User Manual

3.10 FFT Analysis Modes
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Waveform Example
This instrument provides a circular auto-correlation function.
Analysis results are normalized to the maximum value.
Waveform Example
Auto Correlation Function ACR
Shows the correlation of two points on the input signal at time differential t.
Main uses:
• To detect periodicy in irregular signals (improving and detecting SNR)
• To inspect periodic components in a noisy waveform.
See About the Functions "3.10.2 Analysis Mode Functions" (⇒ p. 102)
Axis Display Type Description
X axis Linear
Time display
The center (
t = 0) is the reference. To the right is lag time (+t), and to the left is
lead time (-
t)
Y axis Lin-Mag
+1 to -1 (dimensionless units)
The closest correlation at time differential
t is +1, and the least correlation is 0.
-1 indicates completely reversed polarity.
Because of the characteristics of the function,
t = 0 becomes +1.
X axis: Linear
Y axis: Lin-Mag
Histogram HIS
Acquires the amplitude distribution of the input signal.
Main uses:
• To inspect deviations in the amplitude range of a waveform
• With analysis point distribution, to ascertain whether a waveform is artificial or natural (natural forms exhib-
iting regular distribution)
See About the Functions "3.10.2 Analysis Mode Functions" (⇒ p. 102)
Axis Display Type Description
X axis Linear
Displays input level of the input signal.
Y axis Lin-Mag
Displays analysis data distribution.
Normal display
X axis: Log
Y axis: Lin-Mag