[evlatests] 12.5 MHz BW spectral line mode noise

[Bryan Butler]

if this is in file 342APEVLA, then i can verify that the command to turn 
off self test was in the script:

VlaCorrelator.selftestEnable(0)


	-bryan


Rick Perley wrote:
>     All is *not* well with these modes.  To test if turning off the 
> self-test has 'fixed' the extra-noise problem, I observed a blank field 
> in C-band, in continuum mode, and in mode 'PA' with BW = 25, 12.5, and 
> 6.25 MHz.  The data were calibrated using 3C147.   The channelwidths 
> provided are 3.125, 0.781, and 0.195 MHz.
>     Data quality was excellent -- even outstanding -- for all 
> observations.  The only complaint (other than 5B, which is already 
> fixed) is with the 'short shallow drop' problem, which affects most EVLA 
> antennas (but with negligible effect on sensitivity). 
> 
>     Noise histograms were made of the imaginary part of the Stokes I, Q, 
> U, and V correlations of the noise field for the EVLA antennas.   In all 
> cases, the width of I equaled that of V, and Q equaled that in U.  All 
> four should have equal width, but as the table below shows, they do 
> not.   The values given are in mJy. 
> 
>  BW                  I, V                  Q, U                       
> Comment
> ----------------------------------------------------------------------------------
> 50 MHz          17.0                     16.8                    Actual 
> BW ~ 44 MHz
> 3.125              60.0                     60.0                   
> Exactly as expected
> 0.781             200.0                   130.0                  Q, U 
> are correct.  I, V are 50% too high.
> 0.195             250                      255                     
> Exactly as expected. 
> -----------------------------------------------------------------------------------------------
> 
> I can't confirm if the 'self-test' was actually off.  But if it was, we 
> still have a problem with extra noise in Stokes I and V (actually, in 
> the correlations RR and LL). 
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/evlatests