154                                                                                                                     Keysight N9927-90001 User’s Guide
SA (Spectrum Analyzer) Mode
SA Mode Settings
— Ref Pos Manually set the position of the reference line. Values must be 
between 0 (TOP line) and 10 (BOTTOM line). Default position is zero (top).
How to Set Y-axis Units
The Unit setting appears for the reference line, marker readouts, and trigger 
level. All Unit choices are available in both Log and Linear Scale Types. 
The UNIT setting survives Mode Preset, but NOT Preset.
—Press Scale / Amptd
, then More, then Unit 
— Then choose from the following:
—dBm (default setting), dBmV (dB milli Volts), dBuV (dB microVolts), W 
(watts), V (volts), A (amps), dBmA (dB milliAmps), dBuA (dB 
microAmps). 
Antenna correction units are available ONLY by loading or editing an Antenna 
file that contains the desired units setting. Learn more In.
External Gain
When using an external amplifier or attenuator, the SA mode trace amplitude 
values can be offset to compensate for the effect of the external device.  This 
effectively moves the reference plane of the SA measurement port out to just 
beyond the external device. For example, when using an external preamp with 
gain of +10 dB, enter this value for External Gain, and the data trace across the 
displayed frequency span will be adjusted down by 10 dB. 
When RF Atten is set to Auto, you may see a change in the RF Attenuation 
value. This is an attempt to measure the signal at top of screen (the 
acquisition) without overloading the SA first mixer.
How to Set External Gain
—Press Scale/Amptd.
—Then More
—Then External Gain
— Enter a value using the numeric keypad, the   arrows, or the rotary knob 
(positive for gain; negative for loss). Values less than 5 dB must be typed 
using the numeric keypad. Then press Enter
ExtGain xx dB is shown at the top of the screen.
Attenuation Control
Both the RF Attenuation and Preamp functions control the power level into the 
SA.