How to separate signals with diffrent frequencies

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Srey
Srey 2015 年 1 月 1 日
コメント済み: aarthi arunachalam 2016 年 3 月 11 日
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 件のコメント
mouh nyquist
mouh nyquist 2015 年 1 月 1 日
you must read about chebishev and butter filter
aarthi arunachalam
aarthi arunachalam 2016 年 3 月 11 日
i too want to seperate certain frequency range from my original signal. can you help me?

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採用された回答

Shoaibur Rahman
Shoaibur Rahman 2015 年 1 月 1 日
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)
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Shoaibur Rahman
Shoaibur Rahman 2015 年 1 月 1 日
編集済み: Shoaibur Rahman 2015 年 1 月 1 日
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.
Srey
Srey 2015 年 1 月 1 日
Thank you so much..It works.:)

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その他の回答 (1 件)

Pourya Alinezhad
Pourya Alinezhad 2015 年 1 月 1 日
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 件のコメント
Srey
Srey 2015 年 1 月 1 日
I want a signal with freq range:say 3-10Hz and another signal with freq say 50-100. I want to plot them separately.How can be done from my original signal
Pourya Alinezhad
Pourya Alinezhad 2015 年 1 月 1 日
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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