HP 83480A User Manual

General Purpose Oscilloscope Menus
FFT Menu
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Window
The three FFT windows you can select from are:
rectangular
Hanning
attop
The FFT operation assumes the time record repeats innitely. Unless there
is an integral number of cycles of the sampled waveform in the record,
a
discontinuity
is
created
at
the
end
of
the
record.
This
is
referred
to as
leakage.
In order
to
minimize
spectral
leakage
,
windows
that
approach
zero
smoothly at
the beginning
and
end
of
the
record
are
employed
as
lters
to
the
FFT.
Windows work
by
weighting
points
in
the
middle
of
the
waveform
record
higher than
those
at
the
ends
of
the
record.
F
or
example
,
a
Hanning
window
looks
like
the
rst
half
of
a
sine
wave.
The
Hanning
window
multiplies
the
points
in
the
center
of
the
record
by
1 and
multiplies
the
points
at
the
start
and
the
end
of
the
record
by
zero
.
The
rectangular
window
is
essentially
no
window
.
All points
in
the
record
are
multiplied
by
1.
The
rectangular
window
is
useful
for transient
signals and
signals
where
there
are
an
integral
number
of
cycles
in
the
time
record.
The
Hanning
window
is
useful
for
frequency
resolution
and
general-purpose
use
.
It
is
good
for
resolving
two
frequencies
that
are
close
together
or
for
making frequency measurements.
The attop window is the best window for making accurate amplitude
measurements of frequency peaks.
K
ey
Path 4
FFT
5
N
NNNNNNNNNNNNNNNNNNN
Window
10-24

HP 83480A Specifications

General

Brand	HP
Model	83480A
Category	Measuring Instruments
Language	English