Calculate and display the average power spectrum by using the calculate equation. When the simultaneous 4-ch measurement of noise from the target object in four points (top and bottom, right and left) is performed, the average power spectrum can be obtained by the following formula,

 

 

The PWR1, PWR2, PWR3, and PWR4 are described each power spectrum of ch1, ch2, ch3, and ch4.

 

If the power spectrum is stored in a file, calculate data after display it to the screen. Input the calculate equation formula by clicking the registration name of the screen data from the Input Data section on the Calculate Equation Set screen or inputting it by the keyboard. For example, in eight screen display, screen data of the upper left of the screen are DISP1 to DISP4, and screen data of the lower left are DISP5 to DISP8. The calculation formula is specified at the screen data display position.

 

The following is an example that stored data are displayed in DISP1 to DISP4 and the calculation results is displayed in the DISP5.

 

 

Measurement example

1. Click [Display > Display Condition] to select 8 screen display.

 

2. Click [File > Open Data File] to display the stored power spectrums on the DISP1 to DISP4.

 

3. Click the DISP5 frame to activate it (Character is changed to blue.).

 

4. Click [Analysis > Calculate Equation Set] and create the following calculation formula to DISP5, and put check mark on [Equation]. When you click [OK] button, the calculation is executed and the result is displayed in the DISP

 

5.

A to D: Power spectrums of DISP1 to DISP4

 

Calculate equation set screen

 

 

Calculate equation result display

 

 

<Memo>

The stored power spectrum data is square value of amplitude A (effective value). According to this, it displays log A² when Y-axis scale is log, and displays √A² when Y-axis scale is LIN.

 

 

In the above calculation formula, following calculation is carried out.

 

●When Y-axis is LIN scale

 

●When Y-axis is log scale (dB)