[Loadstone] Saving accurate point coordinates.

Shawn Kirkpatrick shawn at odyssey.cm.nu
Thu Jul 19 05:23:27 BST 2007


You may have waas enabled but might not be getting it anyway. On my royaltek 
I've never seen it get a waas signal. You can check this by checking the gps 
quality, if it says differencial fix then you have waas, if not then you 
have standard gps. The accuracy for standard gps is around 15 meters. If 
your points are within that then things are ok. You can make manual 
adjustments to the coordinates with the point update window. The problem 
there is you wouldn't know what the "accurate" value should be. Every time 
you were on the point the gps receiver could give different coordinates. So 
a correction that seemed to work one day could be completely inaccurate the 
next. No matter how accurate the point coordinates are you still have the 
gps drift to deal with. In the worst case those two inaccuracies add 
together to create a bad result but in practice this doesn't seem to happen 
too often.
I guess the real solution to this is to wait for better quality consumer 
receivers to come out or get your hands on some military-grade hardware.

On Wed, 18 Jul 2007, Dave Mielke wrote:

> [quoted lines by Shawn Kirkpatrick on 2007/07/18 at 17:30 -0700]
>
>> What you're experiencing is gps drift and it's to be expected.
>
> Yes, I understand this.
>
>> If your is waas capable this drift can go down quite a bit when standing still
>> but will still be there.
>
> It is, and I always leave it on.
>
>> We've considered putting in some sort of averaging
>> but you'd have to be standing still for some period of time for it to work.
>
> Wel;l, in this case I was sitting, but I understand what you're saying.
>
>> Even then it would only be an average so still not quite accurate.
>
> However inaccurate it may remain, it'd surely be better than an instantaneous
> single capture which just might be way off.
>
> Another approach mightr be for the user to be able to move a point by an amount
> in a direction. That way, he could make an imperical judgement based on several
> measurements and then make manual adjustments.
>
> -- 
> Dave Mielke           | 2213 Fox Crescent | I believe that the Bible is the
> Phone: 1-613-726-0014 | Ottawa, Ontario   | Word of God. Please contact me
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