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The ASKAP
Update includes reports on new firmware with improved correlator
stability, progress on VAST pilot survey phase II observations, and
the recent call for revised survey science proposals. After extensive
testing and investigation over the last few months, the digital
firmware team have implemented several changes to address the issue of
correlator "dropouts" in ASKAP data. Several likely causes of data
stream stalls were identified and improvements were packaged into a
test build that has been running on the array for over a week.
ASKAP’s control system monitoring database logs instances of
detectable correlator alignment problems, but there is another class
of "ghost" dropout that has only been visible in the astronomy
data. The latest firmware addresses probable causes for both classes,
with changes to the data stream alignment mechanism and corner-turn
buffer management logic. The image above shows colour-coded
monitoring data from ASKAP’s control system showing fewer unexpected
alignment failures (red blocks) after the test firmware
deployment. Date increases to the right for one month. The new
firmware was deployed at the beginning of August. Red lines at full
height are intentional resets or system downtime. Monitoring shows
significantly fewer alignment failures since the latest firmware was
deployed. This means that future observations should experience fewer
dropouts impacting groups of fine frequency channels.
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