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WingWriter

GPS brand & model listed on all cache pages...

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I am very new to geocaching, but I have already noticed anomalies in GPS readings specific to the brand/model used. Why not provide a box for GPS brand/model used to mark a cache site on each cache page? This would give those of us who own both Garmin and Magellan units an opportunity to adjust accordingly when seeking extremely precise coordinates.

 

I fully recognize that GPS performance can be greatly affected by a multitude of factors (weather, satellite position, WAAS acquisition, etc), but I would bet that many GPS users have noticed brand/model consistencies when comparing GPS readings.

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quote:
Originally posted by WingWriter:

I am very new to geocaching, but I have already noticed anomalies in GPS readings specific to the brand/model used. Why not provide a box for GPS brand/model used to mark a cache site on each cache page? This would give those of us who own both Garmin and Magellan units an opportunity to adjust accordingly when seeking extremely precise coordinates.

 

I fully recognize that GPS performance can be greatly affected by a multitude of factors (weather, satellite position, WAAS acquisition, etc), but I would bet that many GPS users have noticed brand/model consistencies when comparing GPS readings.


Well, as I understand it, that is something being considered for when the site gets redone. For the life of me I don't understand why, but not my site, so I dont't have to, I guess.

Unless you are using a $10,000 pro GPS, the accuracy, especially when geocaching, is a nonissue, in my book. I have both a Garmin and a Magellan, and when we placed our last cache, took multiple readings with both. After averaging the readings together, they came out within a few feet of each other. Knowing what brand GPS was used to place the cache means nothing, especially if you don't know how accuratly the hider came up with the readings. I would much rather know if the hider turned on his GPS, hit mark, and thats it, or if he went back on different days, different times, and averaged thousands of readings. Even then, I still know I might be 40ft or more off when I go hunt it, so whats the point?

And no, after finding over 100 caches, I still have not noticed a difference in accuracy between them. User interface, hell yea. Do I find one brand easier to use then the other? Yup. Is one more accurate then the other? NOPE.

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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quote:
Originally posted by WingWriter:

I am very new to geocaching, but I have already noticed anomalies in GPS readings specific to the brand/model used. Why not provide a box for GPS brand/model used to mark a cache site on each cache page? This would give those of us who own both Garmin and Magellan units an opportunity to adjust accordingly when seeking extremely precise coordinates.

 

I fully recognize that GPS performance can be greatly affected by a multitude of factors (weather, satellite position, WAAS acquisition, etc), but I would bet that many GPS users have noticed brand/model consistencies when comparing GPS readings.


 

I can't say I've noticed brand/model consistencies when comparing

GPS readings at all. I've found a considerable number of caches with perfect coordinates, and not surprisingly, the people hiding them used a variety of different GPS units to get the coordinates.

 

Likewise, I've found a fair number of caches with really horribly inaccurate coordinates, and have observed NO correlation between a particular model of GPSr and bad coordinates.

 

What I DO notice a strong correlation with, though, is the operator of the GPS unit. Some folks consistently provide coordinates that can be counted on. Other folks consistently provide coordinates which are frustratingly inaccurate.

 

It may be there is some systematic relationship between GPSr model/manufacturer and coordinate accuracy, but in my experience, that correlation is very, very, very small compared to the effect of the operator of the unit. The effect of the operator is so strong that I actually started tracking how close the coordinates were to the cache, just so that I could start tracking who provided 'good' coordinates and who didn't. But the bookkeeping overhead was

too high to keep it up for long.

 

icon_geocachingwa.gif

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Are you saying that your Garmin and Magellan units will always read the exact same distance and bearing off from each other? Or are you saying that sometimes you Garmin is dead on and your Magellan is slightly off and other times it’s the other way around? I suspect the latter. Remember that these are not extremely precise devices.

 

http://home.earthlink.net/~whidbeywalk/

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quote:
Originally posted by Whidbey Walk:

Are you saying that your Garmin and Magellan units will always read the exact same distance and bearing off from each other? Or are you saying that sometimes you Garmin is dead on and your Magellan is slightly off and other times it’s the other way around? I suspect the latter. Remember that these are not extremely precise devices.

 

http://home.earthlink.net/~whidbeywalk/

But there is no ryme or reason to which one is off. The Garmin isn't always closer to caches hidden with another Garmin. I haven't noticed anything like "the maggie is always 10ft north of a benchmark, while the Garmin is always 15ft east".

Lets say I take the Maggie in one and, and the Garmin in the other. I sit in the same spot for 5 minutes. Every 30 seconds I mark a waypoint on each GPS. When I avg the 10 waypoints from each GPS together, they will be fairly close to each other. Close enough that you wont detect a pattern to it. Repeat this at different times, and different days. Keep avging the results together. The longer you do it, the closer they will get. Besides, like I said, even if they guy used a sub centimeter grade Trimble to hide the cache, I'm still at the whim of my GPS, and the conditions at the time.

The only thing I can see posting the GPS model to the cache page could do is fuel the "my gps is better then your GPS wars". I can see it now. Some guy hides a cache with a yellow etrex. He does everything right, takes lots of readings on different days etc. Some guy with a Garmin V comes along, and even though he's showing 127ft EPE at the time, posts that his coordinates are better because he has the better GPS. There's plenty of room in your profile to add in what GPS you have. Hell, add a checkmark there for it. Then Groundspeak can use the data from that to approach advertisers. "You sell Garmin products, we have 25,000 Garmin users. Advertise with us!".

I can't see any use for putting it on the cache page, but if I'm missing something I WISH someone would tell me.

 

Tae-Kwon-Leap is not a path to a door, but a road leading forever towards the horizon.

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And you've determined this anomoly after finding two whole caches? I'm with you Mopar, bad idea. By the way, weather has very little (almost undetectable) effect on GPS signals.

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This would be pointless.

 

All code-phase GPS receivers are inaccurate to some degree, and those inaccuracies will certainly vary somewhat from brand to brand. However, they will NOT vary in any predictable way. It's not as if you could say, "Oh, it's a Garmin, and I'm using a Magellan, so I need to correct 63.5 feet West!" There's no useful information to be had from knowing the brand name of the placer's GPS.

 

It WOULD be nice to know the EPE at the time of placement and whether or not WAAS was enabled, so that we'd have an idea of the reliability of the coordinates and how large an area to search.

 

--

Scott Johnson (ScottJ)

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