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928
Input/Output
External Gain
Compensates for gain or loss in the measurement system outside the test set. The External Gain is
subtracted from the amplitude readout (or the loss is added to the amplitude readout). So, the displayed
signal level represents the signal level at the output of the device-under-test, which can be the input of an
external device that provides gain or loss.
Entering an External Gain value does not affect the Reference Level, therefore the trace position on
screen changes, as do all of values represented by the trace data. Thus, the values of exported trace data,
queried trace data, marker amplitudes, trace data used in calculations such as N dB points, trace math,
peak threshold, etc., are all affected by External Gain. Changing the External Gain, even on a trace which
is not updating, will immediately change all of the above, without new data needing to be taken.
NOTE Changing the External Gain causes the test set to immediately stop the current
sweep and prepare to begin a new sweep. The data will not change until the trace
data updates because the offset is applied to the data as it is taken. If a trace is
exported with a nonzero External Gain, the exported data will contain the trace
data with the offset applied.
Ext Preamp
This function is similar to the reference level offset function. Both affect the displayed signal level. Ref
Lvl Offset is a mathematical offset only, no test set configuration is affected. Ext Preamp gain is used
when determining the auto-coupled value of the Attenuator. The External Gain value and the Maximum
Mixer Level settings are both part of the automatic setting equation for the RF attenuation setting. (10 dB
of Attenuation is added for every 10 dB of External Gain.)
Note that the Ref Lvl Offset and Maximum Mixer Level are described in the Amplitude section. They
are reset by the instrument Preset. The External Preamp Gain is reset by the "Restore Input/Output
Defaults" or "Restore System Defaults->All functions. . The External Gain is subtracted from the
amplitude readout so that the displayed signal level represents the signal level at the output of the
device-under-test, which is the input of the external device that is providing gain or loss.
Key Path: Input/Output
Couplings: The Ext Preamp, MS, and BS keys may be grayed out depending on which
measurement is currently selected. If any of the grayed out keys are pressed,
or the equivalent SCPI command is sent, an advisory message is generated.
Readback: 1-of-N selection | [variable]
Initial S/W Revision: Prior to A.02.00
Key Path:
Input/Output, External Gain
Remote Command: [:SENSe]:CORRection:SA[:RF]:GAIN <rel_ampl>
[:SENSe]:CORRection:SA[:RF]:GAIN?