Keysight Truevolt Series Operating And Service Manual page 103

Features and Functions
dBm Scaling
The dBm function is logarithmic, comparing power delivered to a reference resistance, relative to 1 mil-
liwatt:
2
dBm = 10 x log ( reading / reference resistance / 1 mW )
10
The reference resistance value ( Ref R ) may be 50, 75, 93, 110, 124, 125, 135, 150, 250, 300, 500, 600
(default), 800, 900, 1000, 1200, or 8000 Ω. Press Ref R and use the front panel up and down arrows to
make your selection.
See Also
Math - Introduction
Null
Statistics
Limits
104 Keysight True volt Series Operating and Service Guide