274                                                                                                                     Keysight N9927-90001 User’s Guide
IQ Analyzer (IQA) – Option 351 (CPU2 Only)
I/Q Analyzer (IQA) Mode Settings
Manually set Scale, Unit, Acquisition, and Reference Position.
— Autoscale
 Automatically adjusts the Y-axis to comfortably fit the Minimum 
and Maximum amplitude of the trace on the screen. Also, optimizes the 
FieldFox’s signal level at the mixer and adjusts the reference level to  with 
the autoscale settings. 
— Scale/Div
 Manually adjust the scale per division to view specific areas of 
the current trace. Enter a value using the numeric keypad, the   arrows, 
or the rotary knob. Then press Enter
.
— Ref Level
 Manually set the value of the reference line. Enter a negative 
value by pressing Run/Hold (+/-)
 either before or after typing a value. Use 
acquisition in combination with the RF attenuator and the Preamp so that 
the signal at the acquisition is at the optimum level for the FieldFox 
(Spectrum and RF Envelope Only). This can also change the RF Attenuation 
setting (default: 0). See “Attenuation Control” on page 274.
— 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) 
(default: 0, minimum: 0, maximum: 10).
— More
, then 
— Unit
 Sets the display units.
Attenuation Control
Both the RF Attenuation and Preamp functions control the power level into 
the FieldFox mixer.
When too much power is present at the RF Input port, ADC Over Range 
appears on the FieldFox screen. This does not necessarily mean that damage 
has occurred, but that the receiver is probably compressed. 
When high power levels are present at the RF Input port, internal attenuation 
can be switched in to keep the FieldFox receiver from compressing. At 
extremely high power levels, use external attenuation to protect the internal 
circuitry from being damaged. 
The displayed power level is automatically adjusted for RF Attenuation. As the 
attenuation value changes, the displayed power level should NOT change.
How to set Attenuation
—Press Scale/Amptd
.
The FieldFox can be damaged with too much power. 
RF Damage Level: +25 dBm (N995xA & N996xA) and +27 dBm (all others)
DC Damage Level: ±50 VDC