144                                                                                                                     Keysight N9938-90003 User’s Guide
SA (Spectrum Analyzer) Mode (Option 233–Mixed Analyzers)
SA Mode Settings
—Press Enter
Alignments
This section contains the following:
— “Overview” on page 144
— “All Alignment and Align All Now” on page 146
— “Individual Alignments” on page 147
Overview
All Alignment or Align All Now corrects for receiver drift over temperature and 
time. SA measurement applications monitor changes in internal temperature 
and the time since last alignment update and trigger the need for a new 
update when the alignment becomes stale. The alignment is deemed stale 
after a significant change in temperature or a significant time elapsed from the 
last update. The temperature change and time duration necessary to trigger an 
alignment update is predetermined in the factory. Until the update is 
performed, annotation indicating “questionable amplitude” is displayed 
AMPTD?. 
When All Alignment is enabled (by default) the FieldFox performs an 
alignment process using the internal RF source. Although some sweeps are 
delayed, measurement results are never disturbed.
If the Independent Source (tracking generator) is enabled for your 
measurement, it will be borrowed to perform the alignment. Again, the 
measurement results are not disturbed. Learn about the Independent Source in 
“Independent Source/Tracking Generator ” on page 126.
The alignment process can be disabled. You may want to do this, for example, 
if you are analyzing the amplitude stability of a signal. 
SA and all modes built on its infrastructure require three types of alignments:    
— InstAlign Amplitude Alignment 
— RF Burst Amplitude Alignment
— Channel Equalization
These are referred to as Individual Align
.
All three or a subset of the individual alignments are required for each specific 
mode, depending on the type of measurement supported by it:
SA:
— InstAlign Amplitude Alignment
— RF Burst Amplitude Alignment
RTSA: