SA (Spectrum Analyzer) Mode  85 
o  Auto The FieldFox selects the most efficient sweep type based on the Res 
BW. When Res BW is set to 200 kHz and below, FFT sweep type is selected. 
Above 200 kHz, and Step sweep type is being performed. 
o  FFT  The FieldFox uses FFT sweep type regardless of the Res BW.  
o  Step The FieldFox uses Step sweep type regardless of the Res BW. This is 
useful for capturing impulsive noise that may be generated from nearby 
electrical equipment. 
Sweep Acquisition 
When set to Auto, Sweep Acquisition is set to the minimum value required with 
the current settings in order to achieve amplitude accuracy when measuring CW 
signals yielding the fastest sweep update rate.  
However, you can adjust this setting in order to increase the probability of 
intercepting and viewing pulsed RF signals.  
For example, with SwpAcquisition set to Auto a pulsed GSM signal is NOT 
visible on the FieldFox screen, as shown in a blue trace in the following image. 
However, while watching the trace, increase the SwpAcquisition value until the 
pulse spectrum rises out of the noise and reaches its maximum level. Increasing 
the SwpAcquisition value beyond this point only slows the update rate (increases 
the actual Sweep time readout) but does not improve measurement quality. 
 
A GSM signal in a framed data format; timeslot zero ON;  all others OFF;  
 PRF = 218Hz, Duty Cycle = 12.5%. The pulsed signal becomes visible on every sweep 
update with SwpAcquisition = 50. 
How to set Sweep Acquisition Parameter 
  Press Sweep 3. 
  Then SwpAcquistion Auto Man. 
  Then choose from the following: