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Message ID: 58     Entry time: Fri Jul 22 14:22:10 2016
Author: Gabriele 
Type: Electronics 
Category: Configuration 
Subject: Investigations on the signal jumps 

[Rolf, Ben, Rich, Gabriele]

Rolf couldn't find any good explanation on the software side for the signals jumps. He investigated a bit the reason why IOP takes a long execution time, without success. It's still mysterious why it ran with low time for a while.

One effect of Rolf activity is that now the signal jumps happen at ~0.8 seconds (after the start of each second) instead that ~0.45. This is suspiciously pointing to a software issue...

Ben and I spent a few hours trying to better understand the origin of the glitches. Finally, we plugged in a function generator to the four ADC channels, and we could find the glitches again, at the expected time. So we could rule out completely that it's a problem of the QPD analog electronics.

Some more ivnestigations:

  • swapped the SR DS345 with an Agilent 33210A for the timing signal. No change: jumps are still there
  • rebooted and powered off the cymac many time, this never changed the glitches or the position in time
  • swapped the ADC interface board (D1600196) with a new one similar to that of the crackle lab (D1500402): no change, jumps are still there
  • switched off the roughin pump to reduce ambient acoustic noise. Not surprisingly, no change, still jumps
  • according to the motherboad manual, PCIe slots 4 and 6 are PCI-EX16, while the other are PCI-EX8. I moved the ADC and DAC to those those slots. Guess what? No change, still jumps

On a bright side, Rolf recompiled the awgman software, and now excitation channels are working.

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