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2-4-2. FFT Overview & Window Functions
Background
The FFT Math function performs a Fast Fourier
Transform on one of the input signals or the
reference waveforms. The resultant spectrum will
be shown on the screen in real-time. Four types of
FFT windows are available: Hanning, Hamming,
Rectangular, and Blackman, as described below.
Hanning FFT
Window
Frequency resolution Good
Amplitude resolution Not good
Suitable for....
Frequency measurement on
periodic waveforms
Hamming FFT
Window
Frequency resolution Good
Amplitude resolution Not good
Suitable for....
Frequency measurement on
periodic waveforms
Rectangular FFT
Window
Frequency resolution Very good
Amplitude resolution Bad
Suitable for....
Single-shot phenomenon
(this mode is the same as
having no window at all)
Blackman FFT
Window
Frequency resolution Bad
Amplitude resolution Very good
Suitable for....
Amplitude measurement on
periodic waveforms
2-4-2-1. FFT Operation
Panel Operation 1. Press the
Math
key.
MATH
M
2. Press
FFT
from the bottom menu.
3. Select the
Source
from the side
menu.
Range
CH1~4, Ref~4
4. Press the
Vertical Units
key
from
the side menu to select the vertical
units used.
Range
Linear RMS, dBV RMS