Oscilloscope Reference Spectral analyzer window types
Blackman-Harris (see page 776)
Hanning (see page 776)
Flattop2 (see page 774)
Kaiser-Bessel (see page 776)
Tek Exponen
tial
(see page 779)
Your choice of window function will depend on the input source characteristics that you want to observe
and the char
acteristics of the window function. The window characteristics are shown in the following
table.
Window 3 dB BW in bins
Scallop loss
Nearest side
lobe
Zero phase
reference
Coefficients
Rectangular 0.89 3.96 dB -13 dB
50%
1.0
Hamming 1.3 1.78 dB -43 dB
50%
0.543478,
0.456522
Hanning 1.44 1.42 dB -32 dB
50%
0.5, 0.5
Kaiser-Bessel 1.72 1.02 dB -69 dB
50%
0.40243,
0.49804,
0.09831,
0.00122
Blackman-
Harris
1.92 0.81 dB -92 dB
50%
0.35875,
0.48829,
0.14128,
0.01168
Gaussian
2.0 0 .76 dB -79 dB
50% a = 3.75 (not
cosine series)
Flattop2 3.8 0.0065 dB -90 dB
50%
0.213348,
-0.206985,
0.139512,
-0.043084,
0.003745
Tek Exponential 1.42 0.60 dB -67 dB
20%
not applicable
xxx
3dBBWinbins
This is the bandwidth in units of bins, which are the intervals between spectral output samples when no
zero fill is used. The bandwidth is measured between the points on the lobe that are 3 dB down from the
peak of the lobe. The bandwidth in hertz may be computed by dividing the BW in bins by the gate duration
in seconds. This is also referred to as resolution bandwidth (RBW).
Coherent gain
The gain factor normally associated with different window functions is correctly scaled into the magnitude
spectrum output. Therefore, the magnitudes in the output spectrum do not change as different windows
are s elected.
772 DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series
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