman
le 1 Jan 2015
Modifié(e) : Shoaibur Rahman
le 1 Jan 2015
Use any sinusoidal function to generate a signal with that frequency, and then plot that against time. For example:
t = .....
out1 = sin(2*pi*f1*t);
out2 = cos(2*pi*f2*t);
etc....
This is just from the Fourier analysis, that states any signal (with some criteria) can be represented as summation of infinite sinusoidal functions. So, to represent only one frequency, use one sinusoidal function, or to represent multiple frequency components, use summation of multiple sinusoidal functions with those frequencies.
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Pourya Alinezhad
le 1 Jan 2015
1-you can use several filters with different center frequencies (chebishev or butter filter)
h = fdesign.bandpass('N,F3dB1,F3dB2', N, Fc1, Fc2, Fs);
Hd = design(h, 'butter');
filter (Hd,input_signal);
2- you can use an adaptive filter and feed the signal and the desired signals to it (LMS filter).
2 commentaires
Pourya Alinezhad
le 1 Jan 2015
assign Fc1, Fc2 values as 3 and 10Kz for a filter. then make another filter with 50 to 100 kHz spectrum.
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