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11.6 Setting the Display Range of the X-Axis (Frequency) and the Scale Type of the Y-Axis (Signal Amplitude)
Explanation
IM WT3001E-51EN
• Selecting the Scale Type of the Y-Axis (Signal Amplitude)
4.
Press the Vertical Scale soft key to select Lin or Log.
• Selecting the Display Range of the X-Axis (Frequency)
You can set the left and right ends of the power spectrum display.
• Disp Start (left end of the display)
Set the value in the range of 0 to 99990.
• Disp End (right end of the display)
Set the value in the range of 10 to 100000.
• The difference between Disp Start and Disp End must be greater than or equal to 10.
• The relationship between the Disp Start and Disp End settings and the frequencies
at the left and right ends of the power spectrum display varies depending on the
number of computed points (section 11.5). For example, if the number of computed
points is set to 20 k and Disp Start is set to 5, the frequency at the left end of the
display is 50 Hz. If the number of computed points is set to 200 k and Disp Start is
set to 5, the frequency at the left end of the display is 5 Hz.
• Selecting the Scale Type of the Y-Axis (Signal Amplitude)
You can select LIN (linear) or LOG (logarithmic).
• If you select LIN, the maximum value of the Y-axis is determined automatically from
the measurement range. The minimum value is zero.
• If you select LOG, the maximum value of the Y-axis is one digit above the
measurement range, and is a value that is an integer power of 10. The minimum
value is equal to 1/10000 of the maximum value.
Note
•
If the number of computed points (section 11.5) is 20 k (20000 points), the power spectrum
data is 0 to 10000. In this case, if you set a value greater than 10000 as the display range of
the X-axis (frequency), the power spectrum is not displayed above 10000.
•
If the scale type of the Y-axis (signal amplitude) is set to LOG, the data smaller than the
minimum value of the Y-axis is not displayed.
•
If FFT is taken on an input signal that is close to a sine wave with little distortion, the power
spectrum may appear as though it is not displayed. This is because the signal contains little
harmonic components. In this case, the power spectrum is displayed only on the Y-axis at
the left end of the display. If this happens, change the settings as follows.
•
Set the Disp End (right end of the screen) to a small value.
•
Set the scale type of the Y-axis (signal amplitude) to LOG (logarithmic).
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Index
11-13
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