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Camp-CJ

The most accurate upgrade

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I have been caching since 2012 and would like to get a more stable unit. My Etrex 20 is okay but it is nearly useless within 20 feet of GZ. The other day I was looking for the second part of a puzzle cache and I followed the pointer past a tree at 17 ft from target. It lead me in a circle back to my tracks in the snow as I passed the same tree. This time the 20 showed 3 ft from GZ so I poked around and found the container in a hole under one of the roots. When I returned the bottle and stood up my unit was showing 25 feet..... Most of the time when within 25 ft or so I just pocket my gps and look at the most likely hiding spots until I either either stumble onto the hide or give up. 

I have been thinking about getting a 64x for the better antenna and the Galileo access but don't want to waste $300 bucks on a new unit unless it has considerably better performance. Accuracy is the key feature, I don't need maps or tracks or any of the features that don't contribute to good stable numbers at the hide. Any help will be appreciated.

Jerry

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Unfortunately, I don't think you'll find an upgrade to be that much more accurate. The eTrex 20 already has a high sensitivity antenna with GLONASS support. Location jumps of 20 feet are normal for any GPS which is why we recommend that you get within 30 feet and put the GPS away. 

The reasons to upgrade to a newer or more advanced model are to cover other features that your eTrex 20 either lacks or doesn't do well (eg. larger screen, or an electronic compass and barometric altimeter). Otherwise, if the 20 is working for you and the only "problem" is location jump when stationary, just stick with what you have.

There are many reasons for the location jumping around. You could be under heavy canopy reducing the signal:noise ratio with the satellites. You could be on a mountain slope in which the signal bounces off of the terrain causing a phenomenon known as multipath. This happens in cities too where buildings can cause an inaccurate signal. It could be that the alignment of the satellites is too close together to give a more precise estimate of location and that returning on another day would yield more stable data. Either way, you got close enough and were able to use your geosenses to hone in on the prize.

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Mineral2 is exactly correct.

 

The best case scenario for your reported GPSr position includes a minimum 3 meters of error in any direction. The same holds true for the GPSr used to mark the position of the geocache when first published. So your absolute best case scenario is that you could be 6 meters off at any time. The most likely scenario is a margin of error larger than this. Thus, once you are within 10m (30 feet), it is considered best practice to put the GPSr away and start using the fancy computer between your ears! Just ask yourself - "Where would I hide a geocache here?"

 

 

Edited by Atlas Cached

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Thank you Mineral and Atlas for your input. I have been using the "where would I hide it" method since I started with my Etrex 10 HC and for the most recent 5 years with my Etrex 20. It is disappointing to me that improvements are directed toward features and very little relates to accuracy. If I remember correctly the first geo cache was buried and not just hidden in a few sticks or in that hollow tree. Not too many people would enjoy looking for a buried item with 20 to 30 foot radius to dig up. I am retired and caching is just 1 of many hobbies I enjoy. I also only have a few blue frownies to my credit so all is not lost. If you guys keep hiding things I will keep searching for them. TYFTC. Jerry

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6 minutes ago, Camp-CJ said:

It is disappointing to me that improvements are directed toward features and very little relates to accuracy.

GPS accuracy is as good as it's going to get unless the public gets access to the second frequency that the military and airlines use for atmospheric distortion correction. The limitation here isn't Garmin's technology, but physics. And what signals and other resources the government makes open for the public. Survey grade GPS have other tools at their disposal that make them accurate down to the centimeter such as ground stations with a defined position. But even that is subject to error if the coordinate locations aren't updated to reflect movement in tectonic plates.

Just go out and enjoy yourself and don't worry about having technology that puts you right on top of the cache. Remember, many hides are old enough to have been made before high quality antennas were available, or made using less than stellar methods of coordinate recording. So even if you had a military grade GPS to get you there, the coordinate errors from the cache owners would still put you off from the actual hide.

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Most of the time when within 25 ft or so I just pocket my gps and look at the most likely hiding spots until I either either stumble onto the hide or give up. 

 

You've just described Geocaching!  :cute:

But you need to also read the cache description, and at least the recent logs.  If there's no clue to where to look and if it's not a bigger container, prepare for a long search.  Or skip that one. :)

The "accuracy" of your own GPS tends to be irrelevant when the accuracy of the hider's GPS is unknown.  But another thing I try in dense forest cover is to walk into a clearing and see what the device then says.  "150 feet south", I'll walk 50 paces to the object where the arrow is pointing and start there.

 

 

23 minutes ago, Camp-CJ said:

If I remember correctly the first geo cache was buried and not just hidden in a few sticks or in that hollow tree. Not too many people would enjoy looking for a buried item with 20 to 30 foot radius to dig up.

 

The first "stash" was in a hole, with the lid at ground level.  A few very old caches are grandfathered like that, but even those were not designed to "dig up".

 

An "upgrade" you could try is a compact hiking stick.  I have a carbon fiber stick made from a long golf club, fits in the trunk, and I grab it even if I'm stepping only a few feet into the woods.  I poke the likely spots in the cache area, and even "buried" caches have a special sound when hit.   I don't dig up anything.

 

 

Edited by kunarion
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Make sure you have WAAS turned on and let the GPS get a WAAS lock first.  Otherwise, that is it.  Nothing will be better than the etrex 20.

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Do the newer GPSr with GNSS  make them more accurate/better?

Or is GNSS just a generic marketing term?

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15 minutes ago, jakewa said:

Do the newer GPSr with GNSS  make them more accurate/better?

Or is GNSS just a generic marketing term?

First result on my search engine gives all the info you need (or possibly more)

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22 minutes ago, jakewa said:

Do the newer GPSr with GNSS  make them more accurate/better?

Or is GNSS just a generic marketing term?

 

Technically, newer multi-GNSS units can be more accurate, especially those that take advantage of the new Galileo constellation, which is more accurate than GLONASS. The eTrex series does not have Galileo support, only GLONASS, so a newer unit 'could' be more accurate. But this is a technicality. Any modern GPSr will be good enough for 'Geocaching'.

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1 hour ago, Red90 said:

Make sure you have WAAS turned on and let the GPS get a WAAS lock first.  Otherwise, that is it.  Nothing will be better than the etrex 20.

 

I like how compact it is.  I have to make a special accommodation for the size and weight of my Garmin Oregon, even bringing the shoulder bag that has a clip spot for the Oregon.  Then a caching friend produces his Etrex from his pocket.  Nice!  I wish.  :)

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One of the issues with GNSS is that these other systems get turned on in addition to the American GPS. Thus there is no way to, say, only use Gallileo, or only use GLONASS. You can use GPS by itself, or GPS + [others]. In theory, yes. More satellites = more accuracy. In practice, there seems to be a practical limit in which more satellites doesn't add to the position estimate, and in fact could make the estimate worse by increasing the variation. For a while there seemed to be a slight discrepancy in location when Glonass was turned on or off. I can't say for sure what the problem was, but I suspect that the Russian GLONASS system wasn't calibrated to the same degree that the American GPS system was. Or it was an issue on Garmin's end. There has been a firmware update to the Oregon 600 in October that claims to have fixed issues with GPS + GLONASS, so maybe that was addressed?

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On 1/27/2020 at 9:39 AM, kunarion said:

.... 

An "upgrade" you could try is a compact hiking stick.  I have a carbon fiber stick made from a long golf club, fits in the trunk, and I grab it even if I'm stepping only a few feet into the woods.  I poke the likely spots in the cache area, and even "buried" caches have a special sound when hit. 

I find a hiking stick invaluable for woodsy caching. Poking into tree/log holes, poking into leaf/brush, and especially when there is some snow cover.  I call it the "poke and listen" technique. 😉

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On 1/26/2020 at 8:14 PM, Camp-CJ said:

I have been caching since 2012 and would like to get a more stable unit. My Etrex 20 is okay but it is nearly useless within 20 feet of GZ. The other day I was looking for the second part of a puzzle cache and I followed the pointer past a tree at 17 ft from target. It lead me in a circle back to my tracks in the snow as I passed the same tree. This time the 20 showed 3 ft from GZ so I poked around and found the container in a hole under one of the roots. When I returned the bottle and stood up my unit was showing 25 feet..... Most of the time when within 25 ft or so I just pocket my gps and look at the most likely hiding spots until I either either stumble onto the hide or give up. 

I have been thinking about getting a 64x for the better antenna and the Galileo access but don't want to waste $300 bucks on a new unit unless it has considerably better performance. Accuracy is the key feature, I don't need maps or tracks or any of the features that don't contribute to good stable numbers at the hide. Any help will be appreciated.

 

Living in a state with a lot of iron ore makes for signal bounce, but as you find more caches, you get the idea where the hide might be.   :)

Many people get caught doing the bee dance.    ;)    As others said, we get to around 20-25' , put the GPSr away,  and start looking.

We're both still using long-discontinued GPSrs (she uses her phone sometimes) and find caches.

 

With all the new bells n whistles of newer handhelds, civilian GPS "accuracy" hasn't changed yet, still "accurate" to around 10 feet.  

 - That "accuracy"  is for both you and the cache owner, so expect more like 20+feet. 

 

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54 minutes ago, cerberus1 said:

 

Living in a state with a lot of iron ore makes for signal bounce, but as you find more caches, you get the idea where the hide might be.   :)

 

I'd be surprised if the composition of the rock made any difference to the GPS  signal : the density of the rock in cliffs or surrounding valleys/depressions, yes  maybe , but not if it is ferrous or not.

A magnetic  compass though ...

 

There's a nice GPS explanation , accuracy etc here  , intended to help folk who want to help improve OSM do a good job (which is one of the very many many things I intend to do, butjust have not got round to yet ...)

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21 minutes ago, hal-an-tow said:

I'd be surprised if the composition of the rock made any difference to the GPS  signal : the density of the rock in cliffs or surrounding valleys/depressions, yes  maybe , but not if it is ferrous or not.

A magnetic  compass though ...

 

I dunno. Maybe it's ghosts. But I'll be up on some vast granite outcrop or something with no obstructions around, and others in the group mention the bad GPS readings around here, and that it's minerals, reflections, a lot of iron ore here. Whatever, this spot is bad, and “there's no explanation”. B)

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3 hours ago, kunarion said:

I dunno. Maybe it's ghosts. But I'll be up on some vast granite outcrop or something with no obstructions around, and others in the group mention the bad GPS readings around here, and that it's minerals, reflections, a lot of iron ore here. Whatever, this spot is bad, and “there's no explanation”. B)

 

Yep.      In fact, Trimble says :  

"The whole concept of GPS relies on the idea that a GPS signal flies straight from the satelite to the receiver.

Unfortunately, in the real world the signal will also bounce around on just about everything in the local environment, and get to the receiver that way too.

 

We have a lot of boulder fields, and they act just like walking into a river gorge.

There's even a boulder field south of me that has enough ductile-like ore in the rocks that you can play music on them with a hammer.

We had fun trying to get coordinates in there...     :)

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1 hour ago, cerberus1 said:

There's even a boulder field south of me that has enough ductile-like ore in the rocks that you can play music on them with a hammer.

We had fun trying to get coordinates in there...     :)

 

Ringing Rocks is a great Earthcache!

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10 hours ago, cerberus1 said:

With all the new bells n whistles of newer handhelds, civilian GPS "accuracy" hasn't changed yet, still "accurate" to around 10 feet.  

 - That "accuracy"  is for both you and the cache owner, so expect more like 20+feet. 

 

 

Yes, and that is a best case scenario - if both you and the hider were having exceptionally clear and accurate days!

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We focus on the location shown by the pointer on the GPS because that's the information we have, and in the case of most searches, we have been following it for several miles and possibly hours.  Once you get to GZ within 20 feet your geosenses taker over.  The cache description, container size, and hint are now the information that will aid your search. Ghe GPS has done its job.

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On 1/27/2020 at 8:33 AM, Mineral2 said:

GPS accuracy is as good as it's going to get unless the public gets access to the second frequency that the military and airlines use for atmospheric distortion correction.

Whoa.  Isn't that the entire point behind WAAS and EGNOS?  WAAS was BUILT for the airlines in N.A. to deal with GPS errors caused by atmospheric issues, allowing them greater accuracy to the point where a pilot could theoretically (but shouldn't) take a hands-off approach to a landing.

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12 hours ago, ecanderson said:

Isn't that the entire point behind WAAS and EGNOS?  WAAS was BUILT for the airlines in N.A. to deal with GPS errors caused by atmospheric issues, allowing them greater accuracy to the point where a pilot could theoretically (but shouldn't) take a hands-off approach to a landing.

Sure, but I believe that airlines also get access to the extra frequency that the Military uses. Runways are big, but in some cases, landing 30 feet off the centerline is enough to cause problems.

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5 hours ago, Mineral2 said:

Sure, but I believe that airlines also get access to the extra frequency that the Military uses. Runways are big, but in some cases, landing 30 feet off the centerline is enough to cause problems.

Well let's back up, then.   Both the original L1, the newer L2, and the most recent L5 band are available to the public, if that's what you're talking about.  Several GPS chip manufacturers started to work on L5 for automotive and phone use back in 2018.  L5 frequency reception is available for GPS, Galileo, BeiDou and a couple of other systems.  They hadn't originally scheduled deployment until sometime in 2021, but it's here now - started with the GPSII-F launches.  There's at least a dozen of them up there now.  Not exactly a full constellation, but it keeps growing.  One nice thing about it is that it throws out a signal with about 3dB (twice) the punch of the L1 and L2 satellites, probably drilling through overhead canopy a little more easily.

 

L5 was added for, among other purposes, allowing aviation more accuracy in combination with L1.  That's why it SEEMS as though this is what you were referencing.  L5 is not, as far as I know, going to be used by the military for anything in particular -- they'd certainly not get any different signal than the public if they did.  Again, as you mentioned, one of its primary purposes is for dealing with ionospheric aberrations for aviation.  But it's all public, and should help consumer goods that use it get to a tighter location resolution and do it more quickly.

 

You may be thinking about P-Code on L1 frequency (vs. the public C/A signal) or a secondary availability on L2, but that second L2 frequency is also definitely available for consumer use.

 

I'm guessing that we're just in a nomenclature bind here... difference between frequency vs. what's being broadcast on a given frequency, and availability to THAT.

 

FWIW, the following isn't a complete list, but it provides an idea of the Android phones already supporting L5 band reception.  Look over in the next to the right column.

https://developer.android.com/guide/topics/sensors/gnss.html I don't know what kind of development roadmaps the  purpose built receiver companies (e.g., Garmin) have for it, but since the chips are out there now, it's just a matter of time, if it's not in the works already.

Edited by ecanderson

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To get back to commercial consumer grade GPS units for geocaching, my sense is anything made in the last 5 years is going to be equally accurate given the same conditions ( tree coverage, buildings, etc) is that not the case? I know my new GPS is more stable than the one i was using in 2008.

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I think that's a pretty good assumption, yes.  However, not far down the road I expect more of the handheld purpose built stuff to incorporate what we're talking about above, which may well continue to improve accuracy a bit.  As noted, there are already a few phones that are able to make use of the new L5 band satellites.

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On 2/7/2020 at 12:27 AM, ecanderson said:

Whoa.  Isn't that the entire point behind WAAS and EGNOS?  WAAS was BUILT for the airlines in N.A. to deal with GPS errors caused by atmospheric issues, allowing them greater accuracy to the point where a pilot could theoretically (but shouldn't) take a hands-off approach to a landing.

That is correct, that WAAS will help THEM.. Where it ends is right in your hand. The equipment they are using is far more expensive, complex and accurate than the consumer units. It is the same for Land Surveyors. But there units can cost upward of $100k. So you can almost expect them to get much better results. Military grade is the best, and I don't even know if that level is available for purchase to anyone but the military. But then most of us have no need of aiming a satellite that is in orbit to a level that allows us military intelligence material. I'm really amazed that civilians are even allowed to access the signals at all.

Seeker_Knight

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And all the improved accuracy is moot when seeking a cache hidden by a newbie working off their Mio Digiwalker :)

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6 hours ago, Seeker_Knight said:

That is correct, that WAAS will help THEM.. Where it ends is right in your hand. The equipment they are using is far more expensive, complex and accurate than the consumer units. It is the same for Land Surveyors. But there units can cost upward of $100k. So you can almost expect them to get much better results. Military grade is the best, and I don't even know if that level is available for purchase to anyone but the military. But then most of us have no need of aiming a satellite that is in orbit to a level that allows us military intelligence material. I'm really amazed that civilians are even allowed to access the signals at all.

Seeker_Knight

"Land surveyors" are typically using DGPS, which is another entire ball game.  If you have a fixed ground reference at a known point as a 'beacon', that's not even the same game, come to think of it.  WAAS does what it does for either aircraft or consumer -- corrects for aberrations.  But back to the original point, we're all operating on the same frequencies.

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3 hours ago, ecanderson said:

"Land surveyors" are typically using DGPS, which is another entire ball game.  If you have a fixed ground reference at a known point as a 'beacon', that's not even the same game, come to think of it.  WAAS does what it does for either aircraft or consumer -- corrects for aberrations.  But back to the original point, we're all operating on the same frequencies.

It has to do with the number of decimal places the software/hardware is designed to operate at. This whole system works on the time differential recorded between satellite signals. Start moving decimal points around in the process, and you get much different results. So, YES, they do use the exact same signals, but in a much more refined level of accuracy.

Seeker_Knight

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On 1/26/2020 at 8:14 PM, Camp-CJ said:

I have been caching since 2012 and would like to get a more stable unit. My Etrex 20 is okay but it is nearly useless within 20 feet of GZ. The other day I was looking for the second part of a puzzle cache and I followed the pointer past a tree at 17 ft from target. It lead me in a circle back to my tracks in the snow as I passed the same tree. This time the 20 showed 3 ft from GZ so I poked around and found the container in a hole under one of the roots. When I returned the bottle and stood up my unit was showing 25 feet..... Most of the time when within 25 ft or so I just pocket my gps and look at the most likely hiding spots until I either either stumble onto the hide or give up. 

I have been thinking about getting a 64x for the better antenna and the Galileo access but don't want to waste $300 bucks on a new unit unless it has considerably better performance. Accuracy is the key feature, I don't need maps or tracks or any of the features that don't contribute to good stable numbers at the hide. Any help will be appreciated.

Jerry

 

I was able to purchase a used 66st at a pretty good price so I took the new guy and my etrex 20 to a spot where I could do a practical test. The area is a ravine with trees on both sides but no leaves this time of year. It is about 100 feet wide with a creek at the bottom and about 100 feet deep and the sides are about 60 degrees. I started my test on the rim with WAAS on and set both units to GPS only. After 10 minutes the 20 stabilized at 19 ft accuracy and the 66 was at 8 ft. I changed to GPS and GLONASS on both and after 10 minutes the 20 settled down to 13 ft. and the 66 was at 10 ft. The 20 doesn't have Galileo but the 66 settled down to 10 ft as with the previous reading. The bottom of the ravine was a lot different. At GPS the 20 settled in at 27 feet and the 66 settled in at 10 ft. with GPS and GLO. the 20 was at 23 ft. and the 66 was at 10 ft. and with GPS and GAL. the 66 settled in at 10 ft. After I set in coordinates to look at, both units bounced a little more at the bottom than the top and the 66 had a signal bounce of roughly 6 feet across the 3 arrays on top and bottom and the 20 was 10 feet on top and about 18 feet on bottom.

I know this procedure wasn't scientific by any means but it did show me real time results that can make a difference in "caching. The quad helix antenna and newer electronics, although better, were not overly impressive on the top of the ridge. The big difference was at the bottom where the newer technology showed off. At this site it seems like the Galileo addition was no better than GPS and GLO  combination or the GPS array alone and might be more hype than help.

Thanks to everyone for their input and advise.

Jerry

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On 2/8/2020 at 1:59 AM, ecanderson said:

You may be thinking about P-Code on L1 frequency (vs. the public C/A signal) or a secondary availability on L2, but that second L2 frequency is also definitely available for consumer use.

 

https://www.gps.gov/systems/gps/modernization/civilsignals/

 

On 2/8/2020 at 1:59 AM, ecanderson said:

I'm guessing that we're just in a nomenclature bind here... difference between frequency vs. what's being broadcast on a given frequency, and availability to THAT.

 

Not only nomenclature because these features are brand new. I didn't know about L2C signaling at the L2 frequency until now :huh:

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I was surprised at how many phones were already prepared to take advantage of L5.  There are times on certain days where the constellation really does create a crappy HDOP result, and having more signals in the sky to prevent that will always be a good thing.

 

 

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And it seems that another benefit of having L1 AND L2C will be that ionospheric issues can be dealt with without the need for being in a region with WAAS or EGNOS availability. 

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