Gps Accuracy

[+HeatherAndMike]

We just had a full afternoon of geocaching -- our first real adventure at it. We found 4 out of 7 and had a lot of fun. We're using an old Magellan SporTrak (it's got to be AT LEAST 4 years old). Every time we did find a cache today, it was at least 10-15 feet from the GPS. Is that expected, or would a newer GPS give a more accurate reading?

Edited May 29, 2006 by HeatherAndMike

[+greyhounder]

typically within 30 feet is considered pretty accurate. There are lots of factors to consider with accuracy: tree cover, hider's GPS, finder's GPS, number of times the hider confirmed coordinates, and probably lots more. When I get about 30-50 feet away on my GPS, I put it away and start looking.

 

Bec

[+JohnAengus]

I would say that is good accuracy! That's pretty close.

[+Talarspeed]

I'm glad this question came up. Mine was about 15-20 feet away from actual cache. This makes me feel better. (I have a Legend CX).

[+Mile Runner]

when in a city the accuary is quite bad---and sometimes caches are more like letterboxes then anything else.

[+Team JSAM]

for an older unit thats great you will find caches that are 2 feet up to 60 feet, any more than that are bad coords.

[+briansnat]

You will find older units to be anywhere between 5 and 50 feet off when standing at the cache. Newer units will have you anywhere between 50 and 5 feet.

[+Waterboy]

Please remember. The person who hid the cache was also off in his/her accuracy.

 

Waterboy With Wife

[+Team Cotati]

No, there would be no observable difference.

[+Night Stalker]

I used to use a SporTrak and found the accuracy on that unit to be as good or better than on my 60CS. I wouldn't be to concerned if you are that close.

[+Team Gryarvold]

This raises a question for me as well. I have just put out my first 2 caches and on both of them I have had comments of coords being off. But if I go look for caches my gpsr zeros right in on them. What can I be doing wrong in setting mine up?

 

Also I played with my gpsr out in the driveway and found out that if I pointed it in a different direction right over the same spot, just turning east, west, north, south, I got a different location reading mark. I am really stumped and comcerned because I want seekers to be able to find my caches.

[+blindleader]

This raises a question for me as well. I have just put out my first 2 caches and on both of them I have had comments of coords being off. But if I go look for caches my gpsr zeros right in on them. What can I be doing wrong in setting mine up?

"The coordinates were a bit off." and similar statements are at the top of the list of most meaningless things ever posted in a cache log. Don't pay any attention to them. When someone posts their own coordinates for your cache, and they're more than about thirty feet from yours, then you can start considering them. The only time I post coordinates in a log is when I am pointed consistently to the same spot at least two error circle radii (the =/- or EPE number) from the cache and I have very pleasing pattern on the satellite screen. Even then I rarely make a claim that they are any better than the published coordinates. I just consider them another data point. If several people comment that they found the cache some distance in the same direction from GZ, then you want to consider taking more readings.

[+budd-rdc]

We just had a full afternoon of geocaching -- our first real adventure at it. We found 4 out of 7 and had a lot of fun. We're using an old Magellan SporTrak (it's got to be AT LEAST 4 years old). Every time we did find a cache today, it was at least 10-15 feet from the GPS. Is that expected, or would a newer GPS give a more accurate reading?

If you find the container within 10' to 15' of where your GPSr is pointing, that's very good and normal. If you really want to check the accuracy, you'll need to stand still for a few minutes (minimum of 5 minutes) and see if the coordinates will settle closer.

 

People who hide caches should also be that delibrate when obtaining coordinates. Don't forget to factor in tree cover, wall, cyclone fences, power lines, and tall buildings nearby.

[+alexrudd]

Try taking several readings (with WAAS and/or waypoint averaging if you have it): turn the GPS around as you said, walk away and come back, come back a different day, etc. Then average them together for a composite reading.

[+Team Dubbin]

Is that expected, or would a newer GPS give a more accurate reading?

 

There is no need for you to buy a newer unit. Your 4 year old unit will do everything you need it to do for geocaching. I have had a SporTrak Map for a few years now and have yet to find a good reason to upgrade. I keep trying to justify $400 for a new unit but I just cant bring myself to do it.

[+Team Cotati]

Is that expected, or would a newer GPS give a more accurate reading?

 

There is no need for you to buy a newer unit. Your 4 year old unit will do everything you need it to do for geocaching. I have had a SporTrak Map for a few years now and have yet to find a good reason to upgrade. I keep trying to justify $400 for a new unit but I just cant bring myself to do it.

 

Ditto that...Meridian Gold, huge and bulky that it is!! With it's 14hr. plus rechargable battery life, 512mb SD card loaded with DirectRoute maps of my adventure areas and still having over 300mb available. Sweetness to the max. ;-) And oh yeah, did I mention that there is some so-called "slingshot" effect that I never notice? And as for accuracy? When ever I go out with other cachers...it kicks butt. And I do leave WAAS enabled 100% of the time. Huge and bulky thing that it is.

Edited June 2, 2006 by Team Cotati

[+Cog&Gil]

I agree regarding accuracy but antenna sensitivity in much improved in the newest models. I'm getting fixes in places that I was unable to with my older(purchased a year ago) gpsr. Indoors, in commercial aircraft, in narrow canyons, heavily wooded areas etc.

[+Team Dubbin]

I agree regarding accuracy but antenna sensitivity in much improved in the newest models.

 

But its also not bad in the older models like the SporTrak. I can sit in my house and pick up a decent signal and I have never really had a problem anywhere outdoors with it.

[+Team Cotati]

I agree regarding accuracy but antenna sensitivity in much improved in the newest models. I'm getting fixes in places that I was unable to with my older(purchased a year ago) gpsr. Indoors, in commercial aircraft, in narrow canyons, heavily wooded areas etc.

 

Improved compared to what? All of the things that you mention are done quite well by the huge and bulky Meridian Gold. Even to the extent that when I fly commercially, it will maintain a lock when resting on the fold down tray, if the GPSr is positioned properly.

Edited June 2, 2006 by Team Cotati

[+Cog&Gil]

Just what I said. My just purchased GPSr produces fixes more quickly and through much thicker "ceilings" than the last 20 or so units I've owned over the last 15 years. Not much question for me that my new high end model is superior to my previous models. I've tested them side by side and see the difference.

 

I'm just passing on information that I've learned from my first GPSr that I purchased around 1989 and my experence with succeeding brands and models over the years. Yes the NAV 1000 still works!

 

Again, I'm referring to reception due to antenna tech. improvements(quad helix etc.)--not accuracy.

 

I'm not promoting or defending any brand or model. It appears that you are happy with your brands and models---I won't mention my newest purchased brand or model. I just know that it is superior to the last several ones I've owned.

[banffy]

I have been using a GPS for a number of years, however i have just started Geocaching and on three occasions out of four I have been within two meters of the cache location. You could say that is luck, I think if you are within 15 - 20 meters you are doing well.

[+JDandDD]

You will find older units to be anywhere between 5 and 50 feet off when standing at the cache. Newer units will have you anywhere between 50 and 5 feet.

Nicely put Briansnat!!

 

The accuracy is in all the other factors like tree cover, reflectivity from rock walls, satellite positions at the moment, not the GPS unit age.

 

JDandDD

[+JDandDD]

I agree regarding accuracy but antenna sensitivity in much improved in the newest models. I'm getting fixes in places that I was unable to with my older(purchased a year ago) gpsr. Indoors, in commercial aircraft, in narrow canyons, heavily wooded areas etc.

 

Improved compared to what? All of the things that you mention are done quite well by the huge and bulky Meridian Gold. Even to the extent that when I fly commercially, it will maintain a lock when resting on the fold down tray, if the GPSr is positioned properly.

That was one of the things that used to make the Magellan's better than the Garmin's. Clearly, though, the move to SirfIII chipset in the new Garmin's has made the x series far better in terms of reception than Garmin's used to be so I think that COG&Gill are quite right in that aspect of what they say.

 

So, everyone's right, Magellan's had that sensitivity for years, while Garmin's now have the great SirfIII and have caught up. I've got it in a bluetooth GPS and it is even more senstive than my Magellan Platinum.

 

JDandDD

[+Team Cotati]

I have been using a GPS for a number of years, however i have just started Geocaching and on three occasions out of four I have been within two meters of the cache location. You could say that is luck, I think if you are within 15 - 20 meters you are doing well.

 

While I can't explain your experience wrt the numbers that you site, I consider them the exception not the rule. And as a matter of fact, when ever I find a cache that is 'off' the posted coords by more than 30-40 feet or so, I usually make note of that in my log, including my unit's coords. I have yet to recieve feedback indicating a problem with the numbers.

Edited June 5, 2006 by Team Cotati

[JaggedPath]

Hello everyone, first post on the forum.

 

I just started Geocaching yesterday (June 3rd 206).

I was given a Magellan eXplorist 210 by my girlfriend for my birthday (yes, she is amazing!) and have been having a blast hunting caches (I'm up to 5 finds)

 

I was wondering about the accuracy of my unit, as the screen reads between 5m and 8m accuracy most of the time (unless I'm able to get WAAS, then it goes down to 3m, but waas seems to be limited coverage in my areas (Central / Eastern Ontario Canada).

 

I've been finding the caches ok, but most of the time coordinates are off by .001 or .002 (eg, a cache listed at: 44 15.355N might end up being displayed at: 44 15.354N on my GPS)

I was wondering if my unit was misconfigured in some way, but after reading your comments here, I'm guessing that my accuracy is actually pretty good, and that little bit of discrepancy is just from the placers GPS vs. my GPS / weather conditions when the cache was placed / when I search for it, etc... and ads to the fun of the search.

 

Thanks for the reassurances!

[+JDandDD]

Hello everyone, first post on the forum.

 

I just started Geocaching yesterday (June 3rd 206).

I was given a Magellan eXplorist 210 by my girlfriend for my birthday (yes, she is amazing!) and have been having a blast hunting caches (I'm up to 5 finds)

 

I was wondering about the accuracy of my unit, as the screen reads between 5m and 8m accuracy most of the time (unless I'm able to get WAAS, then it goes down to 3m, but waas seems to be limited coverage in my areas (Central / Eastern Ontario Canada).

 

I've been finding the caches ok, but most of the time coordinates are off by .001 or .002 (eg, a cache listed at: 44 15.355N might end up being displayed at: 44 15.354N on my GPS)

I was wondering if my unit was misconfigured in some way, but after reading your comments here, I'm guessing that my accuracy is actually pretty good, and that little bit of discrepancy is just from the placers GPS vs. my GPS / weather conditions when the cache was placed / when I search for it, etc... and ads to the fun of the search.

 

Thanks for the reassurances!

WAAS isn't really limited here in Ontario. What happened between Feb. and April of 2006 is that one of the satellites was moved to a position much further in the west so it is now lower on the horizon for us in Ontario and therefor can be harder to get signal from than it used to be, though I do pretty regularly. The good news is that's to make way for another WAAS satellite going live in September that will be very much higher above the horizon for us up here and our signal should be as reliable as it used to be.

 

JDandDD

[+CharlieP]

We just had a full afternoon of geocaching -- our first real adventure at it. We found 4 out of 7 and had a lot of fun. We're using an old Magellan SporTrak (it's got to be AT LEAST 4 years old). Every time we did find a cache today, it was at least 10-15 feet from the GPS. Is that expected, or would a newer GPS give a more accurate reading?

 

If the GPS put you 10-15 feet from the cache, that is very good accuracy for most geocaches. You will find that the accuracy of YOUR GPS will vary with terrain, tree cover, satellite geometry during the day, and even the proximity of buildings or power lines. Accuracy may vary from 10 foot accuracy under good conditions with WAAS, to 100 feet or more in poor conditions. On top of that, the accuracy of posted coordinates for geocaches also varies tremendously, some are within a few feet of the true position, and some will be off by 100 feet or more.

 

The accuracy required to find the cache also varies. A well hidden cache can take hours to find if the coords are off by even 20 or 30 feet. On the other hand, some caches may be easy finds even though the coords are off 100 feet ... an obvious location or a very good hint.

 

I got tired of "easter egg hunts" and now avoid caches that have log entries like: "extremely well hidden ... coords were off 40 feet". If the cache is well hidden, the coords should be VERY good, IMHO. Good coords require averaging over time to achieve accuracy, and sometimes also projection.

Edited June 5, 2006 by CharlieP