Filtering the data in matlab

[roop123]

helllo,

i am receiving data from a 2-D digital accelerometer..i am provided with a software that reads the accelerometer signal form parallel port and samples it at the chosen sampling rate .....and writes the tab separated text file .....file contains three columns: time,x,y....
after taking this file,i want to apply low pass filter on thia data....

but i am not getting that do i need to take FFT of this data ???also do i need to take iFFT after applying LPF????

please anybody help me out......

thanks

 

[roop123]

Plzzz anyone reply...its urgent..

Thanks

 

[atulbhatia]

for filtering you can use filter command. If you want to see the output in terms of normalised frequency you can use freqz command. you can see the output by uisng following command where
x is the filtered data and fs is sampling frequency.
y=fft(x,512);
df=fs/512;
m=fftshift(abs);
p=unwrap(angle);
f = -(fs/2)+df:dffs/2);
plot(f,m1);title('magnitude');

 

[roop123]

Thanks fo rreplying...

but i wanted to know that why do we need to take fft and inverse fft.....