FFT Graph Options

The FFT Graph Options dialog allows you to control how your data are plotted.

Title:

You can add and change the title text and its color as well as remove the title completely. The title will be placed at the top of the graph.

You can choose special symbols (including subscripts and superscripts) to be included in the title by clicking the  button.


Legend:

Check this option to display a legend using Data Column labels in the graph window.

Peak Frequency:

If this option is checked, the legend will show the frequency component with the largest amplitude.


Grid:

Major and Minor Tick Style: select line style for grid lines
Major and Minor Tick Color: select grid line color


FFT Definition:

Base Column: In most cases, only timed data will be used and will be the first column of the Data Set. Select the column from the pull-down menu.

Data Column: Choose which columns will be analyzed and plotted.

Frequency-Axis Options/Amplitude Axis Options:  Use this option to change the label or axis scaling for the Frequency-Axis and/or the amplitude axis. It is also possible to change the scales on the graph itself by clicking on the left and right limits on the X-Axis or the top and bottom limits of the Y-Axis. You can also use the Autoscale button in the toolbar.

Log Axis plots the Log of the values of the column it traces. Each major tick of the Y-Axis axis is a power of 10.
 
You might have a sound waveform that has a central portion for which you want the FFT, but not the earlier or later portions. Using the Restrict Range fields is the same as using the mouse to select a region on a time graph.

You can get the same results by selecting a region of data on a time-based graph and adding an FFT. The resulting FFT consists of only the selected data, excluding time before and after the selection.