Power Measurement How to Measure Power
80 Agilent 8163A/B, 8164A/B, and 8166A/B User’s Guide, Fourth Edition
How to Set the Power Unit
Pressing the Power Unit softkey allows you to select either W, dB, or
dBm as the units in which power is displayed. The Power Unit softkey
is visible when you move to the [P] or [Ref ] parameters. Alternatively
the Power Unit can be changed by using the Power Meter menu.
What are the Power Units ?
Watts (W) are the SI unit for power measurement.
You can also measure power in dB or dBm. Values displayed in these
units are derived from measurement in Watts.
By selecting dBm, the following calculation is made:
Where,
P
dBm
is the power value displayed in dBm, and
P
input
is the input signal level in Watts.
Power, in units of dBm, is measured relative to 1 mW, it is an absolute
power measurement.
By selecting dB, the following calculation is made:
Where,
P
dB
is the power value displayed in dB,
P
input
is the input signal level in Watts, and
P
ref
is the chosen reference power value in Watts.
Power, in units of dB, is measured relative to a particular reference
power value. For information on selecting this reference value, see
“How to Input a Reference Level” on page 82.
To set the power unit to dBm:
1 Move to the [P] parameter and press the [Power Unit] softkey. You
will see the menu in Figure 42.
P
dBm
10
P
input
W()
110
3–
W()×
-------- ----------------------log=
P
dB
10
P
input
W()
P
ref
W()
------ -------------------log=
To Next Page
Loading...
Need help?
General
