[Galaxy S I9000 General] sjdean:
Bumper GPS Thread

Right, I've had enough of all this wild speculation and opinions about the GPS and why what how where when it is working.

It would be nice to put this to bed with a definitive statement that won't be lost.

Do Some Peoples GPS Work?

Yes it is true that some people have a working GPS. But in that category, we have:

people who don't understand the issue and think that a check on time to fix is all that is needed

people who accept mediocrity as being normal

people who really do have a fully working GPS

Thos who's GPS systems are working, at the moment, we don't know if this is a hardware issue, software issue, or environmental issue - ie, how you hold your phone, where it is positioned in the car, whether they have routes which see them frequently in urban canyons or surrounded by trees blocking the signal.

What do we think it is?

We suspect that from Samsungs announcements, that it is software related. They certainly talk about optimisations in future firmwares and some of the things we see seem to have a software element. But this itself is a double edged sword.

Firstly, Samsung talk about optimisations rather than pure fixes - this could be pure marketing speak, but I hate marketing speak and want to know the full gory details that isn't sugar coated which will assure me that they definitely know the problem and will fix. If these fixes are only optimisations, then this will never be fixed in software and therefore the units have hardware issues.

Secondly, Samsungs track record in optimisations through XXJG1 and XXJM5 show a worrying trend to merely fudge the signal and guesstimate your location based on some readings, rather than a pure fix.

So what are the issues?

It is not the Time to Fix. We get tired of hearing from people who can get a fix in their house in 10 seconds. Im pleased for you, but if that's the scope of your testing, then you have low requirements for a GPS.

A GPS may even track you on the road without problem, but most car navigation programs are known to snap you to the road.

What we see when we dig further, is that the GPS is largely incapable of maintaing a lock. The signal fluctuates all over the place and falls back on fudging your location.

To test this 100%, install MyTracks and monitor your route. Expect some deviations - no GPS is 100% flawless, but when you're constantly off track, then tell me how happy you are.

Different Firmwares

In the original XXJF3 firmware, what we see is that while you have a GPS lock, the track is flawless. As soon as you lose signal (which is very frequent with this phone), the system reverts to using Cell Tower triangulation and you get to see lots of zig zags all over the map.

In XXJG5 firmware, if you lose signal, you could be placed 200 yards off according to triangulation, but the system was then convinced that if had to draw path from your last known good position to where it thinks you should be. Even if you get the GPS signal back, it will draw this false path.

XXJM5 shows that if you lose signal, it will take your last known good position, heading, and speed to plot a path.

What we tend to see with the last two, is that if we take sharp turns, it will have you continuing straight on on your previous path and it may or may not eventually turn back in on itself with a great big loop.

Even the Captivate and Epic GPS fix files I have found to be quite poor with locations often lagging behind. If I go onto a round about, the delayed position will draw a roundabout track further on than the actual roundabout.

NMEA Data

This may be a simple problem of interpreation in the Samsung driver between the GPS chip and the Android OS. However if we extract the NMEA strings, which I assume to come from the GPS chip itself (until someone gives further information), then we see that the NMEA data and reported locations are also off. This ties into my suspicion that it is a hardware issue. Can Samsung release a driver to better control the GPS chip?

No of satellites and SnR

The GPS system also shows a problem locking onto Satellites with an SnR < 20 and locking onto more than 8 satellites. You may see more, but it doesn't lock onto more than 8 - unless of course you're using the Captivate fix.

This may or may not be an issue. The underlying GPS chip according to the raw NMEA data unprocessed by Samsungs drivers, seem to show that the GPS chip can itself lock onto more than 8 satellites and satellites with an SnR < 8.

With more satellite fixes, we should in theory be able to improve the stability of the GPS through urban canyons

Unfortunately the NMEA data clearly shows more locks, and I fear merely tweaking the Samsung driver that does the reporting will not resolve the actual issue.

iPhone 3Gs/iPhone 4

Did you know the iPhone has questionnable GPS? It too uses a Broadcom GPS chipset.

So What is the Fix

I don't know. Im not confident of any fixes from Samsungs but I will give them the benefit of the doubt. I guess all we can do is to try to improve the stability of the GPS signal ourselves as much as possible. This means hanging the thing in the window and hoping for the best.

Bluetooth GPS programs

Bit of a fudge if you ask me, doesn't work with all programs. It is a system that enables "Mock" locations on the Android platform. Quite an intriguing idea and should work with Navigation.

LBSTestMode Fixes

Been there, done it, next. It seems to reset the GPS driver temporarily. Either that or it coincides with a time when you get some GPS satellites directly over head.

I half wonder if the time you get excellent results, is a time when you just get a good constellation of satellites overhead. Would explain the haphazard nature of the GPS.