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SCPI Command Reference 5-75

:DB:REFerence <n>

:UNIT:VOLTage:AC:DB:REFerence <n> Specify dBm reference

Parameter <n> = le-7 to 1000 Specify reference in volts

Query :REFerence?

Description This command is used to specify the dB reference level. When DB units is

selected (:VOLTage:AC: DB), ACV db measurements are made using the

speciﬁed dB reference level.

The reference level is speciﬁed in volts and is not range dependent. For ex-

ample, a dB reference level of 1 is 1V on all ACV measurement ranges.

:DBM:IMPedance <n>

:UNIT:VOLTage:AC:DBM:IMPedance <n> Specify dB reference

Parameter <n> = 1 to 9999 Specify reference impedance

Query :IMPedance?

Description This command is used to specify the dBm reference impedance level. When

dBm units is selected ACV dBm measurements are made using the speciﬁed

dBm reference impedance.

The reference impedance is speciﬁed in ohms and is not range dependent.

For example, a dBm reference level of 600 is 600 on all ACV measurement

ranges. A rational number is rounded to the nearest valid integer value.

[:DC] <name>

:UNIT:VOLTage:DC <name> Specify DCV units

Parameters <name> = V DC voltage measurement units

DB dB DC voltage measurement units

DBM dBm DC voltage measurement units

Query [:DC]? Query DC voltage units

Description This command is used to select the units for DCV measurements. With volt

(V) units selected, normal DC voltage measurements are made for the DCV

function. With DB units selected, DC dB voltage measurements are per-

formed. The DBM units selection is used to make decibel measurements ref-

erenced to 1mW. dB and dBm measurements are explained further in

Section 2.

Keithley 2000 User Manual

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