Garmin accuracy?

[+10es&]

My wife and I just started caching this week and we are very excited about our new hobby.

After much reading on this forum we decided on a Garmin Oregon 450.

 

My question is how accurate should this unit be? When zeroing in on a cache it would show 2ft to go- and all of a sudden it would say 20ft south. After traveling the 20ft south it would show 15ft back the way I started from, this would go on and on.....

Is this normal for this unit?

My guess is the unit is accurate to about 20ft and after that we need to just turn it off and search with out eyes.?.

 

Thanks in advance

10es&

[+Rckhnd]

Apparently, the sattelites are always shifting around a bit. Most GPS Margins Of Error are plus or minus 20 to 30 feet. I can usually get mine down to 4 feet before it shoots off to 20 feet in a different direction. At that point, I consider myself to be at Ground Zero and start searching a circle about 30 feet in diameter.

 

It was pointed out to me that if you put the gps on Waymarking setting and put it down and left, that when you come back 15 minutes later, it would look like a dog trail running around the yard.

 

Anyway, get your number as low as possible, then start the groundsweep.

[+Gitchee-Gummee]

Actually, what you are running into is what many term the "Drunken Bee Dance".

 

Your Garmin is going to be as "accurate" as any other.

 

A GPSr usually will not put you atop the cache. It will put you in the vicinity of the cache. 15 to 20 ft. is the accepted norm.

 

Once you reach that spot, Ground Zero, you really outta put the GPSr aside and start looking for the cache (or its' hiding spot) instead of looking at the unit. If you are busy looking at the GPSr, you ain't looking for the cache, now are you? When you start getting that close to GZ, the unit is going to start jumping back and forth, this way and that. Sure, occasionally it will take you directly to the spot, just not as often as you might think it will.

 

Other variables to consider: Is the cache accurately placed? Remember that the cache hider also used a GPSr -- at least they were supposed to have done so; over time, caches sometimes "migrate" -- that is other cachers may not have placed it back at the exact spot where it was originally hidden.

 

With that said, remember that geocaching is HUNTING for the cache, not being STEERED to the cache.

[michael612]

On my older Magellan Color Trak there is a screen display of satellites the unit, GPSr, is tracking and the azimuth (direction / bearing) they are from the GPSr and their relative signal strength/quality. These will vary during the hour. This variance will cause your GPSr to show varying 'best estimate locations' Anything more than ddd. mm. ss. 3 (.3 of a second) is the unit using "Kentucky windage".

 

A ddd.mm.mmm' display would only be accurate to .005' plus or minus 95% of time

 

I believe that sat locations at given time is the key to accuracy. Weather,clouds,rain or shine have little affect on the GPS lat long reading. Sunspots are another subject.

 

I suspect that comments regards the cache being misplaced could easily just be that maybe the GPSr reading was recorded or viewed by each user at times when distortion was the greatest. Many a time at sea, the GPSr fix would be off the plotted course significantly; a look at the satellites being tracked would show poor triangulation or maybe only 2 satellites active, usable above horizon, at that time, wait 20 minutes and the GPS position would come back in line.

Edited March 7, 2011 by michael612

[+briansnat]

Your unit is acting normally for an Oregon, or any other hand held unit for that matter.

 

You're right, when you get close forget the unit and search with your eyes and head.

Edited March 7, 2011 by briansnat

[+StarBrand]

The general margin of error for all handheld units is around 15 to 25 feet. Once inside that radius, readings can look a little wonky sometimes. Do not expect the unit to lead you to the exact location of the cache very often.

 

Put it away and search!

[+dfx]

My question is how accurate should this unit be? When zeroing in on a cache it would show 2ft to go- and all of a sudden it would say 20ft south. After traveling the 20ft south it would show 15ft back the way I started from, this would go on and on.....

 

While all of what was said above is true, I gotta say that I rarely see this kind of "jumpy" behavior as described here on my Oregon. Readings do vary, but usually only slowly over time, and not suddenly from one second to another, not by that much anyway.

 

Maybe the OP should look into firmware updates, there was quite a bit of improvement in this area and the unit may not have come with the most recent one.

[+10es&]

Thanks for the replies, it sounds like the consensus is the GPS is working as it should and the updates have been installed.

Overall I am very happy with this unit, it really lends itself well to Geocaching.

 

Hopefully the snow will stop this weekend so we can get out there soon!

 

10es&

Edited March 8, 2011 by 10es&

[+Gitchee-Gummee]

You're letting a little snow stop you?

[+kwitsman]

The time when I get the worst 'jumping' is when urban caching and I walk too close to a building. Then the signals start bouncing off the building and throw off the projection. I rarely walk right up to the cache the first time, like Gitchee said you often have to approach from several angles to get an idea, then use the Force and past experience to find that cache. If my GPS took me right to the cache every time, I probably would quit because the fun of the hunt would be gone.

Karl

[+emabie]

I just got the Oregon 450t myself. Its a great handheld and it seems to be very accurate. But as the others have stated its only going to get you within about 15' of the cashe. I too cant wait for some snow to melt. I have been to a few spots where I know that the cashe is there, just 4' below me under the snow.

[+pettydvm]

I just got the 450 yesterday and have never used a gps in my life. I found my first cache with it today . As I drove right by the spot my gps showed 15' which was pretty accurate. Parked and started walking it started jumping around fairly quickly on distance and direction. I put it up when i was at around 30' and it was dead on. If I had stopped at 15' and not walked i would have almost been on top of it. Cant wait to look for my second cache