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Filtering

In some cases you might need to filter your raw data. Very often this will be necessary when you intend to down-sample your raw data (see following section). But it might also be the case that you encounter a constant disturbance in your recorded signal data that cannot be avoided in the recording. Typically these are 50/60Hz hums that might be filtered very effectively using a digital high pass or notch filter. You may design your own filter or use tools like genfilt from the public domain SFS software package7.6. Use a different suffix for the filtered signal files to avoid confusion and double filtering of the same data. Refer also to [13] for a more detailed discussion of techniques to improve the quality of your recorded signals.



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