Download SDS2000 User Manual

SIGLENT
To display a FFT waveform:
1. Press the Math button on the front panel to open the MATH function menu.
2. Press the Operation softkey and then turn the Universal Knob to select FFT. The
resulting math waveform is displayed in white and labeled with “M”.
3. Press the Source softkey, and then turn the Universal Knob to select the source to
do FFT operation. Analog channels (CH1, CH2, CH3, and CH4) and reference
waveforms (REFA, REFB, REFC and REFD) can be used as the source.
4. Press the Window softkey, and then turn the Universal Knob to select an appropriate
window.
Spectral leakage can be considerably decreased when a window function is used.
SDS2000 provides four kinds of FFT window functions which have different
characteristics and are applicable to measure different waveforms. You need to select
the window function according to different waveforms and their characteristics. Please
read the table below carefully to make a appropriate option according to the input
signal.
Window
Characteristics
Measurement
Rectangle
The
best
frequency
resolution;
the
poorest
amplitude resolution; similar
to the situation when no
window is multiplied.
Transient or short pulse, the signal
levels before and after
the
multiplication are the basically the
same; Sine waveform with the same
amplitude
and
rather
similar
frequencies; Wide band random
noise with relatively slowly changing
waveform spectrum.
Hanning
Better frequency resolution;
poorer amplitude resolution.
Sine, periodic and narrow band
random noise.
Hamming
A litter bit better frequency
resolution than Hanning.
Transient or short pulse, the signal
levels before and after
the
multiplication are rather different.
Blackman
The
best
amplitude Single frequency signal, search for
resolution;
the
poorest higher order harmonics.
frequency resolution.
5. Press the FFT Zoom softkey, and then turn the Universal Knob or turn the horizontal
scale knob to select the desired magnifying multiple (1X, 2X, 5X, 10X). Set the FFT
Zoom to an appropriate magnifying multiple to observe more details of the FFT
waveform.
6. Press the Scale softkey to select the unit of vertical axis. The unit of the vertical axis
can be dB or Vrms which use logarithmic mode and linear mode to display vertical
amplitude respectively. If you need to display the FFT frequency spectrum in a
relatively larger dynamic range, dBVrms is recommended.
7. Press the Display softkey to select Split or Full Screen display mode.
 Split: the source channel and the FFT operation results are displayed separately.
The time domain and frequency domain signals are displayed clearly
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