4.6 Viewing Noise Measurement Values (FFT Function)
86
The highest frequency that can be analyzed depends on the sampling setting as follows.
Also, the frequency resolution of noise analysis depends on the sampling rate setting and the number of
points.
Set the minimum acquisition frequency for numerical noise values according to the noise frequency to be
analyzed. The lower limit can be set from 0 Hz to 10 kHz in 1-kHz steps. The setting applies to both
[Noise] and [Wave + Noise]. Make this setting on the [Calc] page of the Setting screen.
Sampling Rate 500 kS/s 250 kS/s 100 kS/s 50 kS/s 25 kS/s 10 kS/s
Highest Frequency 200 kHz 50 kHz 20 kHz 10 kHz 5 kHz 2 kHz
500 kS/s 250 kS/s 100 kS/s 50 kS/s 25 kS/s 10 kS/s
1000 500 Hz 250 Hz 100 Hz 50 Hz 25 Hz 10 Hz
5000 100 Hz 50 Hz 20 Hz 10 Hz 5 Hz 2 Hz
10000 50 Hz 25 Hz 10 Hz 5 Hz 2.5 Hz 1 Hz
50000 10 Hz 5 Hz 2 Hz 1 Hz 0.5 Hz 0.2 Hz
• The instrument‘s internal anti-aliasing filter is set automatically according to the sampling set-
ting, so that aliasing effects are suppressed even at slow sampling rates.
• Changing the sampling rate does not affect power measurements or the measurement fre-
quency range of harmonic measurements.
• Noise analysis display updating is not linked to other measurement data such as power or
harmonics.
Data saving is not synchronized with saving of power or harmonic data.
• The number of points determines the amount of time required for analysis, so larger numbers
of points result in slower update times. Updating 1,000 points takes approximately 400 ms,
5,000 points approximately 1 s, 10,000 points approximately 2 s, and 50,000 points approxi-
mately 15 s.
• To analyze noise frequency details, select fast sampling or a large number of points (e.g., to
analyze the difference between 50 Hz and 60 Hz, select a frequency resolution of 10 Hz or
less).
• The sampling rate setting is linked to the waveform timebase display setting.
4.6.3 Setting the Minimum Noise Frequency
Setting on the Measurement Screen
Screen display procedure:
See "4.6.1 Displaying Noise Voltage and Current" (p. 83)
Select the
numerical value
Enter
Select
[Lowest Noise]
Enter Cancel
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