HP 8163A Series, User Manual

Page: 67 / 207

67
Power Measurement
How to Measure Power
P
input
is the input signal level , and
CAL is the calibration offset.
To set the calibration offset to 40.000 dB:
1 Move to the Power Meter channel and press the [Details]
softkey.
2 Move to the [C
AL
] parameter and press E
NTER
.
3 Enter 40.000 and press E
NTER
.
How to Set the Reference Level
How to Input a Reference Level
dB results are shown relative to a reference level. The Ref
parameter sets the reference level. Setting, or changing, the
reference only affects results that are displayed in dB.
The reference level is displayed in units of dBm or Watts.
Depending on which is selected the following equations are used to
calculate the power level in dB:
P
display
(dB) = P
measured
(dBm)
−
REF(dBm)
or
Where,
P
display
is the displayed relative power,
P
measured
is the absolute power level (see “How to Set the
Calibration Offset” on page 66), and
REF is the reference level.
You can choose the units for the reference using the Power Unit
softkey. If you choose dB, the power value changes to dB and the
displayed reference level changes to dBm.
P
display
dB
( )
10
P
measured
W
( )
REF W
( )
----------------------------------- log =