Glonass / gps ???

pr0230

Suspended
Original poster
Feb 7, 2013
197
47
Location
Assisted GPS and GLONASS


Im trying to understand the iPhone 5s GPS capabilities. Especially for GPS when you are out of range from a cellular signal, T-Mobile's network sucks... So I want to know if I am SOL without a signal...

From the above spec Assisted GPS works with the cellular towers? Y/N

GLONASS is a Soviet --- Sorry Russian -- GPS equivalent - Suppose to be better than GPS and recently updated?

If I have cellular contact this will be the assisted GPS determination of my location? Y/N

GLONASS is selected if cellular is not available?

Why did an american company... Sorry Irish company... pick GLONASS?

In a strict definition the 5S does not use ANY american Global Positioning Satellites?
 

Mr. Retrofire

macrumors 603
Mar 2, 2010
5,039
470
www.emiliana.cl/en
Why did an american company... Sorry Irish company... pick GLONASS?
1. Apple cannot sell iPhones in russia, if they do not have GLONASS.
2. More signals from more satellites are always better, because they reduce the error rate and enhance the precision.
3. Navigation is a global problem, and you do not solve this problem with the U.S. military controlled GPS. You need additional systems if you want higher precision, such as Galileo (EU), GLONASS (russia) or Compass (china).
4. GLONASS is available in all phone baseband chips from major vendors ST-Ericsson, Broadcom and Qualcomm.

I see no good reason why Apple should not use an additional international standard for better navigation results.
 

gnasher729

macrumors P6
Nov 25, 2005
16,990
3,899
LFrom the above spec Assisted GPS works with the cellular towers? Y/N
"Assisted GPS" uses cell towers to get a rough location of the GPS satellites. That makes it easy to connect to them quickly. Unassisted GPS connects to those satellites just fine, only takes a bit longer. Once the satellites are found, there is no difference between assisted and unassisted GPS.

And a good GPS receiver uses _all_ satellites it can find. The more satellites, the more precise it can find your location (because every satellite has some errors, and the more satellites you have, the more errors can be eliminated).
 

jav6454

macrumors P6
Nov 14, 2007
16,876
1,532
1 Geostationary Tower Plaza
1. Apple cannot sell iPhones in russia, if they do not have GLONASS.
2. More signals from more satellites are always better, because they reduce the error rate and enhance the precision.
3. Navigation is a global problem, and you do not solve this problem with the U.S. military controlled GPS. You need additional systems if you want higher precision, such as Galileo (EU), GLONASS (russia) or Compass (china).
4. GLONASS is available in all phone baseband chips from major vendors ST-Ericsson, Broadcom and Qualcomm.

I see no good reason why Apple should not use an additional international standard for better navigation results.
This...


I am going to be very happy when the iPhone starts supporting Galileo and Compass. With this, the iPhone will be very accurate (to the meter) in positioning and height information.

Please people, bear in mind, the Russian GLONASS is just as good (if not better in some technical aspects) vs the US-sponsored GPS.
 

VTECaddict

macrumors 6502
Sep 15, 2008
373
23
As above, the GPS will still work absent a cellular signal. However, you will need an app with offline map data or else the GPS will be useless anyway.
 

jav6454

macrumors P6
Nov 14, 2007
16,876
1,532
1 Geostationary Tower Plaza
As above, the GPS will still work absent a cellular signal. However, you will need an app with offline map data or else the GPS will be useless anyway.
Oh that's an easy work around.

During the moments you have data connection, just open your Google Maps app, and zoom out until you see the area you want to cache, then type "Ok Maps" and hit enter.

Google Maps will download and cache that area of the map down to every detail.
 

scaredpoet

macrumors 604
Apr 6, 2007
6,627
342
From the above spec Assisted GPS works with the cellular towers? Y/N
Assisted GPS uses available cell towers (and nearby Wifi hotspots) to get a faster lock on its position. The GPS/GLONASS receiver doesn't need them, but it helps speed things up.

The idea is simple: GPS and GLONASS satellites are always moving. Cell phones are often moving. It takes a while (sometimes minutes) for a positioning receiver to figure out the motion of the satellites, do the necessary math, and come up with a fix.

But cell towers are stationary, and *always* know their exact position. So if a cell phone with "Assisted GPS" capability has one or two cell towers with known location data nearby, it can use them as landmarks to cut down on the math and get a fix faster.


GLONASS is a Soviet --- Sorry Russian -- GPS equivalent - Suppose to be better than GPS and recently updated?
GLONASS is a Russian GPS equivalent. Currently it's about as good as GPS. There was a time when Russia didn't really put any money into the GLONASS program, and for years they weren't replacing GLONASS satellites as they failed, causing the system to deteriorate badly.

More recently though, Russia's government suddenly decided the system was important again, and have spent a lot of money to rapidly launch new satellites and restore the system to full service.

In the chipset Apple uses, it's possible to combine GPS and GLONASS signals to improve accuracy. And that's one of the things the 5S does.

If I have cellular contact this will be the assisted GPS determination of my location? Y/N
Yes.

GLONASS is selected if cellular is not available?
Both GPS and GLONASS are always selected and usable, even without cellular.

Why did an american company... Sorry Irish company... pick GLONASS?
Because a while back, there was a law being proposed by Russia's government, where if you want to sell a smartphone with mapping/positioning capabilities in Russia, you would get charged a punitive 25% import tax if that system didn't have the ability to use GLONASS. In response to this, Qualcomm and other chipset makers baked-in the ability to use either GPS or GLONASS to help smartphone makers avoid this tariff.

Last I heard, the tariff idea had been dropped, but the chipsets were already designed and being made. The capability is there; why not use it?

In a strict definition the 5S does not use ANY american Global Positioning Satellites?
Wrong. The 5S uses both American and Russian satellites.

Think of it this way: the iPhone 5S has the ability to get location data from the following sources:

- GPS
- GLONASS
- Cell towers
- Nearby Wifi hotspots

The iPhone 5S is capable of using any and all of these to get its location. The more options is has available to it, the more accurate the location data.


One last thing, and it could be a biggy: The apps you use with Location Services (like Apple's Maps app) often require a data signal to retrieve a map on which to plot your position, either via WiFi or cellular. You can, as an alternative, purchase apps from the app store that store all these maps on your phone and don't require data, but they do cost some money, and will take up gigabytes of space on your phone.

If you don't have such an app, and don't have Wifi or a cellular data connection available, the GPS/GLONASS/Location Services system will deliver just a set of latitude and longitude coordinates, and you'll have to figure out what those coordinates mean on your own.
 

takeshi74

macrumors 601
Feb 9, 2011
4,974
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Im trying to understand the iPhone 5s GPS capabilities. Especially for GPS when you are out of range from a cellular signal
Cellular signal only matters for faster aGPS fixes and for your GPS apps that require data connectivity. The GPS receiver still works with or without cellular coverage. This applies to all devices -- not just the 5s. As stated above, if you don't have map data to place your location then all you'll have is latitude, longitude, altitude and time from the GPS receiver and it's up to you to figure out what that means in regard to your position.

From the above spec Assisted GPS works with the cellular towers?
All aGPS does is allow for faster initial fixes by pulling ephemeris data from the assistance servers. If the assistance servers are not available then the GPS receiver will get a fix in standalone mode.

Don't overlook prior discussions as these are fairly common topics.

In a strict definition the 5S does not use ANY american Global Positioning Satellites?
No, it does. GPS refers specifically to the Global Positioning System. It uses the GPS satellites and that's why GPS is listed in the specs. If it only used GLONASS then only GLONASS would be listed in the specs.

Oh that's an easy work around.

During the moments you have data connection, just open your Google Maps app, and zoom out until you see the area you want to cache, then type "Ok Maps" and hit enter.
No need for workarounds with locally stored map data. It's up to each to determine what works for that person. I'd rather just use my usual nav app without dealing with this. YMMV.
 
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