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Hi i have weird problem with my GPS.
While I driving (car is moving) everything is beauty and sweet but once I stop my car my GPS is still moving for about 10 sometimes 20 sec showing 2km/h then 0km/h then 2km/h again. Sometimes when I stop car on junction my Gps will jump on the perpendicular road and from time to time my arrow on the map just turn around to opposite direction and the maps sets a new route! Once i move my car everything going back to normal.
I was using first my TomTom and i just thought it`s a map problem although i haven`t problem with that on my Rhodium either X1. So I decided to try Igo8 and it`s exactly this same. Even on the roundabout my gps can jump somewhere else on different road.
I tried all Radios available for HD2, many Roms and just have no idea what more I can do. Many people on HD2 forum in Poland have this same problem.
I also tried GPS fix cab downloaded here from xda but no luck its ever worst.
I can add that i'm getting GPS fix in few second so its good the problem is just my gps is moving around.
PS. Very, very rarely have no problem with this jumpin gps around. But is like 1/30.
Do you have access to an external Bluetooth GPS receiver you can test out? That could eliminate or isolate some possibilities.
balane said:
Do you have access to an external Bluetooth GPS receiver you can test out? That could eliminate or isolate some possibilities.
Click to expand...
Click to collapse
unfortunately i don`t. but on my Touch Pro 2 and Xperia never had this problem.
hi,
are you using the 'gpsmoddriver' software, that is floating around here in the forum?. its made for using the compass data when no gps fix is available. it causes such failures in igo and copilot on my hd2. after uninstalling it gps works much more percise to me, when im not moving.
regards mad
Happens with mine as well. I have replaced my HD2 and it seems that the 2nd unit acts the same. tried various ROMs/RADIOs (official/cooked) - nothing seemed to fix this.
It's quite funny though... most of the people rather paying attention to the fix time instead of the accuracy (which is quite bad imo) in addition to this weird phenomenon. I doubt that the AGPS is somehow related, but it will be nice to know how to disable this feature, and try to acquire the signal without it. maybe this is the cause.
Btw, check this out - http://forum.xda-developers.com/showthread.php?t=600232
Fatherboard said:
Happens with mine as well. I have replaced my HD2 and it seems that the 2nd unit acts the same. tried various ROMs/RADIOs (official/cooked) - nothing seemed to fix this.
It's quite funny though... most of the people rather paying attention to the fix time instead of the accuracy (which is quite bad imo) in addition to this weird phenomenon. I doubt that the AGPS is somehow related, but it will be nice to know how to disable this feature, and try to acquire the signal without it. maybe this is the cause.
Btw, check this out - http://forum.xda-developers.com/showthread.php?t=600232
Click to expand...
Click to collapse
Agps - this feature is available in NRGZ roms. I tried to turn on and off and it was no different.
PS. thanks for answering.
madbird said:
hi,
are you using the 'gpsmoddriver' software, that is floating around here in the forum?. its made for using the compass data when no gps fix is available. it causes such failures in igo and copilot on my hd2. after uninstalling it gps works much more percise to me, when im not moving.
regards mad
Click to expand...
Click to collapse
As i said before : i was using it. I had feelings its jumping around the places more than without it so I uninstalled it.
Tried to email HTC regarding this. they claim that their HD2's don't exhibit this behavior, even though I've tried two different units, from different batches.
I don't know what to do... this drives IGO nuts - it causes igo to switch lanes, directions and having the route recalculated without any good reason.
Fatherboard said:
Tried to email HTC regarding this. they claim that their HD2's don't exhibit this behavior, even though I've tried two different units, from different batches.
I don't know what to do... this drives IGO nuts - it causes igo to switch lanes, directions and having the route recalculated without any good reason.
Click to expand...
Click to collapse
Sometimes its just pointless to talk with those dickheads.
They ll never say true.
With pink camera was this same. They were saying at the beginning that they have no problem with pink spot at all. And what was next? We need just more people to email or ring them.
Most of them even not using HD2. They've seen for few minutes and think they'll know everything about it.
It was so many bugs with this device they just dont want to hear about another one!
In addition to that, both of my units tended to show different position and altitude readings each time i powered up igo or google maps. while exhibiting the differences I obviously didn't from my current position, not even an inch.
to try to make things clearer. that's what I did :
loading igo -> acquiring signal within seconds -> getting a certain position reading with altitude of 11 meters (for example) -> quit -> reloading igo -> acquiring signal within seconds -> slightly different position, altitude of 75 meters or a negative value (for example).
even the small blinking dot in igo (which determines the actual gps mark) doesn't fit to my physical location on the road which I'm currently driving on. it sometimes blinks few meters to the right/left, and sometimes it tracks behind the guidance arrow (as it should be).
Could be
Simply a limitation of GPS. I have seen it on other GPS's. Garmin etrex. Try walking with one and even thou you are walking in a straight line it plots a zigzag path. More satelites (10+) should reduce this issue.
Basically the GPS is only accurate to a certain range from +-50m to +- 2 meters depending on the no of sats. The location is detemined by timing from when the signal was sent to when it was received. Calcs how far away the sat is (Speed of light??). It is possible you care getting a fluctuation in your current location. Eg
Sample 1 says you are point a.
Sample 2 says you are 2 meters to the right.
Sample 3 says you are 2 meters to the left.
Still in the +- 5 meters but the gps is plotting you moving backwards and forwards.
Guys, it is a problem everyone has, gps position is not as accurate or stable on the hd2 as on most other htc devices. And with an erratic gps position automatically comes an erratic speed. Don't know yet if it is because of a different gps module that's inside the hd2 or because of the inclusion of crappy gps drivers. Will try to find out soon....
Anyway, gpsmoddriver is not the cause of this problem since the problem is also on an hd2 without having gpsmoddriver installed. Because of the functionality of gpsmoddriver to improve the gps readings, in some cases it can amplify your erratic gps position, and that is also what some of you have been experiencing. Remember you can always use gpsmoddriver to add the hardware compass functionality to your navigation software, while additionally configuring gpsmoddriver to leave gps data untouched so it won't make the erratic position and speed worse. For more info or help, please visit the gpsmoddriver thread: http://forum.xda-developers.com/showthread.php?t=571266
EDIT: Of course the HD2 has a new snapdragon chip which has built-in GPS just like many previous generations of phones. Most likely qualcomm changed the way gps works in their new line of Snapdragon processors...
The movement of vehicles around you or even the movement of the sun's rays on buildings nearby can distort GPS signals. The GPS navigator software tries to rationalize this distortion and that usually appears as a movement when you are still. On the other hand, if you drive into a tunnel using TomTom and some other software, you will often see yourself driving straight on in the tunnel well after the GPS is receiving no more satellite signals.
In top-of-the-line built-in navigation systems, the GPS data is supplemented by inertial guidance. (Someone could create a similar supplement for the HD2 The supplementary information allows the system to reconcile the GPS information with information on your car's actual movement.
But for us mere mortals, we just have to live with it.
Well... this particular gps chip is quite useless, then. if my navigation program has to recalculate the route each time I stop at traffic light, then it seems that I either have to purchase a usb-based gps to pair with the HD2, or replace this device. I counted on it to perform well.
Fatherboard said:
Well... this particular gps chip is quite useless, then. if my navigation program has to recalculate the route each time I stop at traffic light, then it seems that I either have to purchase a usb-based gps to pair with the HD2, or replace this device. I counted on it to perform well.
Click to expand...
Click to collapse
Complain to HTC, perhaps if they get enough complains they will come out with a hotfix or a rom upgrade that fixes it. Nobody said that the hardware is not that good (though it's possible), but it could also very well be a bad implementation by HTC!!
Already did.
They have obviously denied my complaints.
thanks again, anyway.
I noticed this behaviour yesterday night, at about 10pm. I was playing with NoniGPSplot, and while I was completely still (and freezing me arse outside believe me), it was tracking a movement back and fro and all around in small step, keeping track of me traveling some meters still while I was standing in the same point.
It was night and I was in my big yard, so no sunrays nor moving vehicles around nor buildings over my head.
I think this behaviour is very well hidden in tomtom since it automatically puts you on a road, and "smoothens" the gps data by making you follow that road no matter what, but a "realtime" software like nonigps tracks that all so well. Gonna notify htc about it now.
Guys, let's not go overboard on this. Non-military GPS is only claimed accurate to around 20 metres, regardless of the quality of the receiver. It's the US Defense Department messing with your HD2, not HTC.
Stephen Selby said:
Guys, let's not go overboard on this. Non-military GPS is only claimed accurate to around 20 metres, regardless of the quality of the receiver. It's the US Defense Department messing with your HD2, not HTC.
Click to expand...
Click to collapse
Yes, absolutely, I've noticed the same behaviour with all three of the BlueTooth GPS I used in the past. So, I would not be too quick to blame HTC for this.
my touch cruise's gps receiver worked with static navigation enabled to avoid this false movement. maybe this is just a usual behaviour?
Agree to that.
But regardless of the fact that the thing is not a military GPS system, It should do it's work correctly as for me the GPS is almost useless when driving slow or within a city. My 2nd phone (HTC DIAMOND) and 3 personal navigation devices are mounted in my car to compare and all work fine when the HD2 isn’t .
The GPS looses all the time the fix to the satellites and then quickly gets the fix back. when using a GPS monitor you can see that the satellites constantly moving really rapidly. (moving --> getting fix and loosing it again)
This is for 4 other reference devices which are running simultaneously not the case so it seems really an issue with the GPS device.
I tested this with different ROMs (1.44 Vodafone, 0.6 dutty WM 6.5.5, 1.66 stock and another one I cannot recall the producer anymore.)
This post is intended for troubleshooting and finding solution to the GPS on Galaxy S ONLY
For arguing, dissing, and the sort, please go in this thread:
http://forum.xda-developers.com/showthread.php?t=722476
Post here your findings, your solutions and your attempt at finding a better fix for the GPS.
If you happend to try something and it doesn't work, please state it also
And keep away from none relevant facts
Here's my finding so far:
The way the device is put (in a pocket or in a car) seems to greatly influence the signal and the streight of it. The antenna is (apparently) situated in the upper left part of the backplate, just outward by the Sim card. if the signal is obstucted or not facing the right spot, it might get a hard time getting a fix.
Someone might confirm this and I will try to record a couple of track while the device is place differently in my pocket to confirm it has an effect.
I'm using it for:
Mostly keeping track of my working with Sporty Pal. As for now, I get an error rate of under 3%, wich is acceptable as far as I go but a lower rate would certainly be taken
As for navigations and Trapster, it's still pretty "on the spot", I'm drinving a 1995 Acura Integra, so I don't know if the insulation of the vehicule could affect the signal and the device is always on a spot where it "sees" the sky.
Settings used
*#*#1472365#*#*
Session Type: Tracking
Test Mode: S/W Test
Operation Mode: Standalone
Start Mode: Hot Start
GPS Plus: ON
Dynamic Accuracy: ON (Please note, putting it to "off" will make the GPS lose signal way too often...
Accuracy: 20
Use SkyHook: OFF
Use PC Tool: OFF
Location Settings
Use Wireless Network: OFF
Use GPS Satellites: ON
Phone Info
FirmWare version:2.1 update1
Baseband:I9000UGJH2
Build Number: Eclair.UGJH2
LagFix used: None
Rooted using: None
Uptime about 16h
Known Workaround
1-TrackerBooster (available on the market)
This is a booster for the GPS, if you have issue where the position goes all around randomly, try installing and running this apps before running your GPS application. It was tested with SportyPal and gave amazing result.
2-BlueTooth GPS, some users have tested this solution here
http://forum.xda-developers.com/showthread.php?t=818688
you can most likely find one under 30$ and it should resolve the issue.
t1mman said:
Settings used:
#*#*1472365#*#*
Click to expand...
Click to collapse
*#*#1472365#*#*
should work better. (Does not work on Froyo JPM).
well lets start with listing the known solutions
like for example using the external GPS receivers via Bluetooth
there are several tested and working Bluetooth GPS apps by our members in the Galaxy S I9000 Themes and Apps section of the forum
Thanks, corrected!
I did start a thread posting 2 videos with "solutions" where users can actually see those "gps solutions" in action eliminating any kind of speculation (seeing is believing), but the thread was removed with no warning or explanation...
Anyway here are the videos:
http://www.youtube.com/watch?v=BM2gm5DAOjM
http://www.youtube.com/watch?v=p6QnNMxuCig&feature=related
In both videos, sgs's gps performance is flawless with or WITHOUT any assist (2nd video)like agps or aid of from an external bluetooth gps receiver (like in the first video).
In the meantime I already did 5 more driving tests, always running Motonav and so far no need for using my external bluetooth gps device.
The firmware is JPH, not customized and no lag-fix of any kind (not needed)
« »
Right, I dont want to start an argument and the video's above are very usefull.
But I think it's possible that the navigation software you are using is optimised and more than likely programmed to keep you on the road, rather than drifting all over the place.
I noticed this while in the car earlier. When using "google maps" my position was often miles out and all over, however when using the "google navigation" it kept me on the road and appeared to track my location really well.
So from a navigation by road point of view I don't have a problem.
So i thought a compare of SNR levels compared to a differant phone might help, so i took a photo of my sgs running GPS Test, next to a Orange Sanfrancisco/ZTE Blade. Both are running froyo, both had gps and a-gps turned on. Both were next to eachother, both were left to settle for five minutes after the apps were started. Both were connected to exactly the same wifi connection. Finally the ZTE was connected to 02 network, and the sgs is on orange.
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From what you can see in the photo's the levels are pretty similar. Maybe with the sgs gaining a higher level on average compared over all satelittes it found.
Now with both devices sat next to eachother this is fine, however on moving around the sgs kept loosing its lock on the sattelites and stopped using them, however the blade kept its lock better. The blade seemed to keep its lock even with the SNR of some satelittes getting very low, however the sgs lost its lock at a far greater snr level.
Now I don't know a great deal about gps, but it seemed to me like the sgs gave up its lock far easier than the blade. Maybe this is what is causing our problems, maybe once it has given up this lock, the sattelite information is decreased causing a less accurate location.
Now I don't know how this could be rectified, but I imagine it is either driver related, or maybe some code in the actual gps chip itself. But im not 100% sure. It would be great if someone more knowledgable than me could give us their two pence.
betoNL: Thanks for the TrackerBooster apps, I've done a run this evening with it and it's trully amazing!! With it, I don't see any "jumping around" issue at all. If anyone has any issues where the position goes "randomly", they should try TrackerBooster.
SkinBobUk: Thanks for the sharing, I'll try GPS test and post image with and without TrackerBooster to compare
personally iv used the gps quite a lot to navigate around the U.A.E and most of it was using the trapster program to keep an eye on radars/speed traps while driving.
testing the gps is totally random, the results are never improving, simply random.
sometimes id get a fix in seconds and other times it wouldn't (guess its an SGS thing), playing around the settings i found the best combination to be...
Session Type: Tracking
Test Mode: S/W Test
Operation Mode: MS Based
Start Mode: Hot Start
GPS Plus: ON
Dynamic Accuracy: ON
Accuracy: 500
Use SkyHook: ON
Use PC Tool: OFF
tho accuracy is high at 500 the test showed better lock on gps and a max of 20m error, with accuracy i found out that the smaller the number , the harder it is for gps to get/maintain a lock ( even with high SnR numbers between 25-40 maintaining a lock was hard, the SGS was jumping around which gps to lock on ) and with a high number it would maintain the lock for a longer period of time. Highest i found was 500 and anything beyond that wont even activate the gps when running the get position test.
last weekend iv been on a fishing trip and needed the gps help , it was working amazingly accurate up to 5m error thruout the trip but every 5 minutes or so it would hang/freeze and the solution was to restart the program which was fine by me.
Conclution is that GPS is simply unreliable being in its Random State
(when under a lot of testing the gps would freeze/hang and a phone restart is needed to get it back up {switching gps off and back on doesn't help}) , i found a small app in the market called GPS optimisation by octy which should optimise signal reception but for me it doesn't but rather fixes the gps and gets it back from its frozen/hung state - time it takes to restart the phone = more than a min but this app does it in seconds
hope this accuracy options helps you people out in getting better/longer locks on gps
I also use tracker booster with sportypal combined, it provide great accuracy
SkinBobUk said:
Now I don't know a great deal about gps, but it seemed to me like the sgs gave up its lock far easier than the blade. Maybe this is what is causing our problems, maybe once it has given up this lock, the sattelite information is decreased causing a less accurate location.
Now I don't know how this could be rectified, but I imagine it is either driver related, or maybe some code in the actual gps chip itself. But im not 100% sure. It would be great if someone more knowledgable than me could give us their two pence.
Click to expand...
Click to collapse
got the same feeling/issues/feedback when i tested the gps. trackerbooster and equivalent apps didn't really help me with the "lost lock too easily" issue
when its locked it seems to work fine (accuracy wise), but it keep losing the lock of all sats at once every now and then
On my SGS I have found that if I hold it with the screen vertical or tilted back slightly I get significantly higher signal than if it is horizontal. Also portrait is better than landscape by 2-3 dB.
Please write your firmware / Rom info and if it's stock or with Root/Lagfix
Currently, the only conclusion I can make is this combination is running flawlessly:
Accuracy on 20
Rom on JH2 (Stock for BellCanada)
TrackerBooster installed/enabled
NO lagfix
NO rooting
Latest run with this combination is right on the spot so far as jogging, I can clearly see where I cross the street or when I ran into a parking lot.
Imho, there are no special fixes or special settings to improve sgs's gps performance, just some "assist" or a-gps if you will.
There are all kind of a-gps possibilities besides the "standard" one that uses cellular towers wich in many situations can be unreliable.
Other types of "assist" are implemented by using the right software to simply download "fresh ephemeris data and injecting it to accelerate the first lock during a cold start* .
The big issue (again, in my opinion) is WHY the majority of the smartphones nowadays (and with that I mean NOT ONLY the sgs), are equiped wich gps chipsets that will require 'ASSISTING" ??
A couple of years ago, experts of the GPSPassion forum performed a comparison test between devices equiped with a sirfstarIII chipset and others with a-gps and the conclusion
was as I quote:
CONCLUSION
While the Qualcomm gpsONE chipset of the HTC P3600 performs better than on the Siemens SXG75 Linux Smartphone where it could take 10+ minutes to get a fix, it remains much less effective than the SiRFstarIII chipset used on most current GPS PDAPhones . This comparison also shows the impact of GPS Assistance (A-GPS) to get a fix and reduce the time to guidance. Even the "offline A-GPS" of the Mio A701 helps significantly, while the "Full A-GPS"(SUPL) of the Orange SPV M650 will bring extra speed and more so as the conditions deteriorate.
Overall, the GPS performance of the SiRFstarIII PDAPhones is excellent and does not pale in comparison with the performance of dedicated GPS systems like the TomTom AIOs as seen in this comparison done in the same area. Let's hope the upcoming GPS PDAPhones like the HTC X7500, the Eten X800, the Mio A501, etc...will maintain these high standards.
Click to expand...
Click to collapse
(here is the whole article: http://www.gpspassion.com/fr/articles.asp?id=175&page=6)
Well, their hope was is vain, cause even the very expensive so called high-end smartphones,
just stoped using sirfstar III chipsets or equivalent and using a-gps dependable ones,forcing users to find, configure or re-invent A-GPS solutions!
The good news (at least for me) is that the gps chipset of the sgs is LESS A-gps dependable than many other smartphones I tested, and even if it wasnt, I can always rely on the aid of my external bluetooth gps receiver(equiped with a sirfstarIII chipset), since programs like "bluetooth gps mouse" and "gps provider" work like a charm on the Android OS (see my first video: http://forum.xda-developers.com/showpost.php?p=8876869&postcount=5).
Another issue is that Google maps could be unreliable for car navigation and of course unreliable for testing as well: http://forum.samdroid.net/f9/maps-navigation-bug-missing-value-gps-accuracy-1247/
Cheers
* - http://books.google.nl/books?id=2Cx...=cold start and hot start definitions&f=false
In the images earlier in the thread where someone posted two pics, one of the SGS and a matched one with another phone, the SGS seemed to be consistently 3 to 4 lower on the same satellite at the same time. That would likely be a hardware (antenna) issue, and could it be that is the problem with fluctuating results, that the reception is just too flaky?
To me, that is an eye opener. Id like to know if it would be likely for the software to cause a reported different in signal strength. You would think that the reported signal strength would be unchanged from the chip, through the driver to the reporting software, no?
SkinBobUk said:
Right, I dont want to start an argument and the video's above are very usefull.
But I think it's possible that the navigation software you are using is optimised and more than likely programmed to keep you on the road, rather than drifting all over the place.
I noticed this while in the car earlier. When using "google maps" my position was often miles out and all over, however when using the "google navigation" it kept me on the road and appeared to track my location really well.
So from a navigation by road point of view I don't have a problem.
So i thought a compare of SNR levels compared to a differant phone might help, so i took a photo of my sgs running GPS Test, next to a Orange Sanfrancisco/ZTE Blade. Both are running froyo, both had gps and a-gps turned on. Both were next to eachother, both were left to settle for five minutes after the apps were started. Both were connected to exactly the same wifi connection. Finally the ZTE was connected to 02 network, and the sgs is on orange.
From what you can see in the photo's the levels are pretty similar. Maybe with the sgs gaining a higher level on average compared over all satelittes it found.
Now with both devices sat next to eachother this is fine, however on moving around the sgs kept loosing its lock on the sattelites and stopped using them, however the blade kept its lock better. The blade seemed to keep its lock even with the SNR of some satelittes getting very low, however the sgs lost its lock at a far greater snr level.
Now I don't know a great deal about gps, but it seemed to me like the sgs gave up its lock far easier than the blade. Maybe this is what is causing our problems, maybe once it has given up this lock, the sattelite information is decreased causing a less accurate location.
Now I don't know how this could be rectified, but I imagine it is either driver related, or maybe some code in the actual gps chip itself. But im not 100% sure. It would be great if someone more knowledgable than me could give us their two pence.
Click to expand...
Click to collapse
Thank's for the input, but in wich conditions and where those pictures were taken? Are they taken with a camera or are they screenshots?
What I can say, eventhough I find OFFLINE software car navigation more reliable (and I always use up-to-date maps) they are not "optimized" to "keep me on the road" as you speculated, is more likely that the full A-gps (SUPL) on the Orange Sanfrancisco/ZTE Blade is better optimized than sgs's but then again that's speculation.
This discussion can go both ways:
A) The complicated way, mostly based on speculation, for instance: saying that Samsung or Google cannot handle A-gps protocols, I mean wich SUPL configurations to use, in wich regions, by wich carriers, with wich software and so on....
And: Nokia wants you to use the server "nokia.supl.com" on their phones and Google wants you to use "supl.google.com" on their phones, but how the different carriers, in different regions and the various software are dealing with those configurations? And again how to deal with full a-gps? And why do we have to( see my last post)?
B) The easy way: Just get a external bluetooth gps receiver (with a sifstarIII chipset or better) connect any gps software using "gps bluetooth mouse" or "gps provider" apps to it and get over with it !
I rest my case
P.s.- On my last 6 trips didnt even have to use the external gps, just the internal one...it is doing just fine;
i must have a specially blessed sgs or Holland is just a better place for gps navigation
« »
betoNL said:
What I can say, eventhough I find OFFLINE software car navigation more reliable (and I always use up-to-date maps) they are not "optimized" to "keep me on the road" as you speculated, is more likely that the full A-gps (SUPL) on the Orange Sanfrancisco/ZTE Blade is better optimized than sgs's but then again that's speculation.
Click to expand...
Click to collapse
A-GPS is only necessary for the initial lock and yes, Navigon, iGo et al are optimized to keep the position on the road.
Oletros said:
A-GPS is only necessary for the initial lock and yes, Navigon, iGo et al are optimized to keep the position on the road.
Click to expand...
Click to collapse
A simple test is to drive down the road using google maps, then drive back using google navigation. The differance couldn;t be more clear.
They have to be optimised to keep people on the road, if not then there is a problem with google maps, and i doubt that!
SkinBobUk said:
A simple test is to drive down the road using google maps, then drive back using google navigation. The differance couldn;t be more clear.
They have to be optimised to keep people on the road, if not then there is a problem with google maps, and i doubt that!
Click to expand...
Click to collapse
Actually, Google maps isn't perfect (if you check the satellite feeds, you'll notice the roads wont always align perfectly) , but anyway, you are correct. Car navigation apps do special work to allow large errors to be made by the GPS without freaking out. That wont work with normal tracks.
Testing consistancy
The problem here is that the testing must be consistent. What is needed is an application to:
1) Create tracks at the highest resolution possible
2) Record speed at many points
3) Maybe have OBD2 integration, so we can match REAL vehicle speed with the track
4) Record the satelites/snr values constantly on the track.
5) Have test scenarios, that takes into account the environment and speed. Because when walking at 1hz, updates of GPS are done every 2-3 meters, but at 100km/h, it's every 28m. We don't even have enough info to know how often updates are done, and some tracks are created by people who are in dense skyscraper ville. We simply can't compare the information at the moment
6) By comparing car tracks to google maps, you could even do some basic GPS benchmark type stuff!
Start with a proper testing procedure, create a means of gathering PROPER information, then we can finally start actually testing how reliable people's phones REALLY is! At the moment, we are simply comparing OPINIONS, because there aren't specific tests to follow. There is nothing scientific about this thread until a process to accurately compare results is created.
andrewluecke said:
Actually, Google maps isn't perfect (if you check the satellite feeds, you'll notice the roads wont always align perfectly) , but anyway, you are correct. Car navigation apps do special work to allow large errors to be made by the GPS without freaking out. That wont work with normal tracks.
Testing consistancy
The problem here is that the testing must be consistent. What is needed is an application to:
1) Create tracks at the highest resolution possible
2) Record speed at many points
3) Maybe have OBD2 integration, so we can match REAL vehicle speed with the track
4) Record the satelites/snr values constantly on the track.
5) Have test scenarios, that takes into account the environment and speed. Because when walking at 1hz, updates of GPS are done every 2-3 meters, but at 100km/h, it's every 28m. We don't even have enough info to know how often updates are done, and some tracks are created by people who are in dense skyscraper ville. We simply can't compare the information at the moment
6) By comparing car tracks to google maps, you could even do some basic GPS benchmark type stuff!
Start with a proper testing procedure, create a means of gathering PROPER information, then we can finally start actually testing how reliable people's phones REALLY is! At the moment, we are simply comparing OPINIONS, because there aren't specific tests to follow. There is nothing scientific about this thread until a process to accurately compare results is created.
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Click to collapse
You raise valid points, but it is unrealistic to expect this kind of controlled testing from an Internet forum.
What I can tell you from personal experience is this: when I run Nexus one with Google Map and SGS with Google Maps at the same time while driving from work to home (or vice versa) the SGS consistently loses lock for about 30% of the route. When I go off the motorway it consistently thinks I am still on the motorway for about 10-20 after I have left it and then needs to reroute. Both the Nexus and SGS are running Android 2.2 and the same version of Google Maps. Nexus One (and an iPhone 4 which I also have) have none of this problems.
The point I tried to make earlier in this thread, admittedly not in the most polite way, is that all the settings discussed here are for AGPS. They only affect the speed of initial lock, not the functioning of the GPS itself. That is why none of the so called "fixes" work for people with non or poor functioning GPS. All that Samsung has done in various ROMs is to tinker with AGPS and also smoothing and predicting of the path while driving; they have not been able to address the underlying issue, which is the inability of the GPS receiver to keep GPS lock.
This can easily be tested by using something like "GPS status" application: it is able to download new GPS assistance data and acquire lock quickly. But if you keep this application running while driving, you will see that the GPS lock is lost many times - at least that is my experience.
darkoroje said:
You raise valid points, but it is unrealistic to expect this kind of controlled testing from an Internet forum.
What I can tell you from personal experience is this: when I run Nexus one with Google Map and SGS with Google Maps at the same time while driving from work to home (or vice versa) the SGS consistently loses lock for about 30% of the route. When I go off the motorway it consistently thinks I am still on the motorway for about 10-20 after I have left it and then needs to reroute. Both the Nexus and SGS are running Android 2.2 and the same version of Google Maps. Nexus One (and an iPhone 4 which I also have) have none of this problems.
The point I tried to make earlier in this thread, admittedly not in the most polite way, is that all the settings discussed here are for AGPS. They only affect the speed of initial lock, not the functioning of the GPS itself. That is why none of the so called "fixes" work for people with non or poor functioning GPS. All that Samsung has done in various ROMs is to tinker with AGPS and also smoothing and predicting of the path while driving; they have not been able to address the underlying issue, which is the inability of the GPS receiver to keep GPS lock.
This can easily be tested by using something like "GPS status" application: it is able to download new GPS assistance data and acquire lock quickly. But if you keep this application running while driving, you will see that the GPS lock is lost many times - at least that is my experience.
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Click to collapse
When using TrackerBooster, not only the "first fix" is current, but all of them. I know that aGps just helps get it quicker, but how do you explain gettings track with 5% error rate to under 1% for the same track using the same software?
I don't know how this program works, but it does and, in the end, the goal is to use the GPS to what our needs are (mine is mostly to keep jogging tracks, with speed and accuracy as high as possible)
As I explained before, so far I can conclude that all my issues are fixed using trackerbooster. It seems like not all users have this kind of result and hardware (or built date) might affect some units, but many of us had good results with the addition of a GPS booster (of some sort).
The bizarre 'wandering' behaviour leads me to suspect the navigation engine. When using a standalone GPS test app the Satellite lock I see is fine and the SNR (assuming it is being reported honestly) is OK.
In addition, when I'm using an app like Open GPSTracker I get convincing and accurate updates at around 1Hz (which is what you would expect) with a good solid position fix to within an accuracy I am happy with (usually 5-10m).
There are two issues I see:
First is that the speed reported by GPS apps is Bunk, or laggy at best. I haven't looked at the NMEA logs from the built-in GPS - do they contain accurate speed information?
Second is the 'wandering GPS' issue, which results in the classic continuing-straight-on-when-you-just-turned issue most of us are seeing.
This second issue, combined with the way you can observe the GPS reported position in something like Google Navigation slowly converging with the location you know you are are leads me to strongly suspect that Samsung are using some sort of IN/GPS mixing and doing it very badly.
GPS simply gives a position in its pure form. There's no interpolation or guessing at 1Hz (if you have GPS that advertises itself as a higher refresh rate then it probably is. but I assume the embedded GPS chip isn't too fancy and updates at a standard 1Hz). Usually the receiver then calculates the speed using a simple time/distance calculation between two points. Heading is simple geometry. Based in this fact I can think of no other explanation for the drifting behaviour.
What I suspect:
For some reason Samsung is mixing magnetometer and/or accelerometer data with the GPS positions (regardless of whether you select the 'use sensor data' option in the location menu), probably to avoid having to do the speed/direction computations from the raw GPS data alone or because their driver isn't providing it in the NMEA line (I assume that at some point the GPS chip provides a NMEA formatted output to the OS, this is that way every other device works!). In theory this should work really well and cut processing overhead - if you've got a good accelerometer giving acceleration and a good magnetometer giving heading why bother to calculate it from GPS position fixes, you can simply bias towards sensors and use the GPS for occasional updates.
However, while the MEM devices in the SGS while good enough for apps like Layar and Google Sky simply aren't up to the job of providing navigational quality mixing. I believe Samsung are being too clever and should re-write their positional engine using GPS position data alone and calculating speed and heading from that. It works for almost every other GPS device on the market.
At some point Samsung have tried to compensate for poor GPS performance by feeding sensors into the mix at the system level without user control. (I suppose this MIGHT be Googles fault??) This is giving a short-term bias towards interpolated positions fed from heading and accelerometer date which is provided by inaccurate sensors corrupting the perfectly good GPS information.
As I say, I don't know how good my guesses above are, it's simply an educated guess based on observation and some knowledge of IN/GPS mixing filters.
What do you guys think?
that's pretty much what i think but i dont have anyway to prove it
Well, standing still with walking directions with google Navigation I can see the zooming in and out
Pretty good assumptions there, dangrayorg. You might be spot on.
Sounds plausible. Of course the fundamental problem is probably poor GPS receiver and now Samsung is trying to work around that unfortunately with not to good results.
Well here I am near the river Thames near where it becomes tidal - ergo, pretty close to sea level (actually about 30ft above). My new all dancing DHD' GPS system tells me I am 230ft in the air. I honestly do not think I am that high!
It seems to me the DHD contains a blast form HTC's past, the Touch Cruise also added 200ft to the GPS heights. Why have they implemented a GPS hardware issue they have known about for years...is the GPS system hardwired into the snapdragon chip? Is it the kind of thing a software update will eventually correct?
I use OS maps a lot for hiking and tracking, and while I know the height issue is not a big thing as I know the problem, my tracks will always be out by 200 ft vertically.
However, the compass works, unlike on my old HD2...but I really hate little faults like this, they gnaw on me...I really hope none of the GPS system implanted in the noses of bombs and missiles don't have this fault!!!
This may be the app you are using.
I use Compass from Catch.com and find it pretty good.
Also make sure you are receiving signal from at least four satellites to get accurate reading.
my bad
thanks for the advice - MM Tracker is clearly out buy 150-200 feet in altitude...I have the compass as well, it has accuracy +/- but I can't see where it has altitude.
Open Compass app.
Tap 'Menu' button, then Compass Type then GPS
On large Green Bar it reads Speed, Altitude and Accuracy.
Bottom green display shows how many satellites are in use.
thanks, I had not seen that feature, very nifty - when it has stopped raining I will go outside and full complement of satellites and check. Certainly held up against the window, the 200ft discrepancy does still seem to be there using the compass...I will check later – thanks for your thoughts on this.
nope there is a problem
according to the compass I am 316 foot in the air. I beleive where I am is about 25 foot above sealevel - looks to me that HTC has reimplented the same fault they has on the Touch Cruise. No biggy, but it is annoying, a little
If you look through this forum, a few other people seem to have a faulty gps .
My suggestion would be, get in touch with who supplied the phone for an replacement, as a wrong reading on GPS will affect footprints, locations, sat nav etc.
Maybe you do not use these programs much, but with the cost of the phone, everything on it should work, especially the hardware.
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.
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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..
Click to expand...
Click to collapse
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..
Click to expand...
Click to collapse
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..
Click to expand...
Click to collapse
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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Click to collapse
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!!
Click to expand...
Click to collapse
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
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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!!
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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.
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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)
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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.
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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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