CALCulate:SCALe:DBM:REFerence {<reference>|MIN|MAX|DEF}
CALCulate:SCALe:DBM:REFerence? [{MIN|MAX|DEF}]
Selects the reference resistance for converting voltage measurements to dBm. This reference value affects
the dBm and dB scaling functions.
Parameter Typical Return
50, 75, 93, 110, 124, 125, 135, 150, 250, 300, 500, 600, 800, 900, 1000, 1200 or
8000 Ω. Default: 600.
+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), or a change in measurement function.
CALCulate:SCALe:FUNCtion {DB|DBM|PCT|SCALe}
CALCulate:SCALe:FUNCtion?
Selects the operation performed by the scaling function.
Parameter Typical Return
{DB|DBM|PCT|SCALe} DB, DBM, PCT, or SCALe
Enable the DB scaling function referenced to the next measurement taken:
CALC:SCAL:FUNC DB
CALC:SCAL:STAT ON
l The PCT and SCALe functions apply only to the 34465A and 34470A.
l DB performs a relative dB computation. The result is the difference between the input signal and the
stored DB relative value reference (CALCulate:SCALe:DB:REFerence), with both values converted to
dBm (dB = measurement in dBm – relative value in dBm). 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. dB
scaling applies to ACV and DCV measurements only.
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)). dBm scaling applies to ACV and
DCV measurements only.
Keysight Truevolt Series Operating and Service Guide
223
SCPI Programming Reference
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