[evlatests] Mystery temperature swings - PS

[Jim Jackson]

PS - if you notice any wild dips in temperature on the PTC board 
during the day on Tuesday or Wednesday, disregard them.  We were 
hitting the FPGA on this board with quick bursts of freeze spray 
while working on the timecode problems. (In case anyone wonders - it 
seemed to have absolutely no effect on the behavior of this board)

Jim

At 10:27 AM 10/16/2008, Kevin Ryan wrote:
>The WIDAR Prototype Correlator (PTC) is in a half-height rack sitting
>in a corner in the outer screen room in the old VLA correlator room.
>It contains 5 boards each with 5 or 6 temperature sensors.  While
>developing software to monitor these temperatures, I've noticed a
>weird oscillation that occurs for a ~ 2-hour period roughly centered
>around midnight local time.  I've asked Ray Ferraro and Bob Broilo
>about it but they did not know of anything that would cause it other
>than that Ray stated that the temperature in that corner is affected
>by the doors opening and closing.
>
>So now I'm asking more people for ideas.  A graph of the temps on one
>board (they are all similar) over the last two days can be seen here:
>http://www.aoc.nrao.edu/asg/widar/temps/mystery-ptc-temps.jpg
>
>The swings from normal daily activity are apparent starting around
>0600 - presumably from the door opening and closing and use of the
>boards for testing - but what about those oscillations around midnight?
>
>It is certainly possible that this is not being caused by ambient
>temperature swings at all; like something going on on the boards
>themselves or possibly even the data gathering system itself.  Can we
>place a recorder near the PTC to monitor its ambient temperature for
>24-hours?
>
>Kevin
>
>
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