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Power Density Spectrum The power density spectrum (V
noise bandwidth of the filter, in hertz. The power density spectrum is displayed on the dBm scale, with 0 dBm
2
corresponding to (V
/Hz).
ref
Sampling Frequency The time-domain records are acquired at sampling frequencies dependent on the selected
time base. Before the FFT computation, the time-domain record may be decimated. If the selected maximum
number of p
oints is lower than the source number of points, the effective sampling frequency is reduced. The
effective sampling frequency equals twice the Nyquist frequency.
Scallop Loss This is loss
Window Functions All available window functions belong to the sum of cosines family with one to three non-zero
cosine terms:
where: M = 3 is the maximum number of terms, a are the coefficients of the terms, N is the number of points of
the decimated source waveform, and k is the time index.
ents of Window Functions lists the coefficients a . The window functions seen in the time
The table of Coeffici
domain are symme
tric around the point k = N/2.
Window Type
Rectangular
von Hann
Hamming
Flat Top
Blackman-Harris
FFT Setup
Setting Up an FFT
1. In the menu b
ar touch
2. Touch a Math
function tra
software o
ptions loaded on you
from the menu.
3. Touch the Single
another math o
peration.
4. Touch inside the Source1 field and select a channel, memory, or math trace on which to perform the FFT.
5. Touch inside the Operator1 field: Select FFT from the pop-up menu if you selected Single function. Select
ath function if you selected Dual function. Then touch inside the Operator2 field and select FFT
another m
from the pop-up menu.
6. In the right-hand dialog, touch the FFT tab.
WRXi-OM-E Rev C
associated with the picket fence effect.
m
Coefficients of Window Functions
1.0
0.5
0.54
0.281
0.423
Math, then
Math Setup... in the
ce button: F1 th
rough
r osc
illoscope. See Spec
or Dual
(functio
n of a function
2
/Hz) is the power spectrum divided by the equivalent
m
a
0
0.0
-0.5
-0.46
-0.521
-0.497
dr
op-down menu
Fx The numbe
r of m
ath traces
ificatio
ns.; a pop-up menu appear
)
button if the FFT is to be of the result of
O
'
PERATOR
a
1
0.0
0.0
0.0
0.198
0.079
.
availab
le depends
lect FFT
s. Se
M
S
ANUAL
a
2
on the
141
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