Following is the operation procedure how to perform Inverse Fast Fourier Transform (IFFT) by frequency band limitation.

 

Operation procedure

 

1. Open a new project.

2. Click the [Window (window function) set] in the input menu to open window function setting page.

3. Select the Rect (rectangular window) and click OK.

 

Figure 1

 

4. Stop the measurement after displaying the dual-screen of the time axis to be performed IFFT and Fourier spectrum.

5. Click the [Input source set] in the data display menu to open the input source setting page and select [Fourier Spectrum] to change the display to Fourier Spectrum.

 

Figure 2

 

6. Change the item of the [Cursor] in the data display menu which is on the bottom of the screen, from Peak to Delta.

 

Figure 3

 

7. In the Fourier Spectrum screen, click the lower limit frequency where you want to put band limitation, and move the cursor (red vertical line) with the ←/→ keys for fine adjustment, and click "Delta Position". The red vertical line is changed into pink and the lower limit frequency is selected. (Figure 3)

8. Operate same procedure as 7 for the time-axis waveform screen. (Figure 3)

9. Click the [IFFT] in the analysis menu to open the [Analysis] page.

 

Figure 4

 

10. Put check marks to the "Set delta-cursor" and "Execute" in the analysis page and click OK. The IFFT for Fourier Spectrum is executed and the time axis waveform with frequency band limitation is displayed. (Figure 4)

 

Upper screen: Original time-axis data Lower screen: IFFT data with frequency band limitation Figure 5

 

11. When you want to change the frequency band, click the [IFFT] in the analysis menu to open the [Analysis] page, and remove the check mark from the [Execute] and click OK to return to the Fourier Spectrum display. After this, execute 7, 8 and 9 operations again.

 

Supplement

IFFT data cannot be used as the time-axis waveform. Please refer to the "How to make it possible to treat the Inverse Fast Fourier Transform (IFFT) data as time waveform".