How to use low pass flter for time domine data

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Thulasi Durai Durai Samy 2013-3-23

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Hello

I need to filter high frequency data and allow only low frequency.

Can I use low pass filter in time domine data to filter noise signal without using FFT to convert data in frequency domine and use a low pass filter then take ifft.

Pls some one help me.

--Thanks

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Youssef Khmou 2013-3-23

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hi, you can use built-in functions "butter" and " filter" , example :

 Fs=8000; % SAMPLING FREQUENCY
 t=0:1/Fs:2;
 f1=500; %lower frequency
 f2=1500; % upper frequency
 y=chirp(t,f1,2,f2); % THE SIGNAL WITH BANDWIDTH 1000 Hz
 Fc=1500; %  cutoff frequency .
 Fn=Fs/2;
 % Filter implementation
 [b,a]=butter(2,Fc/Fn,'low');
 x=filter(b,a,y);

I hope this helps

Actually I didnt make you clear, My aim is to reduce the noise in the time domine data and output I need in time domine data only. The noise is sitting on actual response signal as shown in figure. Pls let me know the solution pls, sampling rate: 500 Hz

href = ""<https://www.dropbox.com/s/iv1pbud4kzet30c/time%20domine%20data.tif ></a>

Thulasi Durai Durai Samy 2013-3-24