[Gb-ccb] more noise tests

[Brian Mason]

hi all- I ran some more noise tests this afternoon, the results from which
look pretty good.  The bottom line is that the differenced power for all
ports shows previously seen ~0.5 counts rms, in this case, tested with the
full system and with numerous scans lasting several minutes.

The setup was

 phase switch signals patched into J1 via that little board
 pot-cable on J2, tweaked well away from mid scale
 DC termination -> detector test circuit -> J3
 all other ports unterminated

I ran both 10 ms and 1 ms integrations, some scans for 1 minute, some for
5 minutes, always collecting data from all ports and switching both phase
switches.  It was all done with the manager & CLEO, and the data analyzed
by adaptions of Cristobal's IDL scripts. The results all looked consistent
with previous results-- 0.5 count rms ADC-counts in the difference.  The
anomalies are J1, which with that setup I don't know what to expect, and
J3, where we know the test circuit adds noise.  Also daughter card 4 looks
a little more ratty in total power (particularly channel... 13), however
the differenced power looks just as good as the others. In general with
different integration times, and different the differenced RMS's are very
repeatable for a given port. The total power RMS's for the long
integration periods are higher than for the short integration periods,
which I think must be aliasing but I haven't looked into it in detail.

Some typical numbers-- all ports, one scan

scan 37  -- 10 ms integ
2005_10_04_22:23:44-rms.dat
port      diff RMS    total power RMS
 J  1       7.91       541.78
 J  2       0.49         2.36
 J  3       0.71        16.10
 J  4       0.47         1.57
 J  5       0.49         1.67
 J  6       0.49         2.15
 J  7       0.48         3.79
 J  8       0.47         1.96
 J  9       0.51         2.81
 J 10       0.46         3.62
 J 11       0.50         3.68
 J 12       0.46         1.40
 J 13       0.53        18.75
 J 14       0.45         4.00
 J 15       0.51         4.41
 J 16       0.50         9.96

typical numbers--  one port, different scans

2005_10_04_22:01:16-rms.dat: J  4       0.48         1.45
2005_10_04_22:02:27-rms.dat: J  4       0.47         1.71
2005_10_04_22:04:20-rms.dat: J  4       0.47         0.76
2005_10_04_22:05:27-rms.dat: J  4       0.48         0.75
2005_10_04_22:06:43-rms.dat: J  4       0.48         0.80
2005_10_04_22:12:05-rms.dat: J  4       0.47         0.78
2005_10_04_22:17:42-rms.dat: J  4       0.48         1.80
2005_10_04_22:23:44-rms.dat: J  4       0.47         1.57

I have more numbers and plots if anyone wants them.

 Brian