I have a low frequency signal, it's a heart beat signal (not an EKG, a pulse ox, its a much simpler shape).
So the heart beats ~.5 Hz to 4.5 Hz
I'm trying to eliminate the wandering baseline through a high pass filter
I used a single pole RC filter (50k Ohm and 220uF) (cut-off is .015 Hz) and found that it works really well except that it takes FOREVERRRRRRRRRRRR for the DC offset to get filtered out.
I don't know an easy way to do a Fourier Tform of the heart beat waveform. I realize that a heart beat is 2 Hz, but is it's frequency spectrum actually composed of much higher frequencies? Could I have a high pass filter with a cut off frequency of .5 Hz and still see the low heart beat?
I hope I explained that well, I found explaining it difficult.
So the heart beats ~.5 Hz to 4.5 Hz
I'm trying to eliminate the wandering baseline through a high pass filter
I used a single pole RC filter (50k Ohm and 220uF) (cut-off is .015 Hz) and found that it works really well except that it takes FOREVERRRRRRRRRRRR for the DC offset to get filtered out.
I don't know an easy way to do a Fourier Tform of the heart beat waveform. I realize that a heart beat is 2 Hz, but is it's frequency spectrum actually composed of much higher frequencies? Could I have a high pass filter with a cut off frequency of .5 Hz and still see the low heart beat?
I hope I explained that well, I found explaining it difficult.