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Since the new E Trex series came out also using Glonass satellites, and since that should be at least a marginal improvement for aquisition time and accuracy, I've been wondering.....

 

Does anyone have any FACTS ?

 

Does using Glonass require a different chipset or other hardware, or can that ability possibly be added by Garmin to a model like the Montana or others through firmware or software updates?

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Then that leads to another question. If the E Trex series has a chipset (what chipset ?) that can process both types of signals, and the series came out so soon after the Montana, what is the possibility that the Montana chipset may actually be capable but just not enabled by firmware?

 

Otherwise, the Montana series will be shortlived (even more than normal) due to obsolescense caused by introduction of the next Glonass enabled model series.

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I can't remember the exact chipsets, but this was discussed not that long ago. The Montana chipset is "American" GPS enabled, but can also do the European GPS, Galileo. Glonass was put online (partially I think), but Galileo is still in a test-phase. I guess it would be possible when Galileo is switched online, it will be enabled in the Montana firmware. But maybe by that time the Garmin California will be the latest GPS which can use all three systems :D

Edited by taeke
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Otherwise, the Montana series will be shortlived (even more than normal) due to obsolescense caused by introduction of the next Glonass enabled model series.

 

Eh, I'm not entirely convinced of that.

 

I used to think that a camera with a higher megapixel count was better than one with less. Implementation is key and in consumer grade GPS units under consumer grade circumstances the benefits of GLONASS+GPS will no doubt be observed but appear to be limited at the moment.

 

I bought a Montana after being first in line for a Colorado, Oregon, and a 62. The reason for my constant early adopting was that I was still yearning for something. After using the Montana extensively for the past 6 months, I can say that I might actually wear the Montana out before I upgrade regardless of GLONASS. Speculating here but it's going to take the token year, at least, before Garmin refines the new eTrex firmware enough to make having GLONASS an observable advantage. By the time Garmin intro's something like the Montana but with GLONASS and refines the firmware enough, we're talking years.

Edited by yogazoo
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teseo II

From the ST Microelectronics website:

 

Teseo II is the industry-first, single-chip positioning device capable of receiving signals from multiple satellite navigation systems, including GPS, Galileo, GLONASS and QZSS.

 

So I guess, rather than the new eTrexes having SiRFIII for GPS and something else for Glonass, they just have this chipset?

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...Speculating here but it's going to take the token year, at least, before Garmin refines the new eTrex firmware enough to make having GLONASS an observable advantage. By the time Garmin intro's something like the Montana but with GLONASS and refines the firmware enough, we're talking years.
Observing, not speculating: My eTrex 10 is the most accurate handheld GPS I've ever had, and there's a definite improvement with GLONASS enabled.
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As I understand it, the Montana has the Cartesio chipset (GPS and WAAS only), and it would take a hardware revision to make the Montana GLONASS ready. I also understand that the Cartesio is a more powerful processor (despite not being GLONASS able) and is able to display more complex mapping faster/better - hence the use in the large-screen Montana which can also handle 3D display.

 

Given that the Russian Federation are whacking a 25% import duty on any non-GLONASS capable positioning devices (and that includes phones) as of next year, I suspect we'll see GLONASS ability being rolled out across Garmin's (and everyone else's) GPSRs in the very near future. Speculating a little, I imagine that it won't be long (months) before all mainstream "GPS" chipsets will be GLONASS capable, because it won't be worthwhile for the makers to produce GPS-only versions. I'm excluding precision and military applications which will have their own requirements.

 

I would think it won't be long before a more powerful GPS+GLONASS chipset will be available to GPSR makers and it will probably find its way into a Montana II. I would think that Garmin would want to maintain its margins in the Russian market.

 

As a professional user of a survey-grade GNSS device, I would say the main benefit of receiving GPS and GLONASS is reliability and ease of getting a position fix. Accuracy is improved a bit, but in marginal conditions (woods, valleys) it's more that you can get a good fix quicker and more reliably than a GPS only device. However, as with all these things, so much depends on where you are, where the satellites are in the sky at a given moment, and what kind of cover (trees, mountains etc.) you're working in. By and large, I'd rather be using GPS and GLONASS than GPS only.

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RamblinBear, i think you're oversimplifying.

 

"Marginal" or "Good" conditions can be described mostly by how many satellites you have in view, arrayed over the widest possible area. More is better.

 

Having GLONASS reception by itself doesn't do anything for either of those. But being able to use both GPS and GLONASS together absolutely does improve how many satellites you'll have in view at any time, as well as how widely distributed they are across your view of the sky. Also, since GLONASS orbits are more inclined than GPS (65 vs 55 degrees), those at extreme latitudes will see a better distribution overall.

 

I think this makes a bigger difference in accuracy than I think most folks realize. And for me at least, this is more important than a fast time to first fix or how complex a map I can display on a handheld.

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RamblinBear, i think you're oversimplifying.

 

"Marginal" or "Good" conditions can be described mostly by how many satellites you have in view, arrayed over the widest possible area. More is better.

 

Having GLONASS reception by itself doesn't do anything for either of those. But being able to use both GPS and GLONASS together absolutely does improve how many satellites you'll have in view at any time, as well as how widely distributed they are across your view of the sky. Also, since GLONASS orbits are more inclined than GPS (65 vs 55 degrees), those at extreme latitudes will see a better distribution overall.

 

I don't believe I am oversimplifying - what I said was that the main benefit of receiving GPS and GLONASS signals is the improved reliability and ease of getting a position fix. I never said that GLONASS on its own would be any better than using GPS on its own.

 

It is a fact that receiving GPS and GLONASS signals will virtually double the number of satellites a receiver can see at any one time, and therefore this will enahnce the reliability, speed and accuracy of computing a position fix - even under marginal or difficult receiving condtions. This may be achieved through having more visible satellites and also better GQ (Geometric Quality) of the satellites that are visible to the receiver.

 

As for accuracy, there may be some improvement, but to be honest, in brief comparison between a friend's Etrex 30 and my GPSMap 60CSx, I really didn't observe a significant difference, and I suspect that under good reception conditions, one wouldn't see much of a difference with consumer-grade units - their chipsets generally don't deliver precision much better than 2-3 metres (whatever the estimated error readout may tell you). You have to pay a lot more for a GPS receiver to get real, measured, staistically repeatable accuracy at the sub-0.5 metre range (using GPS+GLONASS+EGNOS). Trust me on this, I researched it very carefully before spending £3000 of my employer's hard-earned cash on such a unit. :)

 

However, I have little doubt that under less than ideal reception conditions, a GPS+GLONASS capable consumer GPS will (all other things being kept equal) give better accuracy than a GPS only device (of otherwise similar spec.) for the reasons that you and I have both mentioned - that it will be able to see more satellites, and more widely spaced acrossed the sky (better GQ).

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I think this makes a bigger difference in accuracy than I think most folks realize. And for me at least, this is more important than a fast time to first fix or how complex a map I can display on a handheld.

 

Perhaps, when they get the firmware to where it needs to be. All the tests I've seen done that compare tracklog drift against other units show a bias to older, more established, more mature in the firmware units.

 

It's a law of diminishing returns however. 24 Satellites vs 12 won't double your accuracy. Based on everything I've read about GLONASS there will be an improvement to accuracy in challenging conditions but in standard open-sky environments it's likely to be negligible. That said I'd rather have GLONASS than not, but right now the processor on the new eTrex isn't the snappiest thing around and that screen is tiny compared to the Montana. It's all in how you use your GPS. For me I'd rather have the bigger screen and I don't want to wait around for it to update when panning. Some may perfer the extra meter (speculating) of accuracy.

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Or half the cost :)

 

Good point vs the Montana, but even the processors on the 62 and Oregon seem to be faster. Note the other popular thread right now on the eTrex / GLONASS problems. The apparent solution is to disable GLONASS. Sure Garmin will figure it out and fix it but it may take a while. With New processors it always does. When the Colorado was first introduced with the NEW (at the time) Cartesio (STM) chips. Whoa, talk about positional and tracklog issues, but they eventually worked them out.

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Based on everything I've read about GLONASS there will be an improvement to accuracy in challenging conditions but in standard open-sky environments it's likely to be negligible.

The concept of making use of a GPS/GLONASS combination for a position fix is still in its infancy, at least for consumer class devices. Years ago, the best you could get with a consumer class device was +- 6 meters or so (or even worse). Today, we're down to +- 2 meters. I wouldn't be surprised if the manufacturers had some tricks up their sleeves in the future.

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Highly relevant and recent article on the Consumer GPS+GLONASS Tesio II chip.

 

http://www.gpsworld.com/gnss-system/receiver-design/consumer-gpsglonass-12359?page_id=1

 

It's a well written article given the complexity of the issue. In summary, the benefits are really apparent in challenging urban environments and not so apparant when you have 6 or more GPS sattelites under normal conditions.

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Highly relevant and recent article on the Consumer GPS+GLONASS Tesio II chip.

 

http://www.gpsworld.com/gnss-system/receiver-design/consumer-gpsglonass-12359?page_id=1

 

It's a well written article given the complexity of the issue. In summary, the benefits are really apparent in challenging urban environments and not so apparant when you have 6 or more GPS sattelites under normal conditions.

 

Thanks for that link - fascinating, and in depth. Getting more and more tempted by the Etrex 30...

 

Resist...

 

Resist...

 

B)

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Wikipedia:

 

New Civilian L1 (L1C)L1C is a civilian-use signal, to be broadcast on the same L1 frequency (1575.42 MHz) that currently contains the C/A signal used by all current GPS users. The L1C will be available with first Block III launch, currently scheduled for 2013.

 


  •  
  • Implementation will provide C/A code to ensure backward compatibility
  • Assured of 1.5 dB increase in minimum C/A code power to mitigate any noise floor increase
  • Non-data signal component contains a pilot carrier to improve tracking
  • Enables greater civil interoperability with Galileo L1

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Will L1C provide improvement? That's a good question. Even if signal isn't improved, there will at least be more birds in the sky to choose from and perhaps get a better constellation from.

 

At least there's hope that our current new units won't be severely dated in three years.

Edited by yogazoo
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Never mind Block III. I don't think the Garmin units even support L2C signal yet.

I read somewhere that manufacturers are waiting until there are at least 24 L2C capable satellites up there. Otherwise you'd keep loosing the L2C signal.

 

I'd really love to have a dual band L1/L2 GPSr. No more ionospheric error and therefore no need to have a line of sight to the WAAS satellites.

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I read somewhere that manufacturers are waiting until there are at least 24 L2C capable satellites up there. Otherwise you'd keep loosing the L2C signal.

 

I'd really love to have a dual band L1/L2 GPSr. No more ionospheric error and therefore no need to have a line of sight to the WAAS satellites.

 

I'm going to speculate that it will be awhile before consumer GPS makers design, implement, and get the firmware up to snuff for something like this. I'll give it 4 years. Hopefully my Montana lasts that long.

 

Honestly something like this will be the next big thing in dedicated GPS units. With the already available aerial imagery, terrain shaded maps, routing, etc, there isn't any real major step up in innovation left, that I can think of, to employ other than improvments to accuracy and sensitivity.

 

Here's looking forward to the next 5 years of GPS innovation. A toast (raise your glass); to the further development of our , what some people call, nerdy fascination.

Edited by yogazoo
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Will L1C provide improvement? That's a good question. Even if signal isn't improved, there will at least be more birds in the sky to choose from and perhaps get a better constellation from.

Only with new receivers that can use L1C. Old receivers will still be limited to 32 satellites as there are only 32 L1 C/A PRN codes.

 

Do you know when they're going to expand the constellation?

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