FORUMS
Remove All Ads from XDA

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

684 posts
Thanks Meter: 930
 
By CLShortFuse, Retired Recognized Developer on 22nd September 2010, 03:14 PM
Post Reply Email Thread
24th September 2010, 04:44 PM |#21  
Junior Member
Thanks Meter: 0
 
More
(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?
 
 
24th September 2010, 04:45 PM |#22  
Senior Member
Flag St.Louis
Thanks Meter: 101
 
More
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.

Mine has actually been MUCH better since the update. I tested the GPS on the way home from work. Its about a 35mile drive all highway with lots of side streets. Before the update the GPS position would bounce all over thinking I was on side streets when I was not. After the update the GPS position is much more accurate. I did pass undera bridge and the GPS was spot on, and didt really lag for me at all. It never once had a blue circle around my arrow.

Like a few others have stated, We will have to see if this fix stays accurate after a few weeks, as some of the "fixes" seem to work only for a few days.
24th September 2010, 04:58 PM |#23  
Member
Thanks Meter: 0
 
More
When I used my original stock rom & root, it would take a few minutes to get a lock, but after I got the lock, I could travel anywhere and the GPS would be spot on the whole way.

Yesterday I put on Cognition 2.1 with the OTA update. The GPS locks faster and in places it wouldn't lock before, but now I can't move anywhere without it sitting in the same spot then have to lock onto me again.
24th September 2010, 06:03 PM |#24  
Junior Member
Thanks Meter: 0
 
More
I had the same experience. Before it always seemed to do a cold start no matter what I set for AGPS, but once it locked on, GPS was solid and would hot start again until I had the GPS off for a few hours or reset the phone.

Now with Cognition 2.1 I get locks in under 30 seconds no matter what, but it acts like it just makes the lock, then drops it immedately, then it starts all over again and moves me on the map when it gets the next lock in 15-30 seconds. I watched it during the 20 minute drive home (the wife was driving) and the longest it went before dropping and reacquiring was 5-10 seconds.

But I agree. There's nothing wrong with AGPS. The problem is with the GPS itself maintaining a lock. *sigh* Kind of makes me want to go back to stock pre JH7. At least it eventually locked and stayed good then. It only seemed to get confused if I was stopped for a few minutes, like at a red light from hell.
24th September 2010, 07:08 PM |#25  
Senior Member
Thanks Meter: 6
 
More
I wanted to give you guys a heads up...

I just spoke with Samsung's tier-2 support, and they say it was just a misunderstanding that the JH7 OTA contained the GPS fix -- because it really doesn't:

http://forum.xda-developers.com/showthread.php?t=791597

The "real" fix is still scheduled to show before the end of this month.
24th September 2010, 08:09 PM |#26  
Senior Member
Thanks Meter: 1
 
More
I noticed a huge improvement using gps if it is on the dash and not in my lap.

as long as it can see the sky its happy.
24th September 2010, 08:12 PM |#27  
Member
Thanks Meter: 1
 
More
CRAP....typed up a long thing and crashed it by hitting backspace while not in the inputbox...

Ok I wanted to look at all this before even found source for drivers for the 4751 chipset for linux. I wanted to pass AT commands to the chipset. It may be possible using test functions that I've found. I'm just not good at programing, I just do some debugging, compiling, and testing.

Check out /etc/jupiter.xml and you see all the settings at the top, they are settings that apply to all jobs listed in the file. The jobs are specified with "job id". For those not familiar with the XML the <!-- sections are all commented out and DO NOT APPLY, they seem to be for an older chipset.

Check out /system/bin/gpsd also /data/gps and you will want to check out /data/gpspipe when this is running.

If you run "/system/bin/gpsd/glgps_samsungJupiter /etc/jupiter.xml normal" in one adb shell then in another run "cat /data/gpspipe" you will get raw NMEA pipe from the GPS.

You can create your own jobs in the jupiter.xml file, or make your own xml file and just specify it in the command line, while glgps is running you can send commands to the chip via a pipe that is opened to the chip at /data/gpsd/glgpsctrl

AFAIK on lbstestmode, dynamic accuracy off you get a lock only at the specified accuracy and loose lock if its worse. with dynamic on it tries for the best possible accuracy but if it goes over the specified setting for too long it looses lock. Thats why the higher the faster the lock.

I've got like 50 things going on here at work and playing with this, so if typo'd or missing something my bad, but just trying to give some help.
Attached Thumbnails
Click image for larger version

Name:	gpstesting.jpg
Views:	351
Size:	104.5 KB
ID:	407232  
24th September 2010, 08:13 PM |#28  
Kizzmiazz's Avatar
Senior Member
Flag Las Vegas,NV Sin City
Thanks Meter: 72
 
More
Quote:
Originally Posted by iamamp3pimp

I noticed a huge improvement using gps if it is on the dash and not in my lap.

as long as it can see the sky its happy.

Same lol on my lap it would loose me all the time but if I held it in my hand chest level it would work perfect.


Sent From My Samsung Cognition v2.1.1 | Voodoo

Using Tapatalk No Force Close App
24th September 2010, 08:19 PM |#29  
Member
Thanks Meter: 1
 
More
Quote:
Originally Posted by iamamp3pimp

I noticed a huge improvement using gps if it is on the dash and not in my lap.

as long as it can see the sky its happy.

from disassembly pics I've seen the WIFI antenna is on the bottom of the phone or maybe thats the cell antenna, there are two nubs that stick up and touch the battery cover

I'm assumming those have some type of antenna function, since I've seen no other antenna wiring in the phone pics from disassembly.

Used Bluetooth GPS to get data from my bluetooth "i-blue" that I have mounted in my trucks dash with external antenna on top. Used to use that for navigation for work with my laptop. The CNR is always about 20 more than the captivate is, which the "i-blue" used to do the same crap, run me through the woods before i gave it a boost with the external antenna. No matter the number of sats, low CNR will cause slow updates and bad tracking.
24th September 2010, 08:53 PM |#30  
Senior Member
Thanks Meter: 258
 
More
Quote:
Originally Posted by iamamp3pimp

I noticed a huge improvement using gps if it is on the dash and not in my lap.

as long as it can see the sky its happy.

I noticed the same thing. Not only that I found that when I stand the phone vertically (portrait mode) gives me better results than landscape mode.

Use GPS Test app, I noticed that I need 2 or 3 satellites in upper 30 SNR range in order to get mostly error free navigation. In rare occations, I got 40+ SNR on one or two birds. Sometimes, all I got are low 20s and low 30s. That will be a really bad day for GPS navigation.

BCM 4751 is suppose to be designed to work well in weak signals. But it didn't.
24th September 2010, 09:37 PM |#31  
Member
Thanks Meter: 1
 
More
Quote:
Originally Posted by foxbat121

I noticed the same thing. Not only that I found that when I stand the phone vertically (portrait mode) gives me better results than landscape mode.

Use GPS Test app, I noticed that I need 2 or 3 satellites in upper 30 SNR range in order to get mostly error free navigation. In rare occations, I got 40+ SNR on one or two birds. Sometimes, all I got are low 20s and low 30s. That will be a really bad day for GPS navigation.

BCM 4751 is suppose to be designed to work well in weak signals. But it didn't.

Wonder if the extra satellite support SBAS/WAAS is turned on when the driver fires up or if its off, i believe this can be determined from the nmea if logged and looked over.
Post Reply Subscribe to Thread

Guest Quick Reply (no urls or BBcode)
Message:
Previous Thread Next Thread
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes