HP 8753D - Page 332

Calibration Considerations
Measurement
P
arameters
Calibration
procedures
are
parameter-specic
, rather
than channel-specic
. When
a parameter
is
selected,
the
instrument
checks
the
available calibration
data, and
uses the
data found
for
that
parameter
.
F
or
example,
if a
transmission response
calibration is
performed
for
B/R,
and
an
S
11
1-port
calibration
for
A/R,
the
analyzer
retains
both
calibration sets
and
corrects
whichever
parameter
is
displayed. Once
a calibration
has been
performed
for
a
specic
parameter
or
input,
measurements of
that parameter
remain calibrated
in
either
channel,
as
long
as
stimulus values
are coupled.
In the
response
and
response
and
isolation
calibrations
,
the
parameter
must be
selected before
calibration: other
correction procedures
select
parameters
automatically
.
Changing channels
during a
calibration procedure
invalidates
the
part
of
the
procedure already
performed.
Device
Measurements
In
calibration
procedures
that
require
measurement
of
several
dierent
devices
,
for
example
a
short,
an
open,
and
a
load,
the
order
in
which
the
devices
are
measured
is
not
critical.
Any standard
can be
re-measured, until
the
N
N
N
N
N
NN
NN
NN
N
N
N
DONE key
is pressed.
The change
in
trace
during
measurement
of a
standard is
normal.
Response
and response
and isolation
calibrations
require
measurement
of
only
one
standard
device
.
If
more
than
one
device
is
measured,
only
the
data
for
the
last
device
is
retained.
Omitting
Isolation
Calibration
Isolation
calibration
can
be
omitted for
most
measurements
,
except
where
high
dynamic
range
is
a
consideration.
Use
the following
guidelines
.
When
the
measurement
requires
a
dynamic
range
of:
90
dB:
Omit
isolation
calibration
for
most
measurements
.
90 to
100
dB:
Isolation
calibration
is
recommended
with
test
port
power
greater
than
0
dBm. F
or
this
isolation
calibration,
averaging
should
be
turned
on
with
an
averaging
factor
at least
four
times
the
measurement
averaging
factor
.
F
or
example
,
use
use
an
averaging
factor of
16 for
the
isolation
calibration,
and
then
reduce
the
averaging
factor
to
four
for
the
measurement
after
calibration.
100
dB:
Same
as
above
,
but
alternate
mode
should
be
used. See
page 5-53.
Saving Calibration Data
You should save the calibration data,
either in the internal non-volatile memory or on a disk.
If you do not save it, it will
be lost if you select another calibration procedure for the same
channel, or if you change stimulus values
. Instrument preset, power on, and instrument state
recall will also clear the calibration data.
Application and Operation Concepts 6-65