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Basic Operation
DS O5000 Series Digital Storage Oscilloscope User Manual
23
5.3.1.2
5.3.1.2
5.3.1.2
5.3.1.2 Displaying
Displaying
Displaying
Displaying FFT
FFT
FFT
FFT Spectrum
Spectrum
Spectrum
Spectrum
Push the MATH MENU button to display the Math menu. Us e the options to select the Source
channel, the Window algorithm and the FFT Zoom factor. Only one FFT spectrum can be
displayed at a time.
Math
Math
Math
Math FFT
FFT
FFT
FFT Options
Options
Options
Options Settings
Settings
Settings
Settings Comments
Comments
Comments
Comments
Source CH1, CH2 Choose a channel to be the FFT source.
Window
Hanning, Flattop,
Rectangular
Select a type of the FFT window. For more
information, refer to Section 5.3.1.3 .
FFT Zoom X1, X2, X5, X10
Change the horizontal magnification of the FFT
display. For detailed information, refer to Section
5.3.1. 6 .
Fundamental frequency component
F requency component
2 3 4
5
1
1. Frequency at the center graticule line
2. Vertical scale in dB per division (0dB=1V
RMS
)
3. Horizontal scale in frequency per division
4. Sample rate in number of samples per second
5. FFT window type
5.3.1.3
5.3.1.3
5.3.1.3
5.3.1.3 Selecting
Selecting
Selecting
Selecting FFT
FFT
FFT
FFT Window
Window
Window
Window
Using windows can eliminate the spectral leakage in the FFT spectrum. The FFT algorithm
assumes that the YT waveform repeats all the time. When the number of cycles is integral (1, 2,
3 ...), the YT waveform starts and ends at the same amplitude and there are no discontinuities in
the signal shape.
If the number of cycles is nonintegral, the YT waveform starts and ends at different amplitudes and
transitions between the start and end points will cause discontinuities in the signal that introduces
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