Hioki MR8827, Инструкция по эксплуатации

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247
FFT Analysis Condition Settings
13.3.3 Set the Frequency Range and Number of Analysis Points
About the Frequency Range and Nnumber of Analysis Points
• The settings for the frequency range and number of analysis points determine the input signal
acquisition time and frequency resolution.
• The frequency range setting for the FFT function corresponds to the timebase setting of the Memory
function.
Changing the frequency range also changes the data sampling period.
Refer to “Relationship Between Frequency Range, Resolution and Number of Analysis Points” (p. 248).
• The cut-off frequency of the anti-aliasing filter is the same as the frequency range setting.
Refer to “Relationship Between Frequency Range, Resolution and Number of Analysis Points” (p. 248).
• The set number of analysis points specifies the amount of data to be analyzed with each
measurement.
Increasing the number of analysis points increases the frequency resolution, but also increases the time
required for calculations.
Refer to “Number of Analysis Points” (p. A15).
To perform calculations on external sampling
Set the Sampling Clock to
[External]
(External sampling).
In this case, octave analysis, power spectrum density and LPC Analysis (power spectrum
density) are not available.
When [Reference] is set to [From Memory] , the frequency is automatically set.
The setting cannot be changed.
Frequency Range and Number of Analysis Points Setting: Use the Operating Keys
Press the STATUS key to open the Status screen, and then select the [Status] sheet.
Refer to “13.3.11 Set and Change Analysis Conditions on the Waveform Screen” (p. 261).
1
Set the number of FFT analysis points.
Move the cursor to [Sampling Point] .
1000 (Default setting) , 2000, 5000, 10000
Refer to “Number of Analysis Points” (p. A15).
1
2
Frequency Resolution
(during acquisition)
The resolution is affected by of
the selected frequency range and
number of analysis points.
Not displayed for external sampling.
To control sampling by an external
signal, select [External]
When the input data [Reference] is
[From Memory]
The frequency range is set
automatically when analysis is started.
2
Select the frequency range.
Move the cursor to
[Frequency Range]
.
8 MHz (Default setting) , 4 MHz, 2 MHz, 800 kHz, 400 kHz, 200
kHz, 80 kHz, 40 kHz, 20 kHz, 8 kHz, 4 kHz, 2 kHz, 800 Hz,
400 Hz, 200 Hz, 80 Hz, 40 Hz, 20 Hz, 8 Hz, 4 Hz, 1.33 Hz, 800
mHz, 667 mHz, 400 mHz, 333 mHz, 133 mHz, External
Refer to “Relationship Between Frequency Range, Resolution
and Number of Analysis Points” (p. 248).
13
FFT
Function