[arachne] Re: OT GPS

Arachne at FreeLists---The Arachne Fan Club!

On Mon, 6 Dec 2004, Greg Mayman wrote:

> > It's almost good enough now for a lot of site work.  For
> > instance, take a measured fence line.  Walking north to
> > south, the GPS tells me I've gone 8.3 feet MORE than the
> > tape measured distance.  I reset the trip meter, turn around
> > and follow the same fence to the start point, and I've
> > supposedly travelled 9.1 feet LESS than the taped distance.
> 
> Just out of interest, what length was that over - 20 ft? 200ft?

  That was over a 75.0' distance.  

  Just now, I tape measured a concrete walk we have at 
43'9+" (call it 43.75') and walked that with the GPS.  Got 
42.8' going west, and 43.3' going east.  So, much closer on 
both distances to the actual measurement, but still a 
round-trip accuracy better than 9".

  I suspect, all else being equal, the accuracy will be 
about the same regardless of the distance.
  Of course you won't be able to read it with that much 
precision.  Once you cross the 99.9' mark, the readout is in 
even feet, and then you lose precision again crossing the 
527' mark into .10 mi.

  Then again, I suppose you could manipulate your degree of 
precision somewhat by varying the units of measurement.
For instance, a readout of .50 mile has a precision (or 
accepted error) of 26.4'.
  Changing units to yards would give a readout of 880 yards, 
with an indicated precision of 1.5'.

  As the technology stands now, it'd be great for stuff like 
making sure your well is at least 75' from your leach field, 
staking out a garden of a certain size, laying out a 
driveway; stuff like that where anything +/- a foot is close 
enough.

  Of course, back to one of the originally mentioned 
purposes, it's certainly close enough for finding (within 
+/- 8 feet or so) hidden goodies.
  Had some people drop by Sunday to redeem the coupon they 
found,

                Two Loons Coffee
                Gift Certificate

  This Walking Bridge certificate is redeemable for 
 one pound of freshly roasted coffee of the bearer's 
              choice at the roastery.
        Gate at N 34°17.306' W 110°06.052' to
        Roastery at N 34°17.317' W 110°06.498'

(Walking Bridge is the name of the cache where we left this 
coupon.  Other coupons have their respective cache names on 
them... and subsequent coupons will also have store hours 
on them!  ;-)

-- 
Steve Ackman
http://twoloonscoffee.com       (Need beans?)
http://twovoyagers.com          (glass, linux & other stuff)



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-- Arachne, The Web Browser/Suite for DOS and Linux --

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