How can I filtrate recorded time acceleration signal with 4th order Butterworth low pass filter ??

I need to filtrate a recorded time data of acceleration signal with 4th order Butterworth low pass filter of bandwidth 0.1–100 Hz ?? Sample frequency 200 Hz, Time step 0.005 S, Signal length 4048

Answer 1

[Alberto Mora]

If you sampled the signal at 200Hz it is useless adopt a low-passfilter at 100Hz since 100Hz is already the maximum bandwidth that you get, see Nyqyust frequency for more detauls. For antialiasing purpose you MUST use analogic filters, not digital filters. So I did not get the reason why you want to filter the signal at 100Hz.

Anyhow, this could be a possible solution.

Fs = 200;     % Sampling frequency in Hz
 
fcutlow = 20;     % low cut frequency in Hz

Order = 4;
 
[b,a] = butter(Order,fcutlow/(Fs/2));   % Get filter coeff of butter filter
 
Filt_filt_signal = filtfilt(b,a, rawSignal ); % zero phase delay low-pass filtering

As usual, if that helps you, please consider to accept the answer.

Thanks and best regards, A

[Mohamed Abdelkareem]

Thank you for your answer

[Alberto Mora]

Your welcome!