Interesting find regarding location bug... - Hero CDMA General

Many people have noted that some apps, the HTC weather and clock widget in particular, seem to report the wrong location frequently. Some people have traced the problem to the use of an Airave, which at least provides an explanation even if a fix is still lacking. But other people who have reported the issue are not Airave users, so the problem can't be blamed on that in all cases.
I was affected by this myself. While troubleshooting an unrelated problem yesterday I noticed messages scrolling by related to location, some of them containing the latitude and longitude. I plugged these into google maps, and bingo, it placed it smack in the middle of my front yard, even though the HTC widget was showing (what I thought at the time was) a city 150 miles away.
Now comes the part where luck steps in. I just recently moved to this town, and this morning I was doing some random googling to learn more about the area, just the sort of mindless stuff I do to keep my mind occupied until I've had enough coffee to wake up and actually start on something useful, and I eventually landed on the Wikipedia page for the city.
I currently live in Traer, IA. My phone has been saying I'm in Perry, which is a town that I know well, on the other side of the state, leading me to assume that my phone was giving me a location roughly 150 miles off. However, as it turns out (thanks Wikipedia!), the city of Traer is located in the Perry township. For those who don't know, just as states are divided into counties, counties are further divided into townships. But, townships aren't often mentioned in day to day conversation, and the vast majority of poeple have no idea which township they live in (or, for that matter, that there is such a thing as a township).
So all along, it has had the location right, it's just been displaying the township name instead of the city name.
I still consider this to be a bug (obviously the correct behavior would be to display the city name), but at least I now know that it has my location correct even if it's choosing to display an unfamiliar name.
Anyone else experiencing this bug and not able to blame it on an Airave, it might be worth checking to see if the name of the location it's displaying is more closely related to where you live than you might originally think.
EDIT: Ok, I pulled it up on google maps, and it's only 113 miles away, not 150. The actual distance is completely beside the point, but I've been on the internet long enough to know that some smartass will mention it....

I have seen others say that it was showing their county. I never put two and two together. Great detective work.

flipzmode said:
I have seen others say that it was showing their county. I never put two and two together. Great detective work.
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Thanks. It's been driving me nuts.
I'd still really like to see it display the city name, but until that gets resolved at least I can feel comfortable that location based apps will work properly. Bring up local weather, display nearby movie theaters, etc...
It seems like a minor bug on the surface, but when you stop to consider how many apps are starting to utilize location in very useful ways, it's nice to be able to feel confident that they're using the RIGHT location....

weird. I haven't had that problem. it actually updates within 5ish minutes of being in a new county/city. good to know if it does ever happen to me though. thanks

Yeah, the issue was never with the speed of the update. Mine has always updated plenty fast. It's just that in one particular location where I happen to spend a great deal of time (my home), it seemed to be getting it wrong.
I'm going to dig in a little deeper, but my initial instinct is that the bug isn't even in the HTC widget. The most likely explanation, I think, is that the database it's reading from has some values stored in the wrong fields..... (But that's just an educated guess until I get a chance to look more closely....)

I don't get any wrong city info.....but it seems like recently it doesn't update the weather correctly. For instance weather will say it bright and sun shining when its obivouly DARK. LOL oh well thats what they made windows for.
Thanks for bringing this up!

subliminalurge said:
I was affected by this myself. While troubleshooting an unrelated problem yesterday I noticed messages scrolling by related to location, some of them containing the latitude and longitude. I plugged these into google maps, and bingo, it placed it smack in the middle of my front yard, even though the HTC widget was showing (what I thought at the time was) a city 150 miles away.
Anyone else experiencing this bug and not able to blame it on an Airave, it might be worth checking to see if the name of the location it's displaying is more closely related to where you live than you might originally think.
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I'm currently running DC ROM v2.05 and my reported location in GMaps and any weather application is always quite a bit off from the true location.
Prior to installing any OS 2.1 based ROM, the location was always dead on correct even with GPS turned off.
I'm not using Airave.
You mention that you saw coordinates information messages while researching another issue.
Do you happen to know where the file is that these coordinates are stored in the system? I had found them once a few months ago; two plain text files containing only latitude and longitude values.
However I can't find these file now. Maybe they're no longer text files in a v2.1 system?
I'm curious to know if the correct values are being stored in these files.

mkhopper said:
Do you happen to know where the file is that these coordinates are stored in the system?
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Where they're actually stored? No. I found them while I was running "adb logcat". If you connect your phone to your pc and let that run while the phone is just sitting idle, one of the things that will go by every now and then is log messages about the phone refreshing the location info. You should be able to grab latitude and longitude info from there.

Okay here's the solution-crapper.
I have the weather widget and it often displays me as being in Jackson, Ohio when in all reality I am in West Salem, Ohio, about 5 miles east of Jackson. My township name is Congress.
ETA... Jackson township is about 2 miles away from me. I am about 1 mile from the county line, which is where Jackson/Congress borders are.

subliminalurge said:
I currently live in Traer, IA. My phone has been saying I'm in Perry, which is a town that I know well, on the other side of the state, leading me to assume that my phone was giving me a location roughly 150 miles off. However, as it turns out (thanks Wikipedia!), the city of Traer is located in the Perry township. For those who don't know, just as states are divided into counties, counties are further divided into townships. But, townships aren't often mentioned in day to day conversation, and the vast majority of poeple have no idea which township they live in (or, for that matter, that there is such a thing as a township).
So all along, it has had the location right, it's just been displaying the township name instead of the city name.
I still consider this to be a bug (obviously the correct behavior would be to display the city name), but at least I now know that it has my location correct even if it's choosing to display an unfamiliar name.
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My guess is where you live(or where the cell tower is) is not actually in Traer proper but in the outskirts/suburbs in an "Unincorporated area". I have seen such come up in two different areas, where I live and where my parents live, both are unincorporated areas and thus show the nearest city or township name instead. Often the township name is also the name of the largest town in said township but that is not always the case.
I live in Atascocita CDP, an unincorporated area of the City of Humble, in Humble Township, my phone always says Humble even when I am clearly not in the city of humble.

Nanan00 said:
My guess is where you live(or where the cell tower is) is not actually in Traer proper but in the outskirts/suburbs in an "Unincorporated area".
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Well, my house is most definitely inside the city limits. But, you're right, this is a small town and chances are very high that the tower I'm connecting to is a mile or two out in the country. There's only one cell tower actually in town, and as far as I'm aware it's 100% US Cellular, so I'm most likely not connecting to it.
My big concern was that my phone was saying Perry, and the city of Perry, IA is over 100 miles away. Once I was able to determine that the name "Perry" also refers to the location I'm at, I'm much less concerned about the issue. Being 100 miles off would be cause for concern, but as long as it's got me within 2, 3, or even 5 miles, then I'm comfortable that location aware apps are presenting me with relevant info.

Related

Why is location services broken in ALL 2.1 roms?

Do we have any idea how to fix this? I've had problems on literally every 2.1 ROM tried so far. This includes DamageControl 9999 and v1, DarchStar, DarchLegend v2, Toast/Flipz 2.01
Basically (and Gbhil has verified this as well) the network location isn't functioning properly. For example, I am in a suburb of Kansas City, and my location shows on EVERY SINGLE 2.1 ROM as Overland Park, which is over 30 minutes away from me.
GPS will work properly, but this messes up literally every location based app, including my own I'm developing, which grabs your location and does some other stuff with it (which I can't divulge at the moment, ha)
I am literally floored that there aren't more people reporting this. It's not always messed up, I'd say 80-90% of the time it shows as off.
Any devs or others have any idea as to why this is?
Is this a "basically we have to wait for the Sprint 2.1 ROM to come out" issue? Thanks!
kmartburrito said:
Do we have any idea how to fix this? I've had problems on literally every 2.1 ROM tried so far. This includes DamageControl 9999 and v1, DarchStar, DarchLegend v2, Toast/Flipz 2.01
Basically (and Gbhil has verified this as well) the network location isn't functioning properly. For example, I am in a suburb of Kansas City, and my location shows on EVERY SINGLE 2.1 ROM as Overland Park, which is over 30 minutes away from me.
GPS will work properly, but this messes up literally every location based app, including my own I'm developing, which grabs your location and does some other stuff with it (which I can't divulge at the moment, ha)
I am literally floored that there aren't more people reporting this. It's not always messed up, I'd say 80-90% of the time it shows as off.
Any devs or others have any idea as to why this is?
Is this a "basically we have to wait for the Sprint 2.1 ROM to come out" issue? Thanks!
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Mine's better than it was in 1.5!
It shows that I'm in Sugar land, but in 1.5 when I went to school it showed I was in Richmond.
I went out of town recently and I had to refresh it like 5 times to get it to show up. I think it was changed to help battery life. Not really a big thing to me. I just have the location saved as the second spot so I can check if it doesn't want to refresh.
I can't explain your issue, but location services with GPS off on DC1.0 with my phone is dead nuts accurate. Puts the blue dot directly over my house. I haven't tried it outside the house yet. I'll report back when I do.
J
Edit: I tried network based location at three different locations around town today and it worked flawlessly every time. I'm hoping Sprint never decides to target me with a smart bomb using GPS--if they do, I'm a gonner.
There is actually quite a bit written about this but no sure fix that I have found. Location works fine for me in Maps but in everything else it is way off in a weird way. At home it shows my location as 200+ miles away. At work, which is only 8 miles from my house, by location is shown some 30 miles away. You are right. It is only on the 2.1 Roms so I use Beautiful Home or Weather Widget both of which allow me to at least specify my weather address.
I am having the same issue. Its about 20 miles off. I do have a Airwave at home, but I unplugged it and still same thing after doing a refresh. When I go city to city it changes but for some reason I think it is 20 south of my location so when I do switch cities, it would be correct 20 miles south. With that said, my actually GPS for gmaps is dead on target.
it seems to me that its mainly the application being used that makes the location inaccurate..or is that just me?
Mine has not had any issues so far. Better than ever. I'm using DamageControl v1 with the new radio.
superlinkx said:
Mine has not had any issues so far. Better than ever. I'm using DamageControl v1 with the new radio.
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i'm using the exact same thing.. works well for me.
superlinkx said:
Mine has not had any issues so far. Better than ever. I'm using DamageControl v1 with the new radio.
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ditto. Same thing here and no issues with network location.
See, and the inconsistency bothers me too. It should really be broken for everyone, not just a few of us.
GPS is fine, but with network, it's definitely broken. Weird, I guess I'll wait for the Sprint ROM versions.
I bet you it has something to do with us not having something from Sprint in these releases.
no issues here with darchdroid
kmartburrito said:
See, and the inconsistency bothers me too. It should really be broken for everyone, not just a few of us.
GPS is fine, but with network, it's definitely broken. Weird, I guess I'll wait for the Sprint ROM versions.
I bet you it has something to do with us not having something from Sprint in these releases.
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Download a rom like DarchDroid(people don't seem to get errors with it), extract the .zip and browse through the apps on the rom, find LocationPicker.apk and LocationService.apk(With their odex files) and push them to your phone from recovery, delete dalvik cache and boot cache and reboot your phone.
kmartburrito said:
See, and the inconsistency bothers me too. It should really be broken for everyone, not just a few of us.
GPS is fine, but with network, it's definitely broken. Weird, I guess I'll wait for the Sprint ROM versions.
I bet you it has something to do with us not having something from Sprint in these releases.
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mines usually, but not always, accurate. hows that for inconsistancy?
in 1.5 i shut location off unless i have to use my gps I-GO app. location seems to drain the battery.
Coarse (network-based) location seems to usually work fine for me (running DC1.0). I say 'usually', because once in a while it will decide I'm in the Atlantic Ocean ~20 miles east of Miami instead of western Broward County (~10 miles west of the beach)... but I've ALWAYS had that problem, even with stock 1.5.
Has anyone noticed a correlation between tower density, signal strength, and accuracy? If the worst inaccuracies are noticed in fringe suburban areas (where you might be lucky to have a single good tower signal, let alone 3+), that might explain it. The 2.1 algorithm might work better (or at least use less power) in urban areas, but fail more often in fringe areas. This might also be more of an issue with Sprint, because Sprint's network tends to be slightly less robust in fringe areas than Verizon's.
Out of curiosity, is the algorithm known to "cheat" if you're in a fringe rural area where the service is primarily along a single major corridor (like I-75 through the Everglades, or the Turnpike halfway between Orlando and Fort Pierce), and automatically limit its estimates to locations physically along that road?
Mine seems to work fine, at least with the weather widget. I'll double check tomorrow when I drive 150 miles west, and see if it still updates. Even 1.5 wasn't all that good at updating my location without me refreshing.
I do know that my weather is wrong though. Still says it's cloudy here, and the only clouds are a good 50 miles north lol
Hmmm. flashed fresh-2.0b and also installed the new radio. With location setting and GPS on, I get the same location errors I mentioned earlier. With location setting set to '911 only' and GPS off, weather and browser location is accurate. I use GPS for Nav, but if I am not using it, this will work for me. Can anyone try with another 2.1 Rom and confirm if that works for them?
When I first installed 2.1 it was showing me in a different state. But when I flashed the new radio that fixed everything. Now it's only wrong if I'm home and connected to my Airave.
wcgbmd said:
Download a rom like DarchDroid(people don't seem to get errors with it), extract the .zip and browse through the apps on the rom, find LocationPicker.apk and LocationService.apk(With their odex files) and push them to your phone from recovery, delete dalvik cache and boot cache and reboot your phone.
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Think you could do the same with the picker and service from the 1.5 roms? I always had perfect performance before moving to any of the 2.x roms. That's the exact moment when it started happening. I can switch back to a nandroid backup of 1.5 and it runs just fine too. Still kinda baffled at all of this.

Has anyone ever stopped to think that maybe the third party GPS apps are wrong?

Okay so now that I have my vibrant I tested it out (only a few times) but I did test it in different applications, websites, and maps and navigation. Yes in the gps and compass apps it doesn't pick up at all compared to my slide BUT in every other application, on google where it finds your location, on yelp, movie phone, maps, and navigation it finds my location each and every time. It doesn't get me lost, it doesn't show me going in a different direction, and it doesn't show me somewhere else.
What if the configurations or settings are different with samsung, what if the third party app is not completely accurate? Why else would every other program find my location if the app says I am not found by even 1 satellite? I think the"fix" is just a change of setting that helps the app not the gps or the phone.
Time will tell but for me it us working fine for now.
Sent from my SGH-T959 using XDA App
Well you can do gps tests within the os that say basically the same thing...
Ive used my gps with google navigate nermous times with no problem. in fact, it guided me on a 160mile trip just fine... What problems are people having with their gps?
Well, I've only had the phone for a day, so I'm still getting used to the quirks coming from a G1. GPS so far is the biggest disappointment. Android has been pushing location based stuff since the beginning, so the lack of a solid GPS is really screwing up some of my favorite apps. Locale for instance, it's worthless. It can't ever find me. The G1 always worked fine with it on Donut, Eclair, and Froyo.
Google Maps is the ONLY app I have that seems to even be able to get a rough idea where I am, and even then its circle is pretty big, about 4 city blocks. That's not GPS, that's network location, and it's fine for what it is, but not good enough when there aren't a lot of cell towers around. At home, it puts me out in the middle of a corn field. All the time I'm in maps, the GPS icon is up there blinking at me, telling me it can't lock. I've seen it work a couple times, for a short while. In GMaps and in GPS Test. But it takes a LONG time. The G1 could get a lock indoors in about 10 seconds. The Vibrant takes minutes, even with the A-GPS turned on in the test menus. That's insane. And it's not any better outside with a clear sky view. That might be acceptable, if it could hold the lock, but it doesn't.
Even stranger, in GPS Test, I get a single colored bar saying it's using that signal. There are 6 more with the same or higher signal strength being ignored. Very odd. Something is wrong with this GPS. It could very well be software, but Samsung needs to get on this and fast. If I can't find a way to get acceptable GPS performance within my 14 day period, I will likely return it. That will really suck, as otherwise I really like the device, but I need a decent GPS.
ttabbal said:
Even stranger, in GPS Test, I get a single colored bar saying it's using that signal. There are 6 more with the same or higher signal strength being ignored. Very odd. Something is wrong with this GPS.
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This has been my experience as well, and I found the same thing when trying a friend's phone. If only T-Mobile/Samsung would acknowledge that there is a problem and say they are working on it...
No problem here
But as I came from the G1 I use Google Maps exclusively. I haven't had a single problem with it. Inside my house I can get a fix on my location on the map, exactly where it should be. Are you guys using the TeleNav?
ttabbal said:
Even stranger, in GPS Test, I get a single colored bar saying it's using that signal. There are 6 more with the same or higher signal strength being ignored. Very odd. Something is wrong with this GPS. It could very well be software, but Samsung needs to get on this and fast.
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I have the same issue... I can only ever lock on to 1 sat. This is not right. My G1 would lock on to many birds.
zoid_99 said:
I have the same issue... I can only ever lock on to 1 sat. This is not right. My G1 would lock on to many birds.
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I wonder if GPS Test is either wrong about that, or more likely, getting bad data from the OS or GPS driver. IIRC they are just parsing the NMEA data from the GPS driver, so "garbage in, garbage out". You don't get 20ft accuracy with 1 satellite being used.
I fooled with the settings in the "GPS fix 101" thread and got the thing working decently. Took a number of tries, and we'll see if it keeps working over time.
This really is something that TMO and Samsung should acknowledge and at least promise a fix for. Preferably with a close release date. And we shouldn't have to wait for Froyo either, get us a fix for JUST the GPS and a lot of people would be VERY happy. Well, that and the compass, that thing is even more worthless than the GPS before the fixes.
For the poster with Google Maps working, did you try with network locations disabled? Is the GPS icon in the status bar flashing or solid? If it's flashing, you DON'T have a GPS lock. Maps seems to be really good at using the network location stuff. I also enabled Skyhook in the GPS settings screen and Maps really seems to like that. Doesn't help with GPS performance though.
This thread is idiotic.
cashless said:
This thread is idiotic.
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Wow.. that statement was idiotic. Maybe you aren't having the GPS issues that others are having but this thread is helping me debug and decide weather or not I'm keeping the Vibrant or returning it.
You guys are not alone. There is obviously something wrong with either the hardware, or the software. Either way, the buyer's remorse period is halfway through, and neither company has said so much as a peep.
I will definitely be returning my device by the time the remorse period expires. What a shame that would be, because I really love this screen. All it would take is for T-Mobile and Samsung to acknowledge the problem, and state that a fix is on the way.
Here's my post, detailing my contact and findings with the two companies.
It's been a few days now, and I've heard nothing back. Never a good sign.
EDIT. Got it working
Care to share?

Fascinate GPS is officially useful

Not trying to start a fight, but I do want to prove that the GPS on the Fascinate is working, at least on some units.
I started out on my rooftop deck, and got a lock on the GPS. You can see I turned off wi-fi. I got 10 sats locked, ~4ft resolution. I then walked out of the building, and went around my block, purposely crossing the street at time, and even walking 3 sides of a 4 way intersection to see if the GPS would track it. Consider this is Chicago as well, with plenty of buildings around, I think it's doing darn well.
I've got a bunch of screenshots from the GPSTest utility I took during the walk, which I tracked with MyTracks from Google. I'll upload a few images here, as well as the .kml and .gpx file for those who want to break down the trip into detail. I'll post a link to the full gallery. I kept the 0 signal strengths in there, since they showed up every now and then. I assume this is normal, I don't know, I'm not a GPS expert.
The file names are by date/time so you should be able to cross reference signal strength / sat lock at a given time with the track data from the gpx/kml file.
Hope that helps encourage a few people, perhaps you just need to exchange your unit for a new one, instead of return it for a different phone?
Happy to answer questions.
Brandon
Edit - Gallery Link - http://picasaweb.google.com/111158456836091222310/GPSWalk#
Been using it since yesterday and I havent had a GPS problem at all. Google Maps is amazing on this thing, as it always is
namebrandon said:
I started out on my rooftop deck, and got a lock on the GPS. You can see I turned off wi-fi. I got 10 sats locked, ~4ft resolution. I then walked out of the building, and went around my block, purposely crossing the street at time, and even walking 3 sides of a 4 way intersection to see if the GPS would track it. Consider this is Chicago as well, with plenty of buildings around, I think it's doing darn well.
I've got a bunch of screenshots from the GPSTest utility I took during the walk, which I tracked with MyTracks from Google. I'll upload a few images here, as well as the .kml and .gpx file for those who want to break down the trip into detail. I'll post a link to the full gallery. I kept the 0 signal strengths in there, since they showed up every now and then. I assume this is normal, I don't know, I'm not a GPS expert.
...
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Thanks for the detailed test data. The GPS Test screens do look pretty good to me except for that bizarre example that is all zeroed-out. Recurring cases of that do not seem at all normal to me. But at least the unit recovered.
As for accuracy of the track -- and walking tracks are among the more demanding tests you can do -- I would say it is mixed but at least understandable given the conditions. Seems okay on the north-south streets. But it goes a little wonky on the east-west legs, especially near the end along the north side, when I guess you were in the shadow of those high-rise buildings, and the track wandered maybe as much as 15 meters into the block interior.
The pragmatic question about such tracks, which are never perfect, is: How accurate is acceptable? Sometimes it is useful to carry another known, good device recording a simultaneous benchmark so the two tracks can be compared. Also, when walking, it is good to set My Tracks to its maximum granularity of only 1 meter between data points instead of the default of 5 meters. I think the reasonable issue is how this performance compares to competitive smartphone devices.
Do the aberrant part of the track coincide with the places where GPS Test showed the satellites zeroed out? I am guessing that is true for the portion near the end of the circumnavigation.
In any case, this is the sort of test that users here can sink their teeth into, far better than andecdotal impressions.
Hey man! Thanks for the tips on how to correctly (or I guess, usefully) test the GPS. Thanks for taking the time to check the data too.
You can see if you look at google maps the buildings are a bit tall in some areas, so it certainly killed some signal. The zeros seemed to happen when I shook the device, which I had to do to take a screenshot (shaking is the trigger for the program). I think that is when the device lost signal every once and a while.
You'll notice I was on the sidewalk, which I think is portrayed pretty accurately. I was originally confused why I wasn't dead on center to the street.
It also caught when I purposely cut across the street at one point in time to see if it would track to the other sidewalk, and it did.
Regardless, it's accurate enough for me, and hopefully, accurate enough to give confidence to others out there that at least some Fascinate units have a good, working GPS.
Great news! Thanks for sharing. Can't wait to pick up my Fascinate tomorrow and try this out myself where I live.
I've had nothing but good performance from my GPS so far. On the way home from work 2nite I copied a myTrack of it and did a little meandering through a parking lot to see how accurate it was. GPS Test could saw up to 12 satellites at one time, but mostly 10 and locked onto 10 of them for most of the drive home. Accuracy was down to 3.3ft as well, but fluctuated up to 9ft from time to time. highest SNR I saw was 37, while most hung around 27-34. No screen shots of the GPS Test unfortunately, but I do have my tracks. I did stay in the right lane on the free way most of the way home, but had to go around traffic once I hit Modesto. I did go into the fast/left lane just before Jack Tone Rd and again after Briggsmore Ave and it captured that pretty good. I got off the freeway at one point just to mess with Google Nav and it handled it great. Once I got off on my exit I did some driving around the parking spots in a large parking lot. Pretty close to what I did. I'd say with in the 4-10ft estimated accuracy the GPS Test was showing.
Its been about a day since i rebooted the phone, so we'll keep it going to see if has the problem where it will work after rebooting or changing settings and then stop after a few days.
since I cant post links yet, here the map of myTrack
maps.google.com/maps/ms?ie=UTF8&hl=en&msa=0&msid=113114085618005181110.00048ff7980f2df305ac9&t=h&z=12
I haven't had much chance to use it on mine, but I will say that the first time I enabled it, it took about 10-15 seconds to get a lock. After that, it appears to lock virtually instantly every time an app activates it. Also, it seems to be very accurate within Google Maps and Navigation. I guess I'm one of the lucky ones.
I've also had generally good results from the GPS. The only problem I've seen is that it is sometimes slow to lock on, especially indoors or inside a car. Once locked on, accuracy has been perfect. I tried out Google's new "walking directions" feature, and it announced "You have arrived" right as I stepped up to my mailbox.
Even the slow lock-on hasn't always been an issue. I was rather amused on Saturday night when I stepped outside with a friend who has a Droid X so I could show him how to use the walking-directions feature. My Fascinate locked on as soon as we got outside, and the X was still searching several minutes later.
I'm sure the GPS issues are real, since lots of people are seeing problems (and Samsung has acknowledged the issue). But for me, it has worked well enough; after Samsung ships the fix, I can only assume it will be even better.
My phone arrived today and the first thing I tested was the GPS. Seemed to lock on much quicker than my previous Android devices.
After leaving the phone's GPS alone for a while, I went back into GMaps and it would not lock on...which is not to say its a phone problem. It would lock onto the wifi signals, so it was locking in my general area. However, I also experienced this on my other phones (it actually locked to the exact spot my other phones would). A simple exit of Maps and reopen and it locked to my location in 2 seconds.
For now it seems to behave as it should. I do have all three settings checked, btw.

[OFFTOPIC] all irrelevant topic spam, trolls, unecessary comments, etc... moved here

that doesn't make any sense at all, the phones screens are super strong and anti scratch out of the box from factory without any add-on.
if you cracked yours like you described, you must to have put it over a very hot surface, or with saline/acidic solution.
i've seen the video where the guy repeatedly intentionally drop the screen with no problem, until he tried to smash it over 1.5m high, anything less than 1.0 drop is safe for the screen.
i can see why samsung doesn't believe you, as it's physically imposible for it to break in the way you described it.
all that aside, if you can find a replacement screen, usually it is a plug and play piece.
i've done many of those on my old Treo and Blackberry phones, the SGS will be no different.
Replying to AllGamer's post. I had just taken my galaxy off my battery charger. So the phone was pretty hot. I believe that there was some defect or tension on the screen. The cracking started from the corner of home button.
AllGamer said:
that doesn't make any sense at all, the phones screens are super strong and anti scratch out of the box from factory without any add-on.
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Click to collapse
Im not sure about this.
My 2 weeks old phone dropped from the sofa and down at the floor today. About 50 cm and landed flat on the floor with the front first. Screen cracked all over, phone still usable though.
I´m ordering a replacement package. To much hassle trying to arguing against samsung or the shop i bought the phone in, stating the same as a bow.
But the lesson is, be careful people. The screen cracks surprisingly easy.
dangrayorg said:
Having studied the effects seen with the MS options over measured trials and based on my assertions in my previous post I believe that MS stands for ‘Multiple Sensors’ or ‘Motion Sensors’.
Click to expand...
Click to collapse
And here did I stop reading.
You don't even know what MS-Based and MS-Assisted stands for, and you think you can work out what the problem is?
Really. Thank you for trying, but changing the settings is no solution.
maesebit: Care to help then?
BS...
maesebit said:
And here did I stop reading.
You don't even know what MS-Based and MS-Assisted stands for, and you think you can work out what the problem is?
Really. Thank you for trying, but changing the settings is no solution.
Click to expand...
Click to collapse
Actually I can't find any decent quotable source. That said I may be slightly embarrassed as I come up with this:
What is MS-Assisted mode of operation?
In MS-Assisted mode, the network elements calculate the location of the device. This mode is suitable for one-shot fixes, wherein the location does not need to be updated frequently.
Back To Top
What is MS-Based mode of operation?
In MS-Based mode, the network provides the satellite information to the device, based on a rough estimate of where the device is located, and the device acquires the GPS signals from the satellites and calculates its location. After the initial fix, the device operates like an autonomous GPS receiver, until the satellite information must be refreshed, at which time the device goes back to the network to update the satellite information. MS-Based mode is appropriate for applications that require the device location to be updated rapidly, such as a navigation application.
Back to the OP again.....
Peer review, ain't it a *****.
Brownstone said:
maesebit: Care to help then?
BS...
Click to expand...
Click to collapse
I wish I could. But I can't provide you with a better antenna.
I'm just pointing out that this thread is not offering any solutions to the problem, and never will, unless it adds some sort of hardware modding tutorial.
maesebit said:
And here did I stop reading.
You don't even know what MS-Based and MS-Assisted stands for, and you think you can work out what the problem is?
Really. Thank you for trying, but changing the settings is no solution.
Click to expand...
Click to collapse
If you don't have corrective information, just P*SS OFF...
You've trolled every GPS related thread out there, with no information what so ever and only whinning about how your life sucks without GPS... I guess you must be hitting the walls in your place without a descent GPS eh?
It is specified by the OP that he "assumes" it stands for X and Y. This is speculative but still, this is at least someone trying to DO SOMETHING else than whine pointlessly and troll everything...
What did you do to make it right? Did you concact your reseller, did you contact samsung, did you tip any news site with the information?
As for the informations, this is what MS stands for:
MS = Mobile Station = your cell phone or handheld
MS-based = it gets GPS information assistance to find the satellites, then continues calculations on its own. Used for example with VZ Navigator.
MS-assisted = gets GPS assistance, and then sends raw GPS readings to another server to do the location calculations. Used a lot for E911 locating.
Click to expand...
Click to collapse
Yesterday my GPS started going totally berserk on me... I usually have a good track, better than I used to have with my HTC Vogue to track my workout but wierd thing appened yesterday, got me this track:
http://sportypal.com/Workouts/Details/776945?key=121d6fcdae3e1f2a69d349083a6f18affae9cd0a&ms=0
So I've disabled WiFi, rebooted the thing and it was still inacurate...
http://sportypal.com/Workouts/Details/776280?key=f7ae25b101afde4752bfd15d940e289ef8c4b8c4&ms=0
Better still, but unusable to track jogs
So I went ahead and strted GPS Status to clear and redownload A-GPS data and did a small test
http://www.google.com/maps/ms?ie=UT....436748,-71.004682&spn=0.005479,0.013894&z=17
I've played around in here and crossed the street a couples of times... I would say it's within 2 meter accurate of my real position and no weird jumps...
Still, this was a small 5 min. test. I'll check it out when I get another jog but it seems like the fix was more stable.
I know AGps is only used for the first fix, and shouldn't affect the accuracy once fixed, but what if (this is speculation, it should need further investigation) the GPS status accuracy issue was more likely caused by a lost and retreival of a fix? In this case, the fact that the fix was lost/regain would mean that the aGPS would affect the accuracy as it is constatly regained.
Any way to force disable the AGps overall?
It wouldn't be folish to belive that Samsungs engineers used MS for another meaning, they're often not very good in English.
I'm curious of the possible effects of moving the internal GPS antenna. Aka opening the phone, moving the antenna far away from other components and testing the GPS with default settings. Sometimes does wonder.
maesebit said:
And here did I stop reading.
You don't even know what MS-Based and MS-Assisted stands for, and you think you can work out what the problem is?
Really. Thank you for trying, but changing the settings is no solution.
Click to expand...
Click to collapse
That doesn't mean that the OP settings don't work best on our phones in real world testing. Has anyone proved which setting is best?
MS-Based = Mobile Station Based.
MS-Assisted = Mobile Station Assisted.
Standalone = no A-GPS used at all?
From this page, we can see that "Mobile Station" (MS), refers to the GPS receiver, ie the phone itself in this case. Therefore MS-Based means the phone itself computes the location with a combination of data from the GPS signals and the A-GPS server. MS-Assisted, means the phone sends it's GPS data to the server for the server to calculate the location for it. Standalone presumably means that the phone doesn't ask the servers opinion (is that correct?)
The point is that the OP was running a series of guesses based upon their experience of testing the device in the real world and trying to make sense of the data they saw. Therefore unencumbered by ideas of which should be "better" they have gone purely on test data. This might go against knowledgeable instincts, but doesn't mean it is wrong... even if the explanations of "why" are miles off!
If you have something to offer, then please DO carry on reading past the bit that was wrong, and see the bigger picture. Do the settings mentioned help or not?
I seem to remember that my phone was set to standalone when I got it, and someone trying to help suggested I switch to MS-Based, which I did, but I've had problems since then. I'll try it back on Standalone for a while and see if it helps! Maybe the A-GPS stuff is still part of the problem on this unit, and it performs better in standard GPS mode? Or maybe we can find a better server to use for the assistance?
Mike
t1mman said:
You've trolled every GPS related thread out there, with no information what so ever and only whinning about how your life sucks without GPS... I guess you must be hitting the walls in your place without a descent GPS eh?
Click to expand...
Click to collapse
Hey, I actually published a track showing how the GPS performs well when used in open spaces, and awfully when it's sorrounded by stuff like buildings.
I guess that's more helpful for investigation pourposes than blaming the world for not being alligned with the Galaxy S' GPS, as others do. XD
No offence, but all this thing about recording tracks and looking for miracolous configs is starting to be ridiculous. You might notice slight improvement by doing so. But it won't be enough.
So, sorry for bringing people's hopes down, but if the GPS could be fixed by simply changing some settings Samsung would have already done that. You know, even their useless engineers could be able to do that in 6 months time.
I'm going to come to maesebit's defence. I was talking arse about MS nav and he called me on it. The wandering behaviour which I had put down to INS could easily be caused by having a base-station try to DF you and pass that position back (doppler shift maybe? That would explain why it keeps you moving for a while until it decides that you have stopped.)
Actually it doesn't make any difference. The loudest cry in this forum seems to be for 'MS-Assisted' which is precisely the wrong mode.
They're not well named modes, given that MS-Based is actually assistive while MS-Assisted is actually based - quite counter intuitive!
I know it's cheeky but I'm going to keep ammending the OP because I think it's important that that paints a picture of what can be done. Simply put I'm under no illusions that Samsung will do anything about this because it needs a hardware fix so it's for us to look at the 'art of the possible'.
bilboa1 said:
It wouldn't be folish to belive that Samsungs engineers used MS for another meaning, they're often not very good in English.
I'm curious of the possible effects of moving the internal GPS antenna. Aka opening the phone, moving the antenna far away from other components and testing the GPS with default settings. Sometimes does wonder.
Click to expand...
Click to collapse
MS- Based and MS-Assisted is standard tech slang. But who know. They could be changing the achronyms meanings. Maybe they could be using "GPS" as "Great Piece of ****" instead of "Global Positioning System" too.
As of changing the antenna placement. That'd be interesting. Anyone dares to give it a try? We could also try to attach an external GPS antenna to the phone and see what happens.
maesebit said:
Hey, I actually published a track showing how the GPS performs well when used in open spaces, and awfully when it's sorrounded by stuff like buildings.
I guess that's more helpful for investigation pourposes than blaming the world for not being alligned with the Galaxy S' GPS, as others do. XD
No offence, but all this thing about recording tracks and looking for miracolous configs is starting to be ridiculous. You might notice slight improvement by doing so. But it won't be enough.
So, sorry for bringing people's hopes down, but if the GPS could be fixed by simply changing some settings Samsung would have already done that. You know, even their useless engineers could be able to do that in 6 months time.
Click to expand...
Click to collapse
I would agree with you, but considering some have good tracks, some have bad tracks; there must be something that affects the GPS usability.
And, as I replied, A-Gps will have an effect if the signal is constantly lost and regain, as it is most likely the case in urban area, where the signal is known to bounce off of buildings or be disrupted by radio signals in the surroundings. I don't know how much you've tested any settings at all, but considering most of your answers consist in discrediting the whole A-Gps theories, I would assume “none”. So, your “theory” that it doesn’t affect anything at all is still a theory, just as OP’s or any of us.
maesebit said:
So, sorry for bringing people's hopes down, but if the GPS could be fixed by simply changing some settings Samsung would have already done that. You know, even their useless engineers could be able to do that in 6 months time.
Click to expand...
Click to collapse
I don't think so. We all would like to believe that the Samsung engineers are as involved as the XDA crowd is. Forget it. Why did it took months for Samsung to come up with their Froyo version? Look at it, what's are the extras that Samsung puts in Froyo that legitimate months of delay?
Samsung just sees this as a calculated risk:
- only 25% of the customers will use the GPS
- 25% of those will have used a GPS phone before and are able to compare
- 25% of those will bother
- 25% of those will look at forums like XDA
- 25% of those will rant on forums like XDA
So, 0,098 % of customers will have a problem, big deal. Samsung just doesn't bother. Maybe a few engineers do, but they are already working on the Galaxy S2, and we are blessed with people like the OP to help us out.
I have a Samsung Blue Ray Player also. The thing has a RJ-45 network socket. To this day, it's unable to find Windows Network shares in the network (you know those shares invented in the Windows For Workgroups era). So you can type in the IP adress, username and password manually (painstakingly with the remote) so it finds your shared media. But.., the engineers didn't bother to make the player SAVE that IP, username, passwords when you power off the Blue Ray Player.... That's the level of engineering at Samsung.
PS: my GPS works fine from the start. Fix in a few seconds, and just an occasional hop on a nearby road.
FadeFx said:
Sorry for proving you wrong, but i can tell you one thing
our GPS actually works well
The problem we do have is not really GPS, the root of the problem actually is the shaky compass sensor. With not knowing where exactly north is, the best navigator can't tell you where exactly you are. .
Click to expand...
Click to collapse
Are you serious? North and South, East and West have never been relevant in determining your GPS position....
Direction is based on the followed track between two or more determined GPS locations, not the poles.
Only a Compass can indicate North when stationary, a GPS device has to be moving (been moving) to indicate North, which it doesn't do based on poles but on the GPS locations it determined in the previous seconds.
pwhooftman said:
Are you serious? North and South, East and West have never been relevant in determining your GPS position....
Direction is based on the followed track between two or more determined GPS locations, not the poles.
Only a Compass can indicate North when stationary, a GPS device has to be moving (been moving) to indicate North, which it doesn't do based on poles but on the GPS locations it determined in the previous seconds.
Click to expand...
Click to collapse
A compass isn't involved in traditional plain GPS. Correct.
However, is it definitively proved that the compass doesn't interfere with GPS tracking on our phones, by adding another sensor feed in to the mix?
It probably doesn't have an affect, but are we absolutely sure?
Have people tried re-calibrating their compass and accelerometer, even just so we can dismiss them completely as being not part of the problem?
Mike
xpcomputers said:
A compass isn't involved in traditional plain GPS. Correct.
However, is it definitively proved that the compass doesn't interfere with GPS tracking on our phones, by adding another sensor feed in to the mix?
It probably doesn't have an affect, but are we absolutely sure?
Have people tried re-calibrating their compass and accelerometer, even just so we can dismiss them completely as being not part of the problem?
Mike
Click to expand...
Click to collapse
if by recalibrating you mean running the sensorcalibutil_yamaha, then yes, i recalibrate it all the time, since the bloody thing gets screwed up so often.
I just wondering why people keep asking question here rather than using discussion thread... Also people keep reporting bug here rather than using issue tracker...
@codeworkx: I think you should ignore any question here and push them to discuss there... at the link that you have post... BTW... thanks for your great works...
+100000000000
People, if you have questions, need any kind of help or need to discuss something not relevant for the devs: use the f*cking user thread!!! And do not report any bug here, do it through the issues list!!!
I wonder how can exist so many people that know how to write but not to understand what they read!!!
Sent from my GT-I9000 using Tapatalk

Want to know why the SGS GPS is crap? Read here

We all know that the GPS unit on our beloved SGS sucks badly. Firstly it takes ages and ages to find a good signal, and secondly it chews up bucketloads of battery to get there.
The other day I was talking to someone about GPS units within some handheld devices at work, and he told me something that completely blew me away - how GPS units ACTUALLY work as opposed to how most people think they work.
Firstly let me preface this by saying that he used (and I will use) the "Lies to Children" method of technical communication. If you are not a Terry Pratchett fan, it basically means that instead of explaining a subject to the Nth degree and getting the full detail across, you sum it up with what is essentially and technically a lie - but one that's a half-truth that will pave the way for future understanding.
Example? "The sun rises in the east and sets in the west". Comparatively speaking against the Earth, the Sun does NOT move. The actual truth is the sun moves within the galaxy and within the galaxy cluster and within the universe. The earth also moves in a similar manner and also rotates on its axis with a slight wobble that technically provide seasons. How does that relate to a 5 year old? "Yeah, uh, kid. The sun, you see, it rises in the east". A "lie" but one that works for everyone, and when their brain absorbs enough other information you can explain it properly (with another "lie", but one that's more truthful than the previous one)
Back to the topic:
I thought, like most of you probably think, that a phone's GPS works by having some kind of 2-way method of communication. When you enable the GPS unit and go into maps, the device starts broadcasting to the satellites to say "I'm here, now where is 'here'?" That's not the case.
It works a bit like this (and pardon the analogies)
Let's say there are 3 satellites are in geosynchronous orbit at fixed locations. For the sake of the description we'll call them FRED, GEORGE, and BILL. A lot of time and money was spent to make sure that they don't vary that location by a factor of a few cm before they re-correct their location. A bunch more time and money went into their internal time-keeping mechanisms so that they are also VERY accurate.
From their location they broadcast a signal outward. Fred says "HI I'M FRED LOCATED AT POSITION X AND THE TIME IS SUNDAY 18TH MARCH 2012 7:15PM AND 38.123456789 SECONDS"..."HI I'M FRED LOCATED AT POSITION X AND THE TIME IS SUNDAY 18TH MARCH 2012 7:15PM AND 38.123456790 SECONDS" and so on.
George says "HI I'M GEORGE LOCATED AT POSITION Y AND THE TIME IS SUNDAY 18TH MARCH 2012 7:15PM AND 38.123456789 SECONDS"..."HI I'M GEORGE LOCATED AT POSITION Y AND THE TIME IS SUNDAY 18TH MARCH 2012 7:15PM AND 38.123456790 SECONDS" and so on.
And Bill...I can't be stuffed writing it, let's just say Bill screams out his location and the current time, multiple times a second.
Now, while some satellites broadcast in higher or lower timings, the basics are the same: Current position, plus the current (accurate) time. (Some also send information regarding the other satellites it "knows" around it. Eg, "HI I'M BILL AT POSITION Z AND THE TIME IS BLAH AND I CAN SEE GEORGE AND FRED. THEY DON'T SAY MUCH, SO IT SURE IS LONELY UP HERE").
My point here is that the satellite neither knows nor cares who you are or where you are, it just pumps out that racket like a noisy teenager with a new stereo and what they THINK is the coolest music ever.
When the 3 signals are received on the ground by the GPS unit, it works out: "Bill thinks it's THIS TIME....George thinks it's THAT TIME...and Fred thinks it's this OTHER TIME....that means my distance from each one is actually THIS FAR and the real time is NOW". From that you can bang your location in LATITUDE and LONGITUDE on a map.
Sure, there are complications due to altitude and speed and direction, and you really need more than 3 satellites to work out where you are. But the reality is that, based on the lag in the signal from transmission to receiving (able to be calculated due to the speed of light), we can work out how long each signal took to get to the unit and therefore how far from the satellites we are. If you know where the satellite is supposed to be, you can work out where you are on the globe.
It really is that simple.
So when I found all of that out, I asked the question: If the satellite is really all that counts in this case, why does our GPS blow? In fact, why does any GPS work better than others?
Well, there are multiple factors:
Firstly, just like a good barman or psychologist, some "listen" better than others. The PASSIVE radio signal needs to be received by a unit that has a decent antenna and doesn't have other electrical crap affecting it. Anyone look inside their phone and see the antenna (and it's location)? Yup, it's in a pretty bad position and it's a pretty bad antenna.
Even if we were somehow to isolate the GPS unit and bring it out away from the interference, it's a pretty bad receiver. If you've ever listened to a transistor radio and compared it to a $4000 stereo unit, you know what I mean. Noise = bad data = bad location finding.
Secondly, the signal needs to be interpreted. When each broadcast hits the phone, the receiver accepts it and shunts it to the processor to work out. Slower phones can process less signals, especially when the OS may put a limit on how much processor time should be dedicated into working out the signals (there's no point using 100% of your processor when that means you can't display it properly on the map or let the user actually interact with the maps app)
Thirdly, we don't know all the positions of the satellites. When the signals first start getting processed, your phone communicates with the NTP servers it has located in your GPS.CONF. It asks which satellites are where and where that actually may be on the globe. Remember how I said each satellite tells you it's position? That was a "lie to children" moment. The damned thing is in the SKY after all. So, while we technically know where it is, the information means jack and sh*t to the GPS unit unless it has more information available.
What I mean here is: What part of the world can that satellite see/broadcast to? The satellite doesn't know or care, and it's not broadcasting that information at any case. There's more than a couple of satellites up there, so the phone needs to check back the NTP.ORG to work out some basics. As your phone uses the GPS function more and more, it stores up the addresses of the satellites that you know and love in your neck of the woods (including ones that are not geostationary) and will need to rely less on a data connection.
That's why when you use GPS the first time after a fresh flash it is just plain crap, but after a few more tries it works better. And that's why it's important to use FasterFix or a like app to nominate the closest/best NTP server for you - the closer servers respond quicker over the 'net and also have the list of "closest" stationary satellites stored at the front of the file. If you're in Australia you don't care about the 'merican or European sats, but they come afterward "in case you're overseas"
Lastly, when you take it all into account, if you have bad weather or tall buildings around you, then the signals blasted down from on high either get muted, muddled, or bounced around. The error correction in our phones is non-existent - it doesn't actually need to be due to the fact it's a PHONE and not a GPS unit, but some devices can and do filter out the known "dodgy" signals before processing. I'm pretty sure that when the techies run out of toys to add to or fix in our phones, they'll add altimeters and thermometers and they'll fix the GPS post-processing to get the signal down pat.
In case you're wondering, the whiz-bang GPS units that can get extra awesome resolution (down to beyond cm) have the list of every single satellite location up there stored internally, the on-board processor is dedicated to working out what the signals mean, and the GPS chip itself normally has a great big honking antenna on it and is extra receptive. Ours is a 2 dollar job from some bulk offload sale.
There you have it. Thanks for letting me brain dump. Hope this helps some people's understanding!
Interesting. I had always thought it was a simple two-way communication between the phone and a geostationary satellite. But in retrospect, that would be extremely inaccurate seeing as how the attenuation over such a long distance, as well as the interference with other phones (which might be using the same frequency because GPS is not network controlled, unlike calls) would make it difficult for the satellite to tell where the signal came from. This explanation makes much more sense. Thanks!
So, its still better to use an app like GPS Aids so the GPS would be "up" faster... Thanks for explanation, you sir, get a thanks.
Wow! Nice post, well written and very informative!
But I don't understand, how the help is GPS free when all this technology is so expensive!?
Sent from my GT-I9000 using XDA
Yes. Good post. Except the GPS satellites aren't geostationary. They orbit the earth twice a day at an altitude of approximately 20.000km. There are 6 different orbit planes and 4 satellites per orbit.
A geostationary satellite sits directly above the equator at an altitude of about 36.000km. One orbit lasts excactly one day and thus the satellite appears as if it's standing still in the sky.
You can google all that if you like.
GPS would be simple if all the satellites were geostationary, but that would make triangulation very difficult. Especially around the polar areas. Therefore they must be orbiting crisscross all over the globe. But that also makes geostationary orbits impossible (it is only possible directly above the equator).
Thanks given simply for the Terry Pratchett reference (I'm addicted to Discworld novels)
Here are my 2 cents about this whole "closer NTP server = better results"
1) NTP server is just a time server. It doesn't store any info regarding any satellite in your neighborhood. That's the role of A-GPS server - in our case it's supl.google.com that you see in every gps.conf.
2) We all get our current time from our mobile provider or manually setting it in settings. So we don't sync our clock to NTP server time. Our phone will just use NTP to figure out the offset - i.e. how accurate our clock really is. It can also take into account the delay factor caused by network latency since it's something relatively easy to measure. So in the end of the day it won't really matter what NTP server you use as long as it works and you don't have any network issues with it.
From my experience all these NTP games are one big placebo effect.
The only tips I got for better GPS are:
A) Clear GPS cache after not using it for a long period of time (or let android do that for you eventually).
B) Use mobile network data for faster fix (A-GPS).
C) Keep the antena free from any obstacles - In car place the phone directly under the front glass, don't expect it to work under the roof.
While running if you use armband, place the phone with its screen toward your arm since if placed otherwise your arm will blocks the gps signal completely.
Any one know why mine is fine and grabs lock within 10 seconds indoor with iGO and GPS test?
I didn't f*)Kin camp outside a electronic store JUST to get one on release date I got one from later batch which fixes hardware GPS reception issue
All GPS use one-way communication.. it would become too expensive n complicated to have two-way communication
1) The GPS receivers here on earth would require complicated and high power circuitry to send signals to satellites miles above the earth. It would suck a battery dry in minutes
2) The GPS satellites would require to handle communication with an exponentially increasing number of GPS units on the ground. That would require huge processing power, multiple channel support and communication management to avoid clashes between communicating units. Satellites are situated so high up that signals to and from satellites accrue a lot of noise n distortion.. For proper signals, satellites can only transmit data at very low data rates and have low bandwidth..
GPS requires exact timing, and I mean atomic clock exact. Its impossible to have atomic clocks in today's small devices. So satellites have a very accurate atomic clock on board.. Heck, some satellites have 3 on board to correct clock drift and error!! Even then, GPS devices were very expensive.
Then, some scientist found a way to find the exact location and time by using the really small timing variations in satellite signals. Coz of that, we can now afford GPS chips at $50..
Our phones don't have space for large ceramic antennas (one GPS unit I have has a 25x25x4 mm antenna on top!!) And the timing variation trick helps even low power units pick up satellite signals, but they are slightly less sensitive.. They won't be able to pick up weak signals, which your car nav unit will..
Also, processing GPS data doesn't take that much processing.. Almost all GPS units output their data in a standard format called NMEA format and the location data looks something like:
$GPGGA,<time>,<latitude>,<longitude>,<fix quality>,<no. of satellites>,<altitude>......
All the processor has to do is use this data.. A processor doesn't have to calculate anything at all with regards to actually locating the device. The GPS chip does it all..
Sorry for the really long post.. I hope it makes sense.. I'm doing a project which uses a GPS unit, so I've been studying on it..
First let me start by saying that I have a habit of drunk posting. So I logged into XDA today at work and went "huh? An extra bunch of 'Thanks'? What the hell have I done now?"
Which means that while the information in the OP does a decent job of summing up what I was told, some was a little off. Cheers for pointing out where I got things wrong.
Remember, last week "my mind = blown" by the fact that GPS isn't 2-way...which makes sense but is one of those things that I never considered...
Don MC said:
Yes. Good post. Except the GPS satellites aren't geostationary. They orbit the earth twice a day at an altitude of approximately 20.000km. There are 6 different orbit planes and 4 satellites per orbit.
Click to expand...
Click to collapse
You are quite right, there are a whole bunch of sats whizzing around up there in set orbits. Some of them "talk" to ground stations to get updates about the world in general, but a bunch just go screaming past blaring out their message.
I asked my mate at work who told me about how GPS works....his response? "Yeah, Lies to Children works like that." Apparently a combination of his half-explanation and my beer meant I got something wrong there. Sorry.
To give the full information about the different sats flying about, and how they get send the information....well, apparently it was easier to say "geostationary" !!
mike.sw said:
Here are my 2 cents about this whole "closer NTP server = better results"
1) NTP server is just a time server. It doesn't store any info regarding any satellite in your neighborhood. That's the role of A-GPS server - in our case it's supl.google.com that you see in every gps.conf.
2) We all get our current time from our mobile provider or manually setting it in settings. So we don't sync our clock to NTP server time. Our phone will just use NTP to figure out the offset - i.e. how accurate our clock really is. It can also take into account the delay factor caused by network latency since it's something relatively easy to measure. So in the end of the day it won't really matter what NTP server you use as long as it works and you don't have any network issues with it.
From my experience all these NTP games are one big placebo effect.
Click to expand...
Click to collapse
Again, you're right. But in the GPS.conf file there are both NTP and A-GPS servers. I was of the understanding the NTP address information also gave ...wait, disregard - just Googled that.
NTP only gives you time. And it won't matter which NTP server you get unless you have networking issues. I suppose the answer there lies in the fact that a "closer" NTP server will get you a quicker response to begin with, so your phone can start the process of working out the offset quicker....
Good tips, though I'm too much of a beer drinker to go running. Screen in or out.
ilabs said:
All GPS use one-way communication.. it would become too expensive n complicated to have two-way communication
1) The GPS receivers here on earth would require complicated and high power circuitry to send signals to satellites miles above the earth. It would suck a battery dry in minutes
2) The GPS satellites would require to handle communication with an exponentially increasing number of GPS units on the ground. That would require huge processing power, multiple channel support and communication management to avoid clashes between communicating units. Satellites are situated so high up that signals to and from satellites accrue a lot of noise n distortion.. For proper signals, satellites can only transmit data at very low data rates and have low bandwidth..
Click to expand...
Click to collapse
Correct...but kids these days also assume that steak literally grows on trees. Assumptions are the mother of all....
ilabs said:
Our phones don't have space for large ceramic antennas (one GPS unit I have has a 25x25x4 mm antenna on top!!) And the timing variation trick helps even low power units pick up satellite signals, but they are slightly less sensitive.. They won't be able to pick up weak signals, which your car nav unit will..
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Correct, that was my point about the crappy GPS chip being like a crappy transistor radio. The combination of the quality of the chip plus the really really bad antenna (and it's position) means that people will not get car-gps like quality from their phone....and they shouldn't !!!
ilabs said:
Also, processing GPS data doesn't take that much processing.. Almost all GPS units output their data in a standard format called NMEA format and the location data looks something like:
$GPGGA,<time>,<latitude>,<longitude>,<fix quality>,<no. of satellites>,<altitude>......
All the processor has to do is use this data.. A processor doesn't have to calculate anything at all with regards to actually locating the device. The GPS chip does it all..
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You're talking about the "final" output, but when I mentioned processing I meant the processing of the signal received.
I asked again about this. It was explained thusly: If you have interference in the form of tall buildings (for example) then the signal will actually bounce around a bit before being picked up. That "echo" can sometimes give a false reading if you took that one bit of information as a whole, as it's not a true representation of the time it took for the signal to get down from the sat.
So the device collects constantly and shunts that information to the processor to determine the length of time between when the sat spat it out and when the unit received it.
Now say every 10th "message" is a bounced/echo one. If the device is only able to process every 5th message, then it's potentially going to have up to half the messages be a dodgy echo job = bad location. It will catch up, eventually, but will take longer to know something weird is going on.
If, on the other hand, the more powerful processor was able to work out every 3rd message or more, then a more accurate fix comes quicker.
ilabs said:
Sorry for the really long post.. I hope it makes sense.. I'm doing a project which uses a GPS unit, so I've been studying on it..
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Dude, the more people who post (sober) the better the information we have!!! Post away and make it long! Mine was!!
MrAndroid12 said:
Any one know why mine is fine and grabs lock within 10 seconds indoor with iGO and GPS test?
I didn't f*)Kin camp outside a electronic store JUST to get one on release date I got one from later batch which fixes hardware GPS reception issue
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Luck....pure kiwi luck? lol.
I know my hardware blows. Takes anything from 30 seconds to 1 minute to get a dodgy half-lock.
I was thinking about packing it in for a new phone but a) still got a plan to pay off and b) ICS made the device more than useable in every other aspect.
wogfella said:
You're talking about the "final" output, but when I mentioned processing I meant the processing of the signal received.
I asked again about this. It was explained thusly: If you have interference in the form of tall buildings (for example) then the signal will actually bounce around a bit before being picked up. That "echo" can sometimes give a false reading if you took that one bit of information as a whole, as it's not a true representation of the time it took for the signal to get down from the sat.
So the device collects constantly and shunts that information to the processor to determine the length of time between when the sat spat it out and when the unit received it.
Now say every 10th "message" is a bounced/echo one. If the device is only able to process every 5th message, then it's potentially going to have up to half the messages be a dodgy echo job = bad location. It will catch up, eventually, but will take longer to know something weird is going on.
If, on the other hand, the more powerful processor was able to work out every 3rd message or more, then a more accurate fix comes quicker.
Dude, the more people who post (sober) the better the information we have!!! Post away and make it long! Mine was!!
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Haha.. Yeah, the assumptions that you hear from time to time!! Makes even standard fiction seem possible!!
When I was talking about the processing, yeah, it was the final processing. But the processing of the GPS signal is only done by the GPS chip, not the processor to which the data is output. Generally GPS satellite signal frequencies are such that they die out very quickly when reflected off or passing through objects and buildings. That's why you get the best signal out under the open sky. The processing of the final received signals is done completely by the GPS chip. A standard GPS chip has only TX/RX serial pins apart from power pins. As soon as you power it up, it starts spitting out GPS data. Externally interfaced processors don't have to calculate anything at all.
Apart from this, everything is spot on!!
---------- Post added at 04:34 PM ---------- Previous post was at 04:27 PM ----------
MrAndroid12 said:
Any one know why mine is fine and grabs lock within 10 seconds indoor with iGO and GPS test?
I didn't f*)Kin camp outside a electronic store JUST to get one on release date I got one from later batch which fixes hardware GPS reception issue
Click to expand...
Click to collapse
Generally, when you first start up a GPS unit, its called a cold start coz it takes time. It will take time to scan for satellites and make a database of satellites around. Once it has at least 3 satellites in view, it has enough data to perform a proper triangulation to give your location. As the antennas on a phone are weaker, there's a certain error in a signal, which is why Google maps first shows your estimated location in a blue circle. As you begin to move, more data like heading and stuff is known and your position becomes accurate.
Sometimes even I get a lock in 10 seconds, sometimes not even in half an hour. That happens when there are no strong satellites above. If you always get a lock, I guess you're lucky to have a good number of satellites hovering over your phone like guiding angels..
wogfella said:
NTP only gives you time. And it won't matter which NTP server you get unless you have networking issues. I suppose the answer there lies in the fact that a "closer" NTP server will get you a quicker response to begin with, so your phone can start the process of working out the offset quicker....
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The "quicker" result may be important if you query ntp servers every second (the default rate for GPS sample I think), however ntp is being queried once in a while - not sure the exact interval maybe one of the developers here can help with that.
If everyone of us would query the ntp servers every second they would be hammered to horrible death.
In "normal" NTP setups, client systems, like your desktop, query a small number (perhaps between 1--10) NTP servers every so often, e.g. once per minute (or 64 seconds in a common UNIX implementation). This can vary depending on response.
NTP is designed to get microsecond wall-clock time accuracy despite round-trips to NTP servers often taking tens, or even hundreds of milliseconds.
I believe most Android phone GPS chips update position once per second. There are apps that will confirm this.
I don't believe there's any need to repeatedly query NTP servers every second.
However, the hardware clocks in phones are terrible. Mine drifts up to one second per day, until the clocksync app uses an NTP query to drag it back to reality. Note this is different to how it's normally done on a PC: there, the OS clock is sped up or slowed, so that the time can gradually skew towards reality. For a large difference, the time has to be stepped, all in one go, which isn't ideal from an OS perspective (e.g. timed callbacks, etc).
So I can see that more frequent NTP checks might help a little, for GPS, but not a lot.
Note that consumer GPS units (e.g. automotive, handheld) do not use NTP at all, nor do they have expensive hardware clocks. So I'm not at all convinced why NTP is "required" on Android GPS, unless it's because most phones default to getting the time from the mobile network, which can be *minutes* off.
Finally, sadly, none of the above even remotely explains why our SGS phones have a reputation for (or in fact "are") worse at GPS than other similar phones...
Edit: meant to add: the latter is perhaps mostly likely explained by a combination of poor antenna design, and sub-optimal GPS implementation in the Broadcom chip (which I believe is the one involved).
I wanna kno why the x10 has such a bad camera
OMG. Counter Strike On Android! http://cs-portable.net/
I wanna kno why the sgs has such a bad camera
Very interesting
ilabs said:
Haha.. Yeah, the assumptions that you hear from time to time!! Makes even standard fiction seem possible!!
When I was talking about the processing, yeah, it was the final processing. But the processing of the GPS signal is only done by the GPS chip, not the processor to which the data is output. Generally GPS satellite signal frequencies are such that they die out very quickly when reflected off or passing through objects and buildings. That's why you get the best signal out under the open sky. The processing of the final received signals is done completely by the GPS chip. A standard GPS chip has only TX/RX serial pins apart from power pins. As soon as you power it up, it starts spitting out GPS data. Externally interfaced processors don't have to calculate anything at all.
Apart from this, everything is spot on!!
---------- Post added at 04:34 PM ---------- Previous post was at 04:27 PM ----------
Generally, when you first start up a GPS unit, its called a cold start coz it takes time. It will take time to scan for satellites and make a database of satellites around. Once it has at least 3 satellites in view, it has enough data to perform a proper triangulation to give your location. As the antennas on a phone are weaker, there's a certain error in a signal, which is why Google maps first shows your estimated location in a blue circle. As you begin to move, more data like heading and stuff is known and your position becomes accurate.
Sometimes even I get a lock in 10 seconds, sometimes not even in half an hour. That happens when there are no strong satellites above. If you always get a lock, I guess you're lucky to have a good number of satellites hovering over your phone like guiding angels..
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My cold starts take no longer than 10 seconds for a 50-30 meter lock. After it is warmed up, GPS takes a matter of 2 seconds to grab lock @ 10 meters and 5 shortly after.
---------- Post added at 07:41 PM ---------- Previous post was at 07:40 PM ----------
MattyOnXperiaX10 said:
I wanna kno why the sgs has such a bad camera
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It's not that bad, is it?
I wanted to shoot a video for my YouTube channel using my mums phone. Galaxy s and it wasn't focusing on the camera, video quality was bad (sorry for of topic)
Ask us any Android Related Question @FeraLabsDevs on Twitter or @HowToMen
MrAndroid12 said:
My cold starts take no longer than 10 seconds for a 50-30 meter lock. After it is warmed up, GPS takes a matter of 2 seconds to grab lock @ 10 meters and 5 shortly after.
---------- Post added at 07:41 PM ---------- Previous post was at 07:40 PM ----------
It's not that bad, is it?
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I get the same start timings, provided there are satellites to lock onto.. Sometimes my cold start time is a little over a minute!! But with no satellite cover, I could be better guided by a rock than my phone..
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