User manual

Acquire the Sign
al
1. Push BW to bring
up the resolution
bandwidth side menu. This allows you to set
the smallest frequency difference that the
instrument can
discern in the frequency axis.
Bandwidth
2. Push RBW Mode
to select either Auto or
Manual.
Auto sets the resolution bandwidth
automatica
lly as you change the span. The
default behavior is RBW = Span/1000.
Manual allows you to set your own
resolution
bandwidth.
RBW
Mode
Auto
Manual
3. To manually adjust the RBW, push RBW
and turn Multipurpose a.
RBW
(a)
600 kHz
(Auto)
4. Push Span
:RBWand turn M u ltipurpose
a to set the span/RBW ratio.
ThisratioisusedwhentheRBW Mode is
set to Aut
o. The default is 1000:1 but you
can set it to other values in a 1-2-5 sequence
(e.g. 1000, 20000, 50000).
Span :
RBW
1000 : 1
5. Push Win
dow and turn Multipurpose a to
choose which FFT window type to use.
The choices are: Kaiser, Rectangular,
Hammin
g, Hanning, Blackman-Harris, or
Flat-Top.
Window
Kaiser
The RF
bandwidth FFT feature provides six windows. Each offers a trade-off between frequency resolution and magnitude
accuracy. The choice of which window to use depends upon what you want to measure and your source’s signal
characteristics. Use the following guidelines to select the best window:
Description Window
Kaise
r
The frequency resolution when using the Kaiser window is fair; the spectral leakage and
amplitude accuracy are both good.
The K
aiser w indow is best used when frequencies are very close to the same value but have
widely differing amplitudes (the side lobe level and shape factor are closest to the traditional
Gaussian RBW). This window is also good for random signals.
MDO3000 Series Oscilloscopes User Manual 85