Estimation IIR filter resources

A cutoff f 1/50k is possible with large fir or small iir but a transition band of -80dB at 10/50000 is just not realistic for fir or iir.

This requirement is too drastic for such a slow system. The likely best solution is multi stage decimation as suggested by FvM at some point in a previous related thread.

I will keep the band 1 ~ 10 Hz at 0dB (passband) during decimation then at the end say reaching Fs of 1000 (instead of 50000) will start final chop sharp at 1Hz down to 10Hz using Butterworth for the sake of the thread.