pick any 3 random files from this database, : https://physionet.org/pn3/ecgiddb/ They are subject to 50 Hz powerline interference.
We wish to convert from time domain to frequency domain and remove the 50 Hz frequency then transfer back to time domain showing clean signal.
I'm looking for some pointers in how I go about designing a Butterworth low pass filter which will eliminate 50 Hz powerline interference from an ECG.
How do I determine which order of filter, and how I determine the poles and zeros in order to calculate magnitude, phase and filter coefficients. Where do I start?