dBm Scaling
The dBm function is logarithmic, comparing power delivered to a reference resistance, relative to 1 mil-
liwatt:
dBm = 10 x log
10
( reading
2
/ reference resistance / 1 mW )
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.
dBm scaling applies to ACV and DCV measurements only.
% Scaling
%
performs a percent change operation. The result is the percent change of the measurement from the ref-
erence value:
Result = ((Measurement – Reference) / Reference) * 100.
Press
Measure Reference
to use the first measurement as the reference value, or press
Ref Value
to spe-
cify the reference value.
% scaling applies to all measurement functions except Ratio, Continuity, and Diode.
Mx-B Scaling
For Mx-B scaling, the result is the measurement multiplied by the
Gain (M)
value minus the
Offset (B)
value.
The
User Units
softkey allows you to specify the custom alphanumeric label of up to four characters (for
example, RPM or °C) for Mx-B scaled measurements.
Mx-B scaling applies to all measurement functions except Ratio, Continuity, and Diode.
Features and Functions
106
Keysight True
volt
Series Operating and Service Guide
