Instructions

Digital Storage Oscilloscope 19
4. Press Center softkey and then turn the Universal Knob to adjust the frequency of
the frequency domain waveform corresponding to the horizontal center of the screen.
5. Press Span softkey and then turn the Universal Knob to adjust the the horizontal
scale of the frequency domain waveform.
6. Press the Vertical Units softkey to select the unit of vertical axis. The units of the
vertical axis can be dB or Vrms which use a logarithmic scale or a linear scale 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 Scale softkey to select the vertical scale.
8. 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. The
series of scope provides six 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 an appropriate option according to the input
signal.
Window
Measurement
Characteristics
Rectangular
Pulse or
Transient
Waveform
Special-purpose window applicable to
discontinuous waveforms. This is actually the
same as no windows.
Hanning
Periodic
Waveform
Better frequency, poorer amplitude accuracy than
Flattop
Hamming
Transient or
short pulse
A litter bit better frequency resolution than
Hanning.
Blackman
Single frequency
signal, search for
higher order
harmonics.
The best amplitude resolution; the poorest
frequency resolution
Bartlett
(Triangle)
Narrow band
signal with
stronger
Better frequency resolution.
Flattop
Periodic
Waveform
Better amplitude, poorer freq
uency accuracy
than Hanning