[Discussion] GPS Problems, Lock speed, Accuracy, Fixes - The Poll

larryccf · Aug 3, 2010

don't know if this will have any bearing but i'll throw it out there as earlier you guys were commenting about other nav programs interfering

on the tmobile forum, someone posted that telenav gps is running in the background, even though it doesn't show to be, he pulled up another management app that indicated it was

he suggested an app called "startup auditor" to dis-able it

if you guys are rooted, i assume you've eliminated that program, but in case

boomerbubba · Aug 4, 2010

larryccf said:
on the tmobile forum, someone posted that telenav gps is running in the background, even though it doesn't show to be, he pulled up another management app that indicated it was

I don't like the bloatware, but I think it is a red herring as far as the real GPS issues go. Besides, I believe that is T-Mobile's bloatware inflicted on its U.S. customers, so irrelevant here. We yanks are sort of trespassing in the I9000 forum.

appelflap · Aug 4, 2010

sjdean said:
Let me clarify.

Firstly we see in the NMEA logs than sometimes it does achieve ten satellite fixes, but when reported in Android in programs like GPS Test, the accuracy only ever reaches at minimum 16.4ft and never fixes onto more then eight satellites.

This gave us some hope that maybe something else was going on so that whatever was reported to Android in terms of positioning was different to raw data and we only had to rely on Samsung to get everything sorted out.

But unfortunately, the NMEA info is out too.

For those curious, I have links to both the NMEA data track, and the MyTracks log:

NMEA
http://maps.google.com/maps/ms?ie=U...=52.474338,-1.799355&spn=0.0149,0.045319&z=15

MyTracks
http://maps.google.com/maps/ms?ie=U...2.476011,-1.793132&spn=0.014899,0.045319&z=15

I opened the two kml files in Google Earth and what is interesting to see is that the NMEA log records more points than mytrack:

(white line is MyTrack log, blue line connected to blue squares is from the NMEA log)

The fact that you've seen 10 fixed sats in the nmea log is really interesting. It may (thus) be that we never see such rare fixes because they slip between the measurements on a higher api level or are simply not polled by the different GPS apps on Android.

For those who want to compare the tracks made by Simon, I've attached the two kml files of these trackings in a zip file. They can be opened in Google Earth.

tejajuloori · Aug 4, 2010

Guys I was thinking of getting this phone or nexus or desire,and read a few posts suggesting it could be a hardware problem with galaxy s...any news on whether it will be fixed?
Sent from my GT-I5700 using XDA App

appelflap · Aug 4, 2010

tejajuloori said:
Guys I was thinking of getting this phone or nexus or desire,and read a few posts suggesting it could be a hardware problem with galaxy s...any news on whether it will be fixed?
Sent from my GT-I5700 using XDA App

I'm not convinced that there's something wrong with the GPS hardware. It could very well be that the majority of GPS apps running on android aren't as sensitive as the GPS itself

tejajuloori · Aug 4, 2010

appelflap said:
I'm not convinced that there's something wrong with the GPS hardware. It could very well be that the majority of GPS apps running on android aren't as sensitive as the GPS itself

Well the same apps run fine on other android devices...

Sent from my GT-I5700 using XDA App

appelflap · Aug 4, 2010

tejajuloori said:
Well the same apps run fine on other android devices...

Sent from my GT-I5700 using XDA App

Ok, now you're adding nothing to my comment

My comment implies pretty much what you are saying.

Kilack · Aug 4, 2010

appelflap said:
Ok, now you're adding nothing to my comment My comment implies pretty much what you are saying.

Maybe we are misunderstanding you because from your comment I picked up that you think it is a problem with the apps rather than the hardware. I am not sure how you come to that conclusion given that the raw nmea data was incorrect coming from the chip also?
Perhaps a driver issue or something between the chip and the apps but i cant really see how the apps can be at fault here....

tejajuloori · Aug 4, 2010

Kilack said:
Maybe we are misunderstanding you because from your comment I picked up that you think it is a problem with the apps rather than the hardware. I am not sure how you come to that conclusion given that the raw nmea data was incorrect coming from the chip also?
Perhaps a driver issue or something between the chip and the apps but i cant really see how the apps can be at fault here....

+1

Sent from my GT-I5700 using XDA App

appelflap · Aug 4, 2010

Kilack said:
Maybe we are misunderstanding you because from your comment I picked up that you think it is a problem with the apps rather than the hardware. I am not sure how you come to that conclusion given that the raw nmea data was incorrect coming from the chip also?

incorrect is I think not the right word. I've seen worse tracks.
Simon's tracks are for more than 90% on the road. Again, I can't imagine that a navigation program would have many trouble with it.

Kilack said:
Perhaps a driver issue or something between the chip and the apps but i cant really see how the apps can be at fault here....

My speculations are driven by some observations I made before with a program called OzuxMaps. (quote from a post in this thread

myself somewhere in this thread said:
I once made a very significant observation.
During a walk in the forest I just couldn't get a fix with my favorite off-road map program OruxMaps. For 20 minutes or so I walked without getting any fix. Then, really tired of this, I decided to do some ad hoc experiments to see if I could get a fix after all. I went into the settings menu of OruxMaps and without any clue I changed the time between two GPS measurements from 2 (default value in OruxMaps) to 1 seconds. I left the settings menu, back to the map display and *bam* immediately I got a fix. I just couldn't believe my eyes! The fix was really stable and for at least 2 minutes I was testing the fix the satellites stayed fix. I thought I just had a lucky hit so I decided to go back in the settings menu and changed the time between the measurement back from 1 to 2 sec. and again I couldn't get a fix. I changed it back again to 1 sec. and during a 1,5 hour walk I constantly had a fix.

If the gps gives a lot of changing data and a program takes just one datum so now and then from this pool without a statistical analysis it is not suprising that it can hit on a sequence of wrong data.

Also the fact that Simon observed that the NMEA data stream have shown some fixes on 9 or 10 sats, and we never seen such a fix in programs like GPS Test and GPS Status can also point to the fact that some relevant data is missed.

What I want to do is to write a GPS app that will infer all relevant GPS data from a NMEA stream and compare that to the data it will get from other interfaces.

tejajuloori · Aug 4, 2010

@appelflap - a part of your statement may be true,but the known fact is this device has a malfunctioning gps,it may be the software drivers or the hardware that is faulty..and many apps which run on the desire and othrs- google navigation for example don't get proper fix on galaxy s..

Sent from my GT-I5700 using XDA App

appelflap · Aug 4, 2010

tejajuloori said:
@appelflap - a part of your statement may be true,but the known fact is this device has a malfunctioning gps,it may be the software drivers or the hardware that is faulty..and many apps which run on the desire and othrs- google navigation for example don't get proper fix on galaxy s..

Sent from my GT-I5700 using XDA App

Here is a little track of 6km I did with OruxMaps with a setting of 1s between two measurements. I don't think my GPS is malfunctioning. In fact, I think it is very accurate!

Track on google maps

tejajuloori · Aug 4, 2010

appelflap said:
Here is a little track of 6km I did with OruxMaps with a setting of 1s between two measurements. I don't think my GPS is malfunctioning. In fact, I think it is very accurate!

Track on google maps

Thts good to know,but if everyone s gps was so good then this thread wouldn't have been created..

Sent from my GT-I5700 using XDA App

appelflap · Aug 4, 2010

tejajuloori said:
Thts good to know,but if everyone s gps was so good then this thread wouldn't have been created..

Sent from my GT-I5700 using XDA App

The trick here is that I changed a parameter when logging the track. I recorded measurements once every second. See our discussion...

Beowulf_pt · Aug 4, 2010

tejajuloori said:
Guys I was thinking of getting this phone or nexus or desire,and read a few posts suggesting it could be a hardware problem with galaxy s...

I am also waiting to buy/or not and hoped that by now we'd have at least some good information on if the problem is hardware-dependent and can never be really fully fixed.

Well, I guess that even it its just drivers/firmware there are no guarantees that Samsung/Broadcom will ever bother to fine-tune it much.

Out of curiosity, has anyone tried the SGS with one of those cheap external 1.5 GHz GPS antennas just to see how it performs when getting a bit better SnRs.

Case_ · Aug 4, 2010

I've done a little comparison myself as well today - once again, the cheapo Vodafone 845 (about 100€) vs. Galaxy S (about 500€). I've had the VF in my pants front pocket and Galaxy in my shirt's breast pocket, so I'd say the signal conditions for both were pretty even. Red path is Galaxy, blue is VF845 and green is the real path taken as accurately as I was able to reproduce it.

GPS Comparison - VF845 vs Galaxy S

The thing I find interesting is how consistent the GPS in VF845 is (it fluctuates a lot, but otherwise the tracking is pretty solid) in comparison with Galaxy's GPS, which is sometimes actually more precise than the VF's, produces much "neater" tracks...and then all of a sudden something happens and the track is all over the place (see the end). I've been desperately trying to find that "something" and one thing occured to me - 20 or so meters before the railroad crossing I've heard a text message notification on the Galaxy, but didn't bother to read it. And strangely enough, GPS accuracy seems to be degrading from then on. Could that be a factor as well? And one more thing - that last third of the track is located very near our local strongest BTS - could that perhaps have some effect as well? Though I really might be grasping at straws here. You could say that the last part is so bad because of the trees, but then again I went through the park as well, where the trees are quite dense and you can't actually see the sky at all there, unlike the last part by the river, but in the park the GPS performed flawlessly.

TravUK · Aug 4, 2010

Beowulf_pt said:
Well, I guess that even it its just drivers/firmware there are no guarantees that Samsung/Broadcom will ever bother to fine-tune it much.

Both companies are working on getting the fix out asap. The amount of testing that goes into ensuring they make things better and not worse shouldn't be underestimated.

sjdean · Aug 4, 2010

appelflap said:
If the gps gives a lot of changing data and a program takes just one datum so now and then from this pool without a statistical analysis it is not suprising that it can hit on a sequence of wrong data.

Also the fact that Simon observed that the NMEA data stream have shown some fixes on 9 or 10 sats, and we never seen such a fix in programs like GPS Test and GPS Status can also point to the fact that some relevant data is missed.

This is not a reason to suggest that the Apps are in anyway at fault, or are not as sensitive in reading in NMEA data.

I have seen the same GPS Test App run on a HTC Desire showing a 10 satellite fix with some below 20 SnR.

The problem is therefore not the Aps, but in how the information is reported from the GPS chip to Android. This will either be Samsung and their libgps.so interface, perhaps Broadcoms GLL library or GPS driver. Or perhaps there's a problem with how the raw data itself is generated, some kind of Rf issue on the chip, or other programming error.

appelflap said:
What I want to do is to write a GPS app that will infer all relevant GPS data from a NMEA stream and compare that to the data it will get from other interfaces.

Whatever program you write, you will see the location and NMEA information in one place, and the satellite status information in another. The position will be off in both.

Here's another map, walking. Im yet to dig out the NMEA data... but...

http://maps.google.com/maps/ms?ie=U...52.498655,-1.705413&spn=0.005173,0.01929&z=16

sjdean · Aug 4, 2010

TravUK said:
Both companies are working on getting the fix out asap. The amount of testing that goes into ensuring they make things better and not worse shouldn't be underestimated.

Just wish Samsung would actually come out and say something, not hide behind giving out instructions on how to use Google Maps when you phone up to find out if the phone you have is faulty or whether its a firmware bug.

If Samsung would just say yes, there's a bug, we're working on it, then we can leave them alone and say, ok, fair enough, anything we can do to help? Any chance of a pre-release so we can see the progress and provide feedback?

andrewluecke · Aug 4, 2010

sjdean said:
Just wish Samsung would actually come out and say something, not hide behind giving out instructions on how to use Google Maps when you phone up to find out if the phone you have is faulty or whether its a firmware bug.

If Samsung would just say yes, there's a bug, we're working on it, then we can leave them alone and say, ok, fair enough, anything we can do to help? Any chance of a pre-release so we can see the progress and provide feedback?

Is there any reason to assume they aren't though?

[Discussion] GPS Problems, Lock speed, Accuracy, Fixes - The Poll

Your GPS oppinion

I use GPS a lot and it works great.

I use GPS a lot and sometimes it's Ok, other times unusable.

I use GPS a lot and it's really bad.

I don't use GPS a lot, when I try - it's OK.

I don't use GPS a lot, when I try - it's really bad.

Other/See Results.

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