My Coords Are Always Off

[+back2eight]

Well, I have found caches and at times been right on with the coordinates. I have found some that have shown it being 80 feet away. But what I don't understand is why are my coordinates off on my own caches? You would think that when going back to my own cache that was marked with my own GPS that it would lead me right to it. But it doesn't. One was off by 50 feet. Another one I marked while standing directly above the cache but then I had 2 DNFs. When I went to check on it it was pointing about 50 feet over a river. So no wonder they didn't find it! Why is my GPS acting so crazy and is there a way I can fix it? I have Garmin etrex. Also, I have been going back in and updating the coordinates to my caches when I go back to one and the coordinates are off, but how do I know if this new set is right or if my GPS was just acting up when I went back to check on it?

 

Kristi

[+Moore9KSUcats]

A lot of this has to do with the satellite configuration. You can set your GPSr on the ground, or a picnic table, and watch the coordinates change constantly, or if you have it set to find a cache, the distance to ground zero will constantly change. This is all part of the range of error. To help alleviate the problem, many geocachers will average the waypoints when they set a cache. Some machines will average for you, other geocachers will take 20 readings and average it themselves.

 

Tree cover or cliff blockage will alter your readings, also.

 

I am sure some of the more technical geocachers can explain it better than I did, and I hope someone else will chime in!

[+Prime Suspect]

Well, I have found caches and at times been right on with the coordinates. I have found some that have shown it being 80 feet away. But what I don't understand is why are my coordinates off on my own caches? You would think that when going back to my own cache that was marked with my own GPS that it would lead me right to it. But it doesn't. One was off by 50 feet. Another one I marked while standing directly above the cache but then I had 2 DNFs. When I went to check on it it was pointing about 50 feet over a river. So no wonder they didn't find it! Why is my GPS acting so crazy and is there a way I can fix it? I have Garmin etrex. Also, I have been going back in and updating the coordinates to my caches when I go back to one and the coordinates are off, but how do I know if this new set is right or if my GPS was just acting up when I went back to check on it?

 

Kristi

Set the GPS down, and leave it for several minutes before you mark the location. If after several minutes, the coordinates haven't settled down, you may just have a bad constellation in the sky. Come back later and try again.

[Team Carrington]

Well, I have found caches and at times been right on with the coordinates. I have found some that have shown it being 80 feet away. But what I don't understand is why are my coordinates off on my own caches? You would think that when going back to my own cache that was marked with my own GPS that it would lead me right to it. But it doesn't. One was off by 50 feet. Another one I marked while standing directly above the cache but then I had 2 DNFs. When I went to check on it it was pointing about 50 feet over a river. So no wonder they didn't find it! Why is my GPS acting so crazy and is there a way I can fix it? I have Garmin etrex. Also, I have been going back in and updating the coordinates to my caches when I go back to one and the coordinates are off, but how do I know if this new set is right or if my GPS was just acting up when I went back to check on it?

 

Kristi

 

There has always been a bit of debate as to whether mobile (cell) phones can cause problems like the ones you are experiencing. Worth a try?

[+Team Neos]

And I've noticed that my units become more accuarate the longer I leave them turned on. My accuracy can jumpe around when I first turn them on, and by the end of the day the accuracy readings are low and I am practically walking right up to caches.

[+badlands]

I find I get a more stable read in the afternoon than in the morning.

[+pigpen4x4]

I had (well still have) a Etrex Vista, and I found as soon as I went under tree cover it was very inaccurate. In real light pines I could let it settle down and get fair readings, anything denser I had to stand out from under when possible and get a bearing and distance and look for a landmark. I have since bought a 60csx and it is all the difference in the world. I had a cranial flatulance not long after buying it, but all is great now. I went way back in heavy woods to grab one and since the kid's were in shorts, I carried it back out. The reading was off by about 50' from listed, so I took a reading right on the cache location. When I went to return it, I could not find the location. (it was getting dark) I then remembered the reading, pulled out the 60 and walked right to it. Just as the sky opened up.

Also, heavy clouds made my Vista go nuts as well.

PP

[+Lizzy]

I have a Garmin 70CS my husband bought this past Christmas. I'm not thrilled with it's accuracy either. My old Garmin IIIplus seemed better. My friend bought the latest Garmin 70CSx (x being the difference). It was the newer model with a better antenna. She can stand right next to me & mine will show 30ft error rate while hers shows 15ft. I guess accuracy all depends on the model/type.

[+back2eight]

Okay, thanks for the replies. I guess I'm doing it right. I do not have an averaging feature on mine and I don't know how to do an average myself, but only one of my cahces had the coords off really bad. I fixed that one. My others have been found with no problem so they must be accurate. I have noticed also that in the morning it is off more than in the evening. Evening/nighttime I seem to get better readings. Tree cover really messes it up. It will jump all over the place. I guess I just need to make sure to post a note that the coords may be off ,especially when it is in a heavily covered area, which most of mine are since I live in a national forest.

[Earleheart°]

You mean satelite. I'm sure the stars don't effect anything but your horoscope. lol

Well, I have found caches and at times been right on with the coordinates. I have found some that have shown it being 80 feet away. But what I don't understand is why are my coordinates off on my own caches? You would think that when going back to my own cache that was marked with my own GPS that it would lead me right to it. But it doesn't. One was off by 50 feet. Another one I marked while standing directly above the cache but then I had 2 DNFs. When I went to check on it it was pointing about 50 feet over a river. So no wonder they didn't find it! Why is my GPS acting so crazy and is there a way I can fix it? I have Garmin etrex. Also, I have been going back in and updating the coordinates to my caches when I go back to one and the coordinates are off, but how do I know if this new set is right or if my GPS was just acting up when I went back to check on it?

 

Kristi

Set the GPS down, and leave it for several minutes before you mark the location. If after several minutes, the coordinates haven't settled down, you may just have a bad constellation in the sky. Come back later and try again.

[+orionshunter]

Unless you are kidding with your comment, Constellation refers to the current configuration of the GPS satellites not stars.

Edited August 8, 2006 by orionshunter

[+LetterDude]

Get a Magellan.

[+kwitsman]

Don't give up, Back2Eight. I didn't think that my Garmin had an averaging feature. Found it NOWHERE in the owner's manual. Then while reading a book about Geocaching, it said to hit the menu button while you are marking the spot and lo and behold, there is the averaging feature. So keep looking, it could be in here somewhere in the menus....

Karl

[+LifeOnEdge!]

It has been a while since a reply was given to this thread, but I would like to add some thoughts of my own.

 

Generally, the newer the GPSr AND the more expensive the GPSr, you will get better accuracy AND the faster information on coordinates from the unit. I have replaced GPSs to get these advantages. You will find that some units just are better than others, especially under trees, around buildings, etc.

 

That being said, and assuming you don't want to upgrade just yet, there are several things you can do to get more accurate readings from YOUR GPSr. This is a good thing while seeking caches and especially good when are have hidden your own caches.

 

Fresh batteries are a must. I have given up using anything except Good Quality Rechargeable Batteries. For the time and frustration they reduce, paying less than $50 will get you 4 nice batteries and a car charger. Plug it in your cigar lighter. Keep two batteries charging. Use the other two in your GPS, making sure you always have the maximum battery symbol, and you'll be set!

 

Bake your GPS. Please don't place your GPS in the oven. Instead, take it outside with clear view of the sky, and leave it on a steady surface for 30 - 45 minutes. This will update or complete the catalog of satellite data in the unit for your location.

 

Enable the WAAS setting. This will drain your batteries as a higher rate, but will also give you more accurate readings on site. "D" indicated for a satellite indicates that you have a good lock, helped by a ground-based system that increases accuracy.

 

Check the satellite configuration. You want as many "birds" in the sky, but remember that satellites near the horizon OR directly overhead do not increase accuracy. You want as many as possible at about a 45 degree angle to the horizon. Your GPS should show an open bulls-eye diagram with two circles. This pictures the sky above you, as though you were laying on your back. You want several (5 - 8) inside the outer circle, but not near the middle of the inner circle. Satellites on the inner circle are okay. You will notice this pattern change, with better accuracy when more satellites are in view.

 

Know something about your GPSs antenna. If you have a patch antenna (this looks like a stamp or chip (integrated circuit) that may or may not be visible through the case) you want to hold your GPS level with the ground. If you have a helical antenna (this looks like a thick stump) you want to point the antenna to the sky when under less than desirable conditions.

 

When using your GPS, allow it to be on for a while (at least 5 minutes, if not 15 - 20 minutes) prior to taking data at the desired location. Make sure that you have some of the battery saving features in place to minimize unnecessary functions that eat up battery strength.

 

On location, either your cache or approaching someone else's cache, let your GPS have a clear view of the sky and allow it a minute or two to settle down. You may notice how driving towards a cache site, the distance decreases as you drive, but once you stop it takes 20 - 40 seconds for it to catch up. Garmin eTrex units commonly overshoot your location and have to backtrack.

 

I am sure you have noticed, on caches that take several minutes to locate, that your GPS unit eventually calms down and zeros in on where it wants you to go. This is a function of a lot of what I have described above.

 

When determining your caches location, mark several waypoints. Take 5 minutes and mark one every 30 seconds, giving you ten points. If your unit (or a new unit you may buy) can average waypoints, let it take a two to three minute reading (120 - 180 data points) before clicking "ok." Always walk away from the cache and try to find it again with the newly marked point. If you have marked 10 waypoints, walk away (100 or more feet) and return to the cache, wait 30 seconds, and take a couple more points. Compare those waypoints with the original 10.

 

You have probably started to realize, when looking for someone else's cache, some of that 50 - 80 feet error you saw was that cache owner's error in determining their cache's coordinates. As a new cacher, I commonly saw caches across the street from the posted coordinates. I tease those cache owners today about those very caches!

 

If you find any or all of this information useful, contact me via geocaching.com and let me know.

[+michigansnorkelers]

Correct me if I'm wrong, but you should never activate the energy saving mode when using WAAS. WAAS needs to "run" constantly, while the energy saving mode interrupts power to your GPS intermittantly. At least, I believe this is true for my Garmin 60cs..

Edited October 16, 2006 by michigansnorkeler

[+Prime Suspect]

Correct me if I'm wrong, but you should never activate the energy saving mode when using WAAS. WAAS needs to "run" constantly, while the energy saving mode interrupts power to your GPS intermittantly. At least, I believe this is true for my Garmin 60cs..

Actually, you can't do what you're warning against. The unit will automatically disengage WAAS if power-saver mode is engaged. The OS knows that they're mutually exclusive, and behaves accordingly.

[+LifeOnEdge!]

There is a difference between battery saver mode and "battery saving features."

 

Turning your electronic compass Off when it is not needed is an example.

 

Making sure backlighting is Off or at a Minimum is an example.

 

You can even disable sounds, saving some energy.

 

None of these energy draining functions are needed when you are baking a GPS or waiting for it to settle under dense cover conditions.

 

Of course disabling your WAAS is going to reduce your ability to get the best possible coordinate measurement. I would not reccomend riding the brake in a drag race either.