How to take good coordinates

[+ipodguy]

I'm planning on hiding a difficult cache and I want to make sure that the coords I give for this one are as accurate as I can provide. I've read several posts where hider take several readings and average them. How is that done? Anything else I can do to make sure that my coordinates are good? So far, I've hidden two multicaches with no complaints about fuzzy coordinates, but I want to be better and learn how other hiders do it.

 

Any tips or tricks you have are much appreciated.

[+simpjkee]

I place my cache and then write don the coords I have at it. Then I walk away about 20 or 30 feet and walk back and take coords again. I walk away about 20-30 fett and walk back and write down the coords again. I do this about 8-12 times until I get a good feel for what the coords are and then average them to get my final coords. Then I walk away about 75 feet, put in the coords I just decided on and then hit go to and follow the arrow just to make sure the arrow leads me to my cache. If it all seems to be right, I use them.

 

I've never had someone tell me that my coords were off.

[+Gitchee-Gummee]

Some GPSr units have an [averaging] function. Check yours out.

 

Otherwise, take many readings. Each time leaving and re-approaching from a different direction, allowing the GPSr to settle for 5 minutes or so at the site. You can either save them as waypoints, or write them down. It is good to take multiple readings on different days, as sometimes weather (and unknown "stuff") can affect readings.

 

When you have compiled many (10 or more), just do the simple math of adding the final three digits and divide by the total readings #. Do it for both lat and lon, of course.

 

Best too, if you can have somebody else do a "test run" with your set of averaged coordinates, with a different GPSr.

 

Good luck.

Edited April 26, 2010 by Gitchee-Gummee

[+ipodguy]

Yeah but how do you average them? That's what I'm not getting. Divide A by B and subtract C? Explain that to me.

[+ipodguy]

Thanks for explaining GG

[+wrtiii]

I think most people just kinda wing it.. .402 .403 .404 .406 .407 .408

 

Well Hey Looks like .405 is right in the middle lets go with that...

 

There are lots of ways to find an average... What was it agian? means, medians and modes?

 

Or you could try reading this if you want.. http://stackoverflow.com/questions/583576/...gps-coordinates

 

I deal with calibrating final approach radar systems in my trade and it seems to be a bit easier than doing gps averaging calculations on the trail

 

just my 2 cents,

 

ciao.

[+bootsycat]

Averaging (finding the "mean") means adding all the scores and dividing by the number of scores you had.

 

Say you take 8 readings and get the following as the last 3 digits:

102, 104, 102, 105, 103, 103, 106, 105 you add them up and divide by 8 (because you have 8 readings). These readings add up to 830, which you'd divide by 8 and get 103.75 which you would round up to 104 (because it's closer to 104 than it is to 103).

 

HTH

 

bootsycat

 

I think most people just kinda wing it.. .402 .403 .404 .406 .407 .408

 

Well Hey Looks like .405 is right in the middle lets go with that...

 

There are lots of ways to find an average... What was it agian? means, medians and modes?

 

Or you could try reading this if you want.. http://stackoverflow.com/questions/583576/...gps-coordinates

 

I deal with calibrating final approach radar systems in my trade and it seems to be a bit easier than doing gps averaging calculations on the trail

 

just my 2 cents,

 

ciao.

[+niraD]

Also, once you have your coordinates (however you get them), be sure to return to the site and approach the cache from different directions. The GPSr arrow should be pointing right at the cache no matter which direction you approach from. For even more certainty, repeat this on several different days (when the satellites are in different configurations).

[Storm Buster]

Averaging (finding the "mean") means adding all the scores and dividing by the number of scores you had.

 

Say you take 8 readings and get the following as the last 3 digits:

102, 104, 102, 105, 103, 103, 106, 105 you add them up and divide by 8 (because you have 8 readings). These readings add up to 830, which you'd divide by 8 and get 103.75 which you would round up to 104 (because it's closer to 104 than it is to 103).

 

HTH

 

bootsycat

Don't forget to throw out obvious anomalies. Say you have as the last 3 digits:

102, 104, 102, 105, 103, 300, 106, 105

You'd want to throw out the 300 before averaging.