allanhurst:
Could you tell us the specifications of the filter you wish to implement? Both analogue and digital. Why?Bandwidth - 1-3 Hz - OK. I presume -3dB points.
attenuation rate outside the passband in dB/octave.
Stopband attenuation.
Acceptable ripple.
Phase response.
So I am building a contactless heart monitor, using a parallax x-band motion detector. The detector at its highest sensitivity can detect movement anywhere from the beating of a heart to a person walking. So I am trying to to just detect the heart beating which is typically between 1-2Hz but, I've expanded that window that width to 1-3Hz in case of a very high heart rate.
Attenuation rate would need to be high. I don't want any signals above 4Hz
Stopband attenuation -10dB or less
I am not necessarily worried about ripple.
I am not really worried about phase response either though, I am reading values in real time so maybe I should be.
EDIT. I am using Matlab's Filter Design and Analysis Tool. To design a Bandpass Equiripple filter