Atek HP 8753D, User Manual, Page: 331 / 677

Calibration Considerations
Measurement P arameters
Calibration procedures are parameter-specic , rather than channel-specic . 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
specic 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 dierent 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 NNNNNNNNNNNNN
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
Y ou 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