User Manual

3.4 Setting FFT Analysis Conditions
53
About the frequency range and number 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
(time/division) setting of the Memory function. Changing the frequency range
also changes the data sampling period.
See "Relationship Between Frequency Range, Resolution and Number of Analysis
Points" (
⇒ p. 55)
The cut-off frequency of the anti-aliasing filter is the same as the frequency
range setting.
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.
See "Number of Analysis Points" (⇒ p. 105)
When using the external sampling to calculate:
Set the Sampling Clock to [EXT] (External sampling).
In this case, octave analysis, power spectrum density and LPC power spectrum
density are not available.
The following two methods are available for setting the frequency range:
• Using the operating keys
• Using the TIME/DIV key (settable regardless of cursor position)
3.4.3 Setting the Frequency Range and Number of
Analysis Points
Frequency Range Setting: Using the TIME/DIV Key
To open the screen: Press the SET key → Select with the SUB MENU keys →Status Settings screen
See Screen Layout (
⇒ p. 40), To set from the Waveform screen (⇒ p. 67)
Lower frequency Higher frequency
The value changes with each key press.