AnsweredAssumed Answered

limitations of FIFO?

Question asked by bfris on Sep 4, 2013
Latest reply on Sep 12, 2013 by nielsj
I've been playing with the FIFO and FASTCW commands on my N5224A with Opt 118. From reading the help file, it doesn't appear that I can do a frequency sweep with the FIFO. Golfnut seems to think there is a fast sweep option, but I don't know how he arrives at this conclusion.

If I back off and settle for a FASTCW measurement, and measure one frequency per external trigger, the results are less than stellar. I did an experiment and the fastest trigger rate I could achieve was about 30 Hz. Any faster, and the data doesn't show up in the FIFO count. Does this sound about right? Also, can I get corrected S21 (or S12) data in this mode?

Honestly, 30 Hz is a little slow for me. I need to measure data at roughly 2 million antenna orientations. 30 Hz translates to about 19 hours to measure one frequency. So I'm effectively tying up my equipment for a full day per frequency. And an absolute bare minimum for me is to measure 3 frequencies in 2 bands. So now I'm up to 6 days. 

My next experiment is to see how fast I can do CALC:DATA? commands. Maybe that can be quicker than 30 Hz. Though I'm not sure how to know when to grab the data and measure timing accurately. A crude hack is to poll status registers. Once I get the first data ready signal, I'll start a timer. If I don't get enough data readies in a known amount of time, then I'll know I've dropped a trigger.