[Galaxy S I9000 General] cbdrift:
(long) GPS History of an i9000 \phone in New Zealand

When I first got my phone it thought I was in south korea

living in nz at the time i realised "so THIS is what the gps issue is like"

After some hunting around I changed the supl server to google from sprint - and it thought I was in new zealand

found that the 2.1 firmwares for me gave pretty much the same results as everyone else - some wont lock - some will lock - all drifted around and none liked locking from inside

I got "gps assist" and "trackerbooster" and found that altho they allowed other programs to "lock on to the gps" nice and fast - they didnt cure the issues it had once locked - its accuracy when moving....

2.2 jpm did improve things for me... BUT

from my north facing bedroom i could see and lock to 11 satellites and then I noticed that if i pointed the phone north - it would get a much better lock than *ANY* other direction

I live in nz and basicly it looks like the phone has a hardware issue with the antenna

reasons :

if I aim the phone north (where most of the gps satellites are going to be grouped in covering the american and euro land masses) it instantly picks up another handfull of satellites and accuracy becomes a smaller number - eg from 50 meters down to 10 or 5 meters

if I stand still - the phone gets all these little raw packets that it recieves and can build up a list of satellites datapackets and the more GOOD packets it gets - the more accurate the fix is

from the looks of things - drift happens when (and can be seen using the android app "gps test" which gives a realtime list of "prn, snr, elev, azim and flags"

if you watch the snr value colum - you can see when the list updates the satellites - and you'll see that the WHOLE list is NOT updating all the time - its getting one or two updates at a time and others stop updating - so to build a position of where you are - you need a constant stream of these datapackets

you then take the most recent packets and triangulate them and get your position

when you are moving however - you have a list of packets that cant be triangulated unless they are very recent or you have a constant stream of them constantly arriving at a high speed

if you DONT have either of these - then the calculations will be working off a position at the start of the trip, one 20 meters down the road and one where you are now 40 meters away - you cant use those 3 positions to get a fix of where you are because the solution to the position is not going to be findable

the gps software seems to be not getting a stream of raw data packets from the chip due to bad reception of the data

this can be caused by

not pointing the right way

bad antenna design

local conditions and shielding (car / building / walls / weather / whatever)

hardware design of the gps chip

software that processes the output of the gps chip

if the gps chip has a bad antenna or is getting a weak signal or not getting constant updates from each satellite then it will show as a "jumpy" gps lock - but it will say that its recieving data

if the stream of updates from the gps chip to the gps software is jumpy then the software has nothing to work with and will give crappy results - software fixes will not cure the missing data from the stream

caching the data you collect and then processing it for fixes will give some of the results we are getting - laggy updates (as the software caches the fixes from the chip) and jumpy results (as the software calculates position fixes from out of date position data it gets from the chip)

this would explain why when you are driving in a straight line - the software "seems" to work - its doing inertial calculations as well and when you turn - it gets thrown out - the stream of signals from the gps chip are not constant - so the combination of the inertial input, cache of previous fixes and turning direction all add up together to make it so that the position fix is broken even tho reception of signal is shown....

Im guessing that I would get nigh on perfect gps tracking if

a) i kept the phone pointing north

b) the phone has line of sight to the sky when pointing north

c) there is no electronic or electrical interference in the area

and I do - i can walk around my backyard on google maps and have it accurate anywhere in the back yard - I can tell what side of a chair im standing on and where in the yard im walking to and it tracks starting and stopping straight away...

but if I turn the phone to point NOT north - HA! bye bye all accuracy - it starts drifting all over the place and the satellites that send me regular updates drop way down - it can show 5 meters accuracy - and position me in the neighbours back yard two houses away.

point it north again and you can see it work back to where you are standing as it builds up a list of datapackets from the satelites and has more to triangulate with

Oh yeah - this is with the phone sitting on a block of wood - no human touching it - so no grip of death occuring.... (yeah - i can see signal strength issues with cell coverage depending on where I hold the phone - but gps it just seems to be which direction i point it that affects signal - not where I hold the phone)

to me the fault is hardware and samsung have done wonders with the software making it as good as it is...

if you live in an area that has good coverage by the gps satellites - you will get good results IF your phone is configured with the correct settings

if you got a phone and live in the area that the gps software driver writer lives in who wrote samsung's drivers - you'll get good gps

if you got a phone and ive in an area covered by sprint and their supl servers work for you - im guessing you'll get good gps

IF YOU DONT KNOW WHAT GOOD GPS IS and its correctly configured - you'll think you have working gps.....

if your like the rest of the world and you got your phone with the wrong supl server, dont live in korea or america and dont have gps satellites raining from the skys overhead - you'll KNOW what the gps issue is about

with the sprint supl server in nz - i was gps located in korea

with the google supl server in nz - i was gps located in nz

with the nokia supl server in nz - it locks on faster than google and with more satellites - but the accuracy is still ****e due to the "not getting enough raw packets" so the calculated lock is wrong if your moving....

and because im so bored today (yeah - at home from work sick today damnit) I thought i'd just write a response to the troll here :)

Dude

heres a way you might understand NOT WORKING properly

IF you owned a ferrari f40 - and the f40 pulled to the dangerously left all the time while driving - YOU would be the person who took the f40 and told the wheel alignment specialist that it was perfect and that they must be lying when they told you it was not working correctly and was wrong - becasue you can see all the parts sitting there being used - it must be right.... Even after ferrari send you a recall notice saying its faulty - you'll be the one who crashes and burns in their ferrari because "its working perfectly"

Please, do enjoy your perfectly working galaxy... :)