GLONASS or GPS?

January 21, 2012

Another newbish question here...My Garmin eTrex 10 can be set to receive from just GPS satellites or GPS and GLONASS sats. What would be the better setting? Is there any sort of advantage to using one sat system over another?

The manual offers no helpful information on this topic.

-Dave

Edited January 21, 2012 by davetherocketguy

38.2k · January 21, 2012

I don't know enough about GLONASS to know if it would make a positive or negative difference in accuracy, but since pretty much all caches have been placed using GPS I would use that

January 21, 2012

I have an eTrex 10 as well and have both GLONASS and GPS enabled and accuracy is normally around 3 meters.

Haven't tried running either by themselves but using both apparently improves accuracy.

8.6k · January 21, 2012

I have an eTrex 10 as well and have both GLONASS and GPS enabled and accuracy is normally around 3 meters.

Haven't tried running either by themselves but using both apparently improves accuracy.

Perhaps accuracy for your unit, but what about the unit used to hide the geocache?

To my line of thinking, the advantage would be in creating cache placements, not in finding them.

But then, we generally have an EPE reading of three meters or less anyway. That said, it is only Estimated Positional Error, regardless.

Just thinkin'...

7k · January 21, 2012

I have an eTrex 10 as well and have both GLONASS and GPS enabled and accuracy is normally around 3 meters.

Haven't tried running either by themselves but using both apparently improves accuracy.

Perhaps accuracy for your unit, but what about the unit used to hide the geocache?

To my line of thinking, the advantage would be in creating cache placements, not in finding them.

That doesn't make sense. If you take a GPS receiver with only +-30 meters of accuracy, would you think it's easier to find caches? Or would it be the same?

Or would it be harder? Cause if it's harder, then improved accuracy would make it easier. That holds true even if it's beyond the accuracy of the cache coordinates.

January 21, 2012

Perhaps accuracy for your unit, but what about the unit used to hide the geocache?

To my line of thinking, the advantage would be in creating cache placements, not in finding them.

Well, that's why I am asking. The eTrex unit also has a way point averaging function as well which I plan on using prior to listing a cache. So I am just trying to find out if using the GLONASS and GPS constellation of satellites would improve or reduce the averaging accuracy or not make a difference.

-Dave

1k · January 22, 2012

I have an eTrex 10 as well and have both GLONASS and GPS enabled and accuracy is normally around 3 meters.

Perhaps accuracy for your unit, but what about the unit used to hide the geocache?

To my line of thinking, the advantage would be in creating cache placements, not in finding them.

What dfx said.

Just because the hider's device wasn't perfectly accurate doesn't mean ours shouldn't be as accurate as possible. It might not be a huge advantage, but I can't see how it would ever be a disadvantage.

3.3k · January 22, 2012

I am poorly informed. Until this thread I don't think I was aware of the GLONASS system. If my GPS unit allowed me to use both at the same time I can't think of any reason not to do so.

January 22, 2012

I am poorly informed. Until this thread I don't think I was aware of the GLONASS system. If my GPS unit allowed me to use both at the same time I can't think of any reason not to do so.

Don't feel bad dude! I wasn't aware of it either!

All mine does is satellites and then you can turn WAAS on or off. I turned it on because it's supposed to increase accuracy.

I would guess this GLONASS deal is supposed to increase accuracy, so use it. If it's faulty, you can always turn it off.

January 22, 2012

I would guess this GLONASS deal is supposed to increase accuracy, so use it. If it's faulty, you can always turn it off.

But how do I know if it increases/decreases accuracy?

January 22, 2012

I would guess this GLONASS deal is supposed to increase accuracy, so use it. If it's faulty, you can always turn it off.

But how do I know if it increases/decreases accuracy?

What I would do is turn it on, and go to someone's coords that you know are correct. Check their logs and see if anyone says their coords are off or if they lead straight to the cache. Turn off GLONASS and go check it out. Are you off? Turn on GLONASS. Any better?

I think it's gonna be a lot of interpretation on your part and what you are or are not impressed with. I don't know why they put something on a GPS that would decrease accuracy, but people do silly things :anibad:

3.3k · January 22, 2012

I would guess this GLONASS deal is supposed to increase accuracy, so use it. If it's faulty, you can always turn it off.

But how do I know if it increases/decreases accuracy?

Try it both ways on a cache convenient to you? Just a thought.

8.6k · January 22, 2012

I have an eTrex 10 as well and have both GLONASS and GPS enabled and accuracy is normally around 3 meters.

Perhaps accuracy for your unit, but what about the unit used to hide the geocache?

To my line of thinking, the advantage would be in creating cache placements, not in finding them.

What dfx said.

Just because the hider's device wasn't perfectly accurate doesn't mean ours shouldn't be as accurate as possible. It might not be a huge advantage, but I can't see how it would ever be a disadvantage.

Never said "disadvantage" myself, so please don't imply that I did. Nor did I ever imply that you would not want yours to be as accurate as possible. Is there anything else that you care to read into it?

Simply stating that finding a less-than-nearly-exact placement with a nearly exact unit does not increase efficiency at finding. Nor did I say it would make it more difficult. Using such a unit for placement is, at this point in time, the best use of the device. In time, the rest of us will probably also catch up to the "latest, greatest and bestest". In the meantime however, we who are either too cheap or too broke to upgrade will muddle through the best that we can.

7k · January 22, 2012

Simply stating that finding a less-than-nearly-exact placement with a nearly exact unit does not increase efficiency at finding.

And I'm saying: yes it does.

January 22, 2012

I would guess this GLONASS deal is supposed to increase accuracy, so use it. If it's faulty, you can always turn it off.

But how do I know if it increases/decreases accuracy?

When I want to check the real world accuracy of a unit I take it to a stable NGS benchmark and see how close it is there.

January 22, 2012

I started geocaching in July of 2010, and my first GPS'r was a Garmin Legend HCx, a GPS only unit. With it I found over 500 caches, I also had more than a few DNF's... In saying that, I can't blame the Legend in any way for my 'failures', they are down to ME!! I've recently sold the Legend and bought one of the new Etrex 20 units, which is a dual-sat device. I don't expect my find rate, or failure rate to change significantly as a result of me changing units, because any GPS'r will only get you close to GZ, finding the cache is still down to the operator!

So why did I decide to buy the Etrex 20? Well, I thought long and hard whether I should (or not)... my final decision had a lot to do with its ability to use the new Russian GLONASS sats, not because it would get me closer to GZ, or increase find / reduce failures. No, just because they (GLONASS sats) are here, so why not use them!

By the way...shouldn't we have a new name for dual-band-sat recievers now, some, are not just GPS recievers

3.2k · January 22, 2012

Don't know anything about either system but whoever came up with the name GLONASS certainly wasn't a marketing guy.

January 22, 2012

Hmmm...I am starting to think that using both GPS and GLONASS decreases the accuracy. As I am sitting at my 'puter using the GPS and GLONASS the accuracy is 62'. When using the GPS for the same amount of time and same location the accuracy is 34'. By no means is this conclusive so I am going to have to do some experimenting outside when the weather isn't so nasty to see if I get similar results.

Now my GPSr is saying it's getting 24' accuracy with GPS & GLONASS... :huh: This really isn't a matter of great importance to me in my GC adventures - I just find the topic interesting and am trying to learn more.

Edited January 22, 2012 by davetherocketguy

January 22, 2012

Don't know anything about either system but whoever came up with the name GLONASS certainly wasn't a marketing guy.

GLONASS is russian. GLONASS is basically the same thing as GPS except it is Russian built/maintained. There is not a logical reason that using both should do anything but increase your accuracy.

Think of it as just double the amount of GPS satellites out there... only difference is the "brand" if you will.

The only issues that have been reported on *some* units is that you get a "sticky" effect every now and then... The sticky effect occurs when you are moving but very slowly (like when approaching GZ). When it happens, it will appear to your GPS that you are not moving at all. This in turn is frustrating and has given GLONASS somewhat of a poor name for this latest eTrex series.

Now, do keep in mind as of now it all seems to be a firmware issue with Garmin units, which means it is likely to improve greatly as they release new firmware.

For more information on GLONASS and the eTrex series, check out this forum here

Edited January 22, 2012 by Arndtwe

2.2k · January 22, 2012

Simply stating that finding a less-than-nearly-exact placement with a nearly exact unit does not increase efficiency at finding.

And I'm saying: yes it does.

And I'm saying: no it don't :anitongue:

at least not the efficientcy at finding the cache. Maybe it increases the accuracy of finding the listed coordinates, but that's not really the goal.

7k · January 22, 2012

Simply stating that finding a less-than-nearly-exact placement with a nearly exact unit does not increase efficiency at finding.

And I'm saying: yes it does.

And I'm saying: no it don't

at least not the efficientcy at finding the cache. Maybe it increases the accuracy of finding the listed coordinates, but that's not really the goal.

Of course it is: it's the first step. Once you know where the coordinates are, you can proceed to look for the cache. The more sure you are about where the coordinates are, the easier (or faster) it will be to find the cache. Of course, the less accurate the cache coordinates are, the less helpful that will be, but it still is at least a bit, always.

January 23, 2012

GLONASS is a Russian owned/operated satellite positioning system, just as GPS is owned/operated by the USA and BEIDOU is owned/operated by China. I was not aware that any devices for sale in the US were able to use a satellite system other than GPS, but it appears that they are available (as several of you have mentioned you own them). The major difference between these systems is the area of the world they provide coverage over. GPS works VERY well for people in the northern hemisphere, primarily in the US and Canada (although the system is operable in other locations as well). The GLONASS & BEIDOU systems provide coverage for other areas of the world more relevant to the countries that built them. Hope this info helps.

8.3k · January 23, 2012

GLONASS is a Russian owned/operated satellite positioning system, just as GPS is owned/operated by the USA and BEIDOU is owned/operated by China. I was not aware that any devices for sale in the US were able to use a satellite system other than GPS, but it appears that they are available (as several of you have mentioned you own them). The major difference between these systems is the area of the world they provide coverage over. GPS works VERY well for people in the northern hemisphere, primarily in the US and Canada (although the system is operable in other locations as well). The GLONASS & BEIDOU systems provide coverage for other areas of the world more relevant to the countries that built them. Hope this info helps.

Lets see, the satellites are in low earth orbit, which means they circle the earth. The military needs the system to drop bombs all over the world, unless they only drop bombs on North America. Seems to me that GPS will work any where in the world equally well. Same for GLONASS. What is only for North America coverage is the WAAS satellites, but that is only to improve accuracy of the GPS system for aircraft and in operated by the FAA. GPS and GLONASS work any where in the world.

January 23, 2012

The only issues that have been reported on *some* units is that you get a "sticky" effect every now and then... The sticky effect occurs when you are moving but very slowly (like when approaching GZ). When it happens, it will appear to your GPS that you are not moving at all. This in turn is frustrating and has given GLONASS somewhat of a poor name for this latest eTrex series.

Now, do keep in mind as of now it all seems to be a firmware issue with Garmin units, which means it is likely to improve greatly as they release new firmware.

It's my understanding that the "sticky" issue has more to do with the algorithm used to make the Garmin units appear more "stable" when they're at rest. For example, with the inherent 3 meter inaccuracy in all modern receivers your coordinates, and any recorded track, may move around in a 6 meter circle any time you sit still or even when you move very slowly. In real life conditions with overhead cover and such, that circle normally grows to much more than 6 meters. So, Garmin and other manufacturers make algorithms which attempt to determine whether you're really moving. If they think you're not really moving, they don't report the wandering on your track, which is a good thing. Imagine an ordinary hiker taking a lunch break and logging a quarter mile of movement from wandering coordinates when he sits still for half an hour. Making the receiver a little bit sticky is great for making his tracks and distance covered more accurate. However, on some of their new units Garmin got it a little too tight. They look incredibly stable when you're sitting still, because they require you to move several meters before accepting it as real movement. (That's an oversimplification - apparently the algorithm takes into account speed, distance moved, the current accuracy of the GPSr, etc.) This is too sticky for geocachers who would prefer enhanced sensitivity to movement rather than enhanced stability when at rest.

I understand that Garmin is working on the issue. In their Explorist models Magellan had implemented profiles for driving, hiking, geocaching, etc. that the user can choose on the fly. Some parameters which could cause perceived "stickyness" are modified by those profiles. I haven't read anything about how other manufacturers address the issue.

January 23, 2012

The only issues that have been reported on *some* units is that you get a "sticky" effect every now and then... The sticky effect occurs when you are moving but very slowly (like when approaching GZ). When it happens, it will appear to your GPS that you are not moving at all. This in turn is frustrating and has given GLONASS somewhat of a poor name for this latest eTrex series.

Now, do keep in mind as of now it all seems to be a firmware issue with Garmin units, which means it is likely to improve greatly as they release new firmware.

It's my understanding that the "sticky" issue has more to do with the algorithm used to make the Garmin units appear more "stable" when they're at rest. For example, with the inherent 3 meter inaccuracy in all modern receivers your coordinates, and any recorded track, may move around in a 6 meter circle any time you sit still or even when you move very slowly. In real life conditions with overhead cover and such, that circle normally grows to much more than 6 meters. So, Garmin and other manufacturers make algorithms which attempt to determine whether you're really moving. If they think you're not really moving, they don't report the wandering on your track, which is a good thing. Imagine an ordinary hiker taking a lunch break and logging a quarter mile of movement from wandering coordinates when he sits still for half an hour. Making the receiver a little bit sticky is great for making his tracks and distance covered more accurate. However, on some of their new units Garmin got it a little too tight. They look incredibly stable when you're sitting still, because they require you to move several meters before accepting it as real movement. (That's an oversimplification - apparently the algorithm takes into account speed, distance moved, the current accuracy of the GPSr, etc.) This is too sticky for geocachers who would prefer enhanced sensitivity to movement rather than enhanced stability when at rest.

I understand that Garmin is working on the issue. In their Explorist models Magellan had implemented profiles for driving, hiking, geocaching, etc. that the user can choose on the fly. Some parameters which could cause perceived "stickyness" are modified by those profiles. I haven't read anything about how other manufacturers address the issue.

Excellent explanation. Thank you.

Still looks like an issue with firmware in the end, and hopefully those major quirks will get worked out fairly quickly.

January 31, 2012

Welp...some real world experience here. I had a cache that I used the GPS+GLONASS on and I could not find it at GZ. I was about to give up and switched it to GPS only. The GPS only setting moved me 50' from my previous GZ and reported GZ about 5' from where we actually found the cache.

Not only did it appear to be more accurate in GPS only but GZ was far easier to locate. With GPS+GLONASS it seemed I was getting more "bounce" and sometimes no matter how far I moved in the right direction it seemed GZ was moving with me...so if it said that cache was 30' to the north and I move 30 feet in that direction, it would say I am still 30' away. :blink: And this is the second time I've had this issue.

By no means is this enough experience to draw a conclusion so I am going to keep fiddling with it.

-Dave

January 31, 2012

IN RUSSIA, GLONASS FINDS YOU!

8.3k · January 31, 2012

Welp...some real world experience here. I had a cache that I used the GPS+GLONASS on and I could not find it at GZ. I was about to give up and switched it to GPS only. The GPS only setting moved me 50' from my previous GZ and reported GZ about 5' from where we actually found the cache.

Not only did it appear to be more accurate in GPS only but GZ was far easier to locate. With GPS+GLONASS it seemed I was getting more "bounce" and sometimes no matter how far I moved in the right direction it seemed GZ was moving with me...so if it said that cache was 30' to the north and I move 30 feet in that direction, it would say I am still 30' away. And this is the second time I've had this issue.

By no means is this enough experience to draw a conclusion so I am going to keep fiddling with it.

-Dave

That is pretty much my experience also. I no longer have GLONASS on since it seems to really fuzz up the results. There is still the sticky problem that Garmin denies exits. Hopefully the utube videos will help change their minds and get a fix out.

3.3k · January 31, 2012

The biggest advantage I see right now to GLONASS is that should GPS go down, those with GLONASS will be able to continue caching while you other hapless GPS-only users look on in envy. :anitongue:

(Mine is turned off for the same reasons davetherocketguy experienced.)

Edited January 31, 2012 by Chuy!

February 1, 2012

Welp...some real world experience here. I had a cache that I used the GPS+GLONASS on and I could not find it at GZ. I was about to give up and switched it to GPS only. The GPS only setting moved me 50' from my previous GZ and reported GZ about 5' from where we actually found the cache.

Not only did it appear to be more accurate in GPS only but GZ was far easier to locate. With GPS+GLONASS it seemed I was getting more "bounce" and sometimes no matter how far I moved in the right direction it seemed GZ was moving with me...so if it said that cache was 30' to the north and I move 30 feet in that direction, it would say I am still 30' away. And this is the second time I've had this issue.

By no means is this enough experience to draw a conclusion so I am going to keep fiddling with it.

-Dave

That is pretty much my experience also. I no longer have GLONASS on since it seems to really fuzz up the results. There is still the sticky problem that Garmin denies exits. Hopefully the utube videos will help change their minds and get a fix out.

Again, it comes down to a firmware issue. Everything I have been reading over in the GPS & Technology forum states that Garmin does admit it's a problem and that they are going to work hard to pump out some new firmware for the unit. Hang tight, keeps your eyes open for new firmware and upgrade when you can. Hopefully it won't be long before it is fixed.

Edited February 1, 2012 by Arndtwe

February 4, 2012

If my limited understanding of both GPS and GLONASS systems is correct, using both on a unit able to do so won't increase or enhance accuracy. Your gps unit only needs three sats to triangulate your position as well as give elevation information. Of course the more sats your unit is able to communicate with, the better. With having the ability for your unit to be able to communicate with more sats the chances for your unit to have a stronger signal to work with will enhance the accuracy. Therefore, having more sats for your unit to be in communication with is a good thing. Having as strong a signal with these sats is what provides your unit with better accuracy. Again, this is just my personal logical interpretation of this issue. I hope this helps.

GLONASS or GPS?

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