Keysight Technologies CXA N9000B, Manual

Page: 60 / 88

60 N9069C Noise Figure Measurement Guide
Measurement Related Tasks and Concepts
Setting the Measurement System
Table 3-1 User Cal vs. Internal Cal
Items User Cal Internal Cal
System connection and
setting procedure
User Cal needs a different system
connection. To perform User Cal, you
need to connect the noise source
directly to the signal analyzer first,
without the DUT, as shown in
Figure 2-1
on page 15. And then on
the instrument,
1. Press MEAS SETUP , Cal
Setup , User Cal .
2. Press CALIBRATE .
Internal Cal does NOT need the special system
connection. Just connect the noise source, DUT,
and signal analyzer as desired, and perform the
Internal Cal.
On the instrument, press
MEAS SETUP , Cal
Setup , Internal Cal .
Calibration Theory In User Cal, the instrument measures
the P
cold
and P
hot
values directly and
stores them in the instrument.
Internal Cal uses the internal cal files stored in the
instrument and USB preamp. The information
contained there allows the instrument to calculate
the P
cold
and P
hot
values.
When to perform
calibration?
For cases described in “When to
Perform Calibration” on page 59 ,
you need to change the system
connection to the calibration setup and
perform the User Cal again.
Internal Cal takes most of the cases of “When to
Perform Calibration” on page 59 into
account inside the instrument. So you don’t need
to make an Internal Cal again and again for most
cases.
However, if the ambient temperature is
significantly changed, it is recommended to
perform the Characterize Noise Floor operation on
the signal analyzer by pressing System ,
Alignments , Ad vanced , Characterize
Noise Floor .
Advantage Accurate calibration results Simple system connection without a mechanical
connection change for calibration.
Recommended use
cases
Choose User Cal when
— you are very concerned about
getting accurate data.
— the DUT is not connected to
the noise source and signal
analyzer directly, but via some
test fixtures or automated test
equipment.
Choose Internal Cal when
— you are very concerned about
measurement speed.