Trim data and spike removal
Automatic spike removal  (active channel only) allows you to delete or fix voltage 'spikes' or other inaccurate data.  There are several options for removing spikes:

  • Single-point spikes that exceed a user-defined amplitude are easily removed with the Spike Sweep operation.  However, this will not work effectively for multiple-sample spikes.  Spike sweep searches for single data points that differ from their nearest neighbors by the threshold value or greater (in absolute units).  Points meeting these criteria are converted to the average of the two nearest neighbors.   You can use the popup menu to select whether to fix 'upward' spikes (those attaining larger values than neighboring points), 'downward' spikes, or all spkes.

    Two options are available for sweeping: 'Single Scan' makes a single pass through the data; 'Spike Sweep' repeats scanning until all appropriate spikes are removed.

  • The Trim Data option searches for data points that are greater or less than preset limits; all data outside these limits are set to user-defined values.  Both sweep and trim can be performed within blocks only (if a block has been selected).
            The Absolute Value option converts all data to its absolute value (positive or zero); this is also available in the transforms window.

    In this example, the user has performed a spike sweep with a threshold value of .02, and the program found and removed 78 spikes.  Also, the trim data options have been set such than any value exceeding 5 will be set to equal 5, and any value less than -.15 will be set to zero.

    After trimming or removing spikes, a button allowing you to save the current settings as defaults will appear.

    An alternate manual spike removal is the Interactive mode.

    Other links: