11-3
IM 253710-01E
Waveform Analysis
11
Explanation
Select the computation region for performing waveform computations that are described
later (see section 11.2), or select the start point for the FFT (see section 11.3).
Turning ON/OFF the waveform computation mode
Select whether or not to perform waveform computations.
• OFF
Does not perform waveform computations.
• ON
Performs waveform computations. The menu used to set the waveform
computation is also displayed.
Setting the computation region
The waveform computation region is set to the region between the two cursors (start
and end points) that are placed on the screen.
• When the measurement mode is normal and the time base is set to internal clock,
the start position (dot-dashed line) and end position (dotted line) can be moved in
the range from 0 s (the left end of the screen) to the observation time (the right end
of the screen). When the time base is set to external clock or when the
measurement mode is harmonic, the start and end positions can be moved in the
range defined by the number of data points in the record length. For example, if
the record length is 100 k-words, then the range is from data point 0 (the left end of
the screen) to data point 100 k (the right end of the screen).
• Because the cursor position is displayed in the menu in terms of time when the
measurement mode is normal and the time base is set to internal clock, the start
and end points can be set by specifying the times even when the waveform is not
displayed. By using a display format that displays the waveform, the start and end
points can be set while viewing the waveform.
• When the measurement mode is normal and the time base is set to internal clock,
the start and end points can be set in steps of (observation time
÷
display record
length). When the time base is set to external clock or when the measurement
mode is harmonic, the start and end points can be set in steps of one data point.
• To move the start and end points simultaneously, which keeps the distance
between them constant, the jog shuttle must be set to control both [Start Point] and
[End Point].
Re-computing
• The computation region can be changed and waveform computations can be re-
performed while the data acquisition is stopped.
• The upper and lower limits can be set on the computation waveform. There are
two methods available to set the upper and lower limits. One method is auto
scaling in which the upper and lower limits are automatically determined from the
computed waveform. The other method is manual scaling in which the upper and
lower limits are set to predetermined values. For the procedures, see section 11.2,
“Setting the Equation, Converting the Scale of the Computed Waveform.” You can
also select whether or not to display the upper and lower limits. For the procedures
related to turning ON/OFF the display, see section 9.6, “Turning ON/OFF the
Upper and Lower Limit Displays.”
Note
The number of points from the start point to the end point is counted from the start point up to
a maximum of 100 kW.
11.1 Setting the Computation Region, Re-computing
