•Remote Interface Operation: You can use the following commands to
make dB measurements. Math must be enabled before you can store a
value to the Relative Regist er.
CALCulate:FUNCtion DB
CALCulate:STATe {OFF|ON}
CALCulate:DB:REFerence {<value>|MINimum|MAXimum}
dBm Measurements
The dBm operation calculates the power delivered to a resistance
referenced to 1 milliwatt.
dBm = 10 × Log10 ( reading2 / reference resistance / 1 mW )
Applies to dc voltage and ac voltage measurements only.
•You can choose from 17 different reference resistance values.
The factory setting for the reference resistance is 600Ω.
The choices are: 50, 75, 93, 110, 124, 125, 135, 150, 250, 300, 500,
600, 800, 900, 1000, 1200, or 8000 ohms.
•The reference resistance is stored in non-volatile memory, and does not
change when power has been off or after a remote interface reset.
•Front-Panel Operation: After enabling dBm, you can select a new
reference resistance by pressing Shift > (Menu Recall). Turning
on the menu does not disable the dBm operation; the multimeter
will resume taking measurements when you turn off the menu.
4: dBm REF R (MATH MENU)
See also “To Make dBm Measurements,” on page 41.
•Remote Interface Operation: You can use the following comma nds to
make dBm measurements.
CALCulate:FUNCtion DBM
CALCulate:STATe {OFF|ON}
CALCulate:DBM:REFerence {<value>|MINimum|MAXimum}
Chapter 3 Features and Functions
Math Operations
68