Ok, the other thread found here is close but the wrong contacts are circled. I've uploaded several pics to reference as you read through this post. The first pic has the correct contacts circled. The contacts circled in the other thread are for the cellular radio.
So What's The Deal With The GPS on my SGS!?
Essentially, the problem is two fold.
Problem #1: Samsung has no clue how to put out decent firmware.
Problem #2: The copper contact that Samsung chose to connect the GPS Receiver to the GPS Antenna is about the crappiest selection they could have possibly made.
THE PURPOSE OF THIS THREAD IS TO ADDRESS PROBLEM #2. If we address and solve one then we can (hopefully) tackle the other effectively one day. Here is a technical, but relatively easy to understand explanation of why Firmware alone can't fix the GPS problems that plague ALL SGS phones (even if your GPS is "fine" it still has weak SNR Numbers)
Explanation (Courtesy of T313C0mun1s7):
Q) Is it hardware?
A) It's complicated. We are talking about very high frequency RF here, you gotta understand how electricity acts when you reach these frequencies to fully get this, but I will summarize. At zero hertz or DC current electricity flows through the body or center of the conductor. As long as you have enough conductor to carry the required current you are good. So the type of spring contact they used is fine for DC, in fact I went looking for replacement contacts and the only thing I can find are designed for either battery tabs or for grounding contacts. As you go higher in frequency the AC current of electricity takes on what we call skin effect, it travels as waves around the surface of the conductor. For this reason large diameter, low loss coax usually has a hollow center conductor. It make no difference electrically and makes it more flexible, lighter, and less expensive because it saves copper. Connections have to be solid and shielded because the RF can "leak", noise can be introduced, and the conductor should be tuned to the frequency carried. In short, these spring connectors are about as bad a connection as you could have picked. It is not enough that they touch the pad, you need good solid contact for a good transfer with the skin effect and to minimize loss. It seems that this problem is exasperated by poor contact. This fix it to simply improve the contact by increasing the pressure and hope to minimize the ill effects of this poor choice of contact design. To complicate things there are in fact things that can be done in software to improve the situation - this made trouble shooting harder because people tend to see these things as black and white and therefore either hardware OR software. If you want to know how software can affect this, then you will need to read back through the thread as I have already explained it twice and this answer is already too long.
Q) Should I ever expect a fix?
A) Read the OP. It was "fixed" (ie they improved the connection, but they did not re-engineer a proper fix) already. It seems if it was made in September there is a good chance it is ok or marginal. If it was made (or possibly re-manufactured?) in October it seems they are at least as good as the fix we are applying in this thread. Either they are using better contacts or they are increasing the angle to apply more pressure.
Q) Will T-mobile replace it?
A) They recognize the problem. This is what the app Samsung released is for. It resets everything to the stock settings (and nothing else). If you use it and can show unacceptable performance with the GPS (via the measurements the app makes - it is the official guide replacement), then they should replace the phone for you without any fight.
Now that you know why you should consider applying the hardware fix to your SGS, read on to determine if it may actually help your situation. I.E. does your unit's manufacture date and/or modem make this modification worth your time?
Prerequisites (Courtesy of T313C0mun1s7)
If you don't yet have at least JI6 then you need to be at least at that modem level FIRST. If you are already using the JI6 (or newer) modem and your GPS still sucks AND your phone was manufactured prior to October, then try this. Otherwise don't expect results. To determine your manufacture date, look on the box. If you no longer have the box, then look under the battery. The middle line has the serial number marked with a S/N. To the right of that will be a set of numbers with a period in the middle. It is month and year in European format, so 10.09 would be September of 2010.
* Phone made in October 2010 or after - this should not be needed
* You have not upgraded to at LEAST JI6 - then do that FIRST
Steps To Apply The Hardware Fix:
NOTE THAT THIS TECHNICALLY VOIDS YOUR WARRANTY especially if you choose the alternate method that involves a soldering iron
However, there is nothing noted on the phone that says if you remove this or go beyond that your warranty is voided.
Also, as goes without saying, don't blame me if you snap your GPS Antenna Contact off, break your plastics, or lose the ability to procreate!!!
* Turn off your GPS and shut down.
* Remove the back of your SGS and take out your battery, SIM Card and MicroSD Card.
* Remove the 7 screws that hold the back plastics. All you need is a Philips Head screwdriver from any jeweler's kit or glasses repair kit (you can get one from CVS/Wal-Mart, etc). Here is a video that shows you how to open up your phone. Take your time with this. I know it seems unsettling at first, but everything will be OK as long as you take your time and use a little common sense!
Be sure to watch for three small things after you get the back off. If you aren't careful, all three will sprout legs and run away :
1) Volume Rocker
2) Power Rocker
3) A little round plastic circle next to the lower right of your SIM Card slot that may fall out
* Refer to the 3rd and 4th pictures I uploaded (courtesy of androidmonkey). These photos depict the CORRECT CONTACT to gently bend up. The 4th photo depicts the position your contact should be in. You'll probably find that yours is laying flatter and thus isn't making contact with the GPS Antenna (which is on the plastic backing that you removed). As I said a second ago, gently bend this contact up. I used a flathead screwdriver from a glasses repair kit. It doesn't take much bend this contact. I started from the side that the fourth photo depicts. After I got the contact up a bit, I moved my screwdriver over 90* where the hump is and pried a little more. That's it! It's really simple. Just don't go happy with your bending. I have no experience replacing a snapped piece of copper so I can't be of any help if you destroy yours.
* Button everything back up. The back plastic will pop back in 10000% easier than it came off. Put the screws back in, pop your SIM and MicroSD back in and your battery. When you boot back up, you might wanna clear your GPS settings just for the heck of it. I did. DO NOT be shocked if it takes a few minutes to get a lock. It's probably the first time your SGS has ever had a real chance at a lock. Subsequent locks (Hot and Cold Start) will be faster.
* Boot up, leave your GPS off. Just because it can't hurt, clear your GPS settings. Here's how:
1) Download this app http://forum.xda-developers.com/showthread.php?t=775154
You can find it by searching for "sgstools" in the market. Click on Secret Codes then Lbstestmode. At the bottom you'll see "Delete GPS Data". Just click that!
2) Open your dialer and hit *#*#1472365#*#*
Click "Delete GPS Data".
* Turn your GPS on. Wait for a lock! If you want to know what's going on, download two apps:
"GPS Status & Toolbox" by EclipSim
"GPS Test" by Chartcross Limited
ALTERNATE METHOD - ADDING SOLDER TO YOUR GPS CONTACT
*WARNING* As I mentioned earlier IF YOU CHOOSE THIS METHOD THERE IS ZERO CHANCE OF YOUR PHONE REMAINING UNDER WARRANTY *WARNING*
If you feel inclined to modify your phone in a much more permanent way, you can opt to add some solder on top of the contact (no need to bend the contact up, in fact, don't). I attached a zip with some pics that show what two posters, regp and Mannymal did. I've soldered a few things in the past, but I'm by no means an expert. If you choose to do this, a few things to remember.
* First, seriously consider avoiding this if you have no experience with a soldering iron. In what I've seen on a limited base, you'll get minimal SNR gain in return for the effort that goes into this. I can't emphasis this enough.
* There are probably a 100 tutorials on how to solder floating around on YouTube, watch them (all).
* The absolute largest diameter solder I would use is .022.
* Find the smallest tip possible.
* Heat the CONTACT with your soldering iron, not your solder, or you will create what is called a cold solder joint that will probably lead to your GPS not working at all on down the road. You have to get the contact hot enough to receive the solder, which is touched to the part (in our case, the contact) that you want to apply the solder to.
* Be careful not to make your solder to high. I suggest looking at the photo that shows the angle of the contact after it's been raised and using that as your benchmark. We want to make contact with the GPS Antenna, not break the thing when we snap the back plastic on.
* If you end up with two much solder you can either clean the tip of your soldering iron and touch the hot tip to the solder to remove some or you can use an emery board to file it down.
* Use an small emery board (nail file essentially) to file down and smooth off your joint. I suggest doing this holding the phone upside down so you don't end up with 1000 tiny solder particles floating around your phone.
* REMEMBER, phones are tiny. These boards are tiny. A soldering iron that is too hot left on ANY board for too long will destroy it. Multiply this rule x10 for delicate parts.
Observable Data Changes
(Grabbed from this thread after several days of playing with this fix).
Accuracy: 16-28 feet stationary 38-50 feet moving (moving accuracy has improved and is now on par with stationary numbers since I started running the Stock JL4 Rom)
Average SNR: 22-35. Obviously you'll always have one or two that are lower and one or two higher. My max I've observed was 42.
Number of Sats Locked/In View: 8/11 most of the time. Yesterday afternoon I was locked on 10/10 with a 22 foot accuracy inside. I've had 11/14 before as well, just depends on the time of day.
Cold Start Lock: 30 seconds
Hot Start Lock: 5-15 seconds
For reference, my Garmin Nuvi is currently connected to 7/10 with a 16-18 foot accuracy and my Vibrant is connected to 7/10 with a 21-25 foot accuracy. (stationary of course)
Unnecessary re-routing: No
Wandering on Google Nav/Lost Signal with Nav: Very rarely. For me it happens when I lose signal which is only if the phone is resting on my jeans. If it's in my cupholder, center console, hand, etc it's fine. Earlier today I lost signal with it in my cupholder but I was traveling in an area where my Garmin Nuvi only had a connection to 5 satellites.
My Tracks: No data from me yet
There are some after screen shots in this post.
Other notes: I'm on the road a lot. Today is my first day to really extensively test it. Basically, it's MUCH better. Is it perfect? No, but I will say that unlike these other fixes that involve changes in lbstestmode and reset apps that only last for a couple of hours at best, my GPS performance has been very consistent ever since I adjusted the antenna contact. Is it as good as my old Blackberries with signal strength? No. How does it compare to other Android devices? I have no clue.
What I do know is that it works well enough for me to be comfortable not having to grab my Nuvi everytime I switch vehicles.
I hope this works for those of you like me that have tried almost every firmware update, tweak, etc. Between this fix and JL4, all I can say is that this device is probably as near to perfect as it'll ever be. I've been running this fix for well over a week and I've experienced no signs of the modified contact losing it's contact with the antenna.
If You Still Have Problems
* Even though you used the Samsung GPS Restore App (Found in the market for Vibrant/Captivate only)
* Even though you deleted GPS Data
* Even though you have your WiFi Off like Plato56 recommends in this post
* Even if you tried a full system wipe
Don't panic if you don't have a ton of locks. Like mentioned above, there is still a firmware component to this issue. I see times where mine doesn't want to lock. Usually if I turn GPS off and then turn it back on it runs smoothly from there on out. Depending on where you live, time of day may make a difference. Inevitably, in the afternoons I may only get 6 of 11 locked on. All other times I can get 9-11 of 11 or 11 of 14, etc. Bear with it. This fix is NOT a silver bullet, but give it a day or two of reasonable playing time to determine if it helped.
For example, right now I'm indoors locked on 7/11 with a 21 foot accuracy and SNR's averaging 31. I used to see 0/3 with SNR's averaging 29. That's a definite improvement. If any other Android was in the same position it would probably show 8/11 with a 10 foot accuracy and SNR's averaging over 65.
So take it for what it's worth, but the fix is DEFINITELY worth the effort!
Check out this thread here and read through the OP carefully. A few days ago I flashed "S.gps.zip" and I've had great results with it on Bionix 1.3.1 with the KA7 modem. I didn't see an increase in accuracy, but I did see a HUGE improvement on the speed my GPS locked and the number of birds locked too. I played around with all of the 2.2 modems last night and they all saw improved results.
If you decide to flash one of those zips, I recommend making a Nandroid backup first. In reading through the thread it appears that there are a few people that had their flashes result in broken GPS's. I have no idea why, I'd imagine it's because they didn't clear GPS data and they just think it's broken. I recommend making a backup, shutting off your GPS, booting into CWM, flashing the zip, rebooting, clearing GPS data, turning your GPS on and enjoying locks. And, as always, I recommend using GPS Test by Mike Lockwood to test your GPS every time you make a change.
The Super GPS should work on any ROM on an Vibrant, but it looks like a lot of people have tried it on 2.2 ROMS so be aware that, as always, there's the chance you may brick your device. If it works for you, be sure to thank jellette for his work. As always, I take no responsibility if this messes up your phone. I'm just relaying what worked for me.
I should have posted this a couple of months ago. I also have a theory about why sometimes this fix fails over time. For example, I run Overstock 2.4.1 and I often flash the S.gps2.zip when I redo my system. It's been a fantastic combo on Bionix 1.3.1, but often, after a few weeks my GPS begins to turn retarded and will eventually no longer lock. In the past I've always believed it's purely because the antenna contacts have started to relax. However, what I've discovered is that when I go back into CWM and reflash my kernel and reflash the GPS zip, everything is happy and perfect again. I'm by no means a hardware genius or a developer. I'm just an average end user that loves to tinker with things and be methodical in testing, but I'm starting to believe that there truly is something going on that corrupts our GPS Drivers over time (in reference back to how we know Samsung screwed the pooch on firmware for the GPS Receiver).
So, that said, before you crack your phone open over and over yanking and bending on contacts, reflash your kernel and the GPS Zip of your choice. And, like I've always said before, if the hardware fix doesn't seem to work for you when it seems to work for others on the same ROM as you, try another kernel, and try it more than once. I still fully believe that every GPS Receiver on every SGS can be made usable. It's not perfect, but it's a strong improvement from not being able to obtain a lock. http://forum.xda-developers.com/show...3&postcount=12