TGBT15A_915_101 - Detailed fftshift and scale tests for incoherent modes

Goals

  • Find best combination of fftshift and vegas.scale to eliminate/minimize FFT overflow artifacts and get good output levels from VEGAS. Also test coherent 32-channel modes.

Details

Session begins at
  • Session began at 14:15
  • Switched to Justin's VPM branch
  • Set iniitial fftshift to 0xffffffff and vegas.scale to 1000. Will use GUPPI when possible to verify data. Initial guppi.scale set to 0.125.
  • Using CoherentFFTSHIFTTest SB
    • SB submitted at 14:35
    • Scan #1 is c0800x0032
      • Got a balance failed error but tried to keep going
      • Scan aborted.
      • Trying to resubmit
      • Same result
    • Will skip 32-channel modes and try other modes.
    • Resubmitted SB at 14:42
    • Scan #3 is c0800x0064, vegas.scale = 1000
      • Balance failed but scan executing
      • Saturated. Need to significantly reduce vegas.scale
    • Scan #4 is c0800x0128, vegas.scale = 500
      • Balance failed but scan executing
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #5 is c0800x0256, vegas.scale = 1000
      • Balance failed but scan executing
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #6 is c0800x0512, vegas.scale = 500
      • Balance failed but scan executing
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #7 is c0800x1024, vegas.scale = 1000
      • Balance failed but scan executing
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #8 is c0800x2048, vegas.scale = 100
      • Balance failed but scan executing
      • Levels look good
    • Scan #9 is c0800x4096, vegas.scale = 1000
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #10 is c1500x0064, vegas.scale = 300
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #11 is c1500x0128, vegas.scale = 300
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #12 is c1500x0256, vegas.scale = 300
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #13 is c1500x0512, vegas.scale = 150
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #14 is c1500x1024, vegas.scale = 300
      • Not saturating but need to decrese vegas.scale anyway
    • Scan #15 is c1500x2048, vegas.scale = 800
      • No subints written on Bank D
    • Scan #16 is c1500x4096, vegas.scale = 1000
      • Scan aborted. Many messages about illegal values in several parameters.
    • Will try to use some lower fftshift values.
    • SB submitted at 15:22
    • Scan #17 is c0800x0064, vegas.scale = 100
      • Balance failed but scan executing
      • Still high. Maybe go down by a factor of 5--10
    • Scan #18 is c0800x0128, vegas.scale = 100
      • Balance failed but scan executing
      • Still high. Maybe go down by a factor of 2--3
    • Scan #19 is c0800x0256, vegas.scale = 100
      • Balance failed but scan executing
      • Pretty good. Could maybe lower by a factor of 2.
    • Scan 20 is c0800x0512, vegas.scale = 100
      • Balance failed but scan executing
      • Perfect.
    • Scan #21 is c0800x1024, vegas.scale = 100
      • Balance failed but scan executing
      • Good. Could even by 1.5 times higher but not essential.
    • Scan #22 is c0800x2048, vegas.scale = 200
      • Perfect.
    • Scan #23 is c0800x4096, vegas.scale = 500
      • Pretty good. Could even by 1.5 times higher.
    • Scan #24 is c1500x0064, vegas.scale = 100
      • Still too high by a factor of about 10.
    • Scan #25 is c1500x0128, vegas.scale = 100
      • Still too high by a factor of about 8.
    • Scan #26 is c1500x0256, vegas.scale = 100
      • Still high. Decrease by a factor of 2--3.
    • Scan #27 is c1500x0512, vegas.scale = 100
      • Pretty good but could decrease by a factor of about 1.5
    • Scan #28 is c1500x1024, vegas.scale = 100
      • Perfect.
    • Scan #29 is c1500x2048, vegas.scale = 100
      • Bad bandpass.
    • Scan #30 is c1500x4096, vegas.scale = 100
      • Aborted again.
  • Switching to release branch at 16:48
    • Looks good
  • CheckMode1 SB submitted at 16:52
    • Looks good
  • CheckMode29 SB submitted at 16:53
  • Session ended at 16:55

Conclusions

I was able to find some pretty good vegas.scale values but there are a few that need refined. 32-channel modes did not work. Balancing issues on many of the c0800 modes. c1500x4096 kept aborting.

-- RyanLynch - 2017-07-13
Topic revision: r1 - 2017-07-13, RyanLynch
 

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