CALCulate:SCALe:DBM:REFerence {<reference>|MIN|MAX|DEF}
CALCulate:SCALe:DBM:REFerence? [{MIN|MAX}]
Selects the reference resistance for converting voltage measurements to dBm. This reference value affects the dBm
and dB scaling functions.
This command applies only to ACVand DCVmeasurement functions.
Parameter Typical Return
50, 75, 93, 110, 124, 125, 135, 150, 250, 300, 500, 600 (default), 800, 900, 1000,
1200 or 8000 Ω
+3.00000000E+02
Enable dBm scaling with a reference resistance of 300 Ω:
CALC:SCAL:DBM:REF 300
CALC:SCAL:FUNC DBM
CALC:SCAL:STAT ON
l The instrument sets the reference value to its default value after a Factory Reset (*RST), an Instrument Preset
(SYSTem:PRESet), a change in math function, or a change in measurement function.
CALCulate:SCALe:FUNCtion {DB|DBM}
CALCulate:SCALe:FUNCtion?
Selects the operation that will be performed by the scaling function:
l DB performs a relative dB computation. The result will be the difference between the input signal and the stored
DB relative value (CALCulate:SCALe:DB:REFerence), with both values converted to dBm (dB = measurement in
dBm – relative value in dBm).
l DBM performs a dBM computation. The result is logarithmic and is based on a calculation of power delivered to a
reference resistance (CALCulate:SCALe:DBM:REFerence), relative to 1 milliwatt. (dBm = 10 × log
10
(measurement
2
/ reference resistance / 1 mW)).
This command applies only to ACVand DCVmeasurement functions.
Parameter Typical Return
{DB|DBM} DB or DBM
Enable the DB scaling function referenced to the next measurement taken:
CALC:SCAL:FUNC DB
CALC:SCAL:STAT ON
l For the dB function, the reference value can be automatically selected using the first measurement converted to
dBm as the reference value (see CALCulate:SCALe:REFerence:AUTO), or it can be specified by
CALCulate:SCALe:DB:REFerence.
l Scaling function results must be in the range of -1.0E+24 to -1.0E-24, or +1.0E-24 to 1.0E+24. Results outside
these limits will be replaced with -9.9E37 (negative infinity), 0, or 9.9E37 (positive infinity).
l This parameter is set to its default value after a Factory Reset (*RST) or Instrument Preset (SYSTem:PRESet).
Agilent Truevolt Series DMM Operating and Service Guide 127
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