Applying Fast Fourier Transforms to Table Data

You use a fast Fourier transform data set to analyze the sound pressure level at different frequencies.

To apply fast Fourier transforms to table data:
  1. Right-click the Tools > Data Set Functions node and choose New > Point Time Fourier Transform (G[p]).

  2. Right-click the G(p) 1 > Tabular node and select New derived data from table.
  3. Expand the Tabular node and rename the Tabular > Tabular node to OTF_FWH_Minus90deg100r.


  4. Set the properties of the OTF_FWH_Minus90deg100r node:
    Property Setting
    Update Active Activated
    Input data OTF_FWH_Minus90deg100r
    X Column 1 Acoustic Time
    Y Column 1 Sound Pressure Surface Total
  5. Repeat this process to create three more Tabular nodes, for a total of four. The four nodes have identical properties, except for names and Input data.


  6. Select the G(p) 1 node and set the following properties:
    Property Setting
    Update Interval 1
    Start Time 0.02 s
    Cut-off Time 0.0533 s
    Amplitude Function Sound Pressure Level
    Analysis Blocks 2
    Overlap Factor 0.5
    Window Function Hann
  7. Select each of the four nodes under the Tabular node and activate Update Active in each one.