13.9 FFT Analysis Modes
238
Waveform Example
Nyquist display
• If the cursor is displayed, the total harmonic distortion (THD), which sets the
fundamental wave as the cursor position, is displayed. When 2 cursors appear,
the one with the low frequency becomes the fundamental. When results can-
not be obtained,
[---%]
is displayed.
• When only sine waves are input, the level of this component becomes approx-
imately 1.4 times (3 dB) larger than the overall value. To measure at a refer-
ence the same as the overall value, analyze using RMS spectrum or power
spectrum.
See:
RMS Spectrum (
p.238), Power Spectrum (
RMS Spectrum
The oscillation component (actual value) is calculated by the frequency axis waveform of the input signal.
RMS and power spectra displays use the same analysis results displayed logarithmically (amplitude in dB).
Main uses:
• To inspect the execution value of the frequency component of the waveform
• To inspect the RMS value at each frequency
See:
About the Functions
"13.9.2 Analysis Mode Functions" (
Axis
Display Type
Description
X axis
Linear
Frequency is displayed with equal spacing
Log
Frequency display of logarithm interval
Y axis
Lin-Mag
Analysis values are displayed linearly.
Log-Mag
Analysis values are displayed as dB values. (0 dB reference value: 1eu)*
Lin-Real
The real-number component of analysis values are displayed.
Lin-Imag
The imaginary component of analysis values are displayed.
* eu: engineering units that are currently set are the standard (e.g., when the unit settings is volts, 0 dB = 1 V)
Normal display
X axis: Log
Y axis: Lin-Mag
Summary of Contents for 8847
Page 1: ...MEMORY HiCORDER Instruction Manual 8847 December 2010 Revised edition 4 8847A981 04 10 12H ...
Page 2: ......
Page 18: ...Operating Precautions 8 ...
Page 26: ...1 4 Basic Key Operations 16 ...
Page 74: ...4 4 Waveform Observation 64 ...
Page 98: ...5 5 Managing Files 88 ...
Page 110: ...6 6 Miscellaneous Printing Functions 100 ...
Page 126: ...7 8 Seeing Block Waveforms 116 ...
Page 160: ...8 10 Making Detailed Settings for Input Modules 150 ...
Page 198: ...10 6 Numerical Calculation Type and Description 188 ...
Page 296: ...15 7 Controlling the Instrument with Command Communications LAN USB 286 ...
Page 304: ...16 2 External I O 294 ...
Page 362: ...Appendix 5 FFT Definitions A28 ...
Page 368: ...Index Index 6 ...
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Page 370: ......
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