 |
|
A custom filter can be made using Matlab or by contacting us. The filter coefficient file format is the same as the Matlab mat-format, but change the extension name from .mat to .emp. An example on generating and saving filter coefficients in Matlab is given below. Note that this generates a filter that is unstable if it is inverted so it can only be used for pre-filtering, not for post-filtering (since the post-filtering uses the inverted filter). Since the purpose of this filter is to band-limit the output below 80 Hz for the sampling frequency 48000 Hz, this is no problem for this application.
Fs=48000; % Sampling frequency in Hz
FcutOff = 80; % Cutoff frequency in Hz
Wn= FcutOff/(Fs/2); % Normalized cutoff frequency
FilterOrder = 6; % Filter order
FilterType = 'high'; % Filter Type
[b,a] = BUTTER(FilterOrder,Wn, FilterType); % Generate filter
save HighPassFc80Hz_Fs48000Hz.emp a b -mat
To use this filter, run the code and copy the generated file ‘HighPassFc80Hz_Fs48000Hz.emp’ to the ‘Filters’-folder under the WinMLS-folder.
The example below generates a bandpass filter for the frequency 250 Hz and sampling frequency 22050 Hz.
Fs=22050; % Sampling frequency in Hz
FcutOff = [125 500]; % 250 Cutoff frequency in Hz
Wn= FcutOff/(Fs/2); % Normalized cutoff frequency
FilterOrder = 6; % Filter order
FilterType = 'bandpass'; % Filter Type
[b,a] = BUTTER(FilterOrder,Wn, FilterType); % Generate filter
Contents
Index
Search
Previous
Next