HP 8753D - Page 311

Averaging
Menu
The
4
A
VG
5
key is
used to
access
three
dierent
noise
reduction
techniques:
sweep-to-sweep
averaging,
display smoothing,
and variable
IF
bandwidth.
All
of
these
can
be
used
simultaneously
.A
veraging and
smoothing
can
be
set
independently
for
each
channel,
and
the
IF
bandwidth can
be set
independently if
the
stimulus
is
uncoupled.
The
following softkeys
are
located
within
the
averaging
menu:
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AVERAGING RESTART
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AVERAGING
FACTOR
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AVERAGING
ON
off
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SMOOTHING
APERTURE
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SMOOTHING
ON
off
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IF
BW
[
]
A
veraging
A
veraging
computes
each
data point
based on
an
exponential
average
of
consecutive
sweeps
weighted
by
a
user-specied
averaging factor
. Each
new
sweep
is
averaged
into
the
trace
until
the
total
number
of
sweeps
is
equal to
the
averaging
factor
,
for
a
fully
averaged
trace
.
Each
point
on
the
trace
is
the
vector sum
of
the
current
trace
data
and
the
data
from
the
previous
sweep
.
A
high
averaging
factor
gives
the best
signal-to-noise
ratio
,
but
slows
the
trace
update
time
.
Doubling
the
averaging
factor
reduces
the noise
by
3
dB
.
A
veraging
is
used
for
ratioed
measurements: if
it
is
attempted
for
a
single-input
measurement
(e
.g.
A
or
B),
the
message
CAUTION: AVERAGING
INVALID
ON
NON-RATIO
MEASURE
is
displayed.
Figure
6-24
illustrates
the
eect of
averaging on
a
log
magnitude
format
trace
.
Note
If
you switch
power ranges
with averaging
on,
the
average
will
restart.
Figure 6-24. Eect of Averaging on a Trace
6-44 Application and Operation Concepts