Agilent Technologies Signal Analyzer N9030a - Manual (Page 619)

6 RLC Swept SA Measurement Front-Panel & SCPI Reference
Input/Output
Entering an External Gain value does not affect the Reference Level, therefore the trace position
on screen changes, as do all of the 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 that is not updating, will immediately change all of the above,
without new data needing to be taken.
Changing the External Gain causes the analyzer 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.
In the Spectrum Analyzer mode, a Preamp is the common external device providing gain or loss.
In a measurement application mode like GSM or W-CDMA, the gain or loss could be from a BTS
(Base Transceiver Station) or an MS (Mobile Station). So in the Spectrum Analyzer mode MS and
BTS would be grayed out and the only choice would be Ext Preamp. Similarly in some of the
digital communications applications, Ext Preamp will be grayed out and you would have a choice
of MS or BTS.
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
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 analyzer 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.
Remote Language Compatibility Measurement Application Reference 619