remove noise from measured data
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Hi All,
I am reading this page from Matlab, and I have the following question from it. Can you please explain? It says: "The filter is designed to allow all frequency components with a period less than 48 hours and block all components higher than that." So my question is: based on what it says, how did it come up with the following values?
% Filter Order
N = 3;
% Passband frequency
Fpass = 1/(24*60*60);
% Stopband frequency
Fstop = 1/(6*60*60);
% Ripple Factor and Attenuation in stop band
Rp = 0.5;
Astop = 50;
Thanks
3 Comments
John BG
on 29 Jun 2017
1/(24*60*60) is the slowest fastest signal that the filter is going to let in, or should let in, without significant attenuation. 1/(6*60*60) is a 6 hours cycle signal that the filter will block. 6 hours cycle is the frequency (f=1/T) where the 1st notch of the filter is going to be placed to attenuate faster signals.
The question reads 'let through frequencies lower than 1/2days' the 48 hours, but the pass / stop frequencies chosen are not that stringent.
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