[esa-t474] Updates

[Alexey Lyapin]

Hi Mark et al,

I suggest - for consistency - we show 1 vs 2 (fig23_12) as we do 4 vs 
3,5 and 10 vs 9, 11 to show the intra-station stability. Then, we have 
the linked system stability plots, which don't look as good as we hoped. 
  We suspect BPMs 1 and 2, so we show 1 vs 3, 5, 9, 10 (fig23_10) and 2 
vs 3, 5, 9, 10 (fig23_8) and say that both behave the same way and the 
drift is huge, so the screwup is there, but I don't think we can really 
explain it, can we? We could say though that we decided to move all the 
BPM 1,2 electronics to the racks in the ESA to avoid additional 
systematics due to longer cables and different environment, to use 14 
bit digitisers to improve the resolution of 1 and 2, and to build the 
calibration system and monitor drifts online.

Cheers,
Alex


Mark Slater wrote:
> Dear All,
> 
> I have tried to address some of the points raised at the meeting on 
> Monday. To that end, I've put some additional analysis points on my elog:
> 
> http://pcfj.hep.phy.cam.ac.uk:8080/slater/35
> http://pcfj.hep.phy.cam.ac.uk:8080/slater/36
> 
> These cover the problems with BPMs 1 and 2 and the position drifts against 
> time. Essentially, it looks like the scale changes in BPM 1 are also 
> present in BPM 2 and these are not based on the cross-talk in this BPM. 
> This therefore explains the relatively poor stability of the linked 
> system. I believe this answers most of the problems that were voiced but 
> do please let me know if this is not the case.
> 
> I will hopefully add another entry on SVD coefficents, etc. on Friday.
> 
> Many Thanks for all your patience!
> 
> Mark
> 
> P.S. The plots shown in the ELOG also demonstrate some additional runs for 
> the long stability plots.
> 
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