[evlatests] December Engineering/Tests Meeting

[Bryan Butler]

some data on how many band switches we make.

numbers are approximate because i'm not including test time (though we 
don't often switch bands during testing), and i don't catch quite 
*everything* that is science observing, but they are first order 
probably about right.  i did three scales of length of time as a sanity 
check that the values scale about right, which they do.

over the month of november 2016 we had ~570 hours of science observing 
time in 274 SBs on the VLA.  during that time there were ~1942 true band 
switches, and ~12400 scans that didn't switch bands.  i give "~" values 
because i'm assuming that the first scan of an SB always switches bands, 
which isn't necessarily true, but i figured was the most conservative, 
and it will catch some of the missed test time band switches.

over the year from december 1 2015 to december 1 2016, we had ~5912 
hours of science observing time in 3214 SBs on the VLA.  during that 
time there were ~20800 true band switches, and ~163000 scans that didn't 
switch bands.

over the four years from december 1 2012 to december 1 2016, we had 
~24250 hours of science observing time in 12126 SBs on the VLA.  during 
that time there were ~86300 true band switches, and ~656780 scans that 
didn't switch bands.

steve tells me that hichem says that if there is no change in bands at a 
scan boundary, the switch is not told to do anything.  if that is really 
the case, then these switches have not gone through anything even close 
to 1000000 cycles.  if, however, for some reason they actually are 
cycling at such a scan boundary, then we're getting to about 3/4 lifetime.

	-bryan


Rick Perley wrote on 12/14/16 15:24 :
>     All:
>
>     We have three items (so far) for discussion.  There's time for more
> -- let me know if you have something to show/tell/discuss.
>
>     1) Steve:         RF Switches.
>