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Sgt_Strider

Is the Garmin eTrex 30 the most accurate GPS? Also questions about the unit.

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Recently I became aware of GLONASS and that the iPhone 4S supports it, which increases its accuracy and lock time. As far as I know, the eTrex 30 is the only Garmin portable unit that supports GLONASS. Is it fair to say that it's the most accurate GPS unit out there? Any particular comments about its performance? I currently have the Garmin 62st and I'm really interested in picking that unit up if it's more accurate.

 

Also, can someone tell me if the unit is capable of producing a .gpx file? I am primarily using my GPS unit to geotag my photos. Does the tracklog record the compass direction information into the track log? What I mean by compass direction is whether north, west, south, and east is recorded in the log file or not.

 

In terms of altitude, is it capable of using GPS itself to determine the altitude or it relies on its barometer to determine the altitude?

 

Thanks for the help in advance!

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As well as the 30, both the Etrex 10 and 20 use GLONASS. My experience (comparing my Legend H to my 20) shows that they are more accurate, and this is confirmed in this article:

 

http://gpstracklog.com/2011/10/garmin-etrex-20-review.html#more-12856

 

No idea about geotagging, sorry, although they will navigate to geotagged photos.

 

Both the 10 and 20 rely on GPS to determine altitude, how accurate that is I've not yet discovered but in general GPS altitude accuracy is worse than positional accuracy.

 

Hope that's of some help.

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As well as the 30, both the Etrex 10 and 20 use GLONASS. My experience (comparing my Legend H to my 20) shows that they are more accurate, and this is confirmed in this article:

 

http://gpstracklog.com/2011/10/garmin-etrex-20-review.html#more-12856

 

No idea about geotagging, sorry, although they will navigate to geotagged photos.

 

Both the 10 and 20 rely on GPS to determine altitude, how accurate that is I've not yet discovered but in general GPS altitude accuracy is worse than positional accuracy.

 

Hope that's of some help.

 

How is GPS altitude accuracy worse than positional accuracy? What do you mean by positional accuracy? Is that data derive from the barometer?

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Not sure how it works on the 30, but on other Garmin GPS with a built in barometer they can use both GPS and the barometer. On GPS without one it's simply based on position in relation to the GPS satellites just like your ground position is. The reason why it's less accurate is complicated but see here for some info:

 

GPS provides Altitude information when it is able to communicate with 4 or more satellites. This is referred to as Three Dimensional (3D) signal. Latitude, Longitude and Altitude are the three dimensions. If you want to get technical then the fourth dimension would be time.

The big question most people ask is "Why do I need a barometric altimeter when I have GPS altitude?" A barometric altimeter uses the atmospheric pressure to determine your altitude above sea level. It turns out they are able to determine altitude within +/- 3 vertical meters or so. The altimeter will detect your change in altitude based on the change in the atmospheric pressure (the higher you go the less pressure).

The problem with a barometric altimeter is the requirement to calibrate it every time you start your activity. If you don't the altimeter will still work and relative measurements will be accurate, but absolute measurements will be off. This means that your cumulative elevation gain/loss will probably be correct, but all of the elevations along the way will be offset by the difference of the actual altitude and the altitude on the device.

GPS altitude doesn't need any calibration, but for complex reasons the GPS unit is not able to determine elevation as accurately as a barometric altimeter.

Combining both GPS and barometric altimeters, Garmin GPS units are able to provide the most accurate altitude readings of any handheld device. Absolute location is provided originally by the satellite to help auto-calibrate the barometric altimeter, then the barometric altimeter is used to provide a more stable elevation change. The GPS device will constantly calibrate the barometric altimeter throughout an activity because the pressure may change due to weather conditions. This is a great advantage during long days of hiking, biking or running.

 

Don't know if that helps or not :laughing:

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Also, can someone tell me if the unit is capable of producing a .gpx file? I am primarily using my GPS unit to geotag my photos. Does the tracklog record the compass direction information into the track log? What I mean by compass direction is whether north, west, south, and east is recorded in the log file or not.

It's definitely able to produce a tracklog in GPX format (it even does so by default), but it doesn't record compass information. At least I'm pretty sure it doesn't, as none of the other "modern" Garmins do that.

 

GPS altitude doesn't need any calibration, but for complex reasons the GPS unit is not able to determine elevation as accurately as a barometric altimeter.

Not that complex really. Basically, if you wanted vertical accuracy to be as good as horizontal accuracy, you'd have to lock onto satellites that are below the horizon. Obviously that's not gonna happen.

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The gps height accuracy depends of the angle the sat's are seen by the gps, a wide angle view gives a better accuracy compared to a narrow angle, like in a (urban) canyon.

Meaning, your gps might see 4 or 6 sat's, but if they are in a narrow angle, more or less behind or near to each other, you accuracy is not good, EVEN if your gps says it is.

The gps will calculate according to reception, it does not really look at the sat's angle.

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Here is Garmin's official statement, from their knowledge base:

______________________________________________________

 

Support

Frequently Asked Questions

 

How accurate is the GPS elevation reading?

 

02/02/2011

 

GPS heights are based on an ellipsoid (a mathematical representation of the earth's shape), while USGS map elevations are based on a vertical datum tied to the geoid (or what is commonly called mean sea level). Basically, they are two different systems, although they have a relationship that has been modeled.

 

The main source of error has to do with the arrangement of the satellite configurations during fix determinations. The earth blocks out satellites needed to get a good quality vertical measurement. Once the vertical datum is taken into account, the accuracy permitted by geometry considerations remains less than that of horizontal positions. It is not uncommon for satellite heights to be off from map elevations by +/- 400 ft. Use these values with caution when navigating.

 

You have been warned!!!!!

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I've found that Garmin's altitude engine is much less accurate than Magellan's. I've both and when I'm at the coast, walking along the ocean shore, my Magellan will be right on, but quite often my Garmins will show me several meters below sea level. I contacted Garmin about this some time ago and was told I was right, their engine doesn't fix altitude very well.

SKTQCH

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Also, can someone tell me if the unit is capable of producing a .gpx file? I am primarily using my GPS unit to geotag my photos. Does the tracklog record the compass direction information into the track log? What I mean by compass direction is whether north, west, south, and east is recorded in the log file or not.

It's definitely able to produce a tracklog in GPX format (it even does so by default), but it doesn't record compass information. At least I'm pretty sure it doesn't, as none of the other "modern" Garmins do that.

 

GPS altitude doesn't need any calibration, but for complex reasons the GPS unit is not able to determine elevation as accurately as a barometric altimeter.

Not that complex really. Basically, if you wanted vertical accuracy to be as good as horizontal accuracy, you'd have to lock onto satellites that are below the horizon. Obviously that's not gonna happen.

 

dfx,

 

If what you say is true, then how come the altitude in my GPX log from my Garmin 60CSX doesn't appear right? It has a barometer, but even when the GPS unit have a lock with the satellites, it doesn't seem to show the correct altitude. I think airplanes tends to fly at 33,000ft or so and yet the recorded altitude or height is much less than that. I think I've read somewhere that units which records the GPS altitude and doesn't rely on a barometer tends to be much more accurate. Do you have any comment on that?

 

Also, do you feel that with the support of GLONASS, is the eTrex series the most accurate of all of Garmin's units? Like I said earlier, I only use my GPS devices for geotagging purposes and accuracy is extremely important to me. My current unit is the Garmin 62st and I wouldn't mind upgrading to the eTrex 30 if it's more accurate.

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Not sure how it works on the 30, but on other Garmin GPS with a built in barometer they can use both GPS and the barometer. On GPS without one it's simply based on position in relation to the GPS satellites just like your ground position is. The reason why it's less accurate is complicated but see here for some info:

 

GPS provides Altitude information when it is able to communicate with 4 or more satellites. This is referred to as Three Dimensional (3D) signal. Latitude, Longitude and Altitude are the three dimensions. If you want to get technical then the fourth dimension would be time.

The big question most people ask is "Why do I need a barometric altimeter when I have GPS altitude?" A barometric altimeter uses the atmospheric pressure to determine your altitude above sea level. It turns out they are able to determine altitude within +/- 3 vertical meters or so. The altimeter will detect your change in altitude based on the change in the atmospheric pressure (the higher you go the less pressure).

The problem with a barometric altimeter is the requirement to calibrate it every time you start your activity. If you don't the altimeter will still work and relative measurements will be accurate, but absolute measurements will be off. This means that your cumulative elevation gain/loss will probably be correct, but all of the elevations along the way will be offset by the difference of the actual altitude and the altitude on the device.

GPS altitude doesn't need any calibration, but for complex reasons the GPS unit is not able to determine elevation as accurately as a barometric altimeter.

Combining both GPS and barometric altimeters, Garmin GPS units are able to provide the most accurate altitude readings of any handheld device. Absolute location is provided originally by the satellite to help auto-calibrate the barometric altimeter, then the barometric altimeter is used to provide a more stable elevation change. The GPS device will constantly calibrate the barometric altimeter throughout an activity because the pressure may change due to weather conditions. This is a great advantage during long days of hiking, biking or running.

 

Don't know if that helps or not :laughing:

 

I have never calibrated any of my Garmin GPS units before. So would you say that the altitude or elevation data in the GPX files are off? How much faith should I have on the data that I have given that I have never calibrated the units?

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If what you say is true, then how come the altitude in my GPX log from my Garmin 60CSX doesn't appear right? It has a barometer, but even when the GPS unit have a lock with the satellites, it doesn't seem to show the correct altitude. I think airplanes tends to fly at 33,000ft or so and yet the recorded altitude or height is much less than that. I think I've read somewhere that units which records the GPS altitude and doesn't rely on a barometer tends to be much more accurate. Do you have any comment on that?

 

I do!

 

None of the mentioned GPS models (60csx, eTrex, Oregon etc) "rely" on the barometer for an altitude reading. The barometer is merely intended to provide better (more accurate) altitude readings than readings from the GPS system alone.

 

I don't know for sure how the 60csx works, but I can assume that if it has the barometer enabled, then the altitude recorded in the tracklogs will be the one taken from the barometer (it's what all the other Garmins do as well). The problem with the barometer is that when it isn't calibrated correctly, then the altitude that the barometer reports can be way off. On the other hand, the GPS receiver part doesn't need to be calibrated, so the altitude the GPS system provides will always be within a certain error margin, only depending on how good GPS reception is currently. On the other other hand, if the barometer is calibrated correctly, then it's able to deliver much more precise and accurate altitude information than the GPS system ever could.

 

Unfortunately, the barometer calibration has an inherent problem: it's always only valid for a relatively short period of time. Meaning that if you calibrate today, tomorrow you would already have to calibrate again. If you don't, then the altitude readings will be off, potentially by a large amount. I believe the 60csx has an option to simply turn the barometer off and fall back to taking altitude readings from the GPS system, but I could be wrong.

 

The more moderns Garmins (starting with the Colorados I think) have an option for "auto-calibration" of the barometer instead of disabling it completely. With this enabled, the unit constantly compares the altitude that the barometer reports with the altitude that the GPS system reports, and if there's significant deviation between them, it will adjust the barometer's calibration to eliminate this deviation. I don't know the precise mechanisms behind this auto-calibration, but on my Oregon it seems to work reasonably well. I never had a need for highly accurate altitude readings though, so I never really paid close attention to it. Also, in pressurized cabins (planes) this obviously doesn't work.

 

As for your other question: I don't know, because I don't have one :D

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If what you say is true, then how come the altitude in my GPX log from my Garmin 60CSX doesn't appear right? It has a barometer, but even when the GPS unit have a lock with the satellites, it doesn't seem to show the correct altitude. I think airplanes tends to fly at 33,000ft or so and yet the recorded altitude or height is much less than that. I think I've read somewhere that units which records the GPS altitude and doesn't rely on a barometer tends to be much more accurate. Do you have any comment on that?

 

I do!

 

None of the mentioned GPS models (60csx, eTrex, Oregon etc) "rely" on the barometer for an altitude reading. The barometer is merely intended to provide better (more accurate) altitude readings than readings from the GPS system alone.

 

I don't know for sure how the 60csx works, but I can assume that if it has the barometer enabled, then the altitude recorded in the tracklogs will be the one taken from the barometer (it's what all the other Garmins do as well). The problem with the barometer is that when it isn't calibrated correctly, then the altitude that the barometer reports can be way off. On the other hand, the GPS receiver part doesn't need to be calibrated, so the altitude the GPS system provides will always be within a certain error margin, only depending on how good GPS reception is currently. On the other other hand, if the barometer is calibrated correctly, then it's able to deliver much more precise and accurate altitude information than the GPS system ever could.

 

Unfortunately, the barometer calibration has an inherent problem: it's always only valid for a relatively short period of time. Meaning that if you calibrate today, tomorrow you would already have to calibrate again. If you don't, then the altitude readings will be off, potentially by a large amount. I believe the 60csx has an option to simply turn the barometer off and fall back to taking altitude readings from the GPS system, but I could be wrong.

 

The more moderns Garmins (starting with the Colorados I think) have an option for "auto-calibration" of the barometer instead of disabling it completely. With this enabled, the unit constantly compares the altitude that the barometer reports with the altitude that the GPS system reports, and if there's significant deviation between them, it will adjust the barometer's calibration to eliminate this deviation. I don't know the precise mechanisms behind this auto-calibration, but on my Oregon it seems to work reasonably well. I never had a need for highly accurate altitude readings though, so I never really paid close attention to it. Also, in pressurized cabins (planes) this obviously doesn't work.

 

As for your other question: I don't know, because I don't have one :D

 

lol, I didn't realize this. So the pressurized environment will throw the barometer off?

 

I'm really curious if the eTrex series will perform better due to its support for GLONASS. I wonder if there have been any in-depth review recently? The GPS Typepad blog is basing its assessment on early hardware and firmware. I'm not so sure if I can really rely on that information.

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lol, I didn't realize this. So the pressurized environment will throw the barometer off?

 

Yes of course, way off. Plane cabins are pressurized to what, the equivalent of 6,000 ft or so? Something like that, and of course that's the altitude that the barometer will then read. The altitude taken from the GPS system will disagree greatly, but since the barometer is supposed to be more accurate, that's the one you will normally see. The devices aren't smart enough to figure "oh! I must be in a pressurized cabin!"

 

Even calibrating the barometer will be useless, because the cabin pressure will remain mostly constant for the duration of the flight, even if the altitude actually changes. Same problem with auto-calibration: even if you wait long enough for the auto-calibration to catch up (assuming it's actually able to catch up - it might not be, as the difference between pressure and altitude is very high), you won't notice altitude changes as the pressure doesn't change accordingly.

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I believe the 60csx has an option to simply turn the barometer off and fall back to taking altitude readings from the GPS system, but I could be wrong.

 

 

Oh how I wish it did. It's been a pain for ages that you cannot view GPS altitude on a 60CSx in a pressurised cabin of a plane as its corrected by the pressure transducer and you can't do much about it. The best you can do is record to the track log which can record gps altitude and then view it later

 

 

Even calibrating the barometer will be useless, because the cabin pressure will remain mostly constant for the duration of the flight, even if the altitude actually changes. Same problem with auto-calibration: even if you wait long enough for the auto-calibration to catch up (assuming it's actually able to catch up - it might not be, as the difference between pressure and altitude is very high), you won't notice altitude changes as the pressure doesn't change accordingly.

 

Luckily with my Montana, there is now a field "GPS Elevation" which can be used so this should overcome the problem of altitude in a plane for me. Would have been so easy for them to add that field to the 60CSx, but they didn't.

Edited by WrongwayUK

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...The gps will calculate according to reception, it does not really look at the sat's angle.

Not necessarily so. There are several different ways to estimate precision or confidence in a fix, and GPS manufacturers don't tell you how they they're doing it.

Edited by Portland Cyclist

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing, so I pulled out my iPhone 4s and it walked me right to the cache. I think GLONASS had something to do with it, I turned it off (GLONASS) on the eTrex and sure enough it settled in. The area I was caching in had some decent tree cover, although almost all the leaves are down. It was also very rocky.

 

I was highly surprised by this. This may have been a fluke, but I will be testing the unit out more.

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I just ran a test on my 60CSx, SiRF, connected to the external antenna on the roof.

Altimeter Setup: Auto cal On and Fixed Elev.

No,on the Correct Elev, and set the Correct Pressure to the house Baro pressure of 29.74. The Alti elev shows 6505 ft in the Data field.

To the Sat page and menu>GPS Elevation, to get a snapshot of it at that moment in time. Reads 6591 ft.

Then back to the Altimeter page to watch the Alti elev change from 6505 to 6591 ft. Took an hour and 22 minutes to do so.

Pressure was 29.73 at the end.

Checked the GPS Elev several times during the run, varied from 6584 to 6591 ft.

 

I did cook up a 13X9 pan of Brownies, and ate several, while the test was going. The smell of Brownies cooking in the oven, on a cold morning, is worth at least 50 cents!

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing

Yes, I see the same behaviour on my eTrex 20. Sometimes I can move slowly 25-30 meters away from a location without the

GPS position beeing updated. Even with full 20 sat's in view.

Chris (eTrex 20 V2.4)

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I was a unsuspecting Colorado tester(ie early adopter paying customer) and it had that issue to. They eventually fixed it with a new firmware.

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing, so I pulled out my iPhone 4s and it walked me right to the cache.

 

It's unfortunately nothing new - it's the so called "sticky issue" or "sticky position" well known among the Oregon or 62s users.

It is discussed on many forums, e.g. garminoregon.wikispaces.com, geoclub.de etc.

 

Last week I got rid of my one year old Oregon 450 because of this really annoying problem, hoping that the new eTrex will be better.

Yes, it's better in many ways (definitely more accurate), but the sticky issue is still there... :mad:

Using the older models like Legend HCX or 60CSX I had never experienced such an odd behavior.

 

Please report this issue to Garmin, the more people will report the more probably they will finally do something about it.

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Don't know about the 30, but I am more pleased with my 10 every time I take it out. Certainly accurate enough for geocaching, as good or or better than any other GPS I've owned, and really amazing battery life. I think any slowness to update (which I have seen but haven't regarded as a big problem) will probably be improved with firmware updates.

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It's unfortunately nothing new - it's the so called "sticky issue" or "sticky position" well known among the Oregon or 62s users.

It is discussed on many forums, e.g. garminoregon.wikispaces.com, geoclub.de etc.

 

Last week I got rid of my one year old Oregon 450 because of this really annoying problem, hoping that the new eTrex will be better.

Yes, it's better in many ways (definitely more accurate), but the sticky issue is still there... :mad:

Using the older models like Legend HCX or 60CSX I had never experienced such an odd behavior.

 

Please report this issue to Garmin, the more people will report the more probably they will finally do something about it.

 

Wow, very interesting. I've been experiencing the same thing on my Montana 650t, including today with the latest firmware (3.63 beta). I found that if I power cycle it, it starts updating correctly again. That obviously shouldn't be necessary. It really makes it challenging at times. I had it happen while I was caching with someone who was using a 76cs. I showed that I still had 300 feet or so to go, while he showed that we were just about to GZ. It appears that 300-400 feet out is the distance at which it happens a lot. Very interesting that an eTrex 30 froze at the same distance...

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I've found that Garmin's altitude engine is much less accurate than Magellan's. I've both and when I'm at the coast, walking along the ocean shore, my Magellan will be right on, but quite often my Garmins will show me several meters below sea level. I contacted Garmin about this some time ago and was told I was right, their engine doesn't fix altitude very well.

SKTQCH

 

I would agree.....on many a trip through various mountain ranges my Mag. Platinum continues to amaze me......its usually just about dead on to the foot what the signs say.

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing, so I pulled out my iPhone 4s and it walked me right to the cache.

 

It's unfortunately nothing new - it's the so called "sticky issue" or "sticky position" well known among the Oregon or 62s users.

It is discussed on many forums, e.g. garminoregon.wikispaces.com, geoclub.de etc.

 

Last week I got rid of my one year old Oregon 450 because of this really annoying problem, hoping that the new eTrex will be better.

Yes, it's better in many ways (definitely more accurate), but the sticky issue is still there... :mad:

 

Yup this is annoying. The 5.00 GPS firmware on the Oregons brought vast improvements, but it still happens occasionally. I mostly notice it when moving from "very good reception conditions" to "kinda bad reception conditions" very suddenly, such as starting to descend into a valley or moving from open area into thick woods. Seems like the device needs some time to "get used to" the new reception conditions and stops updating until it did.

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Hi, after some tests I've found out that this sticky problem seems to be dependent on type of batteries used in GPSr, see the discussion here:

http://garmingpsmap.wikispaces.com/message/view/home/43408702

 

Did anybody noticed something similar or could someone who is annoyed with this sticky issue on his/her GPSr try to test it with different sets of batteries?

 

Thanks, Zdenek

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Regarding the accuracy of the new etrex line there is an excellent review with tracklog comparisons here: eTrex 20 review

 

Likely the firmware will improve over time but I'd be cautious about expecting much more accuracy over current non-glonass systems. There are simply too many other factors involved to overcome the 3 meter field standard error.

 

I know that accuracy is the holy grail to many, it used to be for me. I eventually realized the true capabilites/limitations of handheld consumer GPS units and stopped caring as much.

 

A word on GPS elevation vs Barometer elevation; The Montana series recently made big changes to the way it handles elevation data. The Montana allows you to set both satellite derived elevation and barometer based elevation as fields in the trip computer. It's interesting to see that GPS elevation data (derived from satellites) is often way more accurate to true elevation than the barometer readings within the first hour of operaton. Without constant calibration, the barometer based elevation readings can take some time to auto-calibrate and can get funky if there are pressure changes in your environment. The Montana series is now using map DEM (Digital Elevation Model) data in many elevation based calculations and tracklog elevation recordings. The DEM in the 24K series topo maps will be more accurate and more consistant than the readings from either the barometer or satellites. After all, it's basically the same DEM that's used to generate the actual topo lines for todays USGS topo maps and other high-accuracy maps.

 

I'm not sure how the etrex line will handle tracklog elevation data or elevation based calculations.

Edited by yogazoo

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Hi, after some tests I've found out that this sticky problem seems to be dependent on type of batteries used in GPSr, see the discussion here:

http://garmingpsmap....w/home/43408702

 

Did anybody noticed something similar or could someone who is annoyed with this sticky issue on his/her GPSr try to test it with different sets of batteries?

 

Nothing more than a myth AFAIC. The issue temporarily goes away after a reboot, which is why a battery change "fixes" it.

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I know that accuracy is the holy grail to many, it used to be for me. I eventually realized the true capabilites/limitations of handheld consumer GPS units and stopped caring as much.

Especially when you consider that the person who hid a geocache was also using a consumer-grade GPSr, so who knows how accurate their coordinates are? :anicute:

 

As it happens, I've been extremely pleased with the accuracy of my new eTrex 20, and indeed I've walked right up to a number of caches. But I don't expect that, and wouldn't even if I had the most super-duper-accurate GPSr available.

 

I realize that many of us here also use our GPS receivers for tasks other than geoaching where accuracy may be more important, and I'm not even trying to downplay the helpfuless of accuracy even for geocaching, but I agree with Yogazoo's more relaxed attitude about the subject.

 

Patty

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Nothing more than a myth AFAIC. The issue temporarily goes away after a reboot, which is why a battery change "fixes" it.

 

No, it's not the reboot. It's the observation that with one type of batteries (white Eneloops) during the whole trip I didn't notice any sticky issue, while another day with another set of black Eneloops XX, the problem was more than evident.

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I have the issue with white eneloops... :rolleyes:

Paint them black.

 

Aarrghh! We have gone beyond silly and are now well inside the borders of cuckoo land. Show me proof that the brand of battery - or even color of the casings of a given brand of battery - makes a difference in how often your GPS updates its position, and I'll buy you a 4-pack of your favorite AA cells. Thing is, most of the people claiming this wouldn't know what real proof was if it jumped up and bit them on the nose. "It seemed to work better with brand X batteries" is not proof, that's wishful thinking and selective observation. Not eligible for this offer, void where prohibited by law.

Edited by Portland Cyclist

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"Paint them black"

 

:laughing: I just had to applaud your successful attempt at humor. Thank you. I don't normally laugh out loud while reading these posts but this one had me rolling.

Edited by yogazoo

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Well, it's just a hypothesis, nothing more. To prove it false or true, more tests needs to be done. I can post some images of tracks from last testing.

 

I'm not a microwave expert but if you see inner construction of NiMH AAs and compare them to e.g. alkalines, you will see the substantial difference. If it can somehow interfere with high frequency part of GPSr is the question for some experts... Remember that these new GPS chips are super-sensitive and any little detail can affect them.

 

I'm just trying to find out the sticky problem because it annoys me for more than a year and Garmin didn't reply on any of my reports.

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I have the issue with white eneloops... :rolleyes:

 

Thanks, could you please guess how often you encounter the issue and approx. howmany meters?

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Well, it's just a hypothesis, nothing more. To prove it false or true, more tests needs to be done. I can post some images of tracks from last testing.

Posting "some images of tracks from last testing" will be interesting only if your testing included some scientific rigour:

 

- Acquire at least two identical GPS units, let's call them A & B

- Have someone else, out of your sight, put "white" batteries in unit A and "black" batteries in unit B.

- Go on a long hike carrying both.

- Copy the tracks to a computer.

- Repeat several times, with the batteries being changed by someone other than you, sometimes switching which GPS gets the black or white batteries, and keeping track of which runs were made with which batteries.

- Analyze the tracks

 

It's important that YOU personally don't know which battery type is in which unit while in use OR while initially analyzing the tracks. Then if you -- or even better, someone else -- can analyze the tracks later, and consistently identify which tracks were recorded using which battery type, then you might be approaching proof. Be prepared to have other scrutinize your methodology and results.

 

Got anything like that?

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I was not even aware of the existence of the higher power (2400-2500 Mah) Black XX Eneloop NiMH cells. But if the compass calibration consistency is a function of unregulated battery voltage, then the Black Eneloops might very well maintain their original voltage longer than the older (1900-2000 Mah) White Eneloops. . . . Thus minimizing the need for frequent compass recalibration.

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I was not even aware of the existence of the higher power (2400-2500 Mah) Black XX Eneloop NiMH cells. But if the compass calibration consistency is a function of unregulated battery voltage, then the Black Eneloops might very well maintain their original voltage longer than the older (1900-2000 Mah) White Eneloops. . . . Thus minimizing the need for frequent compass recalibration.

 

All of which has nothing to do with the "sticky" issue.

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Got anything like that?

 

Not yet, but I am planning some bigger testing session. Thanks for the methodology, I will inspire with it - several identical devices side by side with different batteries etc.

I'm gonna send a notice to a local GC forum, I hope that someone will join me. :)

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My hypothesis regarding the type of batteries is very probably wrong... Today I've done a test which completely eliminated the effect of batteries - I removed them from GPSr and used an USB cable connected to my notebook. Later in the field I was witness of one very evident sticky issue... :(

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing

Yes, I see the same behaviour on my eTrex 20. Sometimes I can move slowly 25-30 meters away from a location without the

GPS position beeing updated. Even with full 20 sat's in view.

Chris (eTrex 20 V2.4)

 

Not having read this thread to the end yet, I've noticed that on my Etrex 20 also. I just thought I was nuts and cycled power. Firmware is up to date. WAAS on/off didn't seem to make a difference.

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Is this a common problem with eTrex 20 and 30? Or more prevalent on one of them? I'm fairly new to the GPSr world and I'm considering getting a eTrex 20 or 30. I have read about "sticky" problems with the eTrex 30, and mention about the need to frequently recalibrate the electronic compass and altimeter, and also the compass/altimeter have problems functioning correctly with low battery power?

 

Has anyone come across any new information that sheds some light on whether these are common problems or isolated problems?

 

Who owns a eTrex 20 or 30? What has your experience been so far? :)

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I know that accuracy is the holy grail to many, it used to be for me. I eventually realized the true capabilites/limitations of handheld consumer GPS units and stopped caring as much.

Especially when you consider that the person who hid a geocache was also using a consumer-grade GPSr, so who knows how accurate their coordinates are? :anicute:

 

As it happens, I've been extremely pleased with the accuracy of my new eTrex 20, and indeed I've walked right up to a number of caches. But I don't expect that, and wouldn't even if I had the most super-duper-accurate GPSr available.

 

I realize that many of us here also use our GPS receivers for tasks other than geoaching where accuracy may be more important, and I'm not even trying to downplay the helpfuless of accuracy even for geocaching, but I agree with Yogazoo's more relaxed attitude about the subject.

 

Patty

 

Really? I'm using a Droid 2 Global smartphone, and generally I do expect to be taken right up to the cache; I think the farthest away I've been led was maybe 15 feet, and if I would've been more patient under the trees, it would've probably updated and gotten me closer.

 

On the other hand, it's definitely true that technology is 50% or less of what makes up geocaching; the remaining 50+ percent is your own skill and intuition. I've gotten into the habit lately of not using a. The Hint, b. The Description, or c. The Logs, or a combination of the 3. The next step up in difficulty might be to leave the GPS (phone) in the car before going out to search, and using old-school methods of finding the GZ.

 

LostCoastNinja

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Thanks, could you please guess how often you encounter the issue and approx. howmany meters?

I have the issue very often when caching in the forest (tree cover) and maximum offset was 50 meters.

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing

Yes, I see the same behaviour on my eTrex 20. Sometimes I can move slowly 25-30 meters away from a location without the

GPS position beeing updated. Even with full 20 sat's in view.

Chris (eTrex 20 V2.4)

 

Not having read this thread to the end yet, I've noticed that on my Etrex 20 also. I just thought I was nuts and cycled power. Firmware is up to date. WAAS on/off didn't seem to make a difference.

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Today I did some caching with my new eTrex 30. It seemed highly accurate on some caches. It was downright awful on another. In fact it was over 300 feet off. I could tell I was walking too far and the distance to the cache just was not changing, so I pulled out my iPhone 4s and it walked me right to the cache. I think GLONASS had something to do with it, I turned it off (GLONASS) on the eTrex and sure enough it settled in. The area I was caching in had some decent tree cover, although almost all the leaves are down. It was also very rocky.

 

I was highly surprised by this. This may have been a fluke, but I will be testing the unit out more.

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I have the etrex 30. I am also dealing with it freezing, or locking up. I can go up to 100' without changing. I've been working with Garmin on this issue they seem to be very intrested in hearing about it. The more input they have the sooner it may be corrected.

So give them a call or email, let them know.

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Info from Philip:

It is very hard to get it right.....in addition to your case there is another group of people who do not want to see the position wandering when they are static...

 

Great, thanks for the very insightful information! Is he from ST?

 

What should Garmin do is to make the option accessible in settings and let people to set it appropriately for every profile.

That would make both groups satisfied.

 

May I use this info on another forums?

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