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Features and Functions 3
Agilent U1251A/U1252A User’s and Service Guide 57
Decibel Display
The dBm operation calculates the power delivered to a
reference resistance relative to 1 mW and can be applied to
DC V, AC V, and AC + DC V measurements for decibel
conversion. The voltage measurement is converted to dBm by
using the following formula:
The reference resistance may be selected from 1~9999 Ω in
Setup mode. The default value is 50 Ω.
The decibel of voltage is calculated with respect to 1 V. The
equation for the voltage measurement is as follows:
dBV = 20 log
10
Vin
1 At the , , or rotary switch position,
press to scroll to the dBm measurement on the
primary display. The secondary display indicates the AC
voltage measurement.
2 Press for more than 1 second to exit this mode.
NOTE
If the rotary switch is at the “~ V” position, press to switch
between the dBV and the dBm measurements. The dBm or the dBV
measurements can be selected at the ACV position. The selection will be
the reference for other voltage measurements.