Home › Forums › Geocaching in Wisconsin › Tech Talk › Do you take multiple coordinate readings and average?
This topic contains 12 replies, has 12 voices, and was last updated by Mathman 16 years, 7 months ago.
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01/14/2009 at 8:30 am #1727557
As the title suggests, I have heard of groups doing this. Taking 4 or 5 coordinate readings, standing in place for a good minute or so in different locations within 10 feet of the cache and getting the best accuracy possible…then averaging the coords to ward off any wacky ‘quick logging’ errors that may throw others off by 15-20 feet.
How about it? ๐
01/14/2009 at 11:20 am #1900289It’s always good to take a few coordinates and average them, even better if you do it on different days & better yet at a different time of day.
Another good way to average coordinates would be to use more than one gps unit when taking coordinates.
Allot of Garmin units have an average waypoint function, but I have found in poor signal environments your just averaging a poor/bouncing signal and it does nothing to improve accuracy.
A good example of this is if a cache is hidden at the base of a cliff, if you stand there and let the unit average for 5-10 minutes the averaged coordinates will actually be 50-100ft away from the base of the cliff. I would speculate this is because the signal is blocked in one direction by the cliff, so the gps constellation the unit has is mostly in one part of the sky.01/14/2009 at 3:21 pm #1900290I do this for every cache. I would think this would be considered normal process.
01/14/2009 at 4:21 pm #1900291As Dave said, I would hope this is the norm.
I think everyone does it their own way though. My routine starts at GZ. When I find the spot I want to hide my cache, I place my GPS standing straight up, on the tallest point I can reach right above the cache, and leave it there the whole time I’m planting and disguising the cache. If there is nothing to hold the GPS, then I stand there with it, holding it above my head for at least a minute, more if there is heavy cover.
My second step is to walk about 10 feet from the cache in 3 to 4 directions (sometimes more dependent on cover) and take WP’s at each location. I then average those WP’s, and then average that with the original WP I took.
01/14/2009 at 6:21 pm #1900292Keep in mind that a few cachers (who shall remain nameless) will find GZ while hiding a cache, but post the coordinates on the proximity border, usually 25 feet away. But if they are on the east proximity, for example, the cache COULD be 40-50 feet from the container. And considering varients in GPS units, you could be 50-60 feet away! Supposedly that adds to the thrill of the hunt. I find it very irritating!
I only use the proximity rule if I want a land feature to provide cover, like a tree or wall. We like to hide caches to be FOUND, not just LOOKED FOR! ๐01/14/2009 at 10:57 pm #1900293@jimandlinda wrote:
Keep in mind that a few cachers (who shall remain nameless) will find GZ while hiding a cache, but post the coordinates on the proximity border, usually 25 feet away.
I’ve seen some like that, one of the responses I got as to why that was from the owner: “yeah, they were ‘adjusted’ to get them to fit”
When I place one, I average (garmin) it for around 100 cycles if I can w/o feeling muggled, if I’m not out in muggle view, I’ll average a couple of minutes usually.
I have a couple of times, gone out to place and re-averaged just to make sure. I know there are others who do this meticulously even after the cache is placed.
01/14/2009 at 11:30 pm #1900294We allow our Garmin to sit on the cache site (or held up, as mentioned) for at least 3-5 minutes to gain an average. Once that’s done, we’ll walk some distance….in different directions….set a “go to” and see how close we have it. We try to get within 6 feet, but the terrrain around here in some instances (down in the bottom of a coulee) might require us to live with 10 feet or so.
If we’re doing a maintenance visit, we’ll check our accuracy and make adjustments if needed. Personally, I like my challenges to come in the form of a puzzle, a clever hide or camo, or something like that, not from coordinates way off. Still, we’ll go out 30-50 feet if we don’t find it quickly, just because…..well, one of us in particular gets pretty stubborn about wanting to find it!
01/14/2009 at 11:58 pm #1900295I usually let my GPS sit at the cache location for 5+ min as I handwrite odds and ends or get the cache container ready. I then walk away, pull the coords to my “Go To” and see how far off it is ready. If the cache is close by, I may come back on a clearer or more cloudy day to check. I try to take as much time as needed to get the best coords!!
01/15/2009 at 5:27 pm #1900296@jimandlinda wrote:
Keep in mind that a few cachers (who shall remain nameless) will find GZ while hiding a cache, but post the coordinates on the proximity border, usually 25 feet away. But if they are on the east proximity, for example, the cache COULD be 40-50 feet from the container. And considering varients in GPS units, you could be 50-60 feet away! Supposedly that adds to the thrill of the hunt. I find it very irritating!
I only use the proximity rule if I want a land feature to provide cover, like a tree or wall. We like to hide caches to be FOUND, not just LOOKED FOR! ๐Please note that the guidelines mandate “Accurate coordinates”. This is why you sometimes receive questions from the reviewers like:
“Your cache appears to be 10 feet off the shoreline. Is it an underwater cache?”
“Is there some reason why your cache is in the middle of a traffic intersection?”
“Why is your cache on the berm of a limited access highway?”
“Your description says your cache is right off the road, but the location looks like a 200 foot bushwack. Are you sure the coordinates are right?”Unfortunately, we can’t go out and check the coordinates of each cache. If you feel a cache has been placed with bad coordinates intentionally, please file a Needs Maintenance log on the cache page if you can’t get any results from the cache owner.
01/15/2009 at 5:45 pm #1900297I definitely take multiple “readings” on my new caches that I list. I usually do not come back over a period of days as is mentioned in other posts but I have done so.
One of the main reasons I see that you might have to come back over days is if the cache you are placing is in an urban area around tall buildings. They seem to mess around with your signal at times and it’s always best to make sure that finding the cache will be reliable and repeatable with your coordinates taken. If not, then you might not want to place a cache in that spot.
Another instance would be areas of heavy tree cover. I have revisited some of mine after the leaves have fallen to double-check the coords.
I was known for notoriously horrible coordinates when I first started placing caches (if you’ve ever done Fav Fishing – The Channel you might agree with this statement) but I think as with anything the more you practice the better you are. Also, it helps to own a Garmin ๐
Usually, if you are placing caches with “bad coordinates”, you will learn so in your logs and you can work to get better. Taking multiple readings and reapproaching ground zero from several angles and taking additional readings is definitely one way to ensure better accuracy. Also, depending on the placement (tall buildings, power lines nearby, etc) I will also come back with the coords and attempt to “find” the cache myself to make sure the coords “work”.
I much prefer making up bogus coords to puzzles over getting the accurate ones for the cache itself ๐
01/15/2009 at 6:40 pm #1900298Interestingly, the Colorado/Oregon gps units do not have a button for averaging coords, which is kind of a surprize.
I havent placed a cache with my new Colorado yet, but I suppose I will just have to get several coords, and average em them manually….In the past, with my Legend, I used the average button and averaged em a hundred times.
With any unit, one helpful thing to do, is after you have your coords, that you think are correct, and walk 60 feet away, and then walk towards your cache slowly while looking at the gps and see if it points you right to the cache and gives you something under 10 feet when you get to GZ. If I dont get something under 10 feet, I adust the coords until I can have the gps guide me right in with the arrow pointing to the cache all the way in from 60 feet out and then get accuracy within 10 feet when I get there.
Even with that degree of carefulness, I still get occasional bad coords, so the second thing to do is be willing to adust the coords if that is the feedback from finders.
zuma
01/15/2009 at 7:11 pm #1900299We use 2 different GPS units for placing caches. If both agree, we are happy. If not, we come back a different day, try again, and reaverage.
On the Left Side of the Road...01/25/2009 at 1:51 am #1900300I use the “averaging” feature on my GPS.
I also will walk 50-60 feet away and then see if I can can get to within 5 feet of my reading by walking back to the cache placement. It takes longer to do this but I prefer to get as an accurate reading as I can.
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