October 2014
Page
33
3.1.3
Using FFT function
An FFT breaks down signals into component frequencies, which the oscilloscope
uses to display a graph of the frequency domain of a signal, as opposed to the
oscilloscope's standard time domain graph. You can match these frequencies with
known system frequencies, such as system clocks, oscillators, or power supplies.
FFT in this oscilloscope can transform 2048 points of the time-domain signal into
its frequency components and the final frequency contains 1024 points ranging
from 0Hz to Nyquist frequency.
The following table describes the FFT menu:
Function Menu
Setting
Instruction
FFT
ON
OFF
Turn on FFT function.
Turn off FFT function.
Source
CH1
CH2
DO FFT on Channe l
DO FFT on Channe 2
Window
Rectangle
Blackman
Hanning
Hamming
Type of window for FFT.
Format
dB
Vrms
Display in dB
Display in Vrms
Zoom
*1
*2
*5
*10
multiple *1
multiple *2
multiple *5
multiple *10
Taking the FFT operation for example, the operation steps are as follows:
Press
F1
once to turn on FFT, Press again to turn it off. Be aware that
only to use FFT when Horizontal Menu is set for main Timebase Not on
Window setting mode. Again, the green waveform is displayed as a
result of FFT.
Press
F2
to switch the FFT between CH1 and CH2.
Press
F3
to choose WINDOW for FFT, there are four options here,
including Rectangle, Hamming, Hanning and Blackman. We will give
details of these options later.
