So my information is 9 years out of date? Oh, well, that's not too bad for me.
Peter Shute
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________________________________
From: Dave Torr
To: Peter Shute
Cc: ;
Sent: Mon Dec 28 07:07:04 2009
Subject: Re: [Birding-Aus] Re:The perfect phone for a birder?
Selective Availability - the system that gave civilians a degraded GPS compared
to the military - was turned off in 2000. Wikipedia (of course) has a pretty
good article on GPS describing the various sources of error and what can be
done to improve accuracy.
But as you say 10m is pretty good for most birding locations - unless you are
trying to pinpoint a specific tree in a dense forest, in which case GPS will
probably not be getting signals anyway so will be useless!
2009/12/28 Peter Shute <<>>
Regarding GPS accuracy, my phone generally claims the coordinates are within
10m, sometimes much lower, occasionally higher. I would imagine that's easily
good enough for finding most birding locations again, what kind of accuracy are
you talking about?
I'm under the impression satellite signals are deliberately encoded to prevent
civilians getting too much better accuracy than that, for military reasons,
including making it hard to pinpoint the location of the actual satellites in
order to shoot them down. To get better accuracy (precision might be a better
word), I think a long succession of coordinates must be averaged. This may be
what the more expensive gear does.
Not so very long ago, GPS wasn't even an option. The alternative for those
without access to expensive electronic distance measuring equipment was a tape
measure or triangulation. In my opinion, the decision by the USA to release
even this level of accuracy to civilians is absolutely wonderful, even if it
does occasionally lead you back to the wrong side of the creek.
Peter Shute
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