Iwatsu DS-8814, Operation Manual

Page: 121 / 141

F-8
FFT data with Memory length “Short”
All of the waveform data (1024 points) of the specified source are used for the FFT.
•
When the equal sampling (Equ) is Off, the time axis range is slower than 200
ns/div.
•
When the equal sampling (Equ) is On, the data is displayed on the screen as
shown below in a time axis range other than 5 ns/div and 200 ns/div.
With TIME/DIV settings other than the above, the number of screen display data
points will be different because the waveform display is enlarged. (Refer to document
1 on page 75.)
In this case, after waveform acquisition halt (STOP), the FFT range can be verified in
the same manner by performing the following operations.
•
When equal sampling is Off, change TI ME/DIV and set to 500ns/div
•
When equal sampling is On, change TIME/DIV and set to one delayed range.
Window Selection
The window (Rect (Rectangular), Hanning, Flat Top) during the FFT is selected.
Refer to page F-18.
F Window setting Applicable waveform Characteristic
Rectangular Transient Waveforms Leakage may occur other than
applicable waveforms.
Hanning Repetitive waveform Suitable for frequency resolution.
Flat Top Repetitive waveform Suitable for amplitude resolution.
First acquired data
Last acquired data
Waveform display screen
500 data
points
(5div)
24 data points
Outside screen
computation data
500 data
points
(5div)