Smooth Data

The Smooth Data command is used when the acquired data are less than ideal. Sometimes exterior noise enters the cell and causes the data to have some minor oscillations. The Smooth Data command offers two different types of smoothing algorithms.

• The first is a sliding-window, which takes a number of data points in a window. This window averages the data points, and then slides one spot, and again takes an average. This sliding effect is repeated until all the data have been traversed. This technique is simple but has a downside of causing the heights of peaks to change.
• The second type is a Savitzky-Golay low-pass smoothing filter, which helps to preserve higher moments by approximating the underlying function with a polynomial. This method requires an order, which is the order of the polynomial, as well as a width, which is the number of points to be fit by the polynomial. The defaults of 4 for the order and 16 for the width are suitable for most applications, but you can easily change them.

Procedure:

1. Make the trace you wish to smooth the active trace. Do this by right-clicking on the trace and clicking Activate Trace.
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4. Select the Smooth Data command from the Common Tools menu. This opens the Smooth Data window, and offers you a selection of data you want to smooth.
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7. Select the smoothing-filter type, and then specify the conditions for that filter. Once you are satisfied, click the OK button. At this point the data are smoothed. One side-effect of smoothing is that it, in essence, replaces the original data in the document. To retrieve the original data, you must reload it from the original .DTA file.
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