I have a heartrate signal which is a few hours long. I need to preform a spectral analysis to get the ratio high frequency (0.15Hz-0.4Hz) to low frequency (0.04Hz - 0.15Hz) changes in heartrate within a window.
Maths is not my natrual habitat, but am I right using an FFT and and summing the absolute values of the bins that lie inside my frequency range?
I don't expect a full blown explanation of how fft works, but links to any tuts would be nice. I know what an FFT does, I just don't know how to use it.