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[GPS/AGPS] REAL solution analysis thread (Jupiter Tweaks) - v006! - Froyo JI6

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By CLShortFuse, Retired Recognized Developer on 22nd September 2010, 03:14 PM
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22nd September 2010, 04:42 PM |#11  
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Quote:
Originally Posted by foxbat121

Engadget is full of it.

I think it is more that samsung "is full of it", because they are stating the gps is fixed. Engadget is just relaying what Samsung is saying....
 
 
22nd September 2010, 04:55 PM |#12  
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Wasn't the source released for the captivate kernel? I would love to see the GPS source code

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22nd September 2010, 05:08 PM |#13  
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Quote:
Originally Posted by CLShortFuse

Wasn't the source released for the captivate kernel? I would love to see the GPS source code

Sent from my SAMSUNG-SGH-I897 using XDA App

GPS and most all of the drivers are not part of the source release.
24th September 2010, 05:47 AM |#14  
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Can we recompile the driver, does anybody know?

This is the source code for Nokia's driver for the same chip.

http://www.mail-archive.com/linux-i2.../msg03733.html

But I don't think they use NMEA
24th September 2010, 07:17 AM |#15  
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Ok I hear what you are saying, I never messed with the settings and claimed that it was fixed. I am under the impression that my gps is working and always was but with the new jh7 firmware (ota version) it definitely works better, I had the samsung-firmwares.com release and it made no difference but designgears rooted decided version of thee ota release made a difference. What settings need to be changed to disable all network assisted location to test if I'm actually getting a gps fix without agps?

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24th September 2010, 01:27 PM |#16  
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Quote:
Originally Posted by Dani897

Ok I hear what you are saying, I never messed with the settings and claimed that it was fixed. I am under the impression that my gps is working and always was but with the new jh7 firmware (ota version) it definitely works better, I had the samsung-firmwares.com release and it made no difference but designgears rooted decided version of thee ota release made a difference. What settings need to be changed to disable all network assisted location to test if I'm actually getting a gps fix without agps?

Sent from my SAMSUNG-SGH-I897 using Tapatalk

Network assist is not a problem. There is no need to disable it.

Just take a test drive using Google Navigation. Ignore the fact that it always seems to be dead on your position (because all navigation software snap you to the nearst road). Instead, pay close attention to:

1. Whether or not you see a blue circle surrounding your position. If you do see that, your GPS has failed at that time and the size of the circle is the estimated inaccuracy of the GPS. You need to be patient because blue circle comes and goes randomly.

2. Pay attetion to certain landmarks like bridges, overpasses and intersections. And compare that to your position on the map to see if you experience lags.

3. The navigation software snaps you to the wrong road nearby even though you didn't see the blue circle.

In my personally experience, all three showed up randomly. I have no problem getting a quick lock at all.
24th September 2010, 03:03 PM |#17  
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Quote:
Originally Posted by foxbat121

Network assist is not a problem. There is no need to disable it.

Just take a test drive using Google Navigation. Ignore the fact that it always seems to be dead on your position (because all navigation software snap you to the nearst road). Instead, pay close attention to:

1. Whether or not you see a blue circle surrounding your position. If you do see that, your GPS has failed at that time and the size of the circle is the estimated inaccuracy of the GPS. You need to be patient because blue circle comes and goes randomly.

2. Pay attetion to certain landmarks like bridges, overpasses and intersections. And compare that to your position on the map to see if you experience lags.

3. The navigation software snaps you to the wrong road nearby even though you didn't see the blue circle.

In my personally experience, all three showed up randomly. I have no problem getting a quick lock at all.

This has been my experience too...and while Cog 2.1 has made it better, I still experience these same problems.
24th September 2010, 03:48 PM |#18  
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I changed the first post and hope to make this a community effort.
24th September 2010, 04:34 PM |#19  
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The problem seems to be position estimation. When you take a sharp turn, the GPS position will keep going "expecting" you to follow the same path. After a few seconds, the GPS position will slowly return back to your real position.

If we could just remove position estimation / interpolation, we might see improvement.

You can see what I am talking about in my post here:

http://forum.xda-developers.com/show...58&postcount=2
24th September 2010, 04:44 PM |#20  
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Thank you ShortFuse.

This is the most truly helpful GPS thread in a while. I hope we can get to the bottom of this soon.

Everyone needs to contribute to this thread!
24th September 2010, 04:44 PM |#21  
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(sorry - apparently I am still, after some time, waiting for my account to be verified by a moderator so I can post outside links...)

The driver source does not do anything more than push raw chunks of data to/from the chipset. Apparently, the data is in "MEIF" format - a proprietary Nokia protocol. It doesn't seem the driver is particularly interesting or helpful in doing something useful with the BCM4751.

www spinics net lists linux-i2c msg03690.html

No details of the format are provided, only a document relating to licensing information from Nokia.

www forum nokia com info sw.nokia.com id b265d3aa-8198-4eb0-a0e3-077748ccea40 MEIF_Specification_License.pdf.html

The following talks a bit about MEIF, or the ME interface, describing it is "a de facto standard for GPS/GNSS chip manufacturers." Several related names seem to be "MEIF", "ME interface", and "ME-PE".

books google com books?id=stTSHdFhrFUC&pg=PA280&lpg=PA280&dq=meif+a gps&source=bl&ots=z6QfZFkbPl&sig=pAsP8i1RWIhtF1Yeb n3t1JApc4U&hl=en&ei=q8GcTK-BKcGB8gb67ZWVDw&sa=X&oi=book_result&ct=result&resn um=2&ved=0CBMQ6AEwAQ#v=onepage&q&f=false

It seems a common enough format in the industry, but no specifications were immediately forthcoming. Perhaps the Nexus has a more complete open source tree and includes something relating to MEIF?
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