Does my etrex Vista do coordinate averaging?

[+jtice]

I am planning on starting a few chaches and want to make my coordinates real close. But Ive never tried to average them. Does my Vista do that? And,, lets say that my Vista says its reading at 22 feet accuracy, is that good enough to use the coordinates it says for the cache?

[+nincehelser]

I don't think any of the Garmins have that feature.

 

I'll hazard a guess that most people just take one reading as long as the accuracy indicator is low. The more exacting people probably take several readings at different times and manually average them.

 

George

[+kavuday]

The Vista does not do coordinate averaging, however the GPSMAP 76S does. I'm also fairly confident that the GPS V averages as well, but not completely certain on that.

 

22 ft. is great accuracy in my book. Take a few readings with the Vista, walk away for a minute, then come back and take a few more. I almost trust the manual method of averaging more than auto averaging!!

[+rayt333]

I use a Garmin Legend and as long as I am near 20' or better then I will usally take a couple of reading to be sure and let that be it. If the distance is higher then I may take 4 to 6 readings and avg them.

The way I do this is I walk away a couple hundred in each direction (if possible) and walk back towards the cache area and note the reading, then avg them

[+apersson850]

It's true that the eTrex series can't do averaging, but som other Garmin units can, like the 76S and the GPS V.

 

There is some doubt about if averaging really is an advantage or not. Search for averaging posted by Kerry in this forum, and you'll see.

 

Stand still and get as many sats involved in your position calculation as possible. Leave the place some hundred meters or so, then go back and see if it fits reasonably.

 

Anders

[peter]

quote:

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Originally posted by Anders:

It's true that the eTrex series can't do averaging, but som other Garmin units can, like the 76S and the GPS V.

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Also the 12 series, II+, III+, and eMap among others.

[+Searching_ut]

The Vista, as mentioned, doesn't have an averaging feature. One way to work around it is set your tracklog recording to timed, at an interval of anywhere from a second to say five or ten. Let the receiver sit on the cache for awhile then manually average out the track data when you get back to your PC.

[+GeneralBracket]

quote:

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The Vista, as mentioned, doesn't have an averaging feature. One way to work around it is set your tracklog recording to timed, at an interval of anywhere from a second to say five or ten. Let the receiver sit on the cache for awhile then manually average out the track data when you get back to your PC.

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That's a great idea. Never thought of it. Makes you wonder how terribly difficult it would be for Garmin to write such a routine into the firmware to give these units the ability to average. Couldn't be that much trouble.

[+apersson850]

Especially not since that code already is written, for other receivers. They aren't that stupid that they don't make data structures etc. identical in different units, to facilitate code sharing.

 

Anders

[Kerry.]

Anders, well just recently there's some certain Garmin software updates that actually have auto averaging (just like that other mob ), which is totally different to the normal user selected averaging, which at least gives users the option to or not.

 

What get even more annoying is Garmin's lack of any reply to queries about this software update, actually Garmin has NEVER replied to any query I've ever put to them.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[+Red Barron]

If you want to get into how accurate a GPS is goto Dave Wilson's site or talk to a surveyor that uses the $70,000 units. You will come away with the idea that if you can get with in 50' you are doing great. So what good is averaging? I have found that when I get close to a location if I stop a couple of minutes. Then the accuracy is about as good as it gets.

[Kerry.]

quote:

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Originally posted by Red Barron:

If you want to get into how accurate a GPS is goto Dave Wilson's site or talk to a surveyor that uses the $70,000 units. You will come away with the idea that if you can get with in 50' you are doing great.

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Not to sure what your trying to say there?. What "type" of GPS are you referring and in what mode of operation. NO surveyor buys $70,000 worth of gear to expect with 50'.

 

All have some "limiting" factors.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[+GOT GPS?]

Our accuracy versus a surveyor's accuracy in centimeters.

 

They will leave their expensive units going for awhile to average down to centimeter accuracy.

 

I think that with trees overhead and moving satellites, that averaging can help.

 

Always different...Hit refresh

[Kerry.]

quote:

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Originally posted by GOT GPS?:

Our accuracy versus a surveyor's accuracy in centimeters.

 

They will leave their expensive units going for awhile to average down to centimeter accuracy.

 

I think that with trees overhead and moving satellites, that averaging can help.

---

 

CM accuracy isn't something that comes about from averaging (per say).

 

A "single survey class" instrument basically is not much more accurate than many recreational type units. However one will notice a slight difference but that has more so to do with refinements in the software (and technically the hardware).

 

But a "single survey class" receiver can in no way achieve absolute CM accuracy by itself.

 

Put 2 togeather then that's a different situation. 2 units can accurately determine the "relative difference" (in CM/MM) between them as each taking observations at precisely (and precisely it is) the same point in time has the capability of cancelling any error (put simply) as it really doesn't matter if the "absolute position" is of by say 16.172m/north at stn1 it is basically also off by 16.172m/north at stn2 (in simplistic terms). This "relative difference" based over a series of observations over a time period can be resolved to within CM/MM but one wouldn't call this an average (as such).

 

ON a single baseline the end result of the unknown/required station then will only be as accurate as the coordinates of the known station.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go

[Kerry.]

A bit more on this perception that survey class receivers are CM accuracy. Well obviously they are are but it's more the method than simply being a "survey class receiever"

 

Couldn't find the original (quickly) so appologies regarding the scan/image quality, however one should see the point.

 

The "benchmark comparison" is between a $35,000 "survey class" receiver (Leica 399, 9 channel dual frequency) and a basic recreational receiever of the time (Garmin GPS45, single freq 8 channel MultiTrac).

 

Note this was back in the bad old days of Selective Availability (~1997/98) but probably highlights the basic lack of much difference (in accuracy) better than even if done today.

 

The 24 hour "average" accuracy was 19.7m (Leica 399) to 22.2m (GPS45) but this 2.5m difference in average accuracy (back then) was certainly not worth the additional $34,500 in this type of mode.

 

But put 2 399's togeather in a static/differential mode or in conjunction with other dual freq static data and that's a different story.

 

Cheers, Kerry.

 

everybody keeps telling me where to go