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I am new to signal processing and examine ECG data corrupted with noise. The clean data has a frequency spectrum like this.

Spectrum1

And the corrupted one looks like this (sorry for the different scale) Spectrum2

I am asked to find a FIR band pass filter in matlab to filter out the noise. Unfortunatly I am using filters for the first time so I played with the coefficients and found something like this (The only thing that seems to be clear to me is that the bandpass has to be between something like 1-30 but I have trouble choosing the other parameters.) Fstop1 = 0.01 Fpass1 = 3 Fpass2 = 25 Fstop2 = 60 Astop1 = 80 Apass = 1 Astop2 = 30 Fs = 250

The result is not 100% satisfying (I am still having a lot of baseline fluctuations). Is it possible to get "good" results in doing this? Can anybody see heavy mistakes in my parameters that could lead to problems? Or can anyone tell me better coefficients to use?

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  • $\begingroup$ Could you add links to the figures you mention in your question? $\endgroup$ – Matt L. Jun 6 '15 at 17:08
  • $\begingroup$ Sure. link1 for the first one and link2 for the second one. $\endgroup$ – AlexConfused Jun 6 '15 at 17:53
  • $\begingroup$ Can't access those dropbox files: "Error (403) It seems you don't belong here! You should probably sign in. Check out our Help Center and forums for help, or head back to home." $\endgroup$ – Olli Niemitalo Jun 7 '15 at 7:56
  • $\begingroup$ Sorry, these links should work now: link1 and link2 $\endgroup$ – AlexConfused Jun 7 '15 at 10:55

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