Database Users

GPS Showing me in the wrong location

The other day the GPS had the weirdest issue. I was stuck in traffic and decided to turn on Google Maps to find out how long the traffic is going to be. To my disbelief, the GPS showed me in a different town and MOVING on the street and then onto some freeway about 50 miles from my location. I thought the GPS satellites are screwed up but my car was showing me in the right place (and never has made such a stupid error).
Makes me wonder if the GPS info is actually going to Google servers and coming back to the phone as I guess I was getting someone else's GPS data and the lines were crossed somehow. This continued to about 30 minutes as I was enjoying the error and wondering at the same time. Holding the phone out of the window and stuff did not work. Eventually I reboot (oops! I meant I took the battery out because HTC apparently thinks we never need to reboot te G1 so there is no PIN hole for reboot like most other phones).
has anyone else experienced the same issue?

brooklynite said:
The other day the GPS had the weirdest issue. I was stuck in traffic and decided to turn on Google Maps to find out how long the traffic is going to be. To my disbelief, the GPS showed me in a different town and MOVING on the street and then onto some freeway about 50 miles from my location. I thought the GPS satellites are screwed up but my car was showing me in the right place (and never has made such a stupid error).
Makes me wonder if the GPS info is actually going to Google servers and coming back to the phone as I guess I was getting someone else's GPS data and the lines were crossed somehow. This continued to about 30 minutes as I was enjoying the error and wondering at the same time. Holding the phone out of the window and stuff did not work. Eventually I reboot (oops! I meant I took the battery out because HTC apparently thinks we never need to reboot te G1 so there is no PIN hole for reboot like most other phones).
has anyone else experienced the same issue?
Click to expand...
Click to collapse
The GPS is not being relayed to google... but google maps may be the thing that is wrong here. You can't get your "lines crossed" when using google maps but the maps may be downloading the wrong set. I know I have seen it do some weird things but that is expected to happen when you have several countries you have to have maps for.
As for the reboot issue... is it really that hard to hold down the power button? You do realize that the pin hole on previous devices is for emergencies only. It could really screw up the phone. Similarly like using your computer and unpluging it while it is on... or just pressing its reset button.
Maybe this is the reason for your problems with your G1.

I was just browsing my location and found that the location was in my local Radio Shack that was 2 blocks away. I tried to refresh but wouldn't allow me to.

G1 uses assisted GPS, which performs some calculations away from your phone. Could have been your A-GPS server was sending back some faulty data.

Some Application in G1 read Location info from Proprietary GPS Chip and also relies on Cell Tower GPS Coordination if GPS Signals is not available, in India my Airtel Company have Bad GPS Coordination in my Cell Tower, I Personally know which Cell Tower i am hooked to while i am at home but the Cell GPS Coordination is 8 Miles away from my Cell Tower.
Check that your GPS Signal were Strong and you have not just started seeing maps when that error occured.

I think it was stong. I had all my bars full and the 3g logo on it. Oh well I'll probably fiddle with it a little more tomorrow after I try to get a screen protector for the phone

I thought the problem had gone away until last night it happened again, with one difference. I still had me being shown 20-30 miles away (interestingly not across the globe but simply 30 miles away) the problem corrected itself after about 5 minutes.
I have a car GPS and a portable GPS and I have never seen this happen before. The issue is definately the A-GPS. I always thought during WAR the military may scramble the GPS data to confuse the enemy, I guess that is what promted Europeans to install their own GPS that is much more accurate than ours.
And there are controversies over this as well. Google is recording my location and my cell towers and IP addresses and URLs according to its NO privacy policy. This is definitely not fun.
Sending my GPS info to Google servers (which is in fact the case) without me knowing it and sending it back to my phone through internet channels it not something I am comfortable with. Especially if Google releases information to law enforcement one day that may be incorrect showing me somewhere I really was not at!

CORRECTION: A-GPS is for phones without GPS. It does not apply to this thread.

brooklynite said:
CORRECTION: A-GPS is for phones without GPS. It does not apply to this thread.
Click to expand...
Click to collapse
Where do you get your information? aGPS is for phones with GPS... it uses a data connection to locate you within so many meters than uses the GPS signal to pinpoint so you are located faster.

brooklynite said:
CORRECTION: A-GPS is for phones without GPS. It does not apply to this thread.
Click to expand...
Click to collapse
Wrong.
http://en.wikipedia.org/wiki/GPS_Phone
http://www.apple.com/iphone/features/gps.html

I have the same dxmn problem with the gps f-ing up. It started with RC30...When I was on RC19...I had NO PROBLEMS with gps.
It would pinpoint my location in 5sec. Now it's take 10-15min to pinpoint me. Google need to fix this fast.

whether it is related to this thread or not...A-GPS....
, generally abbreviated as A-GPS, enhances the startup performance of a GPS satellite-based positioning system. It is used extensively with GPS-capable cellular phones
Click to expand...
Click to collapse

same problem here. i also think it started with the update.

Guys, I am not wrong.
A-GPS as Google calls it (and there are other versions of it), is for phones without a GPS chip (thats how Google Maps find you on a T-Mobile WING), it started after an fcc mandate to be able to locate 911 callers from cell phone. It finds your location using a triangulation of the cell towers you are connected to and this particular technology and the extensive data that is required is owned by Google however Google may not call it AGPS.
http://www.techcrunch.com/2007/11/28/google-mobile-maps-pinpoints-your-location-without-gps/
Now it seems to me that Google is enhancing its data network of cell towers using our phones to collect location data. So it collects the cell towers we are connected to with the strength+ the GPS info from our phones and puts all this data in a server to that non-GPS phones using Google Maps can have a better triangulation as more data is gathered from across the country. Eventually the system could be perfected to locate any cell phone without a GPS chip or to locate a cellphone with the GPS feature turned off for privacy, and that is what concerns me.
When my phone shows me 20 miles from where I am, on the freeway, cruising at 55MPH while I am sitting in traffic on the other side of town, it concerns me.

brooklynite said:
Guys, I am not wrong.
A-GPS as Google calls it (and there are other versions of it), is for phones without a GPS chip (thats how Google Maps find you on a T-Mobile WING), it started after an fcc mandate to be able to locate 911 callers from cell phone. It finds your location using a triangulation of the cell towers you are connected to and this particular technology and the extensive data that is required is owned by Google however Google may not call it AGPS.
http://www.techcrunch.com/2007/11/28/google-mobile-maps-pinpoints-your-location-without-gps/
Now it seems to me that Google is enhancing its data network of cell towers using our phones to collect location data. So it collects the cell towers we are connected to with the strength+ the GPS info from our phones and puts all this data in a server to that non-GPS phones using Google Maps can have a better triangulation as more data is gathered from across the country. Eventually the system could be perfected to locate any cell phone without a GPS chip or to locate a cellphone with the GPS feature turned off for privacy, and that is what concerns me.
When my phone shows me 20 miles from where I am, on the freeway, cruising at 55MPH while I am sitting in traffic on the other side of town, it concerns me.
Click to expand...
Click to collapse
Where are you getting your information? The link you provide just says they support phones without GPS but they never say it is only for phones without GPS. In fact it says that it will work on phones with GPS... that is what the whole article is about that phones in the future will have GPS and google maps will be able to pinpoint their location faster. Basically it says they are using A-GPS.
In the link above he links to http://www.techcrunch.com/2007/11/28/google-earth-heading-towards-extinction/ Which says people will be able to add their own commentary about places like a wiki. Nothing about using other peoples devices to send information for google to collect.
It also has this link http://www.google.com/intl/en/press/annc/20071128_maps_mobile_my_location.html Which is googles official press link saying it will work with both GPS and non-GPS phones by using the Cell ID and a special formula that google developed to pinpoint your location within a certain amount of distance. Nothing says it uses other peoples GPS signals. In fact it says "This approximation is anonymous, as Google does not gather any personally identifiable information or associate any location data with personally identifiable information as part of the My Location feature."
All in all I think you are misreading and need to look over your data again.

neoobs said:
Where are you getting your information? The link you provide just says they support phones without GPS but they never say it is only for phones without GPS. In fact it says that it will work on phones with GPS... that is what the whole article is about that phones in the future will have GPS and google maps will be able to pinpoint their location faster. Basically it says they are using A-GPS.
In the link above he links to http://www.techcrunch.com/2007/11/28/google-earth-heading-towards-extinction/ Which says people will be able to add their own commentary about places like a wiki. Nothing about using other peoples devices to send information for google to collect.
It also has this link http://www.google.com/intl/en/press/annc/20071128_maps_mobile_my_location.html Which is googles official press link saying it will work with both GPS and non-GPS phones by using the Cell ID and a special formula that google developed to pinpoint your location within a certain amount of distance. Nothing says it uses other peoples GPS signals. In fact it says "This approximation is anonymous, as Google does not gather any personally identifiable information or associate any location data with personally identifiable information as part of the My Location feature."
All in all I think you are misreading and need to look over your data again.
Click to expand...
Click to collapse
Regardless of above, and you may be correct and I may be wrong, but the thread is getting distracted from the main subject. My main issue is this: Why is the GPS reporting me in the wrong location, and even MOVING which is weird. It was pretty obvious to me from what I saw that the Google Maps software in my phone was reading someone else's location data from someone else's GPS. I could see the person move through the streets and speed up and slow down. This makes me wonder if my locatio data is being sent to Google servers somewhere and then back to the phone (and in some cases crossed over with another persons data). This feels especially more true because Google MAPS has slowed down dramatically from finding "My Location" compared to "pre RC30" upgrade and even compared to the GPS-Chop-Free WING and even my ancient car's GPS system.

Have you talked to Google about this? I think you are just speculating what you want and have a hidden agenda. Did it locate you within so many feet? or was it a real location? If it was a real location than it couldn't be Google as it only pulls the map the actual lat, long is coming straight from the sats... possibly it pulled the wrong location for that tower while using A-GPS and then this calculated the wrong GPS coordinates.
Since you don't know what or how A-GPS works this may be hard to understand. A-GPS works by using that method you described for non-GPS cellphones to narrow the search for satalites. This doesn't find your location it only finds the vicinity. You can see the A part of A-GPS work when it says your location within so many meters. This is what works on your wing. The actual pinpoint location is based only off the GPS and isn't sent to google. Google only needs the map coordinates to download. Your GPS is what tracks you on the map. This is why google maps always load in blocks.
To fully understand a map system you must learn how maps work and be educated in the art of cairegraphy

I think the real concern is that brooklynite was seeing himself moving through traffic while he was actually stationary. I can understand that perhaps the GPS got the wrong co-ords and the incorrect map was loaded showing him in another location, but you would still expect him to be shown stationary in the wrong location. So why would it show him moving when he was stationary?
The fact that he was moving on the map means the data must have been coming from another device doesn't it? How else could you explain it?
I would be concerned too.

neoobs said:
.... Did it locate you within so many feet? or was it a real location?...
Click to expand...
Click to collapse
A real location about 50 miles away from my location. Somewhere I have never been since I have had this phone so it cannot be using the old data in my phone as sometimes it shows my locations from "last night".
...possibly it pulled the wrong location for that tower while using A-GPS and then this calculated the wrong GPS coordinates...
Click to expand...
Click to collapse
I always have the "use wireless networks" off, afterall, the GPS chip is one of the main reasons I switched to the G1 from my older WING.
....
I have to add that I am amazed by the GPS accuracy, it even notices when I cross the stree, turn into a driveway or the side of the street I am standing on. When I switch to Sat. view, it literally shows my exact spot on the sidewalk, not in the middle of the street like a car GPS does.

Probably getting too far off topic but car GPS units are just as accurate, it's just that most of them have a correction feature to fudge your position onto the nearest road on the map if for some reason it is not. For the most part a driver doesn't care where he is on the road in relation to the curb....only that he is on the road he thinks he should be on.

Assisted GPS - Don't use it!

My Touch Pro ran TomTom flawlessly until a couple of months ago when I got a problem with the GPS device (not the signal) being lost every few seconds. It would reappear again for about 5 secs then off again. Despite soft resets etc, I suspected it might be the SD card at first as I tried many restart combinations with the card in/out etc and as it seemed to help on one occasion I put it down to that. But it did happen on a regular basis.
I now have the X1 with its superb GPS implementation, I was very impressed for a few days... until you guessed it, this problem started happening again!
Luckily I remembered the only setting I had done prior to this occuring was to use the Advanced Config application, where I enabled the AGPS feature. So... I went back in and disabled it and the problem disappeared immediately. I used Advanced Config on the Touch too, so that must have been the problem for sure.
I notice that AGPS is disabled by default. Why HTC did this must mean there is a problem with this feature.
So be advised, not to use the AGPS unless anyone knows good reason to and has a fix for the problem I mentioned.

I ran into the same problem. Turned on agps in advance config, used tomtom 7 and keep getting drop signal. It would pick up the sat signal for a few second and lose it, what interesting though when I use google map it would track me fine, no lost of signal. I can see my "dot" on google map moving along. When I drive, haven't tried it with other nav software to see if this was an issue. I still wonder why they have agps turned off though as default.

i think even if its set to "disabled", its enabled. a-gps must be hard coded in the hardware itself!
ps: i have the same problems when its "enabled".

I think it's the AGPS file that might have corrupted. You can solve this by re-download AGPS file and everything will be fine.
It happened to me once or twice, but it's not a reocurring problem so I did not bother much.

which agps file?

Guess you talk about an A-GPS setting in Tom Tom?
I cannot follow your conversation. With Mobile Navigator, which has no switch to enable or disable A-GPS it works pretty fine.
Sat-fix within seconds - thanks to the provided A-GPS function of the X1, which I don't think can be disabled on teh X1, until you don't update the information frequently with the Quick-GPS application.
Maybe Tom Tom can't interpret the A-GPS information?
How long does a Sat-Fix in Tom Tom take, when you disable A-GPS (in Tom Tom)?
Eric

we are talking about a tool called "advanced config tool". there is an option of enabling and disabling a-gps. "disabled" works best for most users...
you can have a 3d fix in seconds also with no a-gps.

Eric X1 said:
I cannot follow your conversation. With Mobile Navigator, which has no switch to enable or disable A-GPS it works pretty fine.
Sat-fix within seconds - thanks to the provided A-GPS function of the X1, which I don't think can be disabled on teh X1, until you don't update the information frequently with the Quick-GPS application.
Maybe Tom Tom can't interpret the A-GPS information?
How long does a Sat-Fix in Tom Tom take, when you disable A-GPS (in Tom Tom)?
Eric
Click to expand...
Click to collapse
It's incredibly quick (even indoors) to fix a position without AGPS. I admit I haven't knowingly had any noticable problems outside of TomTom but this is something I use a lot. It copes admirably inside, in built-up or shaded areas. No real need for AGPS then! I did try updating my QuickGPS file by the way, to no avail. Disabling was the only fix!

The FIX IS TOO FAST!!!
But I don't have this problem.......

DocMAX said:
we are talking about a tool called "advanced config tool". there is an option of enabling and disabling a-gps. "disabled" works best for most users...
you can have a 3d fix in seconds also with no a-gps.
Click to expand...
Click to collapse
My X1i doesnt have an "adavanced configuration tool" application. Is this a 3rd party addon that you have installed, or is my device just configured differently?

DocMAX said:
which agps file?
Click to expand...
Click to collapse
xtra.bin in \Windows directory I believe
one way to verify if the problem is due to the AGPS corrupted file, is if you encounter the problem, delete the xtra.bin and see if the problem goes away.

kiwiandy said:
My X1i doesnt have an "adavanced configuration tool" application. Is this a 3rd party addon that you have installed, or is my device just configured differently?
Click to expand...
Click to collapse
you have to download it http://forum.xda-developers.com/showthread.php?t=317070
it's our swiss army knife, but be careful

I think people may be getting confused between a-gps and what quickgps does.
My take on this is:
QuickGps downloads a file which contains a list of satellites to speed up getting a signal. Works very well on the x1
this is governed by HKLM/Software/HTC/QuickGPS
A-gps gets an approximate location from your cell tower and feeds 6 virtual satellites signals through the com port set up in the control panel.
It constantly does this, using memory-map software you can see that the signal drops and comes back every second or so. it seems to overwrite what is actually coming from the gps chip as I've seen 4 high quality satellite signals disappear to be replaced with 6 from the a-gps nowhere near where I was.
There's a setting in the registry section concerning A-gps which has "GPSmode" which is set to 2 I wonder what the other values are and do, I havent played with those yet.
You can change the refresh interval I set mine to be 5 when on foot
HKLM/Software/HTC/SUPL_AGPS

I agree with pretty much what you have said (the difference between Quick GPS [sometimes also known as Assisted/A-GPS] and the conventional, location-based AGPS)
However, I don't believe, unless somebody scientifically, or empirically prove, that the phone will receive virtual satellite feed/signal once it acquire the proximity based on the LBS signal. Because to do that, you need to have a data carrier, and it's either via GPRS/UMTS data connectivity (not possible since I would have noticed the data transmission), or radio frequency that satellites transmit on. It can't be GSM/W-CDMA since they operate on the different frequency as GPS, or if it indeed transmit the "virtual satellite signal" on the GSM/W-CDMA network, then I'm sure you will notice it as part of your monthly telco billing?
You may argue that the server is transmitting the virtual satellite signal on the GPS radio frequency, if so, that'll be new development in the AGPS technology since HP iPAQ 6515 first come out employ. However, there are few consideration point;
1. GPS radio frequency does not operate well across barriers, which means the 'virtual satellite transmitter' must be transmitting at a higher ground otherwise it won't work
2. The GPS receiver must be able to reconcile signal from virtual satellite signal and 'real' satellite signal, which means added layer of processing at the phone end, which in my opinions offer more complexity than effective solution.
That said, I just read that the Quick GPS service provider supports 50bit navigation raw data streaming, so I might be wrong afterall.
fards said:
I think people may be getting confused between a-gps and what quickgps does.
My take on this is:
QuickGps downloads a file which contains a list of satellites to speed up getting a signal. Works very well on the x1
this is governed by HKLM/Software/HTC/QuickGPS
A-gps gets an approximate location from your cell tower and feeds 6 virtual satellites signals through the com port set up in the control panel.
It constantly does this, using memory-map software you can see that the signal drops and comes back every second or so. it seems to overwrite what is actually coming from the gps chip as I've seen 4 high quality satellite signals disappear to be replaced with 6 from the a-gps nowhere near where I was.
There's a setting in the registry section concerning A-gps which has "GPSmode" which is set to 2 I wonder what the other values are and do, I havent played with those yet.
You can change the refresh interval I set mine to be 5 when on foot
HKLM/Software/HTC/SUPL_AGPS
Click to expand...
Click to collapse

zenkinz said:
I agree with pretty much what you have said (the difference between Quick GPS [sometimes also known as Assisted/A-GPS] and the conventional, location-based AGPS)
However, I don't believe, unless somebody scientifically, or empirically prove, that the phone will receive virtual satellite feed/signal once it acquire the proximity based on the LBS signal. Because to do that, you need to have a data carrier, and it's either via GPRS/UMTS data connectivity (not possible since I would have noticed the data transmission)
Click to expand...
Click to collapse
when you enable a-gps in the registry it establishes a data connection, or at least it does on my phone.
In my house I get a variable signal, it can drop the data connection easily (and does)!
When I first tried A-gps enabled in the registry it tried to connect, couldnt and memory-map reported no signal. It then connected I got 6 satellites listed till the data connection dropped. This makes me think it's using a data connection.
I disabled all data connections using paul modacos "nodata" and didn't get any "satellites" picked up. My quickgps was upto date at the time and outside I would expect to get a decent "proper" satellite lock.
the SUPL-AGPS section of the registry also contains the following.
Server IP 10.1.101.63
Server Port 7275
Which suggests some form of data connection. Remember this has nothing to do with quickgps or the ephemeris data that gets.
Have a look at http://wmexperts.com/articles/gps_vs_agps_a_quick_tutorial.html
&
http://en.wikipedia.org/wiki/GPS_Phone
A typical A-GPS-enabled cell phone will use a data connection (internet, or other) to contact the assistance server.
Click to expand...
Click to collapse
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edit Have just tried again to confirm what I wrote and not getting anything through a-gps at all! I wonder if there's something in this custom rom that's changed things.
But I am being told Ive got a HDop of 666.6m which is a bit spooky..
step outside and I got 9 satellites with 8m hdop back inside and I'm getting standard fix 5 sats 2m HDop flashing on and off every second (signal/no signal) but no data connection being used, so it looks like I'm wrong, so I'll take it all back!
Need to work out what's going on now..

I was having this same issue. At least its good that its not just my device. I tried deleting xtra.bin from both \windows and \temp and it did not help.
Just some clarification on QuickGPS and AGPS. For a regular stand alone GPS to connect, when it first finds a satellite it must download ephemeris data. The ephemeris data contains info about where all the GPS sats currently are in the sky. The ephemeris data is broadcasted by every satellite periodically. A regular GPS must wait for the beginning of the next transmission. If signal is lost mid transmission, the GPS reciever must wait for the next transmission and start all over again. Only once this data is downloaded can a lock begin to be calculated. What quickGPS does is download the ephemeris data from the internet so that next time you request a gps lock, this sometimes lengthy process can be skipped. quickGPS downloads a file called packed ephemeris and places it I believe in the windows directory.
AGPS on the other hand simply supplements info from the sattellites with info from the cell network. What towers you are currently near gives an approximate location (the mechanism that google my location uses) which then tells you which satellites to look for. When fards said it feeds virtual satellite info, he doesn't mean it actually broadcasts fake satellites via RF. It just feeds extra info to the GPS driver. Also, there are lots of calculations to do to maintain a lock. Once the receiver is getting sattelite signals it can send this information over the internet to the AGPS server which is a much more powerful computer that can do these calculations much faster. The server calculates the lock for you then sends you your position information back over the internet. This is why apgs enables a data connection.

GPS.....A-GPS SCAM?? The gps drama sequel....

****************************************************************
"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
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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...
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¿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

Does agps actually work on any Optimus 7 phones?

Been searching all day and found a few with this issue indoors, I phoned LG support who are to get back to me about the issue but by the sound of them I think it seems like a common bug.

I can't confirm aGPS is working with any evidence. However, I can say my Optimus 7 manages to find me incredibly quickly, with it estimating my location pretty much immediately upon launch of any mapping software (indoor or outdoor), and it pinpointing my location soon thereafter (outdoor only). So it seems on my American e900H aGPS is working quite well.

Yes, it works. Goto Maps application. If it is in GPS mode your position has yellow color and possible position range is aprox 10-300m. If your position is in grey color and position range is aprox few km it is in AGPS mode. Also your position will be localized on some strange place, like another building and near BTS tower.
It is possible that your operator does not support AGPS in specific area.
PS you can also check it in 3rd party gps application, they ussualy show what is current GPS mode.

elektryk said:
Yes, it works. Goto Maps application. If it is in GPS mode your position has yellow color and possible position range is aprox 10-300m. If your position is in grey color and position range is aprox few km it is in AGPS mode. Also your position will be localized on some strange place, like another building and near BTS tower.
It is possible that your operator does not support AGPS in specific area.
PS you can also check it in 3rd party gps application, they ussualy show what is current GPS mode.
Click to expand...
Click to collapse
Bing maps searches for a few moments then gives an error can't find location and to try later, My iPhone finds me in seconds so AGPS is supported.

Check your firmware: Vodafone firmware has problems with GPS, so you will have a trouble with locating yourself.

[Q] GPS lock problem after kk

Seems to have GPS lock problems after kk update. Very difficult to get lock, and even when lock is eventually found, signal drops off easily. Anyone with this problem and have a solution for this?

koj012 said:
Seems to have GPS lock problems after kk update. Very difficult to get lock, and even when lock is eventually found, signal drops off easily. Anyone with this problem and have a solution for this?
Click to expand...
Click to collapse
To be honest I have seen that on my 4.3, where GPS lock takes more than twice longer (sometimes 5-10 times) than on my S3 - there is another thread on that somewhere. I was hoping 4.4 to come with improved firmware on that one, but apparently not so much

i'm not on kitkat, but i have problems with gps.
however, problems occurs only when recording a track with "my tracks" from google.. as navigation apps works fine, no issue with the signal. only my tracks is giving me huge gaps between checkpoints..

I dont have gps locking problem in kitkat, but with directions while navigation, gps marker points in opposite direction.
Sent from my SM-N900 using XDA Premium 4 mobile app

xclub_101 said:
To be honest I have seen that on my 4.3, where GPS lock takes more than twice longer (sometimes 5-10 times) than on my S3 - there is another thread on that somewhere. I was hoping 4.4 to come with improved firmware on that one, but apparently not so much
Click to expand...
Click to collapse
I have actually had the same problem, I thought it was only me. I ran stock Italy ROM 4.3, but don't see any improvement under 4.4.2 Poland. Even GPS Status app does not seem to help.

xclub_101 said:
To be honest I have seen that on my 4.3, where GPS lock takes more than twice longer (sometimes 5-10 times) than on my S3 - there is another thread on that somewhere. I was hoping 4.4 to come with improved firmware on that one, but apparently not so much
Click to expand...
Click to collapse
Interesting, my GPS lock in MapsWithMe Pro is almost instantaneous. About 5 seconds, usually. Unless I'm indoors, but you can't blame a phone for the laws of physics.
N9005 DBT 4.3 MK2/MJ7/MK2
If I use Google Maps, it will only triangulate if I turn on 'Use WiFi', 'Allow Google Location' and more of that rubbish, and even then it takes about 5 minutes to get a lock.
My advice: Stop using Google Maps.

ShadowLea said:
Interesting, my GPS lock in MapsWithMe Pro is almost instantaneous. About 5 seconds, usually. Unless I'm indoors, but you can't blame a phone for the laws of physics.
N9005 DBT 4.3 MK2/MJ7/MK2
If I use Google Maps, it will only triangulate if I turn on 'Use WiFi', 'Allow Google Location' and more of that rubbish, and even then it takes about 5 minutes to get a lock.
My advice: Stop using Google Maps.
Click to expand...
Click to collapse
1. I almost NEVER use Google Maps (OK, maybe for testing stuff) - and I can only wonder how you got that idea anyway Generally I am very happy with Sygic and I also use GPS Test for quick testing, also Accurate Compass (for very quickly calibrating the compass).
2. I have now tested MapsWithMe for like 2 days and I can guarantee you that the "instantaneous GPS lock" is COMPLETE bullsh*t - the program is only caching your last position (which generates huge problems if you move between locks), then it tries to use location data from your WiFi connection if that is active; if not it then tries to use some very basic and EXTREMELY INACCURATE positioning based on GSM cell towers (at which point the error displayed for my position was in the order of 1-2 km); during all those steps the program also fires-up the GPS - but it acquires the lock EXACTLY with the same speed (or complete lack thereof) as any other program attempting GPS lock
3. What still remains a little surprising for me is that sometimes (like well over 50% of time but NOT 100%) my GPS lock is MUCH, MUCH faster (in any program) if I have the Mobile Data connection active (which normally I rarely have); once I have the GPS lock I can then stop the Mobile Data connection and the lock remains perfectly good. EDIT: However the WiFi connection does NOT seem to make ANY difference on GPS lock whatsoever.

Isn't this basicly what AGPS should be doing. It requires a data connection to get the positioning fix faster than just using the GPS. once it gets the location it does not need the data that much. Except for google maps to download the map and navigation information, and this is why it needs a data connection all the time.
Sygic does not need a data connection for the map nor navigation. But, of course, having a data connection well get the fix faster.

y2kkingboy said:
Isn't this basicly what AGPS should be doing. It requires a data connection to get the positioning fix faster than just using the GPS. once it gets the location it does not need the data that much. Except for google maps to download the map and navigation information, and this is why it needs a data connection all the time.
Sygic does not need a data connection for the map nor navigation. But, of course, having a data connection well get the fix faster.
Click to expand...
Click to collapse
Oh, I had no surprise from the fact that aGPS can work
What I might have not mentioned above (fixed that now) was:
- a WiFi connection never improves things
- my old i9300 never needed the mobile data connection (or any kind of connection - that made basically no difference on it).
Those two seem to suggest that the Note3 "GPS driver stack" is worse than the old i9300. Also the fact that the mobile data connection does not improve things in 100% of the cases was IMHO interesting to note.

xclub_101 said:
1. I almost NEVER use Google Maps (OK, maybe for testing stuff) - and I can only wonder how you got that idea anyway Generally I am very happy with Sygic and I also use GPS Test for quick testing, also Accurate Compass (for very quickly calibrating the compass).
Click to expand...
Click to collapse
Ah, miscommunication. I did not mean you used Gmaps, I meant people in general. Gmaps is a nightmare, on 50Mbps LTE it still barely loads... Even on my homenetwork of 120Mbps WiFi it takes ages to load the map itself, surely the packages are not 1GB a piece?
2. I have now tested MapsWithMe for like 2 days and I can guarantee you that the "instantaneous GPS lock" is COMPLETE bullsh*t - the program is only caching your last position (which generates huge problems if you move between locks), then it tries to use location data from your WiFi connection if that is active; if not it then tries to use some very basic and EXTREMELY INACCURATE positioning based on GSM cell towers (at which point the error displayed for my position was in the order of 1-2 km); during all those steps the program also fires-up the GPS - but it acquires the lock EXACTLY with the same speed (or complete lack thereof) as any other program attempting GPS lock
Click to expand...
Click to collapse
I travel an average of 600KM a day.
Yes, MWM caches the last position. Which is hilarious from time to time, last week it thought I was still in Zurich when I was actually in Berlin. If you click the gps icon three times again, it repositions. Waiting for it to refix automatically takes ages.
I do not have WiFi on the Autobahn, (If only! ) and 70% of the journey I do not even have a mobile signal.
3. What still remains a little surprising for me is that sometimes (like well over 50% of time but NOT 100%) my GPS lock is MUCH, MUCH faster (in any program) if I have the Mobile Data connection active (which normally I rarely have); once I have the GPS lock I can then stop the Mobile Data connection and the lock remains perfectly good. EDIT: However the WiFi connection does NOT seem to make ANY difference on GPS lock whatsoever.
Click to expand...
Click to collapse
Nothing suprising about that. It uses the celltowers to triangulate by sending a data package, as opposed to attempting to connect to three satelites. If the network is fast enough (UMTS and above) it is much easier to get an accurate position. GPRS doesn't work all that well, nor does having 1 bar of signal on anything but LTE.
WiFi only helps if there are active points nearby (no need to connect to them, detecting them is sufficient) and you have 'use wireless networks' enabled under Location Settings.
I just tested: WiFi and Mobile Data off, No network signal, on the Fyra (Highspeed train. Or as much as the NS can manage, anyway.) from Schiphol Airport to Breda @160kph. Got a lock with SpeedView in 15 seconds, detected 24 sats. Not instantaneous, but then you can't ask for that at such speeds.
I do have to say, on the previous firmware it took much, much longer. About 1-2 minutes. And I tried a Dutch Note 3 yesterday, it required almosylt a minute on the same firnware version.
The weather also influences the signal, clear skies vastly improve things. As does solar activity. Last October you could wait an hour and not get a lock, due to a solarstorm causing too much magnetic interference in the atmosphere. Even my GPS locator itself took almost half an hour.
Send From My Samsung Galaxy Note 3 N9005 Using Tapatalk

ShadowLea said:
...
Nothing suprising about that. It uses the celltowers to triangulate by sending a data package, as opposed to attempting to connect to three satelites. If the network is fast enough (UMTS and above) it is much easier to get an accurate position. GPRS doesn't work all that well, nor does having 1 bar of signal on anything but LTE.
...
Click to expand...
Click to collapse
Actually original aGPS doesn't quite work that way at all - here is some info from some of the guys doing some of the Linux kernel drivers for aGPS devices (I can not guarantee it is 100% accurate but fits OK with other info that I have seen):
http://wiki.openmoko.org/wiki/Hardware:AGPS
And another thing to remember when testing GPS - after a successful GPS lock it is very likely that you will have a MUCH faster 2nd GPS lock for up to about 2 hours. So any such immediate 2nd lock should be see in the above context, also the lack of it

Least this problem isn't just me. Always used to track my rides with Endomondo without a hitch but I went out for the first time since KitKat and I couldn't tell you how many times it dropped out on that 2 hour ride ... but it was alot

Xalies said:
Least this problem isn't just me. Always used to track my rides with Endomondo without a hitch but I went out for the first time since KitKat and I couldn't tell you how many times it dropped out on that 2 hour ride ... but it was alot
Click to expand...
Click to collapse
Seems to be a very common problem. Read somewhere that this is a software issue and there is a fix if the phone is rooted by flashing a patch on it. But I'm not about to root my phone and lose the warranty. SAMSUNG please release an update quickly that fixes this problem.

koj012 said:
Seems to be a very common problem. Read somewhere that this is a software issue and there is a fix if the phone is rooted by flashing a patch on it. But I'm not about to root my phone and lose the warranty. SAMSUNG please release an update quickly that fixes this problem.
Click to expand...
Click to collapse
I am rooted (with knox 0x0 ) and I have looked into that patch - the one that I saw only sets a different AGPS server address and has minimal or no impact - actually I have a strong feeling that there is something in the CSC that overrides it, which explains why the AGPS server only improves things for me when connected only on mobile data and not over wifi.
IMHO that seems to be mostly a firmware / software driver issue - on my old S3 it looked like there was a lot more "caching" of the "GPS almanac" and slightly more pre-calculation of the "GPS ephemeris", possibly on the application CPU on the phone (which has humongous general-computing power compared with the CPU used inside the GPS circuit, which however is highly more specialized). On the Note 3 it seems to work in a "safer" approach in which older (than like 2 hours) GPS almanac data is considered inaccurate and so is the time otherwise used to pre-calculate GPS ephemeris (which time to be honest I have seen WILDLY inaccurate on some carriers, something like 27 seconds away; and of course if the time is not carrier-set the phone time can easily be tens of minutes away ).