Teledyne LeCroy WaveRunner XI SERIES Operator’s Manual - Manual (Page 141)

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