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HP E1312A/E1412A Multimeter Application Information 43Chapter 2
Storing the dB
Reference Value
Do not confuse this operation with the dBm reference (DBM) function. See
the next section, “dBm Measurements”, and take note of the multimeter's
reference resistance setting (dB uses a reference level, dBm uses a reference
resistance).
• The dB reference value is stored in the multimeter’s dB Relative
Register. You can enter a specific number into the register using the
CALCulate:DB:REFerence <value> command. Any previously stored
value is replaced with the new value. Use the following commands to
activate the dBm function and input a reference value. The calculate
state must be enabled before you can store a value in the dB Relative
Register.
CALCulate:FUNCtion DB Set math function to DB.
CALCulate:STATe ON Enable math operation.
CALCulate:DB:REFerence <value> Store a dB reference value.
dBm Measurements The dBm operation calculates the power delivered to a resistance referenced
to 1 milliwatt.
dBm =
• 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 600
Ω
. Set your desired
value with the
CALC:DBM:REF <value> command.
The choices for
<value> 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 nonvolatile memory, and does not
change when power is removed or after the multimeter is reset.
Storing the dBm
Reference Resistance
Value
Do not confuse this operation with the dB reference (DB) function. See the
previous section, “dB Measurements”, and take note of the multimeter's dB
reference setting (dB uses a reference level, dBm uses a reference resistance).
• Use the following commands to activate the dBm function and input a
reference resistance value. The calculate state must be enabled before
you can store a value in the Reference Resistance Register.
CALCulate:FUNCtion DBm Set math function to DBm.
CALCulate:STATe ON Enable math operation.
CALCulate:DBM:REFerence <value> Store a dBm reference.
10 log
10
×
reading
2
(reference resistance) (1 mW)×
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