XL Toolboxes

1. A wildpoint editing routine is included that removes points from a data series according to certain max/min criteria and replaces the edited point using either a zero-order hold or a linear interpolation technique.

2. A smoothing routine is included that performs a moving least squares algorithm on a data series, allowing the user to specify the number of data points on each side of the smoothed data point to be used during the regression process.

3. 1D (low/high pass) recursive filter routines

4. 2D (band pass/reject) for basic modal analysis of data signals.

This Toolbox also includes an xLPowerBook to assist in using the above functions for Filter Design. It is described in more detail below:

 

 

 

 

To support the design of recursive filters for use in the routines in this toolbox, a filter design workbook as been included with this toolbox. The design workbook may be opened by clicking on the entry in the Data Processing Toolbox menu under the main SpreadsheetWorld menu when a worksheet is visible.

The filter design workbook includes two worksheets, one for designing low/high pass (1D) filters and one for designing band pass/reject (2D) filters. A picture from the 1D filter design worksheet is shown below:

 

 

 

 

 

 

Scroll bars are used to adjust the filter parameters for the particular filter. The shape parameters (a) are used to adjust the filter so that particular frequencies are passed or rejected. The plot next to the page will update automatically as the parameters are changed showing the frequency response of the filter. The gain parameter (b) is used to control the magnitude of the filter's frequency response. Unity gains may be achieved by selecting the check box just below the gain parameter scroll bar. The shape and (optionally) gain parameters are the inputs required by the filtering routines in this toolbox.

 

To filter out a particular frequency, filters should be designed so that high filter gains are present in the frequency range that should be preserved while low gains are present in the frequency range that should be removed from the signal. If multiple frequency ranges are to be removed from a signal, a separate filter for each frequency to be removed should be designed and then separate filtering operations should be applied to the data signal.

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