This is the "reame" file for dir "Noise".

Scott Hannon
Last update: 23 June 2000


Overview:
   This file describes the file format of the noise rating files, plus
info on how the ratings were generated, and comments upon some of the
results.


Files:
   There is a separate "m#_all.txt" noise file for each module.  The layout
of the file is: one channel per row, with 14 columns per row (see the file
header).  The 14 columns are:

   index
   "freq" = approximate channel center frequency
   A gain statistics:
      "mean" = mean noise rating
      "std" = standard deviation of noise ratings used in mean
      "ok" = number of OK tests used in mean & std.
      "pop" = number of tests excluded from mean & std due to noise pop
   B gain statistics: same as A
   Opt gain statistics: same as A

(A "-1" value indicates the value was not computed due to noise problems)

The noise statistics are based on SRF measurement tests:

A gain: 7 tests total
   161K: 1403, 1409, 1416
   155K: 1481
   149K: 1616, 1619, 1622

B gain: 6 tests total
   161K: 1406, 1414
   155K: 1479, 1484
   149K: 1620, 1625

Opt gain: 5 tests total
   161K: 1408, 1415, 1418
   155K: 1480
   149K: 1621

The noise rating is a relative value within the array.  Small values
mean low noise; big values mean high noise.  Anything less than 1 is
generally OK.  The rating is more-or-less linear...eg 0.50 is twice
as noisy as 0.25.  The noise rating is based upon an RMS measure of
the SRF beytween 10 and 15 FWHM into the wing.  At this distance the
true SRF is less than 1E-4, which is well below the noise level.  Thus
the measured SRF at 10-15 FWHM is a good estimate of the noise.

These noise ratings in these files refer only to the noise.  A channel
can suffer from other problems not relarted to noise (eg SRF shape
irregularities), and so low noise does not necessarily mean a channel
is "good".


Comments:
   M9  index  11 : bad Opt - worse than B, but even B is marginal.
   M9  index 158 : bad Opt - much worse than A & B, and A is good.
   M2b index 117 : bad Opt - much worse than A, and A is good.
   M1a index  22 : bad Opt - much worse than A, and A is good.
   M1a index  96 : bad Opt - much worse than A & B, and B is good.

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