Smoothing

  •   SMOOTHING...    F          (Active channel only)    Performs nearest-neighbor smoothing with a choice of 3, 5, 7, 9, 11, 15, 19, 25, 35, or 51- point smoothing intervals with one or more repetitions (the default is 1).   The smoothing interval is the number of adjacent cases averaged for each smoothed point.   For example, 5-point smoothing includes the data point itself, the two immediately earlier points, and the two immediately later points in the averaged value.

    The program makes a memory copy of the channel and uses that as its data source (this insures that within a given smoothing iteration, previously smoothed data are not part of the calculations).  When smoothing is complete, the channel is redrawn.  If a block has been selected, you can smooth either all the data or just within the block.  You can also smooth conditionally, changing only those data within a certain range (i.e., greater than or less than user- specified values).  If the file contains less than 40 channels, you can copy the active channel to a new channel before smoothing.

    The example at right shows 19-sample smoothing to be repeated over six cycles.  Notice that the indicated smoothing interval (calculated from the sample interval and the averaging interval of 19 samples) is 27 seconds.  Conditional smoothing is selected, and smoothing will be applied only to data points will values less than 0.15.

    Smoothing can be repeated as often as necessary, but be very careful that you do not obliterate useful information from the data.  For example, smoothing a high-frequency waveform may result in a substantial decrease in the peak amplitude, although this should not affect frequency calculations.  Remember that you can undo only the last smoothing operation performed.


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