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[Q] GPS under-utilization of GLONASS satelites with stock rom

OP natureburger

9th April 2014, 10:04 PM   |  #1  
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It is apparent that when looking at the signals, GLONASS satelites are often ignored even though they are coming in at the same or better strength than US-GPS ones.

Can the code be tweaked?

Who knows about the code and what is needed to hack it?
10th April 2014, 07:57 AM   |  #2  
robogo1982's Avatar
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I had an issue when I got the phone where it completely ignored GLONASS. You can try two things:

1. From the hidden menu (3845#*80x*#, where x is the mark of your phone's model), go to GNSS Test, press Menu, choose Delete Aiding Data, then Menu again and START GPS. Do this while connected to a wifi or mobile network, let the phone connect to satellites. When it does, exit the service menu and see if it will connect to GLONASS then.
2. Download GPS Test from Play Store, go to Settings and clear or update A-GPS data, then try again.
12th April 2014, 03:49 AM   |  #3  
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Quote:
Originally Posted by robogo1982

I had an issue when I got the phone where it completely ignored GLONASS. You can try two things:

1. From the hidden menu (3845#*80x*#, where x is the mark of your phone's model), go to GNSS Test, press Menu, choose Delete Aiding Data, then Menu again and START GPS. Do this while connected to a wifi or mobile network, let the phone connect to satellites. When it does, exit the service menu and see if it will connect to GLONASS then.
2. Download GPS Test from Play Store, go to Settings and clear or update A-GPS data, then try again.

Thanks for the tips. I upgraded to Kit Kat then tried all the above.

Did #1 - It did get a lock (Time to first Fix) in 4 minutes. That was pretty good and it was clear sky.

Did #2 - Still very poor GLONASS utilization. Only locked on 1 GLONASS out of 4 available (all strong signals 20db avg. - same avg as US-GPS ones) But it locked on 8 or 9 US-GPS (100% of available).

LG has authorized me to take it to repair centre and I am hopeful they can fix it. From what some others wrote, they might not get a lock but someone else with same G2 will, even in less ideal conditions. So maybe there is some sort of hardware problem that is causing the avg 20db to 30 db reception even under clear skies. Mine had good contacts under the cover so I am thinking that maybe the GPS unit module come in varying quality and maybe even the patch antenna is subject to quality issues.

Who knows. Still a fact that my 4 year old Blackberry gets better GPS fix than this LG G2.

Crossing my fingers and toes that they can fix it.
12th April 2014, 09:14 AM   |  #4  
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Found this explanation of how the processor chooses between GLONASS and US-GPS:

http://www.qualcomm.com/media/blog/2...ion-your-phone

Quote:

The Snapdragon processor automatically knows when to power on the GLONASS service, and when to leave it off. GLONASS will only engage when an adequate GPS signal canít be found. This extends battery life while providing the best navigation experience possible

Obviously something is going wrong since it appears that it is not switching reliably to use GLONASS when it needs to find a fix.
22nd April 2014, 11:07 PM   |  #5  
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The phone is back from the shop. They replaced the mainboard. The GPS now works 1,000 % better than before.

=== Before ===
First lock with no aiding data, only 1/2 sky available: 245 seconds.
Second lock: 10 - 14 seconds.
Fix while in office 2 metres from big window: never

=== After ===
First lock with no aiding data, on;y 1/2 sky available: 74 seconds.
Second lock: 1.4 seconds.
Fix while in office 2 metres from big window: 2.4 seconds to fix

Bada Boom Bada Bing!


Glonass is showing, but after a good fix, it switches to just GPS. Fine with me, because it at least show 2 or 3 GLONASS while getting the fix and a short time thereafter.

So, if your GPS sucks, maybe you should try getting it repaired.

edit: of course, we will have to see what it does on a cloudy day or while driving. But still, the way the GPS found and fixed the location was waaay faster than before and I never got a fix at home inside 2 meters from the window before - never!
Last edited by natureburger; 22nd April 2014 at 11:18 PM.
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