Re:The perfect phone for a birder?

To: "" <>
Subject: Re:The perfect phone for a birder?
From: Peter Shute <>
Date: Mon, 28 Dec 2009 10:17:01 +1100
So my information is 9 years out of date?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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