Hioki MR8827, Instruction Manual

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277
FFT Analysis Modes
Linear Predictive Cording (LPC) Analysis (Power Spectrum Density)
When the spectrum shape is complex and hard to understand with either linear or power spectra,
a rough spectrum structure can be obtained.
Main uses:
To obtain a spectral envelope using statistical methods
About the Functions, refer to “13.9.2 Analysis Mode Functions” (p. 289).
Axis Display type Description
X axis
Linear Displays the frequency on a linear scale
Log Displays the frequency on a logarithm scale
Y axis
Lin-Mag Displays analysis values linearly.
Log-Mag(logarithm) Display analysis results as dB values. (0 dB reference value: 1eu 2 /Hz)*
* eu: engineering units that are currently set are the standard (e.g., when the unit settings is volts, 0 dB = 1 V 2 /Hz)
Waveform Example
X axis: Log
Y axis: Lin-Mag
X axis: Log
Y axis: Log-Mag
• Always specify the order (from 2 to 64). Higher orders can expose finer spectral details.
• Amplitude values provided by LPC are not always the same as the power spectrum density.
• If an error occurs during analysis, no waveform will be displayed.
• Noise-like phenomena can strongly affect the spectrum shape.
• Not available with external sampling enabled.
13
FFT
Function