Walkthrough Example #1
This walkthrough example shows you how to process continuous random data with overlap averaging. To obtain the data file used for the walk through example below, please contact IMAT support at imat@ata-e.com.
- Start spFRF by typing spfrf at the MATLAB command prompt. If an IMAT unit system has not already been set for the current MATLAB session, a selection dialog will be presented. After the application and modules are initialized, the spFRF user interface appears.
- Read data using the File menu. spFRF supports reading data from several different file types, or from the MATLAB workspace. For this example, time response functions are read from the ATI file ironbird_007r.ati, which is from a four-shaker, random excitation, modal test run. The channels with a force data type are automatically determined to be references. Select the plotted channels from the References and Responses listboxes on the right side of the window.
- Select the channels sieve with the Channels dialog, which is opened from the Dialog menu. Specific references or responses can be disabled by selecting them, accessing the context menu by right-clicking, and selecting Disabled. The Channels dialog can also be accessed from the context menu.
- Select the time range for processing by moving the cursors on the plot. Simply click and drag the vertical line that runs between the horizontal arrows on the upper and lower edges of the plot.
- Set the signal processing parameters by entering the Blocksize and Overlap, and selecting the broadband Hanning window. The common power of two blocksizes can be selected from the context menu on the Blocksize edit box.
- Select the measurements that will be generated during signal processing by checking the corresponding boxes in the lower right corner of the module.
- Start signal processing by clicking the START button at the bottom right of the window. spFRF switches to the Results module when signal processing is completed.
- Review the spectral functions in the Results module. Select the plotted measurement from the Plot Function list. Select the plotted channels from the References and Responses listboxes on the right side of the window. Cursors can be added by right-clicking on the plot axes to access its context menu. The properties of the cursors are set from their context menu.
- Write results in the Results module. The spectral function results can be written to AFU or Universal files or the MATLAB workspace from the File menu. The written spectral functions are truncated to the Clear Lower and Clear Upper frequency range.