Hioki MR8827, Инструкция по эксплуатации

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13 FFT Function
13
FFT Function
13.1 Overview and Features
FFT analysis can only be used with the FFT function.
The FFT (Fast-Fourier Transform) functions perform frequency analysis on input signal data.
Use these functions for frequency analysis of measurement targets such as rotating objects, vibrations,
and sounds.
For details, refer to “Appx. 4 FFT Definitions” (p. A13).
Analysis can be performed on data as it is being measured, on pre-existing analog waveform data
previously acquired with the Memory function, and on data output from waveform calculations.
When using a Model 8968 High Resolution Unit equipped with an anti-aliasing filter, the cut-off frequency
can be set automatically by linking with the frequency range setting.
Major Features
• FFT analysis frequency range: 133 mHz to 8 MHz
• FFT Analysis Modes (16 types)
•Storage Waveform •Cross Power Spectrum
•Histogram •Impulse Response
•Linear Spectrum •Coherence Function
•RMS Spectrum •Phase spectrum
•Power Spectrum •Auto-correlation Function
•Power Spectrum density* •Cross-correlation Function
•LPC analysis (Power Spectrum
Density)*
•1/1 Octave Analysis*
•Transfer Function •1/3 Octave Analysis*
* Not available when using external sampling.
For phase spectra, only the required phase information is highlighted and displayed.
Refer to “13.3.8 Emphasize Analysis Results (Phase Spectra Only)” (p. 255).
When performing FFT analysis with the instrument connected to a sound level or vibration meter,
scaling by dB can be set from the Channel Settings screen if you want to read values directly in
calibrated units of measurement.
Refer to “Scaling” (p. 262).
To suppress the effects of aliasing distortion caused by sampling
We recommend using Model 8968 High Resolution Units that are equipped with anti-aliasing filtering to
suppress the effects of aliasing distortion when sampling.
Refer to “Appx. 4 FFT Definitions” (p. A13).
Refer to “18.3.4 FFT Function” (p. 352) for FFT function specifications.
13
FFT
Function