Filter Examples Lab View William Rose Department of Kinesiology and Applied Physiology

Filter Examples Lab View

William Rose

Department of Kinesiology and Applied Physiology


filter1.vi


filter1.vi


filter1.vi

Zoom in to beginning to see filter edge effects.



filter2.vi

Similar to filter1.vi, but uses Zero Phase.vi.






Another example of edge effects.


Another example of edge effects at each end of a data record.


Fix for Filter Edge Effects Problem

1.Extend the record by adding a segment of time-reversed, inverted-about-the-endpoint data on each end.

2.Filter the extended record.

3.Cut off the extended parts.

4.extend_data.vi does step 1.


extend_data.vi


extend_data_test.vi



filter3.vi

filter3.vi calls extend_data.vi to extend the raw data, then filters the extended data, then cuts off the extended parts.


filter3.vi



No more edge problems.

filter3.vi


filter1.m


filter1.m


filter1.mZoomed-in view of start


Phase-less Philtering•Use filtfilt.m in Matlab.

•Labview routine filter2.vi does forward –backward filtering with Zero Phase.vi, but it has edge effects at start and finish.

•We do not give a Matlab analog to filter2.vi, because, by default, Matlab’s forward-backward filter (filtfilt.m) eliminates edge effects.


filter3.mHighlighted lines differ from filter1.m.


filter3.mNo visible edge effects.


filter3.mNo visible edge effects at either end.


filter3.mNo visible edge effects.Data file: force_isometricelbowext_healthyadult_shortseg.txt


filter3.mNo visible edge effects at either end.Data file: force_isometricelbowext_healthyadult_shortseg.txt

Documents

Filter Examples Lab View William Rose Department of Kinesiology and Applied Physiology