Related
Hi all,
Just wondering if anyone has tried either of the two plug-ins that claim to detect your location more accurately (and save the battery) in Locale? Each plug-in is called "cell" and "location". The locale app has a location condition in it, but you need the GPS turned on, or it uses a crap signal from the phone and/or wifi, which supposedly these apps improve.
I love Locale, I have it set to turn off key lock at home, bring up weather in the morning, silence my phone at work and load last.fm and connect to the wifi when I go to the gym - it's just brilliant! However, I don't claim to understand phones at all, so when it says "Cell" uses whichever GSM cells you are in, while "Location" uses CDMA and GSM (is that right?) cells, and also the option to use the wifi (which I thought the original locale app used too?), I have little idea what it means. I just want to know if anyones tried them, and whether they have an opinion on which is better, in terms of accuracy and battery saving, and what the relevance of the different cell signals are?
Many thanks!
****************************************************************
"EDIT" UPDATE (7 oct. 2010)
Well you dont need to go actually much further then this first post!
Things got out of context over here, furthermore I decided to give
my external gps receiver a break and run some more tests with
the internal one of my SGS.
And the results I got were much better than any
other phone I tested before. Except the ones with a build-in SirfstarIII chipset.
If you have Gps issues,Just move on to this thread:
2nd edit (20 Oct, 2010): That thread was removed without any warning or explanation so I posted the videos in another thread:
http://forum.xda-developers.com/showthread.php?p=8903056#post8903056
END EDIT
RCinFLA said:
Like to share my experience as cellphone chipset designer and my dealing with various parties involved with GPS in phones.
Many of the issues are caused by business interests involved and there are quite a few parties plying to control location based services revenue stream.
SUPL, secure user plane protocol AGPS was created by network operators interest in mine, with the objective of putting them in the controlling position when it comes to extracting revenue from location based applications on their network.
Control plane AGPS is a general system where network operator independent entities can create a assist server along with possible services offering. They can encrypt their access to allow only subcribed (paying) users to access their service. The network operators has little control over this scheme.
With SUPL, in most cases, network operators outsource the location server function. Network operator hold location of their cell tower, as a total database, in close confidence. The network tower locations are also very dynamic over time. I believe the AGPS contractors don't get reliable and timely updates from the network operators.
Then there are third party business like 'Skyhook' which is trying to work around the network operator roadblocks by establishing a 'ponzi scheme' server database. If your phone has a good GPS location lock and detects a WiFi network, Skyhook's background app will have your phone send a message to their server reporting the SSID of the WiFi and its location. They then sell their server AGPS service to other companies, like Motorola, for inclusion in their phone software. Motorola may run into conflict with network operators. A network operator might refuse to buy a Motorola phone model with Skyhook installed on it. I noticed from the Captivate forum that the ATT version of Galaxy S has Skyhook capability.
Google is the 900 pound gorilla and is trying to wrestle control of location based services from network operators.
Finally there are the GPS chip manufacturers. Almost all of them have an AGPS server scheme of their own and try to promote it. The frontend processing (up to recovery of raw 50 bps satellite data) has unique hardware and firmware that are considered proprietary by the GPS chip manufacturer. In most cases a phone manufacturers like Samsung or Motorola are not allowed to have the software source code for this firmware or information on the actual interface protocol to the GPS chip. They are given a bundled binary file that the phone manufacturer software just dumps to the GPS chip at startup.
It is now up to the phone manufacturer to implement the GPS chip and antenna systems (along with WiFI, Bluetooth, Near Field Comm, and multi-band cellular) and provide software interfaces and drivers necessary to run the GPS function.
For size and cost reasons most recent GPS chips rely on the main application processor within the phone to actually do the GPS fix calculations. The software for this is provided by the GPS chip supplier but it must be coordinated with the particular applications processor chip used by the phone. It must share processing time slicing with the apps processor and work with operating system software resources such as RAM and ROM management running on the phone.
This is the first obsticle as most of the GPS chip suppliers have little expertise in the OS's that may be used (like Android or Symbian). The phone manufacturer usually has to provide help to create and debug the GPS driver software but the drivers are responsible/owned by the GPS chip supplier. There can be unique hardware/software interfaces that must be dealt with, like providing GPS TCXO calibration and cellular corrected frequency timebase to the GPS chip.
Then there is the OS's GPS interface. There can be translation software layers involved here. One such interface is based on GPS NMEA protocol but with additional hooks for things unique to phone operation like battery saver power strobing, and the complicated Secure User Plane or Control plane interface.
The AGPS system design landscape is litered with intellectual properties (patents) by many parties. Qualcomm is a dominate player here since their aquistion of SnapTrak company years ago. Royalties are paid to Qualcomm for every WCDMA phone sold, not only in AGPS area, but on basic CDMA patents used in a UMTS (Wideband CDMA) phones.
Now as to Samsung Galaxy S implementation of Broadcom GPS.
I think there is a lot of evidence that Samsung had early issues with the GPS antenna contact hardware. This has probably been corrected on recently manufactured phones.
I think the firmware supplied by Broadcom has the bandwidth of the correlators tighted down to provide greater sensitivity. This is great as long as there is a very good AGPS system to provide initial satellite ephemeris data. Without a good AGPS network providing satellite information the initial search and lock can take a very long time with narrow bandwidth frequency bins.
I have not seen evidence with my experience that my two Vibrants are receiving any reliable AGPS information from the T-Mobile network. They do seem to get rough Almanac satellite info from Google or other third party apps. These may be based on WiFi detection more then T-Mobile cell tower locations.
In LBStest I noticed that GPS Operational Mode has been set to 'Standalone'. I interpret this to mean AGPS is deactived. I don't see any difference when I switch to MS based assist, and clear the GPS saved memory to prevent it from prejudicing time to first fix lock test. Switching SUPL server to supl.google.com and port 7276 (with MS based operational setting) just seems to make my phone lockup for short periods of time.
Once phone does get full lock on satellites its performance is quite good. (my two Vibrant's were purchased in early Feb 2011). It rivals my Garmin SiRFstar III based GPS unit in locked on sensitivity while inside a building.
I think the AGPS system issues will get worked out over time.
The Qualcomm based CDMA2000 systems (like Verizon) will likely have better initial coordination on AGPS system operation. CDMA2000 also provides network timebase directly compatible with GPS.
Click to expand...
Click to collapse
*******************************************************************
All this nagging about GPS.....that it is not working in many devices and it's working in other many.....and of course I am talking about those ones who still would go for ONLINE gps navigation.....
In my humble opinion, what you guys should be asking yourselfs and the big corporations is, why nowadays, 99% of the smartphones(so not just sgs), even the most expensive ones are build with weak, less capable internal gps receivers, forcing users to go online(celular network /a-gps) or using external bluetooth gps receivers to get stable satellite fixes that means stable navigation.
Years ago, many of the first smartphones came with sirfstar chipsets or alike , so once again, why not now? That's the question that should not be ignored or forgotten.
A friend of mine, that would not dare to pay more than a 100 box for a phone, bought an ancient ETEN device on a sale for 40 box with that old windows mobile 5 and guess what...the internal gps get fast fixes just like any standalone gps device because it got the same sirfstarIII chipset
Why the heck, the expensive so called high-end smartphones of today are not build with better gps chipsets? Why A-gps? So we are forced to get data accounts?
And what happens when I want to navigate abroad? Roaming?
For data transfer and internet I use wifi; I have it at home and I find hotspots everywhere...I will save those extra 120 euros(or more) per year (data account costs)
And nobody will force me to get one(internet/data account); not even for gps navigation that I so much use..
I use gps navigation only offline, using a external bluetooth device on a daily basis and, many times abroad; it works like a charm on my SGS; and I am talking about serious GPS car navigation software like iGo, Sygic, Navigon etc. .
Don't even use Google maps or alike.
I cannot tell you how my sgs is doing on online navigation, I dont have a data account so I wont even try it.
But once Samsung get this online gps navigation thing fixed, you guys should concentrate your energy on the real issue:
The A-gps scam
And for all the corporations out there: Just deliver a device with a capable gps chipset and you will sell millions..
And for all the users out there: Just get a good compact external bluetooth gps receiver and stop nagging....
Thanks to 3rd party developers, the Android OS on my SGS can be "fooled" and I can connect any navigation software to my bluetooth gps receiver threw programs like Bluetooth Gps Mouse Unlimited and Gps Provider.
I do have to " allow mock locations" at settings first...
« »
¿Ein? You don need data to get GPS fix, A-GPS is only an aid to get faster fixes
I thtink you're a littel misinformed
LOL.. o boy.. the AGPS is to help say if your indoors so you can get a faster lock... the phone will work without it.
Ummm I can see why you would think what you think, but I do believe you are wrong.
Firstly: as far as I'm aware, the SGS has the same GPS chip as the latest TomTom standalone unit.
Secondly: I guess AGPS is a data feature, it uses the triangulation of cell towers and pulls information to assist a sat lock, but it is not really a different way of using GPS. Ultimately you still need to get a sat lock to use a GPS App.
So it may speed up this lock, but it won't replace it. It just means it'll take you a little longer to get a sat lock than without it.
So you have the choice use it or don;t use it, no-one is forcing you to use data.
Logicalstep
Oletros said:
¿Ein? You don need data to get GPS fix, A-GPS is only an aid to get faster fixes
I thtink you're a littel misinformed
Click to expand...
Click to collapse
Lol those online translators dont work that smoothly...
I don't need a data/internet account to use celular networks aid, that means a-gps.That mean going online via 3g or 2g...
But IF I don.t have a data/internet account added to my phone subscription, my phone costs will be much higher depending on my use....
You are missing the point anyway...
betoNL said:
Lol those online translators dont work that smoothly...
I don't need a data/internet account to use celular networks aid, that means a-gps.That mean going online via 3g or 2g...
But IF I don.t have a data/internet account added to my phone subscription, my phone costs will be much higher depending on my use....
You are missing the point anyway...
Click to expand...
Click to collapse
No, you're missing the point, you don't need any kind of data connection to use GPS, you can use it offline
Exactly...already the first line of Wikipedia says it: "Assisted GPS, generally abbreviated as A-GPS, is a system which can improve the startup performance of a GPS satellite-based positioning system."
There is, however, a related issue w/r/t A-GPS and a data account. Back on WinMo, I could download the ephemeris data to speed up the GPS fix for one week in advance (I think it was called QuickGPS or something on my HTC TouchHD, also had sth. like it on an old Eten). This allowed you to get a quick fix for said week, even without a data connection. Android, on the other hand, seems to download this data on the fly - meaning that if you don't have a data account you will experience a slow fix until your almanac has been filled "naturally" by the satellites you're seeing. I experienced that while on vacation this year without a roaming data contract - it took me a good 3-5 minutes to get the first fix and it was good from there on (well, as good as the SGS GPS gets ). I'd love to have some tool that does exactly what QuickGPS did, but I am not aware of anything like it.
TriC_101 said:
LOL.. o boy.. the AGPS is to help say if your indoors so you can get a faster lock... the phone will work without it.
Click to expand...
Click to collapse
I have always smile in my face when someone thinks he can get a lock indoors..
Yes in a cartoon box you can. Not in real building I'm afraid.
And for all those who think SGS's GPS is usable without A.
Try it.
You will see.
Dont post things you just caught on wikipedia.
xan said:
I have always smile in my face when someone thinks he can get a lock indoors..
Yes in a cartoon box you can. Not in real building I'm afraid.
And for all those who think SGS's GPS is usable without A.
Try it.
You will see.
Dont post things you just caught on wikipedia.
Click to expand...
Click to collapse
I can get a lock on 6-7 Sat no problem inside.... and so can lots of others.. don't know what your doing wrong but its not hard to get a lock inside.
Pics or it didnt happen
seems you all are little misinformed as to how the gps on android specifically sgs works. It is actually three systems at work here. Gps standalone without gprs and cell triangulation which gets lock within a minute same as standalone bluetooth units (they also take up to a minute from cold boot but because generally it is plugged in the car lighter and always on people think its blazing fast).then you have agps that downloads preloads data regarding satellite location in regards to your position via network instead of downloading same data directly from satellite thereby saving time. Both these can be used without checking network location in settings so to recap if your network location is unchecked you are still using agps as long as you have network connection (data connection that is).and samsungs system for agps being better than others cause it downloads data for while week as opposed to others downloading data everyone gps is turned on. Third level is network triangulation via cell towers that gets you that instant lock at the cost of accuracy useful mainly to let apps get your general location without having to engage real gps thereby saving power as well as give maps a chance to start calculating route while gps is still getting lock therefore appearing to operate faster.
Idan73 said:
Gps standalone without gprs and cell triangulation which gets lock within a minute same as standalone bluetooth units (they also take up to a minute from cold boot but because generally it is plugged in the car lighter and always on people think its blazing fast)
Click to expand...
Click to collapse
Standalone gps's got their batterys, and thus they start "warm".
Thing is, standalone SRIF3/4 gps gets a warm lock without any AGPS nor network triangulation within 5-10 seconds. SGS (and bunch of top-of-the pack devices) cant come even close to that.
the GPS on the SGS works fine offline
i don't even have data on when going on long road trips
you just need an offline GPS software with maps, like CoPilot or some other one you like
xan said:
Standalone gps's got their batterys, and thus they start "warm".
Thing is, standalone SRIF3/4 gps gets a warm lock without any AGPS nor network triangulation within 5-10 seconds. SGS (and bunch of top-of-the pack devices) cant come even close to that.
Click to expand...
Click to collapse
Sure they do. Sgs warm lock is 5 to 10 seconds as well. To test get the lock first then turn of data and network lock then start gps.restart of the phone same as restart of the standalone counts as a cold boot and takes about minute.
xan said:
Pics or it didnt happen
Click to expand...
Click to collapse
Here ya go.... I don't have to prove anything just look on youtube.. This is the phone on for just 10sec.. if I had waited it would get down to about 10 feet... this pic was taken in a room where I get the lowest signal. and I live in a Condo with 2 foot concrete walls.. I don't have a digital camera.. this was taken with my old Samsung dumb phone.. but it does prove you can get a lock inside no problem.. also if i'm in a house I can get 6-7 sats to lock in the condo 5 at the most in that room.
only 3 sats and maybe the walls are thin
Polarfuchs said:
only 3 sats and maybe the walls are thin
Click to expand...
Click to collapse
LOL Trust me the walls and not thin.. i'm on the 10th floor of a 25 floor Condo complex. I get alot more signal is a house.. Now my X10 can get about 7 Sats locked in the same room. and down to 5 feet. but the point was you can get a lock inside..
I'll try it.
I live in a 3 stories house at ground floor. The shutters are down and I'm 1 meter away from the windows.
After 3 Minutes I get 5 sats in view but none used.
I'll hang on.
Even after 10 Minutes I only have 5 satellites in View and zero in Use.
So no fix for me.
The numbers on top of the bars are from 15 to 25.
Logicalstep said:
Ummm I can see why you would think what you think, but I do believe you are wrong.
Firstly: as far as I'm aware, the SGS has the same GPS chip as the latest TomTom standalone unit.
Click to expand...
Click to collapse
Most of Tomtom devices got a SiRFstarIII™ GPS chipset
If the GS got such one the amount of GPS threads in this Forum would be reduced considerably
What is your awareness based on?
Oletros said:
No, you're missing the point, you don't need any kind of data connection to use GPS, you can use it offline
Click to expand...
Click to collapse
Idan73 said:
seems you all are little misinformed as to how the gps on android specifically sgs works. It is actually three systems at work here. Gps standalone without gprs and cell triangulation which gets lock within a minute same as standalone bluetooth units (they also take up to a minute from cold boot but because generally it is plugged in the car lighter and always on people think its blazing fast).then you have agps that downloads preloads data regarding satellite location in regards to your position via network instead of downloading same data directly from satellite thereby saving time. Both these can be used without checking network location in settings so to recap if your network location is unchecked you are still using agps as long as you have network connection (data connection that is).and samsungs system for agps being better than others cause it downloads data for while week as opposed to others downloading data everyone gps is turned on. Third level is network triangulation via cell towers that gets you that instant lock at the cost of accuracy useful mainly to let apps get your general location without having to engage real gps thereby saving power as well as give maps a chance to start calculating route while gps is still getting lock therefore appearing to operate faster.
Click to expand...
Click to collapse
LOL... Lets put things in perspective :
1) Wich car navigation software do you use
2) when you UNcheck wireless networks =a-gps(in location and security) and you CHECk "use GPS satellites = build-in gps receiver and then you go outside, you start your car navigation software in you gs( taking into consideration that you have the righ map installed) how long does it take to get a fix so you can start driving?
3) Do you know the difference between a cold and warm start? Why the heck some of you mention car lighters????
Please just answer me these 3 questions and meanwhile I will post some educative information
UPDATE JAN 11:
XDA member Da_G has done some excellent work on GPS performance. To summarise the situation as of Jan 11:
1. There is clearly an antenna issue for some users as highlighted by Samsungs Oct 10 redesign and the reports of good results from some users modifying the GPS antenna connection
2. The GPS implementation is indeed buggy out of the box. In particular my guess at some form of interpolation (see below) appears to be accurate. However I commend this post http://forum.xda-developers.com/showthread.php?t=881941 in the Captivate forums to you. Da_G has done excellent work and has made the gps daemon binary from the Nexus S available to SGS users in addition to modified jupiter.xml and gpssec.conf files which disable interpolation as well as refining several other parameters. He deserves thanks for his work and I can report that with hardcore's Speedmod kernel and the gpssec.conf, jupiter.xml and glgps_samsungJupiter from Da_G's downloads I have GPS performance I am completely happy with on my i9000. Root and some basic shell knowledge required for his fix.
The original post begins below.
Regards
dangrayorg
I’ve tried very hard to write a definitive post on SGS GPS performance. Below I try to give a balanced view of GPS performance in the SGS and provide definitive explanations of the various functions offered by the Broadcom BCM4751 chipset and their effects on the quality of the GPS fix. There is a lot of noise and conjecture on this subject in the XDA-developers forum; some right, some wrong, some missing the point entirely. Below is some educated guess work and some hard facts about exactly what will and will not help with GPS performance on the Samsung Galaxy S i9000.
I have tried to remain non-technical while telling you ‘why’ things happen they way they do. At the very least I hope you come away from reading this post with a good understanding of the various settings available to you and which will actually affect the accuracy of your position fix. There are several excellent technical articles on GPS in the references below.
Mobile Device Design:
I’d like to start by making three points:
1. Obviously The Samsung Galaxy S is not a single-purpose GPS device. There will be inevitable design compromises when trying to fit all the hardware into the phone and in particular the GPS antenna will inevitably be inferior to the one in a standalone GPS or GPS Dongle. Having seen the GPS antenna it is indeed tiny, and halfway down the side, and at the back. But it needs to fit with the constraints of the hardware and has what appears to be a very sensitive chipset attached to it. I cannot find a full technical spec for the chipset but include a link to a technical overview in the footnotes. The GPS antennna on the i9000 is at the back of the main body, 1/4 of the way down the body on the left-hand-side as you view the phone in portrait mode. Image Here
2. If my conjecture is correct then I believe that Samsung/Google have made some design compromises in their software setup of the GPS on the Galaxy S that compromise positional accuracy, these can be overcome.
3. I do not believe that the GPS on any Samsung Galaxy S is fundamentally broken in any models. I do believe that the factory configuration choices are poor and I do believe it is hampered by hardware designs and their interactions with everyday use environments. Obviously any phone may have a one-off manufacturing defect but I cannot account for those.
Available Navigation Modes:
Verizon has this to say about the MS- modes, two of the three fundamental ways (MS-Based, MS-Assisted and Standalone) that you can gain location information:
What is MS-Assisted mode of operation?
In MS-Assisted mode, the network elements calculate the location of the device. This mode is suitable for one-shot fixes, wherein the location does not need to be updated frequently.
What is MS-Based mode of operation?
In MS-Based mode, the network provides the satellite information to the device, based on a rough estimate of where the device is located, and the device acquires the GPS signals from the satellites and calculates its location. After the initial fix, the device operates like an autonomous GPS receiver, until the satellite information must be refreshed, at which time the device goes back to the network to update the satellite information. MS-Based mode is appropriate for applications that require the device location to be updated rapidly, such as a navigation application.
Click to expand...
Click to collapse
The current advice seems to be to enable MS-Assisted as it appears to improve navigation performance. I believe that this is incorrect. When using MS Assisted positioning I see considerable wander occurring as the position is not GPS derived. The MS-Based settings send the GPS Almanac and ephemeris date to the device and save on initial lock times, particularly if the GPS has been unused for many weeks, however in terms of positioning once up-and-running MS-Based and Standalone should deliver identical results.
Environmental factors limiting GPS performance:
Many users are primarily using the GPS in their cars. Here the hardware design compromises come in, but there are also some properties of GPS signals which users should be aware of. Firstly, RF Interference (RFI) is unlikely to be a primary culprit. The problem with a Car is that it’s made of metal which rapidly attenuates the already very low power GPS signal. When dealing with GPS the Signal-to-noise (SNR) ratio is important. Satellites giving the best SNR are always overhead, rather the near the horizon where the signal is competing with any number of other nearby frequencies causing RFI/ general background noise. So in a car, particularly given the design compromises with the GPS antenna, you will be attenuating the overhead signal because of the roof and relying more then you should on the GPS satellites near the horizon with their lower SNR, multipath propagation etc. When driving in a town where there is no horizon you can see where the problems arise. When the SNR becomes too great the GPS can no longer compute the pseudo range from the signal and you loose the ability to use a satellite. You can see a maximum of 12 GPS satellites at any one time if you have a full sky view - if you take away the overhead ones you can see why the number of useful signals drops below the minimum (4) very quickly.
This is a problem not just for Samsung but also for Google, who tout the Google Maps nav as a killer feature in a whole group of phones which have designs compromised by requirements to squeeze a lot of functionality into a small form factor. Samsung may have done a worse job of GPS antenna positioning in the SGS then maybe HTC in the Desire but they were faced with a different set of design constraints.
Before I tell you how to fix the GPS settings for best performance, here are some hints for in-car reception:
1. Place the phone as far forward in the windscreen as you can. Note that Satnav systems usually come with a short-arm windscreen mount for this very reason as it ensures a great view of the overhead sky, yet we insist on comparable performance from our design-compromised phones when we attach them to the air vents or mount them in cup holders.
2. If you really want flawless in-car nav invest in a cheap bluetooth dongle. You will benefit from more flexible positioning options giving a better sky view, a larger antenna giving a better signal gain (and more directionality if it is pointing up) and if you get a SirfIII unit an extremely capable GPS chipset utilised without design constraints . Note that SirfIII does not always include WAAS while the Galaxy BCM4751 does, however for the requirements of in car navigation WAAS is really overkill and the quality of the signal/number of satellites in view is the real issue. It is no surprise that users find a bluetooth GPS unit gives better accuracy then the built in GPS – the antenna is massive and has a completely clear view of the sky!
Phone Settings:
Right, back the the phone.
One recommendation that I keep seeing is to activate "MS Assisted". This is what is responsible for all the drift. Standalone and MS-Based will give a pure GPS signal. MS Assisted tracks based on cell tower signals and gives worse results.
One issue that comes up in particular is the problem of 'position offset', where users see themselves consistently offset from a road by a few meters, often Google navigation will then erroneously re-route you, particularly in built up areas with high street density. There is one thing which I can say with absolute certainty... There is no GPS error I can think of which would generate a consistent offset. The only cause of this would be if you physically positioned your antenna meters away from your phone and this is clearly not the case. The inaccuracies in GPS position (and there are some, caused by timing errors and a low number of satellites available for positioning) are RANDOM. The only phenomena that I can think of that WOULD generate a consistent offset would be doppler-shift, and the mode this would be most likely to influence would be cell-tower based positioning. If you are experiencing consistent offset along straight tracks please double check that you are not using MS-Assisted mode.
About my SGS:
FROYO JPO
Hardcore's 'Speedmod' Kernel
ext4 lagfix
Battery dated: 2010.08.30
So not a ‘post October’ phone (but I think that’s a false lead anyway). The installation of a custom ROM made no significant difference to GPS performance for me. In addition I can assure all readers that I have previously experienced absolutely abysmal navigational accuracy both in-car, walking and running giving tracks so bad that I looked like the worlds only blind, drunk, crack-addicted runner. (as an aside I thoroughly recommend the installation of a custom Kernel and lagfix as it transforms the performance of the Galaxy S).
I have written my own custom GPX logging program to test all this and so have a high level of confidence. I will amend this post with some proof tracks when able.
LbsTestMode:
Here is a complete run-down of the GPS settings (explanations of the functionality they govern and the effects they will or will not have on the GPS signal) that take away the issues described above as set in LbsTestMode and result in the best observed GPS performance:
LbsTestMode can be enabled with the following key combinations in the dialler:
Android 2.1 - *#*#1472365#*#*
Android 2.2 - *#*#3214789650#*#*
Application Settings:
1. Session Type: Tracking
A chipset feature which helps to boost SNR in poor RF environments)
2. Test Mode: S/W Test
3. Operation Mode: Standalone
The most important setting as this is the setting. Standalone or MS-Based. Not MS Assisted. I have had the best results with Standalone, cutting the whole Assisted-GPS segment out of the equation. That way I don't have to worry about who's databases are up to date, which base stations might inaccurate etc. The standalone mode is able to do everything you need at the cost of slightly increased start times if not used for some time.
4: Start Mode: Hot Start
This has nothing to do with re-downloading almanacs. It simply resets precise satellite timing data that must be extracted from the GPS signal to compute an accurate pseudo range. It’s good for about 4-6 hours. If you leave your GPS off for longer then the ‘ephemeris’ data will be re-downloaded anyway regardless of the Hot/Cold start settings. The GPS can’t be ‘more or less accurate’ with or without it, its simply a case that the ephemeris must be updated before you can get any position. You can sync the clock every time if you want, personally I’d choose ‘Hot Start’ and save a few minutes every time a GPS app is destroyed!
5: GPS Plus: On
The GPS Plus is the Wide Area Augmentation Service, extra satellites that transmit a deviation correction to correct minor positional inaccuracies within the space segment of GPSl. Not available globally (North America and Japan, maybe Europe and India by the time the phone is obsolete). Having it on will not cause problems if WAAS is unavailable in your region.
6: Dynamic Accuracy: On
This setting is used to filter data that is judged statistically to be in error based on deviation from the Circular Error Probability (CEP) calculated by the GPS system.
7: Accuracy: 30m
I believe that this is a cut-off for the overall GPS positional accuracy. If over this threshold the GPS will not report the position. I have yet to see a figure of more then 20 meters, so leave at 30. GPS precision is far more complicated then a simple inaccuracy based on distance)
8: GPS Logging: Off
SUPL/CP Settings:
This is a network layer operated by cellular operators. It delivers the AGPS data like timing corrections and the almanac to your phone as well as allowing a network operator to provide you with various location based services (and make more money from you). If you wanted to download the almanac from satellites it would take a minimum of 12.5 minutes and would need to be done every time you turned your GPS on if it had been off for weeks/months. The almanac has a long lifespan, so won’t age out in days, and the GPS receiver is still capable of downloading it from satellites if it can’t get it from the network, It also provides information to your mobile provider about where you are, regardless of your Google privacy settings so that they can provide you with location based services (so Google isn’t the only geolocation bogeyman!)
Again, I think there are lots of false leads here. The one thing that may be true is that the original SUPL provider on
handsets was providing inaccurate data. Recommended settings:
Server FQDN Type: Custom Config
Server: supl.google.com
Server Port: 7276
SUPL Secure Socket: OFF
AGPS Mode: SUPL
Use wireless networks option
Google do map WiFi hotspots in large cities, which is enabled by the "Use Wireless Networks" option in the android Menu. This may allow you to locate yourself accurately in an urban area where GPS is unusable. However, it is unlikely to provide tracking information for runners, probably providing street-corner location to pedestrians.
Use sensor aiding option
Google's own documentation states that this is for use in areas where GPS performance is degraded. I am unsure if the selection of "use sensor aiding" will have an effect if a good GPS signal is available. For those trying to troubleshoot their GPS setup I would advise that the low cost MEM sensors contained in mobile phones (solid state gyroscopes), while good for games are poor over more then a few meters in terms of accurately measuring velocities to determine distance travelled.
It is possible to use solid-state accelerometers when coupled with a GPS to refine positions and attitude information but it is unlikely that android employs the filters needed to do this well. If you navigate frequently in cities or environments with tunnels etc. you may wish to enable this feature but for most navigational needs I would advise leaving it off as the integration of sensor data with GPS positions may well be a source for positional bias and drift seen in the Galaxy S.
And that’s all you need.
I hope that that will be definitive. Using the above settings I get entirely accurate tracks from my phone using my GPS logging program. I may post that soon with my example logs. The reason I wrote from scratch was because I wanted to be sure that I was getting the pure output from Android dumpLocation with no adulteration to allow for a fair analysis.
HOWEVER (and here is where what I know comes to a end…):
When your app selects a location provider it won’t necessarily be ‘GPS’. A developer can select getBestProvider() and use something other then gps to save power. I assume that most developers use ‘gps’ but it would take a knowledgeable android programmer to tell us if we can guarantee to always get unadulterated GPS positions into the application layer with no mixing sneaking in!
References:
http://www.broadcom.com/press/release.php?id=s443754
http://www.broadcom.com/collateral/wp/SUPL-WP100-R.pdf
http://www.broadcom.com/products/GPS/Location-Based-Services/SUPL-SLP
http://www.topcon-positioning.eu/img/pdf/pdf_GPS/HIPer+_English_web.pdf
http://webone.novatel.ca/assets/Documents/Manuals/GPS+Reference.pdf
http://www.telemobilityforum.com/it/images/stories//madwar_telemobility.pdf
These are the settings I found as default ... I never had a problem with gps. Accuracy between 5 and 10 meters indoors. That's really nice in my opinion. But thank you for your time you spend to this “issue“ and I hope it helps other people.
Sent from my GT-I9000 using XDA App
I can tell you that I have those exact settings and my GPS signal is still **** when going into the city with tall buildings and such. In suburbs it's fine, tall city is bad. Had a touch HD previously and it worked FINE in the city.
SGS just got **** gps IMO
How can I enter to the gps settings?
When I enter the code *#*#1472365#*#* the number disappears and nothing happens!
2.2 JPO DocRom v7
I've been running settings similar to these recently and getting 'better' performance than my stock settings, so I'm inclined to agree with the OP here.
It's no where near what I'd call good performance though, my old HTC HD & Nokia 95 running TomTom had no issues keeping track on the road (mounted on the same windscreen position), whereas still GoogMaps Navigation will occationally position me on nearby roads by mistake. I think it's just going to be one of those things I'll have to live with.
That said, at least now I'm occasionally getting proper lock on the little navigation triangle when driving, not a 100m circle around it. So things are improving.
Which side is the GPS antenna on?
If the antenna is small, on one side, and at the back, then running the phone in landscape with the aerial side facing up is bound to have the best chance of "seeing" the sky. Without knowing which side is "up" for the aerial, we have a 50/50 chance of getting it right or wrong.
So do you know which side it is on, and therefore whether we are better having landscape with the buttons to the right, or landscape with the buttons to the left?
Also does firmware version make a difference (other than the default config of these settings)? Or in other words, would all firmware versions have similar performance if set to these recommended settings, or do some firmware versions have better drivers or sensitivity too as well as different settings?
Thanks for the excellent info!
Mike
dangrayorg said:
1. Obviously The Samsung Galaxy S is not a single-purpose GPS device. There will be inevitable design compromises when trying to fit all the hardware into the phone and in particular the GPS antenna will inevitably be inferior to the one in a standalone GPS or GPS Dongle. Having seen the GPS antenna it is indeed tiny, and halfway down the side, and at the back. But it needs to fit with the constraints of the hardware and has what appears to be a very sensitive chipset attached to it. I cannot find a full technical spec for the chipset but include a link to a technical overview in the footnotes.
Click to expand...
Click to collapse
I appreciate the effort here but this is a tad bogus. I have a 3+ year old dedicated GPS device, it's an extra-sensitive Garmin handheld and my puny little 3 year old HTC Touch rivals it's performance track for track. They both blow away the Galaxy S with their 3 year old technology. ...so no it is not expected to be inferior, maybe to the latest and greatest dedicated gps, however I can assure you their is no exscuse not to rival 3 year old technology.
sorry for yet more gps ranting.
Neil
NeoXTC said:
I can tell you that I have those exact settings and my GPS signal is still **** when going into the city with tall buildings and such. In suburbs it's fine, tall city is bad. Had a touch HD previously and it worked FINE in the city.
SGS just got **** gps IMO
Click to expand...
Click to collapse
Well you are talking about the urban canyon effect. There are very few high end GPSes that can deal with that. So you can not judge the GPS in urban canyon environments because then nearly all GPSes has problems.
I thank the OP for a well written "guide". I think that it will enlighten lots of people how a GPS really works and we hopefully can skip the strangest advices on the forum. I still think you could optimize the code better because it seems to slow and imprecise in some aspects. However I have used it daily and are satisfied with it even if I wished for the military grade GPS that many seems to have in there old phones and GPS's.
You are wrong on the "Use Wireless Networks" setting not using WiFi. It *does* also use your WiFi to help triangulate. It says so right in the android UI for pete's sake. It really only works in large cities where Google has mapped APs and APs are dense.
The way the triangulation works is Google has mapped all the ESSIDs in a city and for all the road GPS positions recorded their strengths. Therefore in a city whenever you see 2 or more ESSIDs you can use that info along with your cell tower triangulation to compute a pretty OK estimate of your GPS coordinates - at the very least a much more accurate picture than you can get by the cell towers alone, because the range of a WiFi network is so much smaller.
Basically - if you are in a city and you have this checked and your wifi is enabled you may get more acccurate readings without GPS than you would otherwise.
Great post, I changed the spirent-lcs to supl.google.com and a few other niceties. This is totally unscientific, but before changing (using gps test) I could only see 1 satellite and stayed like that forever. After applying the changes, I had a 30 m fix in about 3-5min. Have to say that my SGS has always been totally unpredictable, some days, it couldn't get a fix in under an hour, others it took 10min, all that while walking outside. I hope these setting will allow me to use the GPS a bit more reliably now. thanx!
Thank you for your guide, however the fact is that other phones that I had or currently have have perfectly functioning GPS. It is only the Galaxy that has problems.
Second "use wireless networks" does use Wi-Fi networks for positioning - an easy way to see that is to turn on "Flight Mode" and then turn on Wi-Fi only, Google Maps will still be able to find your position.
Superb post Dan, one of the best I've read on here in a long time.
Cheers,
BS...
Thanks for all the comments, positive and negative.
I'm not arguing by by any stretch that the Galaxy S GPS is fine (if it were there would be no need for the original post). I am as ****** as the rest about its troublesome performance, that said there is more that can be done then just 'playing with settings'
If Google has mapped WiFi hotspots then I will correct the post. However, using a WiFi signal strength together with a triangulated hotspot location is a HORRIBLE way to locate yourself in a city - what if someone moves the router? Stands in front of the aerial? Moves shop fittings around? That said I guess it could locate you "You are near a starbucks",
However, I will alter the post because I want it to factually accurate. If anyone really does have better results in a city using the wireless locations please let everyone know.
I'll also add the codes to allow access to LbtTestMode in 2.1 and 2.2
neil85ae86 said:
I appreciate the effort here but this is a tad bogus. I have a 3+ year old dedicated GPS device, it's an extra-sensitive Garmin handheld and my puny little 3 year old HTC Touch rivals it's performance track for track. They both blow away the Galaxy S with their 3 year old technology. ...so no it is not expected to be inferior, maybe to the latest and greatest dedicated gps, however I can assure you their is no exscuse not to rival 3 year old technology.
sorry for yet more gps ranting.
Neil
Click to expand...
Click to collapse
You don't say if you've tried any/all of these settings or not. We need to all work together to find the solution. I think the OP might be on to something here, although as he says, some of it is guess work, so there is probably room for improvement!
I would disagree with the OP about the hardware faults, as I'm sure there are bound to be at least some units that have a fault that needs returning to be fixed too. But everyone should at least try these settings to see if it helps at all, as there are bound to be multiple factors at work here.
Also which way up do you have your phone when in the car? That is something very tangible we can sort out to optimise the signal reception in these phones. I currently don't know which side has the GPS antenna, so which way up we should out our phone for optimal signal strength. Once we've found that, we might well find that many have their phones with the antenna pointing down which won't be helping either!
Apologies if you've tried these settings too, and they didn't work, but we need to ask, so that we build a fuller picture! Just disagreeing with the OP without saying what you've tried doesn't help anyone move this forwards.
We all want the GPS fixed, and I for one will try anything in that quest.
Here's hoping the next discovery by Samsung or the community fixes it for good for everyone!
Mike
xpcomputers said:
I currently don't know which side has the GPS antenna, so which way up we should out our phone for optimal signal strength.
Click to expand...
Click to collapse
OP now contains info on GPS antenna position. Answer is straight upright on rotates clockwise (antenna on Left Hand Side 1/3 of way down).
xpcomputers said:
I think the OP might be on to something here, although as he says, some of it is guess work, so there is probably room for improvement!
Click to expand...
Click to collapse
I am on to something - unfortunately that 'thing' is that I think the settings given deliver the best performance the SGS is capable of because its teeny tiny antenna. It simply doesn't have the gain for those awesome feats of satellite lock that we see from other GPS units (either that or the internal wiring generates some huge losses along the signal path to the chip).
This also plays out the earlier comments about "three year old technology". Chipsets move on and Broadcom have clearly had to pour a load of research into optimizing signal strength for mobile devices. Unfortunately the laws of physics don't change. If there is not sufficient signal at an antenna with insufficient gain you will only keep a lock on the strongest satellites.
Once I get the tracks on the OP you'll see what I mean. Where I am with a good clear sky view there is no problem at all, excellent correlation with ground trace and no complaints with the SGS strapped onto my arm while running. Once you increase signal attenuation by adding trees and buildings things start to 'go south' rapidly.
Is this the price for that huge bright screen....?
t1mman said:
Any way to force disable the AGps overall?
Click to expand...
Click to collapse
Isn't that what the OP does with the "Standalone" setting (instead of one of the MS A-GPS options)?
Mike
Op: thanks for the info. To bad all settings accept for accuracy is default on froyo.
I also working on this issue.
Wifi is a bad thing to use.
This is often the main thing people do have on and they get very poor accuracy and blame the gps for it.
When i flash the phone i always put the accuracy to 150.
This is a strange setting and normal i would like it to be less the 5.
So i should use 5 on accuracy, but that don't work good. I have found that putting accuracy over 150 will make the phone use the satellites better. Strange...
I also use standalone made. That's works great for me.
A also think all people should try different settings and se if some works better for them.
There is other things you can tweak to help the navigation.
Also don't use Google map. Use a standalone navigation program.
They works alot better.
Sent from GT-I9000 jpo. My own kernel for z4mod and with 342MB Ram
t1mman said:
I know AGps is only used for the first fix, and shouldn't affect the accuracy once fixed, but what if (this is speculation, it should need further investigation) the GPS status accuracy issue was more likely caused by a lost and retreival of a fix? In this case, the fact that the fix was lost/regain would mean that the aGPS would affect the accuracy as it is constatly regained.
Any way to force disable the AGps overall?
Click to expand...
Click to collapse
AGPS provides you with timing corrections and satellite position data to allow the GPS reciever to 'sync' with the signal transmitted by the satellites. The satellites still provide the location, the AGPS data helps it get there quicker.
MS Based would save 15 minutes month-to-month downloading almanac data, a minute or two day-to-day updating timing data but 'hotstart' will work just fine if you are turning on and off many times in a day.
dangrayorg said:
OP now contains info on GPS antenna position. Answer is straight upright on rotates clockwise (antenna on Left Hand Side 1/3 of way down).
Click to expand...
Click to collapse
So I am hearing you correct? That theoretically the GPS will work best with the phone in landscape, with the home button (and the bottom of the phone) on the left hand side.
If that is the case, then at a guess, I suspect that most right hand users are instinctively using the phone with the buttons on the right hand side, and therefore the GPS antenna at the bottom, which might not be optimal positioning. (this purely is based on an observation of only my own usage of using it the other way up as a right hander, so hardly a large observed sample! I could just be weird!!)
Now of course this is totally hypothetical anyway, and needs to be something that gets tested in the real world, but this alone could account for some of the difference noted by users in the real world, but before we jump to conclusions, we need to test if the theory bears out in the real world.
I am assuming that the phone will work best that left edge facing upwards, as close to the windscreen (and as close to the bonnet as possible). Ideally the phone will be vertical in that landscape orientation, (or even slightly tilted down at the front, so the back is pointing upwards ever so slightly?). But this is pure guess work. unfortunately, I haven't the time, skills or equipment to able to test this theory out. But hopefully someone here can run some meaningful real world tests to see if this position really does give the optimal signal to the antenna compared with other orientations of the phone.
Every little helps...
Mike
Hello,
I was wondering if anyone was familiar with the control plane option in SUPL settings.
The reason I ask is that I was playing around in the secret code area of SG Tools and noticed an area marked GPS
SGS Tools -> Secret Codes -> ServiceMode, Debug, Netz, Audio, Common -> Common -> GPS -> Display and Change CP Status.
I enabled the Control Plane and then set SUPL settings in lbstest to supl.google.com etc and change SUPL Mode to Control Plane. My gps has been crazy awesome since then. Also change application settings Accuracy to 25.. I do have the jupiter file gps fix installed but GPS would still loose me until I made these changes. I was hoping someone could explain Control Plane and or someone would test these settings for themselves and let me know how it works. I am running Axura Beta 5 with Setiron Kernel 1.4.2
None of those settings "fix" GPS.
Thanks for the reply. Are you aware of what the control plane setting is for?
Not that I'm actually interested in this "fix", but is your "crazy awesome" GPS just giving you faster initial position locks?
Getting a position lock is one thing, but having the GPS actually be able to track your movement and be accurate is different...which many overlook when they say their GPS works. If you were to use to Captivate in the car to navigate with, would it be accurate? If you can say yes to that, you could consider your GPS working then.
norcal einstein said:
Not that I'm actually interested in this "fix", but is your "crazy awesome" GPS just giving you faster initial position locks?
Getting a position lock is one thing, but having the GPS actually be able to track your movement and be accurate is different...which many overlook when they say their GPS works. If you were to use to Captivate in the car to navigate with, would it be accurate? If you can say yes to that, you could consider your GPS working then.
Click to expand...
Click to collapse
I am getting faster locks.. more sattelites.. I also tested while driving and it stayed good the entire time.. I am going to test again on my hour drive home tonight..
Sent from me to you over wires using only 1's and 0's
Also my main interest is in finding out more information on what this setting does as well. It is my opinion that this has helped and I wanted more imformation and also to see if it helps qnyone else..
Sent from me to you over wires using only 1's and 0's
+1
I dunno why but set as control plane gives me more sats and faster locks even better tracking.
This is the first thing i do every time after flashing a new rom to my cappy.
ms base mode, google supl sever with control plane mode and secure socket off.
Sent from ATT Captivate operated by Perception build 5
drancid said:
+1
I dunno why but set as control plane gives me more sats and faster locks even better tracking.
This is the first thing i do every time after flashing a new rom to my cappy.
ms base mode, google supl sever with control plane mode and secure socket off.
Sent from ATT Captivate operated by Perception build 5
Click to expand...
Click to collapse
Have you checked to see if the control plane is enabled via sgstools?
Sent from me to you over wires using only 1's and 0's
mpencexda said:
Have you checked to see if the control plane is enabled via sgstools?
Sent from me to you over wires using only 1's and 0's
Click to expand...
Click to collapse
nope but i'll check it now..
Sent from ATT Captivate operated by Perception build 1
Control Plane is an alternative method of accessing the AGPS server from User Plane (SUPL). Control Plane goes over the cellular providers Control Plane (fancy that!) whereas SUPL goes out over the GPRS network (HSPA, 3G, etc.)
For Control Plane to work, the cellular provider has to have in place specific technology intended for use with AGPS. All older AGPS solutions prior to the deployment of SUPL use Control Plane. Basically it's "the old way"
Note that you can obtain the exact same AGPS data through a SUPL connection to the same set of servers AT&T maintains. This is the default setting for "Server FQDN Type" - AUTO Config.
Basically, setting it to AGPS Mode - Control Plane (regardless of other server settings) is the same as setting AGPS Mode - SUPL, SUPL Secure Socket - ON, Server - h-slp.mnc410.mcc310.pub.3gppnetwork.org, Server Port - 7275. AND is also the same as using "Server FQDN Type" - AUTO Config, providing your cellular provider is AT&T (MNC 410 MCC 310).
Note that the specifications for AUTO Config will read the MCC/MNC of your network provider (in my example above, AT&T) and change the mncXXX.mccYYY part to match your providers MNC/MCC. Per the 3gpp SUPL spec, when in a home network, the URL to access for SUPL services is h-slp.mncXXX.mccYYY.pub.3gppnetwork.org, which breaks down to:
h-slp - Home SUPL Location Platform
mncXXX - MNC of the current network the phone is parked on
mccYYY - MCC of the current network the phone is parked on
pub.3gppnetwork.org - A (purposefully) un-registered domain name free for use by cellular providers.
When you are roaming, the URL changes to:
v-slp.mncXXX.mccYYY.pub.3gppnetwork.org
where v-slp instead means Visiting SUPL Location Platform.
So, to sum that up, if your cellular provider is following 3gpp SUPL recommendations properly, when you attempt a SUPL connection to h-slp.mncXXX.mccYYY.pub.3gppnetwork.org, your cellular provider should connect you to THEIR provided SUPL server. In the case of AT&T this is fully functional. Note that this will NOT work on Wi-Fi, the DNS will not resolve (since you aren't connected to a cellular network, the ISP you're on will not maintain a SUPL server for you, unless they are just THAT nice)
Note that if you use a program like MarketAccess to change your MNC/MCC to allow access to other markets, the SUPL address will also change (to reflect the altered MNC/MCC) and thus be broken in automatic mode.
Anywho, all of this only affects the initial lock time, when set to MS-Based. (Defaults on the stock ROM to standalone, which doesn't use AGPS at all, and sane people will use MS-Based)
Tracking once you have a lock should NOT be affected by any of these changes.
In case you're wondering where I got my information, it's not my first go-round to this particular party. I did all the legwork for this a bit over a year ago, and put up a compendium post about it in March 2009: http://forum.xda-developers.com/showthread.php?t=489887 All the info I reference from the SUPL specifications is obtained by spending hours reading the actual, incredibly boring whitepapers.
I haven't had time to properly devote to the GPS problem for captivate like I have for previous WM devices (I just got the cappy), but i'm guessing there's some errors in either the satellite correlation done in the baseband, or in the driver's interpretation of the output in the kernel code. It might also be the case that the phone is relying on a clock generator that isn't putting out the exact cycles they have it programmed for, thus introducing clock drift into the correlation algorithm. The clock has to be precise and synced up to the GPS clocks in order to properly trilaterate location. This might explain the drift over time and then snapping back to a real location once the clocks are properly synced again. (GPS satellites send the complete information required to sync a clock accurately every 12.5 minutes.)
Do note that the clock i'm referring to is the internal GPS reference clock, which is not related in any way to the time set on the device. Internally, the device does keep track of the offset between GPS time and Device Time, but Device Time is not used in the GPS calculations (a different internal clock is used, and synced to the satellites themselves with each transmission) - Previously it has been suggested that ensuring the phones clock is as accurate as possible would make a difference, but that is not the case (due to it not being the same clock)
Either way, any changes to gps.conf or secgps.conf aren't gonna cut the mustard with this particular issue. Initial fix time and number of initial sats, sure. But once the GPS is fired up and running, and has time to pick up a constellation update from the satellites, you're in the same boat as anyone else.
BTW. You can read the adb logcat output to easily see if your phone is utilizing AGPS. You will get an initial fix with an accuracy of appx. 1500m and the log will show that it is not a GPS fix but instead a network provided location. It will then show this location being injected into the GPS driver (AGPS)
Thanks for the info.. that was amazing. I really hope that you get some time to devote to this as you seem informed
Sent from me to you over wires using only 1's and 0's
Thanks
DA G,
Thanks for the information, glad to have you in cappy land!
Da_G said:
Control Plane is an alternative method of accessing the AGPS server from User Plane (SUPL). Control Plane goes over the cellular providers Control Plane (fancy that!) whereas SUPL goes out over the GPRS network (HSPA, 3G, etc.)
For Control Plane to work, the cellular provider has to have in place specific technology intended for use with AGPS. All older AGPS solutions prior to the deployment of SUPL use Control Plane. Basically it's "the old way"
Note that you can obtain the exact same AGPS data through a SUPL connection to the same set of servers AT&T maintains. This is the default setting for "Server FQDN Type" - AUTO Config.
Basically, setting it to AGPS Mode - Control Plane (regardless of other server settings) is the same as setting AGPS Mode - SUPL, SUPL Secure Socket - ON, Server - h-slp.mnc410.mcc310.pub.3gppnetwork.org, Server Port - 7275. AND is also the same as using "Server FQDN Type" - AUTO Config, providing your cellular provider is AT&T (MNC 410 MCC 310).
Note that the specifications for AUTO Config will read the MCC/MNC of your network provider (in my example above, AT&T) and change the mncXXX.mccYYY part to match your providers MNC/MCC. Per the 3gpp SUPL spec, when in a home network, the URL to access for SUPL services is h-slp.mncXXX.mccYYY.pub.3gppnetwork.org, which breaks down to:
h-slp - Home SUPL Location Platform
mncXXX - MNC of the current network the phone is parked on
mccYYY - MCC of the current network the phone is parked on
pub.3gppnetwork.org - A (purposefully) un-registered domain name free for use by cellular providers.
When you are roaming, the URL changes to:
v-slp.mncXXX.mccYYY.pub.3gppnetwork.org
where v-slp instead means Visiting SUPL Location Platform.
So, to sum that up, if your cellular provider is following 3gpp SUPL recommendations properly, when you attempt a SUPL connection to h-slp.mncXXX.mccYYY.pub.3gppnetwork.org, your cellular provider should connect you to THEIR provided SUPL server. In the case of AT&T this is fully functional. Note that this will NOT work on Wi-Fi, the DNS will not resolve (since you aren't connected to a cellular network, the ISP you're on will not maintain a SUPL server for you, unless they are just THAT nice)
Note that if you use a program like MarketAccess to change your MNC/MCC to allow access to other markets, the SUPL address will also change (to reflect the altered MNC/MCC) and thus be broken in automatic mode.
Anywho, all of this only affects the initial lock time, when set to MS-Based. (Defaults on the stock ROM to standalone, which doesn't use AGPS at all, and sane people will use MS-Based)
Tracking once you have a lock should NOT be affected by any of these changes.
In case you're wondering where I got my information, it's not my first go-round to this particular party. I did all the legwork for this a bit over a year ago, and put up a compendium post about it in March 2009: http://forum.xda-developers.com/showthread.php?t=489887 All the info I reference from the SUPL specifications is obtained by spending hours reading the actual, incredibly boring whitepapers.
I haven't had time to properly devote to the GPS problem for captivate like I have for previous WM devices (I just got the cappy), but i'm guessing there's some errors in either the satellite correlation done in the baseband, or in the driver's interpretation of the output in the kernel code. It might also be the case that the phone is relying on a clock generator that isn't putting out the exact cycles they have it programmed for, thus introducing clock drift into the correlation algorithm. The clock has to be precise and synced up to the GPS clocks in order to properly trilaterate location. This might explain the drift over time and then snapping back to a real location once the clocks are properly synced again. (GPS satellites send the complete information required to sync a clock accurately every 12.5 minutes.)
Do note that the clock i'm referring to is the internal GPS reference clock, which is not related in any way to the time set on the device. Internally, the device does keep track of the offset between GPS time and Device Time, but Device Time is not used in the GPS calculations (a different internal clock is used, and synced to the satellites themselves with each transmission) - Previously it has been suggested that ensuring the phones clock is as accurate as possible would make a difference, but that is not the case (due to it not being the same clock)
Either way, any changes to gps.conf or secgps.conf aren't gonna cut the mustard with this particular issue. Initial fix time and number of initial sats, sure. But once the GPS is fired up and running, and has time to pick up a constellation update from the satellites, you're in the same boat as anyone else.
BTW. You can read the adb logcat output to easily see if your phone is utilizing AGPS. You will get an initial fix with an accuracy of appx. 1500m and the log will show that it is not a GPS fix but instead a network provided location. It will then show this location being injected into the GPS driver (AGPS)
Click to expand...
Click to collapse
Da_G? In my Captivate thread? This brings me back to playing with with GPS on the HTC Touch Pro...
It's crazy that was 2 years ago.
Hi, CLShortFuse, long time no see
Actually i've been lurking for a while now, just trying to learn things before I get down to the nitty gritty of modding source code (and writing some new stuff of my own!)
To be fair, I was a GPS fan before I became a PDA fan I remember doing firmware hacks to the SirfStar III chipset to enable functionality above 18,000m, faster than 515m/s, and bypassing the acceleration and motional jerk limiters Why? Because my GPS should work to its full ability, dammit!
As I understand, we don't have access to any of the baseband source. This is probably where a large amount of the GPS calculations are handled (It is so with Qualcomm, at least) and so it may not be something we can address. But a good thorough look at the kernel driver(s) should answer that question.
I wonder if the chipset is even SBAS Capable (WAAS/EGNOS, i'm quite sure it doesn't have a receiver for any land based solutions). The accuracy reminds me of GPS back in the days when Selective Availability was up (artificial GPS accuracy limitations put in place by the military) before DGPS came about.
Ironically, my hacked bluetooth GPS from 2005, a Globalsat BT338 remains the most accurate consumer level GPS I have used to date, with accuracies down to .3 meters in ideal conditions. (During normal in the field conditions like stuck in a backpack, in the back seat of a car, with perhaps a 5 degree view of the sky, and wicked multipath from skyscrapers it's accurate to around 2 meters) - basically, you can count on it to be accurate down to what lane of traffic you are in
The same chipsets are made available to smartphone manufacturers. (The current model being the SirfStar IV, and capable of even better accuracy than that older one) - I only wish more manufacturers would actually use them!
I actually currently use that BT GPS for any navigation I do. But nonetheless, we don't have such a nice platform to work with, so let's see what we can do with what we have Perhaps tomorrow i'll take a drive with 2 captivates, both loaded to stock firmware (updated to the "gps fix" build) + the samsung GPS fix on the market (which we know is worthless, but just for S&G)
I'll record raw NMEA output from both GPS units (Captivate using internal GPS, and Captivate using BT-338 GPS through bluetooth serial NMEA), and post that up along with a google earth .kml for easy comparison. The difference between the two is quite striking. I'll be using that GPS unit as my baseline for "great performance" when the hackery begins
(edit: taking a quick look at the kernel source it looks like we have a BCM4751 and i'm fairly certain all the relevant calculations are handled in the baseband. The good news is that chipset does support SBAS. I doubt it's properly handling it however, as it doesn't even perform up to the level of a GPS without SBAS. If everything IS being handled in baseband, i'm going to need to get my hands on source code to the radio to fix it, which won't be the easiest thing ever )
Getting interesting now...
Did anyone come across this yet? Is this real or a joke?
Samsung Captivate And Vibrant Finally Get GPS "Fix" Via GPSSamsungRestore App
The Galaxy S phones are, without a doubt, among the best Android phones out there, but for some time now, the handsets have been plagued by one potential showstopper – malfunctioning GPS capabilities. Worry not, though – in addition to an update that rolled out a few months ago, Samsung has developed an app called GPSSamsungRestore which is now available from the Android Market for all users of AT&T’s Captivate and T-Mobile’s Vibrant. So what does it do? It undoes any modifications to the GPS and basically reverts it to its original state. While it remains to be seen how reverting the GPS to its original, broken state fixes it, I suppose it can’t hurt to give it a shot if you’re a Captivate or Vibrant owner.
Note: The app only shows up in the Market for Captivate and Vibrant owners, so if you’re looking for it just for kicks, you won’t find it unless you’ve got one of those devices. It isn’t listed on AppBrain, either.
Click to expand...
Click to collapse
Quote from Android Police
Is there a validity with that GPSSamsungRestore fix.
and +1 on awesome person joining this awesome group!
Wow..very informative read there. Looks like we've found our Cappy GPS fixer-upper! Nice to have you aboard.
Sent from my couch on my phone.
Da_G I'm glad to see you have a captivate. Used your roms all the time on my Touch Pro. Glad to see another great dev on this phone. Looking forward to any work you do with it.
Amazing explanation, we are all aware of the AGPS -GPS relation but we like to lie to ourselves that some of these tweaks are actually working and that our devices are as good as any other. The truth is that our device is waaaay better with the latest developments than any other device on the market, and mine is simply perfect.
Honestly, I've been running Cognition 2.3b6 with the Jupiter v6 tweaks and had no problems with the GPS on a trip in the mountains, between trees and under heavy snow (300km round trip). Absolutely none! A bit slow lock but great tracking.
Now I'm using 2 different tweaks, the JM9 GPS drivers + this control plane thing on the same rom, Cog 2.3b6. Got a lock in 10-15 sec on 7 sats (tested for about 10 mins) but didnt have the chance to take it for a test drive. Hopefully will get the same results like before. If not, I'll just revert back to "stock" Cog with jupiter tweaks, that was the best.
I wonder if it is possible to use my GPS without my mobile connection. I like to use GPS in the airplane with an offline navigation.
Whenever I turn off my mobile connection of my HTC DESIRE, the GPS gets lost too . Is there a way?
What application are you using for your GPS? Most apps pull the actual maps from the internet and don't store them internally which might be the reason you can't use your GPS when your network is off. I guess if you could find an app that has the reference to the maps locally and install the maps locally (about 1GB for the US) then you shouldn't have a problem.
http://androidcommunity.com/forums/f12/offline-gps-maps-20226/
Some discussion on the thread above regarding your topic. Many people have posted about it. Not sure what's out there.
it's first bcoz it can't download the maps from the net.
But even without this, if you're using GPS Essentials or GPSTest for example -apps which only display the GPS stats- you'll notice it doesn't work either. And this is because the chips in s-phones are A-GPS chips, which need an internet connection to download precalculated data about satellites approx. positions, almanach data, etc etc. This helps the chip in getting a GPS lock faster, but makes it internet-dependant (the data is valid for 6 days, provided you don't change location by more than 50 miles or so. But usually the device tries to download fresh data each time the GPS is 'cold-started' -first start after a reboot or some prolonged inactivity period- and falls back to the old data if there's no connection. Past 6 days, the data is flagged as 'deprecated' and isn't used anymore whatever the case may be)..
At first only a handful of smartphone makers implemented those chips because they're cheaper to produce and take less space (most of the calculations for determining the user's position is done by the CPU, the A-GPS chip mostly only collects the data, filters it and forwards it), but then some american government agency (can't remember if it was the one regulating automotive transportation or some other though) made it mandatory for all devices sold in the US, to help paramedics and other rescue services in locating injured car-drivers quicker and more efficiently (the theory behind being that an A-GPS chip equipped device demands less interaction from the user to start up the GPS function and get an accurate fix on the position. An A-GPS chip is *supposed* to be able to get a lock and fix all by itself once the GPS is started, so that'd be only a movement of the thumb for the injured person to launch a distress call -provided he/she is able to grab the phone, of course...). But they were a bit shortsighted -as usual, if I may say- in that if the driver 'choses' to crash in a remote location where there's no 2G/3G/4G carrier coverage, he's pretty much screwed anyways, unless he resorts to the good old voice-comm'..
And of course since the US is one of the main phone markets in the world, the same phones are winding up all over the world by now.
thanks for all replies.
it actually worked well in FLIGHT MODE. I used to pre-cache some maps which is possible since the new google maps update.
worked like charm
yea but this is because you got a HTC phone.. They're typically embarking better A-GPS chips than the norm (Qualcomm-made, for the most part).
They're better than the SirfStarIV I have in my SGS2 for example, not by their precision (which is roughly the same and even a bit superior for the SirfStarIv) but by their lock-on times and the quality of their reception (which relies a lot on the built-in antenna which seems to be better by HTC).
With my HTC Desire "S" I was often able to get a lock-on even within a building (=with no clear overview of the sky), just by standing near a window... With the Galaxy S2 I have to extend my arm as far out the window as I can to be able to lock a puny 4-5 sats... :/