MR8740、MR8741_user_manual_eng_20191016H.pdf - 第288页
12.8 FFT Analysis Modes 276 W aveform Example Linear Spectrum The linear spec trum plot s the input signa l frequency . It can be displayed as a Nyquist plot. Main uses: • T o inspe ct the peak frequency cont ent s of a …
12.8 FFT Analysis Modes
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Chapter 12 FFT Function
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For the functions of each analysis mode, see"12.8.2 Analysis Mode Functions" (p.293).
Waveform Example
Waveform Example
12.8 FFT Analysis Modes
12.8.1 Analysis Modes and Display Examples
Storage
Displays the time axis waveform of the input signal.
When the window function setting is other than rectangular, the window function is applied to the
waveform and displayed.
Axis Display Type Description
X axis Linear
Time-domain display
Displays the value of the time-domain waveform corresponding to the set frequency
range.
See: "Relationship Between Frequency Range, Resolution and Number of Analysis
Points" (p.252)
Y axis Lin-Mag
Displays the module waveform
Window: Rectangular
X axis: Linear
Y axis: Lin-Mag
Histogram
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"12.8.2 Analysis Mode Functions" (p.293)
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: Linear
Y axis: Lin-Mag
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Waveform Example
Linear Spectrum
The linear spectrum plots the input signal frequency. It can be displayed as a Nyquist plot.
Main uses:
• To inspect the peak frequency contents of a waveform
• To inspect signal amplitudes at each frequency
See: About the Functions"12.8.2 Analysis Mode Functions" (p.293)
Axis Display Type Description
X axis
Linear Frequency is displayed with equal spacing
Log Frequency display of logarithm interval
Nyquist display
The real-number component of analysis values are displayed linearly.
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.
Nyquist display
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
Normal display
X axis: Log
Y axis: Log-Mag
Normal display
X axis: Log
Y axis: Lin-Real
Normal display
X axis: Log
Y axis: Lin-Imag
Lin-Imag
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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 two cursors appear, A cursor is the fundamental wave.
When results cannot 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.277), Power Spectrum (p.279)
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"12.8.2 Analysis Mode Functions" (p.293)
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