MR8740、MR8741_user_manual_eng_20191016H.pdf - 第287页
12.8 FFT Analysis Modes 275 11 Chapter 12 FFT Function 12 For the functions of each analysis mode, se e"12.8.2 Analysis Mode Functions" (p.293). W aveform Example W aveform Example 12.8 FFT Analysis Modes 12.8.…
12.7 Analysis with the Waveform Screen
274
Use the mouse to move the memory waveform portion in order to
specify the calculation range, and then rotate the mouse wheel to
move the calculation range in order to specify the calculation
position.
To change the number of
analysis points
The setting can be changed at the top of the Waveform screen.
The range is determined by the number of analysis points.
If the analysis range (number of points) is larger than the memory waveform as
shown below, analysis is not performed.
To analyze only a certain
portion
If [Exec] is [Single] in the setting items at the right side of the screen, only the cal-
culation range currently displayed can be calculated.
For settings other [Single], calculation points are calculated until the final data.
To stop mid-way, click [STOP].
Analysis Segment Display
6
Select analysis conditions as occasion
demands.
The analysis segment of the memory
waveform for one pass is displayed.
Memory Waveform
7
Analysis results are displayed on the lower graphs.
When the trigger mode is [Auto] or [Repeat], the num-
ber of analysis points up to the end of the waveform
data is analyzed, and the last data is displayed.
Calculation range (portion in square)
Last range calculated (line portion)
Click [Exec] or [START] to perform analysis.
8
Analysis Starting
Point
12.8 FFT Analysis Modes
275
11
Chapter 12 FFT Function
12
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
12.8 FFT Analysis Modes
276
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