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Drift on EXPLORIST 10 Series
January 22, 2012
12:58 pm
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ShortcutHicksy
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Track Smoothing and Static Nav. are controlled in the Atlas.ini file.

The defaults are;

Vehicle Mode:
Track Smoothing ON
Static Nav. OFF

Outdoor Mode:
Track Smoothing OFF
Static Nav. ON

Graham.

January 22, 2012
9:28 am
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PhxChem
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I have noticed that since purchasing the explorist 310, I actually get "cleaner" (less altitude "drift") tracks using my "old" yellow Garmin etrexH than my new state-of-the-art 310 when both are set to AUTO. I think the problem is in the AUTO (continuous) algorithm. When ever I start and stop while mountain biking (especially up steep hills), my 310 sometimes gives a +/- "blip" in the altitude data. My etrexH never did that. I'm guessing my old non-mapping garmin had a different (better?) algorithm for altitude data and or start/stop. (The old eTrex without the high-sensitivity ("H") receivers also gave much noisier altitude data).

However, I have learned that setting the track sampling rate on my 310 to DISTANCE seems to take care of this, since it's not going to record anything (any "blips") until I'm another 50ft. or so down the trail after I've started again, apparently giving the GPS time to get a better fix.

Just something I've noticed.

January 21, 2012
8:43 pm
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Paganel
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Dustydew wrote:

How do you change the settings of Static on the EX710? I bet that is why I have been unhappy with my GPS at GZ (jumping 30+ feet at times).

I think, eXplorist chooses what it considers fit.
I do not have eXplorist 710. Maybe there is a choice "on foot", "on the car"? In the configuration file, I found several profiles for different modes. They referred Static Navigation (On and Off).

In previous models, Magellan used its own proprietary algorithm TrueFix. When you stop very clearly recorded the lack of movement and began averaging coordinates. I liked it in the GPS 315.

January 21, 2012
5:26 pm
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phild31
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The inherit accuracy of any GPSr is about 15 feet at best, no matter what the manufacturer claims.
So at any time the coordinates are within a circle with a diameter of 30 feet.

When in trouble or in doubt, run in circles, scream and shout

January 21, 2012
5:18 pm
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phild31
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Well, whatever it's called and whatever causes it, my 710 seems to have less of it than my Triton 2000 did.
But whenever you stop for half an hour the time of the track is going to be half an hour longer than when you are moving.
So comparing one unit with another first make sure they are both set the same.

For an accurate track make sure the settings are not on 'Auto Continuous' but on timed.
Auto Continuous setting seems to be set-up to give you the minimum number of points, therefor it will cut corners off the track you walk.
I also don't want a point only when I move so I always leave mine set for every 10 seconds.

When I am creating a track that I want as accurate as possible of the distance and time I hiked I make sure to save track when I'm going to stop for more than a few minutes.
I'm not shutting off the GPSr, just starting a new track after lunch.

The active track of the whole day will be there anyway, including stops.

When in trouble or in doubt, run in circles, scream and shout

January 21, 2012
5:17 pm
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Dustydew
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How do you change the settings of Static on the EX710? I bet that is why I have been unhappy with my GPS at GZ (jumping 30+ feet at times).

Thanks!

January 21, 2012
2:14 pm
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Paganel
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Based on the documentation SirfStar there are much simpler. The drift is controlled by Static Navivgation chipset parameter. This option, you can switch to WinCE devices program SirfTech.
When Static is off, you have all the real coordinates computed without filtering. At the same time you have a drift.
When Static is on, the coordinates are filtered by a simple algorithm. The coordinates will not change as long as your speed does not exceed 4 miles per hour, or until you walk a few tens of meters. This is handy in the car, but very bad for the movement on foot.
Garmin eTrex 10-30 users complain that it is very difficult to find the cache, because the coordinates do not change, and then jump up to 40 meters and all need to start over again.
I am glad that in my eXplorist is drift, but I see a real and not filtered coordinates.

January 21, 2012
1:05 pm
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Sockeye
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That is not Geodrift, what all eXplorist and Triton users experience. It is the result of the settings on the internal firmware of the SIRF chips in a combination with the eXplorist firmware interpreting this raw data.

The sattelite signals the GPS receives can either be direct (correct) or reflected (wrong). The software tries to calculate the current position with a combination of this data.

As older Magellans simply ignore the wrong data and stop to show a current position when having not enough direct signals, the Triton and eXplorist still try to calculate something. The calculation (correction) routines are quite good as long as the GPS is moving. But once you stop, nearly every result on your position is somewhere else...

BR
Sockeye

January 21, 2012
12:01 am
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Yenalom
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Thanks for the replies

It is comforting to know that the EXPLORIST 710 has much less drift than the older TRITON 2000. That corresponds to what I realized that the newer Dakota 20 has much lower drift than the older TRITON 500.

I like the idea of shutting down the GPS for an extended stop. However, I would probably forget to turn it on again.

For a while I was editing out the lunch points but that just became a PITA. Now I carry both my GARMIN and MAGELLAN but only use the data from the GARMIN. I use the MAGELLAN as a backup and to display a different map than the GARMIN. I will sometimes switch to a different map on the Magellan, something that cannot be done on the Garmin.

The reference to GEODRIFT.com was interesting but it appears little has been done in the last few years.

I read something about GEODRIFT some time ago somewhere on the web. It was probably on GPSTRACKLOGS or FREE GEOGRAPHY TOOLS. From there I started to plot the drift and saw the major difference between the units.

Anyway, what little I learned here has reduced my doubts about getting a new GPS. Depending on how much money I get from the FEDS after filing my taxes, I will probably buy an Explorist. I need a new different toy.

January 20, 2012
8:10 pm
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phild31
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The at rest drift of a GPSr is an issue with all consumer handheld units.
The new Explorist 710 that I have has much less drift than the Triton 2000 I used for years.
The amount of at rest drift is dependent on the inherent accuracy of the unit, the satellite signals and the rate the unit is recording points.
The best accuracy for any handheld consumer unit is about 15 feet at best, that means the every point made in the track will be somewhere in a 30 foot circle.
The most accurate track will be when you have it set to make a point every 5 or 10 seconds, but when you stop for a half hour for lunch it's still making a point every 10 seconds.
In the field if you need to have an accurate record of time and movement the best bet is to save the track you have just made when you stop, then start a new track when you start moving again. That way you are not recording points on the track while at rest for half an hour.
After you get home you can edit the tracks in Vantage Point to eliminate any points made while at rest and combine several tracks you saved into one track for the day's hike.

An interesting web site about drift is here - Geodrift.com

When in trouble or in doubt, run in circles, scream and shout

January 20, 2012
6:48 pm
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Sockeye
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Yenalom wrote:

I under stand that MAPS4ME has a fix that will permit the the EXPLORIST 10 line to use RMP files created by Mikhail's program.
If thaty is not true, would like to know.

Believe me, that is true. I wrote the converter.

BR
Sockeye

January 20, 2012
6:47 pm
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Jaker
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I can't offer any help on your first query, but last night I downloaded a RMP from
MAGic Maps and with this fantastic fix from Sockeye I was able to integrate into my
610 very easily.
https://www.exploristforum.com/.....38;id=1911

See --RMP Fix for RMP Creator & Magic Maps

Hope that helps

Jaker

January 20, 2012
5:02 pm
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Yenalom
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I have owned and used a TRITON 500 and TRITON 1500. I was very happy with them. In particular I really used and enjoyed maps that I generated using Mikhail's RMP Creator.

This time last year, I bought a Garmin Dakota 20. I am not unhappy with the unit. It has one feature that beats the TRITONS but the TRITONS have one feature that beats the GARMIN.

The TRITON wins hands down. The implementation of the "Custom Map" on the Magellan units is far superior to the way it is implemented on the GARMIN.

However, in one area the GARMIN is much better. At rest, when not moving, the Garmin drifts very little. The Magellans on the other hand will drift a lot. In a half hour lunch stop with the GPS sitting on the ground not moving, my Triton 500 will drift between a quarter and a half mile while the Garmin will drift less than 100 feet. Both units drift around the fixed point where the GPS is fixed.

Drift is important to me since I analyze the tracks to see how far, how fast, etc we have walked. The Magellan shows us walking further but at a slower pace than the Garmin.

After this long story, my question is:
Has anyone looked at the drift on the EXPLORIST 10 lines? If so, can you give me an estimate of the drift over a half hour.

Thanks,

Bob M

PS: I under stand that MAPS4ME has a fix that will permit the the EXPLORIST 10 line to use RMP files created by Mikhail's program.
If thaty is not true, would like to know.

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