LeCroy SDA, Operator'S Manual

Page: 203 / 397

SDA Operator’s Manual
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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
m
are the coefficients of the terms, N is the
number of points of the decimated source waveform, and k is the time index.
The table of Coefficients of Window Functions lists the coefficients a
m
. The window functions
seen in the time domain are symmetric around the point k = N/2.
Coefficients of Window Functions
Window Type a
0
a
1
a
2
Rectangular 1.0 0.0 0.0
Hanning (Von Hann) 0.5 -0.5 0.0
Hamming 0.54 -0.46 0.0
Flattop
0.281 -0.521 0.198
Blackman–Harris 0.423 -0.497 0.079
FFT Setup
Setting Up an FFT
1. In the menu bar touch Math , then Math Setup... in the drop-down menu.
2. Touch a Math function trace button: F1 through Fx [The number of math traces available
depends on the software options loaded on your scope. See Specifications.]; a pop-up menu
appears. Select FFT from the menu.
3. Touch the Single or Dual (function of a function) button if the FFT is to be
of the result of another math operation.
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 another math function if you selected Dual function. Then touch inside the
Operator2 field and select FFT from the pop-up menu.
6. In the right-hand dialog, touch the FFT tab.
SDA-OM-E Rev H
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