HP HP 8712ES, User Manual, Page: 258 / 507

6-12 ES User’s Guide
Calibrating for Increased Measurement Accuracy
Calibration Choices
Retrieving Previous User-Defined
Calibrations
User-defined calibrations that you have already performed may be
available for you to use again. In some cases, you can retrieve these
calibrations rather than perform new ones. The following user-defined
calibrations, if previously performed (and not cancelled by manually
selecting a default calibration of the same type), may be retrieved when
current instrument settings are compatible:
• user two-port (for all S-parameter measurements)
• user one-port (for S
11
and S
22
measurements)
• user response (for S
21
and S
12
measurements)
Widening the frequency span after retrieving a user-defined calibration
will invalidate it, and the analyzer will automatically restore the default
calibration of the same type. The user-defined calibration will
automatically be retrieved again when you narrow the instrument’s
frequency span to be compatible with that of the calibration.
Note that after you have retrieved a calibration, a "C" appears in the
upper right hand corner of the display. This "C" indicates that a
user-defined cal is in use. If you change to a narrower span, note that the
"C" changes to "C?", indicating the analyzer is now interpolating between
calibrated measurement points. The "C?" notation also appears when
other system parameters, such as power, number of points, or sweep
time, have changed.
User-defined calibrations are always cancelled when you manually select
a default calibration of the same type. The following example illustrates
this point:
A user one-port calibration (for S
11
and S
22
) is cancelled by manually
selecting . Note, however, that user response
calibrations (for S
21
and S
12
) and a two-port calibration (for all
S-parameters) are unaffected by this change.
Current user-defined calibrations are always available in nonvolatile
(battery-backed) memory. Subsequent calibrations of the same type will
cancel the previous calibration unless it is saved using
.
See “Saving and Recalling the Calibration” on page 6-33 . When the
instrument’s power is cycled, the current instrument state and
calibration will be retrieved.
Default 1-Port
SAVE RECALL