Figuring out how far away, and averaging questions...

[M&M Speedracers]

Ok I've been looking at some logs, and have been on several geocache adventures. Sometimes I see the people say "I was only 6ft away and couldn't find it...." or something like that. Now is that a feature of the certain model GPS, or are they calculating it? I have the Garmin GPS II+, and it doesn't give me this kind of info (only reads in miles, up to 100th of a mile)

 

Also I read about coming to a spot to average the coordinates....how exactly is this done? I want to hide some caches, and it sounds like this is the best way to make sure one gets an accurate waypoint.

 

Thanks,

Marc

[+Gliderguy]

Most newer units show distance remaining in feet once you are within .1 miles. You may be able to upgrade the firmware on your GPS II+ to get this precision at Garmin's website

 

Some Magellan units auto average below a certain traveling speed. Most Garmins have an option to average position buried somewhere in the menus. Since SA has been deactivated, there has been some lively debate on whether this gives you any real improvement in accuracy. The main thing is to let the unit stabilize over the intended location for several seconds to a minute before reading it, and verify you have good satellite strength and geometry.

 

The more challenging the situation with weak sat reception and poor geometery, the more likely that averaging might improve the solution, but only if you do it for a meaningful length of time such as 15-30 minutes (to allow the actual sat geometry to at least change slightly)

[M&M Speedracers]

quote:

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Originally posted by Gliderguy:

Most newer units show distance remaining in feet once you are within .1 miles. You may be able to upgrade the firmware on your GPS II+ to get this precision at http://www.garmin.com

 

Some Magellan units auto average below a certain traveling speed. Most Garmins have an option to average position buried somewhere in the menus. Since SA has been deactivated, there has been some lively debate on whether this gives you any real improvement in accuracy. The main thing is to let the unit stabilize over the intended location for several seconds to a minute before reading it, and verify you have good satellite strength and geometry.

 

The more challenging the situation with weak sat reception and poor geometery, the more likely that averaging might improve the solution, but only if you do it for a meaningful length of time such as 15-30 minutes (to allow the actual sat geometry to at least change slightly)

---

 

Ok I just checked my owner's manual again, and it's not very clear about the averaging feature....so basically, I set the waypoint, and then run the averaging feature....and it comes up with a "Figure of merit"....so I should let that

run for a few minutes and what exactly will that do for my coordinates? Will it change them, if necessary, to a more exact set of coordinates, or will I have to manually do that in some way?

[Kerry.]

quote:

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Originally posted by M&M Speedracers:

....so I should let that run for a few minutes and what exactly will that do for my coordinates? Will it change them, if necessary, to a more exact set of coordinates, or will I have to manually do that in some way?

---

 

The Averaging function will change the displayed coordinates and the values stored will be the values at the moment you decide to save them (after whatever period of time you let the average run).

 

Will they be more exact, Yes, No, could be, might be then maybe not as there's about a 50/50 chance of inceasing or decreasing the actual accuracy. Averaging can actually decrease the accuracy and without a reference point it's really something one doesn't know for sure.

 

As for averaging poor coverage, bad geometry (in other words bad data anyway) then the result will generally be a bad average as well.

 

One thing that improves accuraccy is planning to be at a specific location (and all things considered) to take advantage of the best possible conditions.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[Kerry.]

quote:

---

Originally posted by M&M Speedracers:

....so I should let that run for a few minutes and what exactly will that do for my coordinates? Will it change them, if necessary, to a more exact set of coordinates, or will I have to manually do that in some way?

---

 

The Averaging function will change the displayed coordinates and the values stored will be the values at the moment you decide to save them (after whatever period of time you let the average run).

 

Will they be more exact, Yes, No, could be, might be then maybe not as there's about a 50/50 chance of inceasing or decreasing the actual accuracy. Averaging can actually decrease the accuracy and without a reference point it's really something one doesn't know for sure.

 

As for averaging poor coverage, bad geometry (in other words bad data anyway) then the result will generally be a bad average as well.

 

One thing that improves accuraccy is planning to be at a specific location (and all things considered) to take advantage of the best possible conditions.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go