HP 8753D - Page 363

Loss
of
P
ower
Meter
Calibration
Data
The
power
meter
calibration
data
will
be
lost
by
committing
any of
the following
actions:
Turning
power
o.
Turning
o
the
instrument
erases
the power
meter calibration
table.
Changing
sweep
type
.
If
the
sweep
type
is changed
(linear,
log, list,
CW,
power) while
power
meter
calibration
is
on,
the
calibration
data
will
be
lost. However
, calibration
data is
retained
if
you
change
the
sweep
type
while
power
meter
calibration is
o.
Changing
frequency
.
P
ower
meter
calibration
data
will also
be lost
if the
frequency
is
changed
in
log
or
list
mode
,
but
it is
retained in
linear sweep
mode
.
Pressing
4
PRESET
5
.
Presetting
the
instrument
will
erase
power
meter calibration
data. If
the
instrument
state
has
been
saved
in
a
register
using the
4
SA
VE/RECALL
5
key
,
you
may
recall
the
instrument
state
and
the
data will
be restored.
Saving the
instrument state
will
not
protect
the
data
if
the
instrument is
turned o.
Interpolation
in
P
ower
Meter
Calibration
If
the
frequency
is
changed
in
linear
sweep
,
or
the
start/stop
power
is
changed
in
power
sweep
,
then
the
calibration
data
is
interpolated
for
the
new
range
.
If
calibration
power
is
changed
in
any
of
the
sweep
types
,
the
values in
the power
setting array
are
increased
or
decreased
to
reect
the
new
power
level.
Some
accuracy
is
lost when
this
occurs
.
P
ower
Meter
Calibration
Modes
of
Operation
Continuous
Sample
Mode (Each
Sweep)
Y
ou
can
set the
analyzer
to
update
the
correction
table
at
each
point
for
sweep
(as
in
a
leveling
application),
using
the
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EACH
SWEEP
softkey
.
In
this
mode
,
the
analyzer checks
the
power
level
at
every
frequency
point
each
time
it sweeps
.Y
ou
can
also
have
more
than
one
sample/correction
iteration
at
each
frequency
point.
(See the
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NUMBER
OF
READINGS
softkey
description
in
Chapter
9.)
While
using the
continuous
sample
mode
,
the
power
meter
must
remain
connected
as
shown
in
Figure 6-54
.
A
power
splitter
or
directional
coupler
samples
the
actual
power
going
to
the
test
device and
is measured
by
the
power
meter
.
The
power
meter
measurement
provides
the
information
necessary to
update the
correction
table
via
HP-IB
.
Continuous
correction
slows
the
sweep
speed
considerably
,
especially
when
low
power
levels
are being measured by the power meter
. It may take up to 10 seconds per point if
the power
level is less than
0 20 dBm. F
or faster operation, you can use the sample-and-sweep mode
.If
you use a directional coupler
, you must enter the attenuation of the coupled arm with respect
to the through arm using the
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POWER LOSS
softkey.
6-96 Application and Operation Concepts