[MOD] GPS Fix....Faster Location fix.

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sammyDC

Senior Member
Jan 5, 2015
107
3
sprint Note 3 with Dark Lord Reborn ROM all works great BUT the gps.

so i just read this thread... thanks.

I have the problem of late gps fixes...I have a sprint Note 3 with Dark Lord Reborn ROM. all works great but the gps. I had this with MOAR ROM also. It was working well on MOAR and then 'something' happened... not sure what but it has continued onto the Dark Lord ROM

any ideas or links I can follow ? thanks.



I'm just going to say it. This fix appears to be the cumulative product of lots and lots of cargo cult nonsense. It's unlikely to ever help anything, no matter how many people have been posting that it "works great". To someone who is familiar with these technologies, upon close examination this "fix" really sounds a lot like a bunch of people on the internet got together and came up with a cure for the common cold which involves filling a Neti pot with Oscillococcinum, and then gently inserting it into one's rectum. This "fix" is wrong for a positively breathtaking number of reasons. Making matters worse is that it's gone on for so long that a whole bunch of well-meaning (okay well, "desperate for clicks" is probably more honest) blogs and news sites are repeating it, also without examining it carefully. Can we please stop spreading this misinformation around?

First off, those NTP_SERVER lines are unlikely to be doing what is apparently hoped for (I can't be the only one thinking it)... they're setting a variable--not populating an array. It's just replacing the previous value seven times. This means the last value "wins". Secondly, to do NTP properly there should only ever be an odd number of NTP servers involved. Eight is not an odd number... unless you're using Imperial eights or some eights you got off some sketchy Chinese website or something and then god help you. In the event that there's a disagreement among the servers polled, the time reported by a majority of them is what is used (because it's NTP which is a protocol that has been argued to death since before many of you were born, so that's is a fight you would do well to not jump into the middle of). You can't have a majority if four are saying one thing and the other four are saying another thing--you're just dead in the water and have to start over. We don't average the responses from all of them because that would definitely be wrong, despite being "close". It's also appropriate to wait for them all to respond before making this determination. If you try to poll eight and one doesn't respond... there's going to be considerable time lost while deciding it's not going to respond. Using lots of servers just adds complexity and the chance of failure without substantially increasing precision! Compounding this madness is that the pool server names are all querying from the same pool of NTP servers, despite one set saying "north-america" and the other saying "us". The best part is that it's primarily being used to ensure that the time your phone already has (and probably got from the cellular towers) isn't wildly inaccurate. What matters to GPS receivers is the time the satellites think it is (which is generally even more accurate than what you're going to get over the internet!)

Now, we do need to know the present time to get a result more quickly, but we don't need femtosecond accuracy for this, nor would specifying a whole bunch of NTP servers make that possible. We just need a ballpark figure that's accurate to within a few hours. We need to know the time so that we can use ephemeris tables (that's the weird file your phone occasionally downloads from the internet and is good for a few days--don't waste time re-downloading it multiple times a day!) to figure out where the satellites are in their travels, and we're just (pretty reasonably) assuming that no one crossed half a hemisphere since the last time GPS was queried, so... knowing (within a few hundred miles) where we are and where the satellites are, we can work out in advance which servers are most likely to be overhead and visible/audible. This allows us to skip listening for a bunch of satellites we can't hear, (and most importantly) exclude the borderline useful ones near the horizon that we probably won't be able to listen to for long enough to be useful. because of interference, and go straight to listening for the ones we can be pretty sure are overhead in relatively ideal positions.

Now as to "pure" GPS mechanics, let me explain... You need a minimum of three satellites in "view" in order to get a solid fix on your location.... because triangulation isn't something that happens when one tries to swallow a Dorito without chewing. There's be a whole slew of the satellites flying around overhead and things can get very complex very fast, but you still need three to triangulate your location. Additionally your device has to be able to "hear" them for about thirty seconds in order to get their broadcasted location information (which is almost ridiculously precise because getting it wrong can mean falling out of the sky LOL and satellites aren't cheap!). In that time we are also getting what time the satellites think it is with (no pun intended) stellar accuracy.

Your phone uses ephemeris tables and (hopefully) an almanac of satellites it's heard from recently to skip the step of finding three satellites to listen for, and it uses cached time information to skip ahead again instead of waiting for the part of the broadcast with time in it. This is why you get a coarse location within 100m or so really quickly, which is then refined as the satellites' time is heard and perhaps a few more satellites are listened to for good measure. Most of the poking and prodding people are doing (particularly those which flush the almanac or cached location information) tends to actually just slow things down, not speed them up.

TL;DR: Stick with one NTP server in your gps.conf. ...preferably north-america.pool.ntp.org (the numeric host part you see it prefixed with is also largely decorative) if you're in North America because it's better for determining accuracy and less wasteful of public resources. NTP servers that are overworked because people are querying them needlessly can't respond as quickly as ones that are almost bored to death.

To those people who seem to be convinced this "fix" works, please perform the following experiment. Back up all your data and wipe your entire phone (wipe caches, format /system, nuke user data), and then reflash the firmware. Boot it up, go into Maps, and time how long it takes to get a solid location fix. Now, reboot the phone and while it's rebooting, place it in the middle of a large plastic (not metal) bowl filled with Doritos. I personally prefer Cool Ranch flavor for this. Once it's rebooted, again go into Maps and time how long it takes to get a solid fix on your location. Congratulations, you've just proven that Doritos have an almost magical effect on the accuracy and speed of the GPS receiver in your phone by assisting with triangulation! Please remember to chew thoroughly when the experiment is complete.
 
Apr 10, 2013
8
6
so i just read this thread... thanks.

I have the problem of late gps fixes...I have a sprint Note 3 with Dark Lord Reborn ROM. all works great but the gps. I had this with MOAR ROM also. It was working well on MOAR and then 'something' happened... not sure what but it has continued onto the Dark Lord ROM

any ideas or links I can follow ? thanks.

Considering it sounds like the GPS reciever has died (it happens) the simplest thing to do is back up your data and revert the device to using the latest released Samsung stock firmware using Odin. This will rewrite the partitions that contain the radio drivers which may well have gotten corrupted. Before restoring your data, install something like GPS Status & Toolbox that can tell you precisely what's going on with how many satellites it's hearing (you can do this before reflashing stock, and it'll probably tell you the thing isn't working) and if it works, then you can try going back to your firmware of choice (which isn't likely to overwrite Samsung's driver blobs that sit in a different partition from Android)... if it then breaks, you know that firmware is breaking it, and you can go reflash stock, check again to see if it's still working, and then reflash MOAR, check again.

Yeah it's tedious, but it's at least not magical.
 
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sammyDC

Senior Member
Jan 5, 2015
107
3
I did all of that. Odin stock PL1 (the latest) updated PRL's etc... and checked gps. Wasnt working (well). I then flashed Darklord Reborn.

Attached are the signals i am getting but nothing is locking. Sometimes taking 30 minutes... or not at all. (I see dot on google maps but nlpock seldomn and sometimes miles away)

Thanks.


Considering it sounds like the GPS reciever has died (it happens) the simplest thing to do is back up your data and revert the device to using the latest released Samsung stock firmware using Odin. This will rewrite the partitions that contain the radio drivers which may well have gotten corrupted. Before restoring your data, install something like GPS Status & Toolbox that can tell you precisely what's going on with how many satellites it's hearing (you can do this before reflashing stock, and it'll probably tell you the thing isn't working) and if it works, then you can try going back to your firmware of choice (which isn't likely to overwrite Samsung's driver blobs that sit in a different partition from Android)... if it then breaks, you know that firmware is breaking it, and you can go reflash stock, check again to see if it's still working, and then reflash MOAR, check again.

Yeah it's tedious, but it's at least not magical.
 

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Apr 10, 2013
8
6
I did all of that. Odin stock PL1 (the latest) updated PRL's etc... and checked gps. Wasnt working (well). I then flashed Darklord Reborn.

Attached are the signals i am getting but nothing is locking. Sometimes taking 30 minutes... or not at all. (I see dot on google maps but nlpock seldomn and sometimes miles away)

Thanks.

So take the thing outside so that it has the best possible chance of receiving an acceptable signal. If it's still getting nearly no signal with the stock ROM, there would be every reason to believe that this is a hardware problem, and short of opening it up to make sure any internal connections haven't become unseated there's very little that can be done about it other than sending it in for repair.
 
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sammyDC

Senior Member
Jan 5, 2015
107
3
Actually flashing GPSFiXv1.zip did the trick... at last ! Wow.

Get 15 out of 20 satelites lock... no issues. Wow again. Its been a while!


So take the thing outside so that it has the best possible chance of receiving an acceptable signal. If it's still getting nearly no signal with the stock ROM, there would be every reason to believe that this is a hardware problem, and short of opening it up to make sure any internal connections haven't become unseated there's very little that can be done about it other than sending it in for repair.
 
Apr 10, 2013
8
6
Actually flashing GPSFiXv1.zip did the trick... at last ! Wow.

Get 15 out of 20 satelites lock... no issues. Wow again. Its been a while!

This sounds rather like the symptoms suffered by Galaxy S2 owners, where the GPS reciever would start being almost entirely unable to get signal until the phone was cold booted, and would somewhat gradually end in cold booting no longer working anymore requiring the phone to be sent in for repair. Best of luck with that.
 
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  • 23
    I recently went to West Virginia from Ohio and noticed the GPS took forever to get a fix on my location. I changed the GPS file and it went from taking 5 to 10 min to get a fix down to 5 seconds or so. I figured it might help others out so feel free to try it out.

    This is for the Sprint S5 but may work on others I'm not sure. Test at your risk.

    Use root explorer or a file manager with root access to rename gps.conf.txt to gps.conf then copy it to System/etc/ folder. Make sure the permissions are set to RW-R--R-- and then reboot.

    PLEASE MAKE A BACKUP OF YOUR system/etc/gps.conf FILE FIRST JUST IN CASE.

    This is what I added to make this work.
    Will work on most androids and thanks for hitting the Thanks Button Everyone :)


    NTP_SERVER=0.north-america.pool.ntp.org
    NTP_SERVER=1.north-america.pool.ntp.org
    NTP_SERVER=2.north-america.pool.ntp.org
    NTP_SERVER=3.north-america.pool.ntp.org

    NTP_SERVER=0.us.pool.ntp.org
    NTP_SERVER=1.us.pool.ntp.org
    NTP_SERVER=2.us.pool.ntp.org
    NTP_SERVER=3.us.pool.ntp.org

    feel free to use this just give me some credit if you do please.

    UPDATED WITH A ZIP FILE JUST FLASH IN RECOVERY..
    3
    Okay, that's about enough.

    I'm just going to say it. This fix appears to be the cumulative product of lots and lots of cargo cult nonsense. It's unlikely to ever help anything, no matter how many people have been posting that it "works great". To someone who is familiar with these technologies, upon close examination this "fix" really sounds a lot like a bunch of people on the internet got together and came up with a cure for the common cold which involves filling a Neti pot with Oscillococcinum, and then gently inserting it into one's rectum. This "fix" is wrong for a positively breathtaking number of reasons. Making matters worse is that it's gone on for so long that a whole bunch of well-meaning (okay well, "desperate for clicks" is probably more honest) blogs and news sites are repeating it, also without examining it carefully. Can we please stop spreading this misinformation around?

    First off, those NTP_SERVER lines are unlikely to be doing what is apparently hoped for (I can't be the only one thinking it)... they're setting a variable--not populating an array. It's just replacing the previous value seven times. This means the last value "wins". Secondly, to do NTP properly there should only ever be an odd number of NTP servers involved. Eight is not an odd number... unless you're using Imperial eights or some eights you got off some sketchy Chinese website or something and then god help you. In the event that there's a disagreement among the servers polled, the time reported by a majority of them is what is used (because it's NTP which is a protocol that has been argued to death since before many of you were born, so that's is a fight you would do well to not jump into the middle of). You can't have a majority if four are saying one thing and the other four are saying another thing--you're just dead in the water and have to start over. We don't average the responses from all of them because that would definitely be wrong, despite being "close". It's also appropriate to wait for them all to respond before making this determination. If you try to poll eight and one doesn't respond... there's going to be considerable time lost while deciding it's not going to respond. Using lots of servers just adds complexity and the chance of failure without substantially increasing precision! Compounding this madness is that the pool server names are all querying from the same pool of NTP servers, despite one set saying "north-america" and the other saying "us". The best part is that it's primarily being used to ensure that the time your phone already has (and probably got from the cellular towers) isn't wildly inaccurate. What matters to GPS receivers is the time the satellites think it is (which is generally even more accurate than what you're going to get over the internet!)

    Now, we do need to know the present time to get a result more quickly, but we don't need femtosecond accuracy for this, nor would specifying a whole bunch of NTP servers make that possible. We just need a ballpark figure that's accurate to within a few hours. We need to know the time so that we can use ephemeris tables (that's the weird file your phone occasionally downloads from the internet and is good for a few days--don't waste time re-downloading it multiple times a day!) to figure out where the satellites are in their travels, and we're just (pretty reasonably) assuming that no one crossed half a hemisphere since the last time GPS was queried, so... knowing (within a few hundred miles) where we are and where the satellites are, we can work out in advance which servers are most likely to be overhead and visible/audible. This allows us to skip listening for a bunch of satellites we can't hear, (and most importantly) exclude the borderline useful ones near the horizon that we probably won't be able to listen to for long enough to be useful. because of interference, and go straight to listening for the ones we can be pretty sure are overhead in relatively ideal positions.

    Now as to "pure" GPS mechanics, let me explain... You need a minimum of three satellites in "view" in order to get a solid fix on your location.... because triangulation isn't something that happens when one tries to swallow a Dorito without chewing. There's be a whole slew of the satellites flying around overhead and things can get very complex very fast, but you still need three to triangulate your location. Additionally your device has to be able to "hear" them for about thirty seconds in order to get their broadcasted location information (which is almost ridiculously precise because getting it wrong can mean falling out of the sky LOL and satellites aren't cheap!). In that time we are also getting what time the satellites think it is with (no pun intended) stellar accuracy.

    Your phone uses ephemeris tables and (hopefully) an almanac of satellites it's heard from recently to skip the step of finding three satellites to listen for, and it uses cached time information to skip ahead again instead of waiting for the part of the broadcast with time in it. This is why you get a coarse location within 100m or so really quickly, which is then refined as the satellites' time is heard and perhaps a few more satellites are listened to for good measure. Most of the poking and prodding people are doing (particularly those which flush the almanac or cached location information) tends to actually just slow things down, not speed them up.

    TL;DR: Stick with one NTP server in your gps.conf. ...preferably north-america.pool.ntp.org (the numeric host part you see it prefixed with is also largely decorative) if you're in North America because it's better for determining accuracy and less wasteful of public resources. NTP servers that are overworked because people are querying them needlessly can't respond as quickly as ones that are almost bored to death.

    To those people who seem to be convinced this "fix" works, please perform the following experiment. Back up all your data and wipe your entire phone (wipe caches, format /system, nuke user data), and then reflash the firmware. Boot it up, go into Maps, and time how long it takes to get a solid location fix. Now, reboot the phone and while it's rebooting, place it in the middle of a large plastic (not metal) bowl filled with Doritos. I personally prefer Cool Ranch flavor for this. Once it's rebooted, again go into Maps and time how long it takes to get a solid fix on your location. Congratulations, you've just proven that Doritos have an almost magical effect on the accuracy and speed of the GPS receiver in your phone by assisting with triangulation! Please remember to chew thoroughly when the experiment is complete.
    2
    What did you change exactly? I think that would be more helpful than just providing the file.
    2
    I don't have this device so seeing a diff in the OP would help as it would be tedious for me to download the entire S5 rom just to diff that

    I agree, I was just stating thats the only difference ?.

    Sent from my SM-G900P using Tapatalk
    2

    Yeah....really...most mods have went from one android phone to another. Each is a little different on each phone and I did the work for you if you use the zip. Why would you not give credit to someone doing the work for you. Never said I figured this mod out myself just made it easier to apply to the Sprint S5...not really a big deal to me though you can mod it yourself and take all the credit no problem...