The Short Time Fourier Transform (STFT) is very useful to estimate the NVH characteristics of a drivetrain system. The STFT uses the Hamming window to reduce spectral leakage. The steps at each window can be controlled by the overlap and time slice. A Color map can be displayed as result of the STFT using the following steps.

Figure 4.50: Steps for STFT

Step	Description
1	Click STFT in the menu bar.
2	Under Result, select the DFR filename.
3	Under Object, select the object of bearing force, bearing acceleration, or acceleration of measured points and components.
4	Set the Sampling Frequency, which is the maximum frequency of the y-axis in the color map.
5	Set the Time Slice which is the resolution of the x-axis in the color map.
6	Set the Overlap which is the percentage of duplicated time interval for performing FFT.
7	Set the number of data points (nFFT) for performing the FFT.
8	Set the Start time of the data for STFT.
9	Set the End time of the data for STFT.
10	Under Output Type, set the scale method of Original or Decibel.
11	Click the   button to create the graph.
12	Click the   button to close the operation.

Figure 4.51: STFT