MATLAB: Filter sampled excel data in matlab

butterworthdspfilterfilter designsignal processingsimulink

i have sampled data in excel and i want to filter it using high pass butterworth filter in matlab.i imported data from excel sheet .it is alredy sampaled.but how i filter it ?? plz help sampled freq = 44.1 khz, cutoff fre = 200 khz

Best Answer

Filtering in MATLAB is something very easy. Take a look at the BUTTER and the FILTER commands. Here you will find everything you need. For example, let's suppose you have your original data in the variable "signal". On a quick thought:
 fs = 44100; % Sampling frequency [Hz]
 order = 2;  % Order
 fc = 200;   % Cut-off frequency [Hz]
 % Create the filter's numerator and denominator.
 [num den] = butter(order, fc/(fs/2));
 % Filter.
 signalFiltered = filter(num, den, signal);
However, are you sure your values of fs and fc are correct? It is not logic to have a cut-off frequency larger than your Nyquist frequency (that is, half of the sampling frequency). In this case, it would not make sense having a cut-off frequency larger than 22.05 kHz. Notice how in my example, fc is 200 Hz (and NOT 200 kHz).
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