averaging coords

[+luv2run12782]

I am getting ready to place my second cache. It's a really cool container and I wanted to be sure coordinates were accurate, or else nobody is ever going to find it! My first cache I placed had everyone off by about 40 feet and it wasn't in any real tree cover. What is the best method? And do I really need to take 3 days to place a cache?

 

I am thinking that an average of 10 coord readings is sufficient, I'm not sure how to average them on my gps unit (if it even does it...I have an etrex hc).

 

Thanks!

[+Lord Cadogan]

I am getting ready to place my second cache. It's a really cool container and I wanted to be sure coordinates were accurate, or else nobody is ever going to find it! My first cache I placed had everyone off by about 40 feet and it wasn't in any real tree cover. What is the best method? And do I really need to take 3 days to place a cache?

 

I am thinking that an average of 10 coord readings is sufficient, I'm not sure how to average them on my gps unit (if it even does it...I have an etrex hc).

 

Thanks!

I have a Vista HCX and there is a function to do the averaging for you. It is accessed off of the Mark Location screen. I just start the averaging and let it go for at least 200. IMHO, 10 is NOT enough. The more that you can do the better.

 

I would think that you GPS should have the same function.

 

WStemple

Edited July 16, 2009 by WStemple

[+StarBrand]

The Venture HC does have waypoint averaging feature - however it often really does nothing to improve things.

 

Consider 3 cases:

• Sats have poor geometry with weak signals - Result - you just averaged bad data
  
• ok geometry in the sats, ok signal strength - Result - averaged data is a tad better
  
• Good geometry between sats - strong signals - Result - no need to average at all.
  

Let your unit sit and "settle" down for a few minutes before you take a reading and that will be just aabout as good as any other method.

[+user13371]

StarBrand, you raise some good points but could expand on this advice.

 

If you want the most accurate coords, look at the satellite status page to see how the geometry is. You want strong signals from at least four sats (more is better) spaced evenly across the sky. If everything you can see is straight overhead, or clustered in one quadrant, or sitting in a straight line -- maybe you want to come bck in a little while or even the next day.

 

But really, the difference in most cases might be slight. If you want to be sure, record your position today and navigate back to that waypoint tomorrow. If you have a repeatable result, it's good enough.

Edited July 16, 2009 by lee_rimar

[+Chris & Renee]

No matter how accurite your readings are, im sure there will be many others whos GPSr will almost show them a diff location no matter how many reading you take, waypoint averaging a nice little feature but as long as you lett it settle in the same location for a few minutes i'm sure you will be pretty right.

[+briansnat]

Averaging is a waste of time. To do it right you would need to average over a period of days.

 

As Starbrand pointed out, if you have bad sat geometry and/or a bad signal you will just be averaging bad data.

 

If you have a good signal and good sat geometry then there is no need to average because your GPS should be about as accurate as it can get.