On 04/28/2012 02:39 AM, Hal Murray wrote:
The quake talk was not on line so I watched the one on Climate Change and
it's impact on N. California. Interesting, but no human impact data, only
wildlife.
It's up now.
http://online.wr.usgs.gov/calendar/2012/apr12.html
For a good time sink, my favorite talk was March 2011:
Unraveling the Mystery of Avian Navigation
http://online.wr.usgs.gov/calendar/2011/mar11.html
A little more text back at:
http://online.wr.usgs.gov/calendar/2011.html
For anybody in the Silicon Valley area, their open house is May 19-20. It's
kid friendly, both big kids and little kids. You get to talk to the people who
are actually doing the work. They are happy with geeky questions.
-------------
Back to somewhat time-nutty stuff...
Does anybody understand how they are using GPS and/or have performance numbers?
They don't need the actual position (DC), just the changes in position. They
need it now. They can't wait for post processing. I'm not sure how much
accuracy they need. I'd guess in the cm range.
(Maybe I can learn more at the open house.)
Extract the ECEF position, build a long term average position. Subtract
each given position with the known ECEF average, square the differences,
sum and square root to get an RMS value... set a threshold for
trigger... whenever the difference RMS is above threashold start
reporting. Keeping a memory of previous diffs will get a pre-trigger memory.
Not too hard, given good antenna and carrier phase, preferably double
frequency reciever.
Cheers,
Magnus
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