Database Users

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
-----------------------
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.

Assisted GPS Pharos?

The Pharos is supposed to have AGPS. Do they mean QuickGPS or is there really AGPS on it? Where can I find it on the Pharos?
I have the WM6.0 Dutch version.

when i turn on tomtom in my house it says im in the location of the nearest gsm beacon...before i have a satellite fix, thats assisted GPS i think...
quick gps only has the trajectories of satellites in the "local" sky so the gps chip can get a fix quicker

Strange, nothing happens when I start TomTom.
Can you give me your settings in the register:
HKLM>Software>HTC>SUPL AGPS>

i checked but no such key
wat is the setting of your key?

Keysetting in HKLM>Software>HTC>SUPL AGPS> is:
(Default) (value not set)
EnableAGPS 1
EnableGPSSmartMode 1
GPSMode 2
NumberFixes 389AC9FF
QosAccuracy 32 (50)
QosPerformance 59 (89)
ServerIP 195.207.101.126
Serverport 1E6C (7788)
TimeBetweenFixes 1
When I first started with the Pharos there was no AGPS, also not in the registry the Supl AGPS. I found a registry-entry for the Pharos on this site and put it on the Pharos. When I start 'Advanced Config' from Schaft I can see under GPS that AGPS is enabled.
When I start TomTom 7.9 there's no start of GPRS. Also my GPRS monitor sees no action. So I presume AGPS is not working.
Maybe I need some dll drivers, I don't know. Can somebody help?

you have a confusing story
first you talk about GPS and then about GPRS
these are 2 different things
GPRS is your data connection (in case EDGE is not available)
GPS is global positioning system and i didnt know tomtom 7.9 was out, i use 6.
if you do a simple search on the phorum you can see that tomtom 7.9 causes a few problems i suugest you read that!
my advice would be to revert back to 6 .. works great on the pharos

Maybe I'm confused. I thought Assited-GPS uses GPRS to make contact with the gsm beacons and so make a faster fix with these beacons. Am I wrong about that?
The builtin GPS from the Pharos works fine but is not very fast with the first fix. I thought AGPS would help making a faster fix.
I already had TomTom 7.4 and know 7.9 (cracked version). Works fine on the Pharos. I will look for the problems with 7.9 on the forum.
Thanks

hmmm yeah makes sense we do need a server to relay the info... but ive looked it up
http://en.wikipedia.org/wiki/AGPS
http://en.wikipedia.org/wiki/List_of_devices_with_Assisted_GPS
our device is on the list... but i dont think i have a server setting... and my gps (tomtom) doesnt have to have a connection to the internet.
strange but fun to find out how it works...

TomTom does not use the AGPS function. Enable quickgps to do this before you use your navigation software (TomTom). It can automatically download the satellite info for you which is good for about 2 days. You can update through your cellular connection if you have data on your plan or through activesync. TomTom 7 will work without using the AGPS function but it will take longer to find a fix on the satellites. TomTom 7 is required if you want to use the internal gps receiver with TomTom. TomTom 6 does not work without some hacks.

I think that Google Maps do use the AGPS function. It is much faster to find the coordinates than fx TomTom and other GPS software i've tried, so i think that a program needs to be developed with use of the agps function if it uses it..

kaloer said:
I think that Google Maps do use the AGPS function. It is much faster to find the coordinates than fx TomTom and other GPS software i've tried, so i think that a program needs to be developed with use of the agps function if it uses it..
Click to expand...
Click to collapse
the fast "fix" that you see with google maps it's not a gps fix... it shows you the cell radio where you are hooked

poldo964 said:
the fast "fix" that you see with google maps it's not a gps fix... it shows you the cell radio where you are hooked
Click to expand...
Click to collapse
Ohh, okay. That's the reason for the very big radius.. But pretty smart after all..

[Q] aGPS question

Hi
Does aGPS require you to have a cellular data connection in order for it to work? Or will it work with any internet connection (eg. using my laptop's connection through wifi)? I'm asking because I don't have a data plan (yet), and my phone has locked only _once_ since I bought it a month or so ago. I've tried switching to MS based in LbsTestmode, changing the supl server to supl-google-com and supl-nokia-com (can't post links yet).
The one time it did lock was when I was testing the GPS without an internet connection, and I entered a WiFi covered area and it suddenly locked (5-10m accuracy). It wasn't WiFi-based positioning because it was my laptop's WiFi hotspot. And I was using the default settings at that time (www-spirent-lcs-com, Standalone mode). Since then I've tried different combinations of settings but it hasn't ever locked.
Another question: What's the difference between MS based and MS assisted modes?
My phone is an I9000 Galaxy S.

ssj4Gogeta1 said:
Hi
Does aGPS require you to have a cellular data connection in order for it to work? Or will it work with any internet connection (eg. using my laptop's connection through wifi)? I'm asking because I don't have a data plan (yet), and my phone has locked only _once_ since I bought it a month or so ago. I've tried switching to MS based in LbsTestmode, changing the supl server to supl-google-com and supl-nokia-com (can't post links yet).
The one time it did lock was when I was testing the GPS without an internet connection, and I entered a WiFi covered area and it suddenly locked (5-10m accuracy). It wasn't WiFi-based positioning because it was my laptop's WiFi hotspot. And I was using the default settings at that time (www-spirent-lcs-com, Standalone mode). Since then I've tried different combinations of settings but it hasn't ever locked.
Another question: What's the difference between MS based and MS assisted modes?
My phone is an I9000 Galaxy S.
Click to expand...
Click to collapse
Correct me if i am wrong, but as i know aGPS doesn´t need any Data Connection to make the triangulation between the GSM Antennas. So no need for Internet Connection to use aGPS.

TMReuffurth said:
Correct me if i am wrong, but as i know aGPS doesn´t need any Data Connection to make the triangulation between the GSM Antennas. So no need for Internet Connection to use aGPS.
Click to expand...
Click to collapse
AFAIK aGPS is different from cellular triangulation. It refers to downloading satellite information from a server for a quicker fix.

ssj4Gogeta1 said:
AFAIK aGPS is different from cellular triangulation. It refers to downloading satellite information from a server for a quicker fix.
Click to expand...
Click to collapse
I thought it would make a triangulation between the next availabe antennas in range and get over a dedicated channel (not data channel as mentioned above) localisation informations. Because my Nokia N80 had aGPS but not real GPS and in the manual they said something about this triangulation.
But of course i know the download of the actual satelite coordenates from my Touch HD in Windows Mobile with a dedicated App. Just thougth it is something diferent.

TMReuffurth said:
I thought it would make a triangulation between the next availabe antennas in range and get over a dedicated channel (not data channel as mentioned above) localisation informations. Because my Nokia N80 had aGPS but not real GPS and in the manual they said something about this triangulation.
But of course i know the download of the actual satelite coordenates from my Touch HD in Windows Mobile with a dedicated App. Just thougth it is something diferent.
Click to expand...
Click to collapse
aGPS is a technology that downloads satellite data from agps servers at realtime (that is the time you are using the GPS): WIKI article
I guess that the app you are refering to, the one you used on the HTC, is Quick GPS. This program doesn't download satellite postition data in realtime but once in a while. (I believe the data are vallid for 48h) With Quick GPS one can still enjoy the features of aGPS while one hasn't a data connection with a aGPS server.
The Galaxy S GPS (BCM4751) seems to have both, aGPS and a sort of Quick GPS. Only the last is called LTO by broadcom. (see: http://www.broadcom.com/press/release.php?id=s443754 about BCM4571 specs and see here about LTO.

aGPS uses cell tower triangulation, and information from a server, in addition to satellite radio signals, to quickly assist in determining the coordinates of a phone's location. Since cell tower sites are precisely surveyed, they are a reliable source for locational data. A data connection is required. All modern cell phones, at least here in the United States, are required to have aGPS service for use in locating a phone by emergency responders. This is a part of the E911 and is required by FCC mandate. Data is used in tracking down the phone, but it happens behind the scenes and is paid for by fees charged to cellular users on their bills for E911 compliance.
On phones that allow the user to make use of the aGPS chip, there will generally be a setting that allows you to set for E911 use only, or for what is commonly referred to as "location based services." On my Android phones, there are actually two settings, both found in Location & Security Settings. One allows for location based upon use of wireless networks, and the other allowing a fix via GPS satellites. Even with any location based services turned off, emergency responders can still find the phone. The difference being that you cannot use it.
While it is technically possible for you to use your phone's aGPS without a data connection, your chances of getting a signal are sketchy, and your chances of getting a really accurate signal are, under most circumstances, slim to none. Much of the computational work in determining your location is done by the assistance server, and guess how that information moves to and from your phone? Yep, you guessed it, data!
GPS signals sent from satellites are simply radio signals, and your local pop music radio station probably sends its signals with more force. As they are radio signals, they have to contend with everything a radio signal has to deal with, and a large percentage of that is man-made. Signals confusingly bounce off of buildings, are weakened by passing through walls and foliage, or can even be absorbed in some cases by different materials.
Some aGPS chips cannot function as stand alone GPS, and will not work at all without a data connection.
Try this, turn off your cellular radio. Make sure that your WiFi is also off. Now, fire up Google Maps and ask it to start navigation. How did it work?

appelflap said:
I guess that the app you are refering to, the one you used on the HTC, is Quick GPS. This program doesn't download satellite postition data in realtime but once in a while. (I believe the data are vallid for 48h) With Quick GPS one can still enjoy the features of aGPS while one hasn't a data connection with a aGPS server.
.
Click to expand...
Click to collapse
Yeah, that i was talking about. Didn´t know this all I love this forum, you always learn more and more.

rasmith3530 said:
Try this, turn off your cellular radio. Make sure that your WiFi is also off. Now, fire up Google Maps and ask it to start navigation. How did it work?
Click to expand...
Click to collapse
Well, using Google Maps would not be a valid test, of course, since you need data connection to download the local map anyway. If you want to test whether data connection is requires by aGPS, you need to use an offline GPS application.

Thank you for your guys replies.
@rasmith3530: So can that data be downloaded over wifi? (My common sense says yes, just trying to confirm.) If it can, then aGPS isn't working for me at all. I see at max 2-3 satellites in LbsTestMode, without a lock on any of them.

No one said aGPS is working on SGS. They are broken and no fixes yet.

foxbat121 said:
No one said aGPS is working on SGS. They are broken and no fixes yet.
Click to expand...
Click to collapse
I think you're right. The fact that there are no ephemeris and almanac data recorded for satellites let me think that it may be the case that with a certain informed guess aGPS and the advertised LTO function doesn't work on none of the firmwares.

Other people seem to have locking/accuracy problems, they can at least see those satellites. Mine normally shows 0 or 1, so I thought maybe I'm doing something wrong.

ssj4Gogeta1 said:
Other people seem to have locking/accuracy problems, they can at least see those satellites. Mine normally shows 0 or 1, so I thought maybe I'm doing something wrong.
Click to expand...
Click to collapse
In JM1-JG5, I had that issue (couldn't lock onto anything). Switching to JM5 fixed that..

[Q] Garmin Mobile/hd2/data plan....

on a recent trip in our great state of texas , i was going through some area where of course cell reception is very very limited of non-existent all together...
anyway, i was using garmin xt on the hd2, and when it came close to loosing cell/data coverage, garmin would also loose its satellite signal. of course when i lost everything all together,. garmin would say it lost all satellite signals and reception..
question is i thought hd2 had a gps thing built into it and that garmin would use that and satellites and not have to go through out data plan? i mean this might have cost me ****loads of $$$$ since i did go on roaming quite a few times since tmobile doesnt have alot of coverage everywhere.
i had even toggled off data to see if it would connect to a sat, and nothing....
i just found this weird and i sure as hell don't want to pay alot of $$ cuz of roaming...
any thought/ideas? thanks

Make sure your Garmin Mobile shows the 3 or 4 green bars on the GPS intermediate driver. This indicates a lock and the GPS function is working correctly.
Also go into the registry and change these settings:
Change this with your registery
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Contro l\Power\State\Resuming]
"gps0:"=dword:00000001
"gpd0:"=dword:00000001
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Contro l\Power\State\Unattended]
"gps0:"=dword:00000001
"gpd0:"=dword:00000001
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Contro l\Power\State\Suspend]
"gps0:"=dword:00000001
"gpd0:"=dword:00000001
Normmaly the numbers are on 4 put this on one and gps should stay awake even when you put the phone in stanby.
It will stay on until a program stop using the gps.
Make sure you hit exit from Garmin and this will switch off the GPS correctly otherwise it will stay on and sap your battery juice.
Enjoy...

Location services don't work?

I remember why I sold my original Optimus 7 now, I bought a new one yesterday as it was on offer, but for the life of me I can't get location services to work, my iPhone instantly find me, this phone just sits searching and gives and error it can't find me. It seems to be using GPS which when in doors isn't going to find me, it doesn't seem to use WiFi or Cell Towers. Outside its hit and miss if it finds me. I'd say it was a dodgy phone if the original phone I had didn't have the same problems.
Anyone any ideas? Its not that the location is off a bit, it just simply can't find me via wifi or cell

Vodafone's Optimus 7 firmware is broken - I worked out this works:
In MFG, navigate to Engineer Menu / Device Test / Sensor Test / GPS Test / GPS Setting
In User Setting, use following values:
Operation Mode: MS-Based
Accuracy: 100
Aiding Data: Hot Start
Auto Answer: Disable
Interval: 1
Number of Fixes: 9999999
Intermediate Data: On
In System Setting:
URL: supl.google.com:7276
Posnode: 255
2G: Loc Estimate
3G: Loc Estimate
Use Security: Use Security
MO Method: User Plane
PLEASE sign up on the Vodafone e-forum to add your voice to the request to get this fixed on this thread:
http://forum.vodafone.co.uk/t5/Othe.../GPS-Fails-after-WP7-Mango-Update/td-p/872141
Thanks

Thanks for this, Going to flash a generic European ROM and see what happens

Not working for me.
LG E900 Vodafone

I flashed the unbranded European ROM and they still don't work. I am thinking it a bug with all E900 phones.

Tried Nokia maps and it found me instantly in the house, The Weather Channel also found me instantly, so I think it all comes down to the app.