[evlatests] More 3-bit stats ...

[Bryan Butler]

did you do a ratio of A1C1 to B0D0?  my recollection is that one was 
quite a bit better for the 3-bit than the other, and we didn't 
understand why...

	-bryan


Rick Perley wrote, On 12/7/11 9:54 AM:
>      My report yesterday on the 3-bit noise yesterday for the various bit
> levels was incomplete, as I had not compared the 3-bit noise levels to
> the 8-bit 'truth'.  This is now done, but there are no surprises.  A
> couple of perhaps interesting trends, however ...
>
>      To simplify the effort, I compared the histogram noises for the 012
> and 345 bit selections to the 8-bit noises, taken at the same time, and
> in the same frequency subband.  These two observations were taken at
> different elevations (10 degrees different) and at different times (80
> minutes).  There are four ratios of interest:
>
>      1) A1C1/B0D0 at the low elevation
>      2) A1C1/B0D0 at the higher elevation
>      3) A1C1(high)/A1C1(low)
>      4) B0D0(high)/B0D0(low)
>
>      Results:
>
>      1) This shows the usual degradation of the 3-bit system, compared to
> the 8-bit.  The ratios are a little higher than expected -- ranging from
> 1.09 to 1.28.  However, the higher ratios are all associated with
> specific antenna-polarizations:  26A1 is easily the worst (average
> 1.25), and 23C1 a close second (1.17 average).  06C1 is also poor (1.14
> average).
>      2) This is the 3bit/8bit degradation ratio at the higher elevation.
> Curiously, the values average a little less than those in (1) at the
> lower elevation, ranging from 1.03 to 1.30.  The same antenna-IF
> dependency noted in (1) is seen here also, but (for example), ea26A1 is
> now 1.15, rather than 1.25, while ea06C1 is 1.20, rather than 1.14.  'It
> goes both ways'.
>      3) This is the ratio reported yesterday:  The average ratio is 0.98,
> with a dispersion of .05.  The high end of the distribution is dominated
> by ea06C1, with an average of 1.07.  (This is reflected in the ratios
> given above in (1) and (2)).
>      4) This average is  1.01, with a dispersion of .04.  The difference
> in the averages in (4) and (3) reflect the difference between those in
> (1) and (2).
>
>      My bottom line:  There's no salvation here.  The noise is the same
> for any of these 3-bit selections, to within the measurement errors.
>
>
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/evlatests