Tested and Proven gps fix for Samsung Captivate

[BobPaul]

So the phone's GPS receiver can determine how far the phone is from various satellites, but then the phone needs a way to determine where those satellites are in order to turn the distances into a location on Earth. This is where SUPL comes it, it offers a redundant database of the positions of GPS satellites in orbit.

I guess other GPS devices either have this information stored in them or somehow get the information from the satellites themselves. Perhaps the problem is that the Captivate, for whatever reason, needs SUPL to determine where the satellites are, and the SUPL system on the phone is fussy. Hopefully the update will make it so the phone can determine its location even when it is not in range of any wireless network.

I have a question for you. How do regular non phone based GPS devices work without SUPL?

 

[bosbrucec]

It is very misleading, as the results of this "fix" (or the many permutations thereof) are by no means proven by any statistical definition of the word.

Lots of people seem to think that allowing use of cell/wifi to get a very rough static location is also "fixing" the GPS location problem (it is usually good enough for location services other than navigation, after all), and GPS reception is a very variable thing, so even one person proving a fix "worked" for them is difficult, much less proving it really works for a substantial number of people. It could simply be the reboot that makes things better for many.

I've tested all the LbsTestMode options claimed to be successful and more; some help momentarily, some make things worse.

But what it really comes down to is this : No matter how long it may take to get a lock, even with no other location assist, all 10 other GPS devices I've had in the past 15 years can keep the lock once acquired *far* better than the Captivate. Especially when in a moving vehicle, just putting the Captivate on my lap causes it to lose reception on a crystal clear day with my convertible top down. My old LG Incite and a BlueTooth GPS receiver and a Garmin and a Mio all hold the signal no problem on my lap, sometimes even under my seat.

There is a GPS reception problem with the Captivate that is deeper than anything the LbsTestMode settings can address, though perhaps some of them can make things appear slightly better for static GPS location.

It is a shame, because it is a great phone, but mine is going back because I have not been able to get any convincing evidence from Samsung that a *real* fix is even possible, much less truly arriving in September as they state. I suspect they are just hoping we get caught up in all the froyo goodness and so tolerate the deficient GPS.

I'll pay the $35 restocking fee, wait to hear some convincing evidence that the GPS issue is really fixed with the upcoming September "fix," and then get one that is fixed (or wait for the next great Android device if it isn't really fixed).

 

[mongstradamus]

It is very misleading, as the results of this "fix" (or the many permutations thereof) are by no means proven by any statistical definition of the word.

Lots of people seem to think that allowing use of cell/wifi to get a very rough static location is also "fixing" the GPS location problem (it is usually good enough for location services other than navigation, after all), and GPS reception is a very variable thing, so even one person proving a fix "worked" for them is difficult, much less proving it really works for a substantial number of people. It could simply be the reboot that makes things better for many.

I've tested all the LbsTestMode options claimed to be successful and more; some help momentarily, some make things worse.

But what it really comes down to is this : No matter how long it may take to get a lock, even with no other location assist, all 10 other GPS devices I've had in the past 15 years can keep the lock once acquired *far* better than the Captivate. Especially when in a moving vehicle, just putting the Captivate on my lap causes it to lose reception on a crystal clear day with my convertible top down. My old LG Incite and a BlueTooth GPS receiver and a Garmin and a Mio all hold the signal no problem on my lap, sometimes even under my seat.

There is a GPS reception problem with the Captivate that is deeper than anything the LbsTestMode settings can address, though perhaps some of them can make things appear slightly better for static GPS location.

It is a shame, because it is a great phone, but mine is going back because I have not been able to get any convincing evidence from Samsung that a *real* fix is even possible, much less truly arriving in September as they state. I suspect they are just hoping we get caught up in all the froyo goodness and so tolerate the deficient GPS.

I'll pay the $35 restocking fee, wait to hear some convincing evidence that the GPS issue is really fixed with the upcoming September "fix," and then get one that is fixed (or wait for the next great Android device if it isn't really fixed).

Well stated I agree with most of the things you have said. The phone itself is not an bad phone if it were working, I will give samsung the benefit of the doubt to "fix" the gps problem, but with their prior track record i dont if i really should. If all the chatter is correct that their fix is to use wireless networks to help with gps , they havent learned their lesson at all.

If you argue enuf with att and you are still in 30 day window you may be able to get that restocking fee waived, ymmv tho

 

[benbald72]

The position of the satellite is part of the signal it sends to the receiver, along with a time-stamp, which says when the signal was sent. All GPS satellites send the signal at the same time. Based on that data and the fact that signal travels at speed of light, and knowing how long it took for the signal to get to your receiver, it can figure out where they are.

SUPL server allows you to quickly figure out the general area where you are, because cell towers have GPS receivers on them.

Alright, but read the white paper on SUPL, written by the company that developed it, and then let me know if you still feel that way. I linked it in a previous post, but here it is again. My beliefs about how SUPL works are based on what they said on page four.


I'm sure that the satellites broadcast information about their orbits, but it would still make sense for a data network to assist this process. Using cell towers isn't very accurate, so having a GPS device allows the phone to figure out how far away it is from the satellites, which can be measured much more accurately (although I imagine that if you had three cell towers covering an area, you could accomplish the same level of accuracy).

Now, dude, think about this for a second. If all you needed is a connection to internet so you could connect to SUPL server, why would you need a GPS receiver in your device at all?

If the SUPL server told you where the satellites were, but your phone had no way of receiving a signal from them, then the information wouldn't help your phone determine its location.

Also, those numbers alone don't mean anything on this device. I get 8-10 satellites as well and it says accuracy 5-10 meters. Problem is, it puts me no where near where I actually am. I stood in front of my house and it put me literally over 2 miles away on the map, while saying it was accurate to 5 meters.

Did any of the satellites have asterisks next to them? I think this might mean that the phone has locked onto the GPS, although I'm not sure. It does seem, though, that my GPS test won't report a location until at least three of the satellites have asterisks next to them.

As for being 2 miles away, I get this sort of thing too. It seems that if I have "use wireless networks" turned on, the phone will use them to determine my location and, when it can't lock onto any of the satellites, it continues to use its estimate to report your location. If the GPS icon at the top of your screen is flashing between the two different images of satellite dishes, this seems to mean that the phone is still trying to get a lock onto its location using GPS. Once it's locked, the picture of the satellite dish stays still, but until then the phone is using SkyHook.

 

[benbald72]

I have a question for you. How do regular non phone based GPS devices work without SUPL?

I was wondering that too. Perhaps they have a database stored within the device, or maybe the receiver is stronger. One thing I have noticed is that the navigate function of my phone can only work when I have a wireless signal because otherwise it cannot load the street maps, whereas my car's GPS has all of the maps stored on its hard drive and can work when I'm driving on highways in the middle of nowhere. That's not the exact same thing as using SUPL, but it's similar.

I don't understand why a phone should need SUPL, and perhaps this is part of the problem with the Captivate. The white paper makes it seem that SUPL is meant to assist the device in using the GPS to determine its location, so perhaps the intent is to make it faster and/or more accurate, or perhaps it's to make it work when you travel to different countries.

 

[sremick]

I was wondering that too. Perhaps they have a database stored within the device, or maybe the receiver is stronger.

No. Traditional GPS works fine standalone without any supplementary data. Each satellite transmits data that includes its location and the current time. The clocks of all the satellites are synchronized. The GPS receiver, by measuring the time delay for the signal to be received, can calculate the receiver's distance from the satellite. This creates a "sphere" of possible location from each satellite.

With 1 satellite, position is narrowed down to a sphere. With 2 satellites, position is narrowed down to the intersection of those two spheres: a circle. With 3 satellites, it's the intersections of 3 spheres which is 2 points. For the most part, the receiver can make a logical guess to figure out which point is you but generally the GPS receiver wants 4 satellites to nail it down perfectly and get an altitude calculation.

A basic GPS receiver will then be able to spit out your longitude, latitude and altitude above sea level. Most GPS receivers however have a basic static map (road or topographic) already loaded on the device so that this positioning data can be overlayed on top. For phones, typically this is not the case however and the local map layer is fetched in realtime over the phone's cellular data link. A data connection isn't necessary on a cell phone however to simply calculate longitude/latitude.

Further reading:
Trilateration - Wikipedia, the free encyclopedia

 

[BoulderGeek]

I thought that I had remediated my issue with the tweaks to the SUPL locations.

Worked for one day.

Now, fails to see even one satellite, just like stock. getting ready to put it back in the bocx and send it back. Even for free, this Dude can't abide.

 

[BobPaul]

I was wondering that too.

I don't actually wonder about his point, I am just trying to be polite to all that seem to be confused about GPS and the Captivate.

 

[qwertyaas]

I'll be another one to add - if I use GPS Test prior to Google Maps, I get almost instant lock ons. GPS Test during my walk at lunch locked onto 5-8 Sattelites within seconds (within ~30 feet). Right after that went to Google Maps and tracked my walk pretty accurately (when I stood still my heading was off at times).

Now if I don't use GPS Test first, Google Maps has no idea where I am.

 

[SamsungVibrant]

The title to this thread is very misleading. Also the various supposed "fixes" coming out of xda developers are misleading also. None of them is a fix in my opinion. I've tried them all, and they don't do anything worth cheering about.

 

[harryzwd]

of course it's misleading - too many people have too much to say before they really know what they're talking about. i don't mean any disrespect, but instead of trying to educate the masses and beat someone else to the punch and be a "hero" by posting something you think is new...you should instead take the time to investigate and see if the topic has been discussed before. this whole GPS issue and the same "fix" flavio refers to was posted 3 days earlier by kappaG9 AND it was determined a day after that, that the "fix" did nothing, or was at least only a temporary solution.

we have to rely on each other for information, so lets all do our part by NOT misleading each other or reposting things 500 times. do your research, ask questions, ask others to confirm things...in other words, lets all be responsible and HELP one another.

sorry for the rant

 

[George0211]

Alright, but read the white paper on SUPL, written by the company that developed it, and then let me know if you still feel that way. I linked it in a previous post, but here it is again. My beliefs about how SUPL works are based on what they said on page four.


I'm sure that the satellites broadcast information about their orbits, but it would still make sense for a data network to assist this process. Using cell towers isn't very accurate, so having a GPS device allows the phone to figure out how far away it is from the satellites, which can be measured much more accurately (although I imagine that if you had three cell towers covering an area, you could accomplish the same level of accuracy).

Yes, you just reiterated my point. SUPL information is for assistance only, not to provide the most accurate information. Depending how close you are to the towers your accuracy could be anywhere from 1km to 5km. It won't give you accuracy to 5m.

If the SUPL server told you where the satellites were, but your phone had no way of receiving a signal from them, then the information wouldn't help your phone determine its location.

Again, you're reiterated my point.

Did any of the satellites have asterisks next to them? I think this might mean that the phone has locked onto the GPS, although I'm not sure. It does seem, though, that my GPS test won't report a location until at least three of the satellites have asterisks next to them.

As for being 2 miles away, I get this sort of thing too. It seems that if I have "use wireless networks" turned on, the phone will use them to determine my location and, when it can't lock onto any of the satellites, it continues to use its estimate to report your location. If the GPS icon at the top of your screen is flashing between the two different images of satellite dishes, this seems to mean that the phone is still trying to get a lock onto its location using GPS. Once it's locked, the picture of the satellite dish stays still, but until then the phone is using SkyHook.

The fake accuracy is one of the problems with this device's GPS. It locks on to the satellites and thinks it has your location pin pointed but it puts you in the wrong place.

 

[benbald72]

Yes, you just reiterated my point. SUPL information is for assistance only, not to provide the most accurate information. Depending how close you are to the towers your accuracy could be anywhere from 1km to 5km. It won't give you accuracy to 5m.



Again, you're reiterated my point.



The fake accuracy is one of the problems with this device's GPS. It locks on to the satellites and thinks it has your location pin pointed but it puts you in the wrong place.

Okay, I thought you were trying to say that SUPL determines your location by seeing what cell towers are in range of the device, which is what the "use wireless networks" option on your phone does.

Obviously, though, by using SUPL databases to help the phone more quickly learn the locations of the satellites it's picking up signals from, a precise location can be found more quickly than it would if the phone had to get the information from the satellite itself. Saying that using a database to look up satellite locations won't give accuracy down to any length doesn't make sense--either way, you're using the satellites to determine your location relative to them, so the accuracy would be the same, as it would be if the phone had a database of the locations of of all satellites stored on its hard drive.

 

[benbald72]

I don't actually wonder about his point, I am just trying to be polite to all that seem to be confused about GPS and the Captivate.

Did you actually read the SUPL white paper? I assume that Broadcom is more likely to be right about how their system works than we are, unless one of us read the white paper, which I did.

 

[penguinpga]

I learned this from another post regarding GPS issues, now my phone works great. Check it out.

Application Settings
Session Type: Tracking
Test Mode: S/W Test
Operation Mode: MS Based
Start Mode: Hot Start
GPS Plus: ON
Dynamic Accuracy: ON
Accuracy: 100
Use Skyhook: ON
Use PC Tool: OFF

SUPL/CP Settings
Server FQDN Type: AUTO Config
SUPL Secure Socket: ON
AGPS Mode: SUPL

Post 319, thank you, THANK YOU!!! I now have a secure lock with in 1 foot of my location, even closer. I followed directions and also have skyhook on. I do NOT have my "use wireless networks" checked. Seems to hinder the lock. I was ready to take my second Captivate back today. Have tried everything. Hope it lasts.

 

[Jimbritt]

We need a good lawyer to sue Samsung for putting out a phone with so many design flaws! I got mine free through Walmart so my only loss was having 2 more years in a contract.

 

[cmt074]

I used the GPS on my Captivate all weekend and it worked great for the most part. It actually locked onto satellites a bit faster than my Tom Tom usually does.

This was the issue I ran into: the GPS worked nearly flawlessly as long as the Captivate was held near the windshield - very accurate positioning.

It would be fairly spotty if I say, put it in a cup holder next to the driver's seat (where my Tom Tom works fine). Often it would put me on a road to the left or right of the highway (or in the middle of a lake!!) and start spewing out incorrect directions such as 'Take a U-Turn!' as I'm traveling at 70mph on the highway . It's easy enough to tell when it's a bit wonky and ignore the false directions however. I'm hoping a software fix can make it work a bit better inside the car away from the windshield.

 

[Centerman]

This corrected my location quite a bit. My GPS location went from being about 2 miles off to around 1/2 a mile or better.