Displaying Fft Spectrum; Selecting Fft Window - ADInstruments DS2002A Series User Manual

5.3.1.2

Displaying FFT Spectrum

Push the MATH MENU button to display the Math menu. Use 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 FFT Options
Source
Window
FFT Zoom
Fundamental frequency component
2
1. Frequency at the center graticule line
2. Vertical scale in dB per division (0dB=1V
3. Horizontal scale in frequency per division
4. Sample rate in number of samples per second
5. FFT window type
5.3.1.3

Selecting FFT 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
DS2002A Series Digital Storage Oscilloscope User Manual
Settings
CH1, CH2
Hanning, Flattop,
Rectangular
X1, X2, X5, X10
1
Frequency component
3 4
Comments
Choose a channel to be the FFT source.
Select a type of the FFT window. For more
information, refer to
Change the horizontal magnification of the FFT
display. For detailed information, refer to
5.3.1.6.
)
RMS
Basic Operation
Section 5.3.1.3.
Section
5
23