AnsweredAssumed Answered

FIFO, Fast mode, and triggers

Question asked by golfnut on Mar 7, 2011
Latest reply on Apr 16, 2012 by johanericsson
I'm using a PNA-X that has the FAST CW / FIFO option.  I've read the sparse information in the the help file thoroughly, but I'm stuck when trying to implement the needs of my measurement. I have two scenarios.

case 1:
I want to perform an S21 (or S12) measurement and sweep frequencies from A to B GHz  (eg.,  10 GHz to 15 GHz with 401 points and IFBW at 1000 Hz).  I want the measurement results to be stored in the FIFO so that I may retrieve the data a later time.  Further, I want the sweep to be triggered by and external TTL pulse signal (ie., external triggering).  Recap, I want one sweep of S21 performed when one trigger pulse arrives.

case 2:
I want to perform an S21 measurement with alternating frequency sweep direction from A to B GHz then B to A GHz  (eg.,  10 GHz to 15 GHz  then 15 GHz to 10 GHz with 401 points and IFBW at 1000 Hz).  I want the measurement results to be stored in the FIFO so that I may retrieve the data a latter time.  Further, I want the sweep to be triggered by and external TTL pulse signal (ie., external triggering).  Recap, I want external triggers to individually start S21 sweeps that alternate increasing then decreasing direction in frequency.

Should FAST Segments or FAST Groups be used for the examples above?

I've been able to get FAST CW to work via the sample code provided in the help file, but I couldn't find any sample code for FAST Groups or FAST Segments.  I wasn't able to determine from the help file what each of these modes is intended to offer the user.  Also, it's a bit unclear what order the programming commands are intended to be issued to instigate FAST modes, such Fast Groups. In my experimentation, varying the order in which a) the FIFO is turned on and  b) the trigger state is set to groups, affects how the measurement interacts with the triggers significantly. 

Any advice or sample code would be appreciated.  

Outcomes