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Do all GPS units have an averaging function?


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I don't care what anyone thinks but I'm sure that using the averaging option with a GPS is the best way to get the most accurate position. You can have strong signals and weak signals etc etc, after about 200 counts, I'm sure that you can't get better accuracy than that.


However, when I talk about averaging, not many people seem to know that it exists. I know that both Lowrance units I have owned have this function. All I have to do is go to the menu and pick out "averaging" and when I enter a waypoint, the averaging starts. My unit tells me how many waypoints are being registered and when I feel that I have enough of them, I press enter again and the unit averages the results and enters a final result as a waypoint. It's very handy when fishing an exact spot.


My question: Do all GPS units have an averaging function?

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I have a Garmin Venture HC and it has the ability to average your location. On the few occassions when I've used the feature, I've noticed that it hasn't given me a very precise reading, especially if there is some sort of overhead cover or obstruction. What I do instead is walk to and right through GZ, then come at it from another direction and repeat the walk-through. I'll do this anywhere from 6 to 12 times depending on the amount of cover. When I'm finished, on my GPSr map page, I look for the point where all of the tracks cross, put my pointer on that point, and write down the coords. By doing it this way, I've found the accuracy to be much better than letting the GPSr average the location.


I can't say if your GPSr averaging software is any better or worse than mine, but I know that doing a little more leg-work for the coords produces better accuracy on my Venture HC. ;)

Edited by rocketsteve
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Averaging needs time to work...5-10minutes. Otherwise, it's not worth that much. The time allows atmospheric conditions to change. It doesn't do much good if it's only averaging a short period of time when the atmospheric conditions are the same, introducing the same error the whole time.


Not all receivers have it. My 76CSx has it, and the newer touch screens have a different form of it.

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It's very handy when fishing an exact spot.


In this particular situation, you probably have quite a bit of unobstructed sky, and so averaging very well could be more accurate and a time saver. As I mentioned in my earlier post, I think you'll find a marked difference in the accuracy, depending on how much overhead cover and/or obstructions you'd be trying to get the gps signals through.

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Not all units have the function. I've found it to be of questionable value in practice. If you have good conditions then there is no need for it. If you have poor conditions you are only averaging bad data.


For example I have a cache in spot with a lot of signal bounce. Nobody could find it despite the fact that I had averaged it with my 60CSX for several minutes. I went back again with 2 units, a DeLorme PN 40 and my trusty 60CSX and found the coords to be about 40-70 feet off.


I averaged the location again with both units for 5 minutes and and both units basically agreed (within a few feet). I also updated my clue to make it more specific. It was subsequently found by a few thanks to the new hint, but the finders complained that the coords were still 50+ feet off.


Bad conditions = bad coords whether you average or not. With good conditions you don't need averaging.


Averaging is a nice selling point but it has little practical value.

Edited by briansnat
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Averaging is only helpful in certain situations. When there is a lot of RANDOM multi-path (signal reflection), the averaging can help. It needs to be random such as caused by forest and not constant like that caused by a steep hill. Beyond that, it will not make things a lot better as an average of bad readings, is still a bad reading.


I suggest to everyone that you still do it the way it was done before the newer GPS units came out.


1) Make sure the GPS has been left to soak the satellites in a spot with good reception before going to the cache location.

2) Hold the GPS high to clear as many obstacles as possible.

3) Orient it for the best use of the antenna. Quad-helix vertical, patch flat.

4) Wait a short period (10 seconds?) for the GPS to settle.

5) Mark a waypoint.

6) If the unit has averaging, start averaging until the EPE levels off at a low number. If the EPE increases, stop and try again. For the Oregon/Colorado users, wait for 100% confidence.

7) Walk away into an area that has CLEAR reception and GOTO the waypoint.

8 Walk past the cache in a clear area and watch the compass arrow and decide if it points at the correct spot or not.

9) Repeat from a different direction.

10) If the waypoint is off, you can try again or manually move the waypoint by changing the coordinates or by projecting it.


If the cache is hidden in a bad multipath location such as against a tall building, you will never get a good waypoint at the cache location. The better way is to mark a point out in the open and project it to the cache location. Then check by walking past, away from the wall, and ensure the arrow points towards it.


It does not hurt to check on multiple days, but is rarely needed. It only matters if you took the reading on a bad day atmospheric or geometry wise.

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Garmin authored an article about a year ago about the need for averaging. Basically they had concluded that it was of limited value to modern high sensitivity receivers as a single reading is almost never off by more than 30 feet. Therefore you would only be averaging readings between the EPE and 30 feet. A small area.


The averaging function on the Colorado and Oregon receivers is stated to only have value if you gather multiple averages over several days.


I read another study on this that showed the average correction with 5 acerages over 5 days was a mere 11 feet (can't find it now).

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It's very handy when fishing an exact spot.


In this particular situation, you probably have quite a bit of unobstructed sky, and so averaging very well could be more accurate and a time saver. As I mentioned in my earlier post, I think you'll find a marked difference in the accuracy, depending on how much overhead cover and/or obstructions you'd be trying to get the gps signals through.


I found that the newer sensitive units have more "inaccuracies" than the older less sensitive units. The reason I say this, is the fact that the sensitive units accept all those weak bounced signals while the less sensitive units only use the strong direct signals. As for losing signals due to trees etc, I have been using old GPS units for many years and have had no trouble while wandering around in the bush here in northern Quebec.


One day last year, I attended a geocaching reunion. We were in a building and there were 2 small windows. I was sitting in the middle of the room and got a fix with my old Lowrance IPro within a few seconds while the 60CSXs and company could not get a fix. One guy had a Colorado and did not get a fix. Eventually, a lady beside me got a fix with her Etrex.


BTW....I was the only one who had a Lowrance. Everybody else had Garmins. When we went out geocaching....I easily and quickly got within a couple of feet of every cache.


I do not use "averaging" to find a cache. I don't do any geocaching. The only caches I have found was when I attended the geocaching reunion. However, I do use the "averaging" when I want to record an accurate waypoint.


As I said earlier, I do a lot of ice fishing. It's very cold up here and I like to find holes that I have previously cut through the ice because the ice is very thick while the ice in the holes will often only be about 8 to 12 inches thick. It's easier and faster to chop open these old holes with a spud than making new holes. However, the big problem is the fact that these old holes are not easy to spot due to drifting snow. What I do is drive around on the ice with my 4X4 or snowmobile and when I find a waypoint, I can find the hold. I usually get within 2 or 3 feet of my objective. Last year, I reused one hole 4 or 5 times. I was fishing in about 90 feet of water and I could feel my lead weight slide down the same huge boulder that was a good 20 feet tall. It was a great spot to catch fish.

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