[evlatests] Antennas 14 and 16 DTS issue

[Jim Jackson]

It appears that the modifications added to the DTS modules over the last 
week are causing a new problem.

The modification was intended to address the problem with the DTS modules 
coming up with invalid timing states between the digitizer and formatter 
boards. It works by sensing when the min and max values from the digitizer 
are at full scale and resetting things when that occurs.  When Antenna 16 
was put back into service at L-Band yesterday, it was discovered that 
IF-B  was constantly resetting the digitizer. After further analysis, it 
appears this is happening in other IF's as well - it was only more 
noticable in 16B because that module seems to take longer to reset than the 
others resulting in larger disruptions.  It is occurring because bursts of 
RFI, clearly visible on the FFT display, are causing brief fullscale 
readings on the digitizer, resulting in the frequent resets to the 
digitizer. Kerry Shores and Mike Revnell will be working on a solution.

I would be possible to re-install the one unmodified set of modules into 
Antenna 14 but I would like to avoid this if at all possible - it would 
basically be busy work that would delay them from working on fixing the 
problem.  I guess the question is whether antenna 14 is working well enough 
at this point? Though I haven't had a chance to test it, I suspect this is 
mainly and L (and possibly C) Band issue. Our current plan is to work on 
fixing the problem and not putting the original modules back in 14 unless 
there is strong and justifiable argument to the contrary.

Jim