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iPhone 4S & GLONASS Support


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While this will almost certainly help iPhone 4S users with accuracy, I'm curious whether standalone GPSrs will be able to be similarly equipped with a simple firmware update or if it is a hardware matter that would not help existing/legacy GPSrs. Anyone know?

 

http://www.macrumors.com/2011/10/19/apple-expands-iphone-4s-gps-capabilities-with-glonass-support/

Edited by Team Van Dyk
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Interesting... if the hardware already support GLONASS, and now the specs reveal that, I hope it is true. That could really be a boost for 4S in the GPS accuracy upper class range. I have noticed that accuracy has greatly improved over my 3GS, and sped up dramatically. But I skipped the 4, so I can't really compare first-hand the improvement of 4S over 4.

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I used my 4S yesterday for the first time geocaching and didn't notice any improvement. I wonder if this is something that needs to be turned on.

 

Out of curiousity, what was the best accuracy showing on your 4S? I was down to 16 feet and it was working well for me.

 

16 feet was still the limit. And I was caching under some pretty heavy canopy and still had the normal "bouce". Eventually I did end up on what I believe was the GZ but DNFed regardless.

 

So, like I said no improvement noticed.

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GLONASS capability will not (can not) improve accuracy unless you're already in EXTREMELY marginal reception conditions but have a better view of satellites from that system than the existing GPS space segment. And as the existing GPS constellation is currently much better populated than GLONASS, that would rarely happen.

 

This is true no matter whose GPS+GLONASS receiver you're using. For now, having both in a single receiver is a feature meant for international marketing and dodging tariffs -- not performance.

 

Regarding 4 versus 4S GPS performance (apart from GLONASS capabaility), I'm curious about this myself but haven't had a chance to do any side by side testing. I won't be getting a 4S for myself at least until Feb'12 (if at all), but I will definitely try to find an opportunity to compare as soon as one of my co-workers upgrades his phone.

Edited by Portland Cyclist
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Regarding 4 versus 4S GPS performanc (apart from GLONASS capabaility), I'm curious about this myself but haven't had a chance to do any side by side testing. I won't be getting a 4S for myself at least until Feb'12 (if at all), but I will definitely try to find an opportunity to compare as soon as one of my co-workers upgrades his phone.

 

Next time I am out I will try and compare 4 to 4s. My wife still has a 4 so we can see.

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It was my understanding that GLONASS isn't fully active yet?

GLONASS needs 24 active satellites to be "complete". Currently there's 27 satellites up there, 23 of which are operational and one is in commissioning phase, which will probably go live shortly. So while it's not "fully complete" yet, there's plenty of birds up there to give a position fix. The new eTrex models have no problem at all receiving and using GLONASS signals.

 

It would indeed be good to get away from the iPhone == poor accuracy falacy.

Nah :laughing:

Edited by dfx
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GLONASS capability will not (can not) improve accuracy unless you're already in EXTREMELY marginal reception conditions but have a better view of satellites from that system than the existing GPS space segment....
As common as it is for folks to argue around here, it's not often you see somone argue with themself :)

 

"Lee, you're wrong!" Yep, I was. After using my eTrex 10 for a few days, watching both the satellite status page and accuracy of this tiny and cheap GPS, I can see that combined GPS+GLONASS support is a lot more helpful than I thought it could be.

 

I think the biggest gain isn't simply that it can get data from more satellites - but the fact that having that many more satellites makes it much more likely to get a "good geometry." In theory, you could get a terrfic fix with as few as four satellites in view -- if one of them was directly over head, and the other three were eequally spaced around you and all between 35-50 degrees above the horizon. If there were all clumped together in one part of the sky view, there wouldn't be enough differnce in signal strength, timing, etc to get the best accuracy.

 

But combine all those GPS and GLONASS satellites together, and you're almost always going to have a dozen or more in view, and a good spread across the skyview more likely.

 

So bringining that back to the ORIGINAL question: If the iPhone 4S can simultaneously process GPS and GLONASS signals, it should be a big gain. I doubut this will be a simple firmware update for older phones though.

Edited by Portland Cyclist
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