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Verfügbare Sprachen
Verfügbare Sprachen
Taking the FFT operation for example, the operation steps are as follows:
1.
Press the MATH MENU button and call out the WAVE MATH menu.
2.
Press F1 to turn on/off FFT after entering FFT menu, and please note that FFT is prohibited in Window
setting mode. The green waveform F is shown in the screen after calculation.
3.
Press F2 selection button to switch over source channel CH1 and CH2.
4.
Press F3 button to select WINDOW, including Rectangle, Hamming, Hanning and Blackman.
5.
Press F4 to choose the Format as dB or Vrms.
6.
Press F5 to zoom in or out the wave of the multiple including *1, *2, *5, *10.
7.
Adjust the "Horizontal" knob in horizontal control zone to move the waveform and the shown frequency of
M Pos is the exact frequency of the cursor point in the middle of spectrum.
8.
Turn off FFT and then press math menu button to go back to the second page of wave math.
22.1. Selecting an FFT Window
The FFT feature provides four windows. Each one is a trade-off between frequency resolution and magnitude
accuracy. What you want to measure and your source signal characteristics help you to determine which
window to use. Use the following guidelines to select the best window.
Type
Rectangle
Hamming
Hanning
Description
This is the best type of window for resolving frequencies that
are very close to the same value but worst for accurately
measuring the amplitude of those frequencies. It is the best
type for measuring the frequency spectrum of nonrespetitive
signals and measuring frequency components near DC.
Use rectangle for measuring transients or bursts where the
signal level before and after the event are nearly equal. Also,
use this window for equal-amplitude sine waves with
frequencies that are very close and for broadband random
noise with a relatively slow varying spectrum.
This is a very good window for resolving frequencies that are
very close to the same value with somewhat improved
amplitude accuracy over the rectangle window. It has a slightly
better frequency resolution than the Hanning.
Use Hamming for measuring sine, periodic and narrow band
random noise. This window works on transients or bursts
where the signal levels before and after the event are
significantly different.
This is a very good window for measuring amplitude accuracy
but less so for resolving frequencies.
Use Hanning for measuring sine, periodic, and narrow band
random noise. This window works on transients or bursts
where the signal levels before and after the event are
significantly different.
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Window
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