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WAAS coordinates vs non WAAS coordinates

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It will show the same, depending on condtions. WAAS is a method used to reduce some of the errors in postion caused by things like signal delay caused by disturbances in the ionosphere. All conditions being perfect they will show the same coordinates. BUT conditions vary enough to where no two units will show the exact same coordinates (WAAS or not) in most cases.




"See the wonderous works of Providence! The uncertainty of human things!" Geo.Washington

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Reverse how you look at it.


The Cache is at a spot that can be represented exactly with coordinates.


A WAAS GPS with WAAS enagled is able to come closer to the actual coordinates of that cache than one without WAAS enabled.


Of you had to put money on which GPS WAAS or non WAAS was going to hit the actual location of the cache your money should go on the WAAS gps.


GPS's all have errors in their calculated coordinates due to moisture in the air, and other factors. WAAS tries to account for some of those errors thus giving a better representation of where the cache is actually at.



Wherever you go there you are.

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I've convinced myself that WAAS is all hype. I've heard that sometimes the accuracy can DECREASE as much as it sometimes increases, when you have WAAS turned on in your GPSr.


I haven't tested my theory... haven't studied up on it much at all, really. icon_smile.gif I am just stubborn, I think it eats more battery life, and I'm sceptical of its usefulness in our hobby - since being within 15 feet (non-waas) seems good enough anyway.


What does this have to do with the topic post? Not much, I guess. Don't mind me... icon_biggrin.gif


geobanana.gifThe Toe Pages

"Now with 50% less yuck, and 100% more color!!"

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It's not hype but it doesn't necessarily help us where we need it the most. That is, in the tree cover. It is important to see what the status of your 3D differential readings are to judge how well it works. Just having WAAS enabled doesn't mean that you're receiving enough information to make it work. More accuracy is obtained by referencing a ground based station that is co-processing the signal and transmitting the error correction to your GPS. As I understand it, surveyor quality GPS when referencing something called a Trimble ground station will have accuracy to two centimeters, less than one inch. These also cost more than most cachemobiles. I'm all for greater accuracy, but it is amazing what we get for just a few hundred bux.


Steve Bukosky N9BGH

Waukesha Wisconsin

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WAAS hasn't proven all that advantageous for me either. Most often, I'm in my truck driving down the freeway/highway when I get a WAAS lock, which tells me I'm 6' closer (according to the satellites) to the lane I'm actually traveling in than if I wasn't using WAAS. icon_smile.gif


I've stopped using it out in the boonies because it uses more batteries than make it worthwhile. The places where it would really matter, it doesn't, due to the environment prohibiting the receiving of signals in the first place (i.e., near rock faces, heavy tree cover).



Team A.I.

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That's one of the problems as the cache, although could be represented exactly with coordinates, isn't as the coordinates aren't exact.


Apart from that there is absolutely no reason why a single (or short term set of) coordinates taken with a straight GPS couldn't be better than some of the augmented systems.


There is a reduced chance of it occuring but that won't (and doesn't) stop it from occurring.


The integrity of the result is generally what it's all about probably more so than the actual accuracy especially with recreational type receivers.


As for Trimble Ground Stations (or any of the others dual freq real-time systems) these have limitations as well. Certainly cm type accuarcy but at a the expense of distance.


Really every type of accuracy endeavour comes at some type of price or limitation. WAAS is hellinglish expensive considering the overall cost and the (small) ground footprint it covers compared to the GPS system proper. Since WAAS was concieved many things have changed which really knocked the edge of the "amount of improvement" that was going to be possible for the $$'s. That difference is now not so much accuracy but integrity and error conditions/warnings, which just about all recreational receivers don't (probably won't) support.


The same Trimble type receivers that are capable of cm accuracy in real-time over limited distances can pull mm accuracy over much further distances (100's km's) but that comes with a "time" limitation, in that it takes time (sometimes hours, days) and being pro-processed it's not an imediate solution.


Cheers, Kerry.


I never get lost icon_smile.gif everybody keeps telling me where to go icon_wink.gif

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