Related
I bought the HTC Touch HD a few weeks ago and noticed that the accuracy is not just bad, but atrocious. It can't even locate me within a 300 meter radius. Is that normal? Does anyone else have this problem? I am using the latest Google Maps.
Thanks in advanced.
I would try a proper GPS program and see if it is the same, if so your HD is faulty.
No problem here. .Maybe silly question, but did you click on "Use GPS"?
--cheerios
skotler said:
I bought the HTC Touch HD a few weeks ago and noticed that the accuracy is not just bad, but atrocious. It can't even locate me within a 300 meter radius. Is that normal? Does anyone else have this problem? I am using the latest Google Maps.
Thanks in advanced.
Click to expand...
Click to collapse
Are you sure you have a satalite lock? Google maps also determines position from cell towers and gives an estimate to your location within approx 500M. Once gps is activated and satlites have been aquired, a more accurate position is displayed (and i get a blue triange above the location - i guess to indicate actual position).
The little blue trianlge shows the direction you're moving - so the GPS is pretty accurate! Sometimes it doesn't get a lock for a while (it'll say at the top-right when it has active satellites) - if not, then it just uses that cell tower triangulation thing which gets it within about 500m as mentioned above.
aabye said:
No problem here. .Maybe silly question, but did you click on "Use GPS"?
--cheerios
Click to expand...
Click to collapse
Ya, it is on.
It can get working when I'm on the move, but as soon as I am still, it screws up. For instance, I can be driving to work and it works fine as far as telling me where I am at the moment. As soon as I close it and reopen it at work, it tells me I am somewhere 300-500 meters from work.
I guess I don't understand how it can work so well on the move, but as soon as I need an accurate reading, it is way off. Does this happen to anyone else?
skotler said:
Ya, it is on.
It can get working when I'm on the move, but as soon as I am still, it screws up. For instance, I can be driving to work and it works fine as far as telling me where I am at the moment. As soon as I close it and reopen it at work, it tells me I am somewhere 300-500 meters from work.
I guess I don't understand how it can work so well on the move, but as soon as I need an accurate reading, it is way off. Does this happen to anyone else?
Click to expand...
Click to collapse
Once it's closed it loses the "Use GPS" setting and you have to turn that back on and wait for the Satellites to be located all over again.
Well i think there is a gps delay issue with the latest HTC phones as blackstone, Raphael and diamond and i believe there is a little on the x1. Well there will is always ways to tweak settings in the registry i guess. well you'll probably find something here at xda...
Ok, I see what you are saying...sa we speak, I am trying to get the location of where I am at on my phone. The status has been on "Seeking GPS satellites (0)" for about 3 minutes now. It just relocated my location nowhere near me.
Ok, I just got a message telling me that my "GPS receiver is having trouble tracking GPS satellites." It's a very clear night in southern California, no clouds, no trees, etc...If it is because I can't get a satellite, is there a way to configure it?
Can it be because I am inside my house? If so, that is absurd!
skotler said:
Ok, I see what you are saying...sa we speak, I am trying to get the location of where I am at on my phone. The status has been on "Seeking GPS satellites (0)" for about 3 minutes now. It just relocated my location nowhere near me.
Ok, I just got a message telling me that my "GPS receiver is having trouble tracking GPS satellites." It's a very clear night in southern California, no clouds, no trees, etc...If it is because I can't get a satellite, is there a way to configure it?
Can it be because I am inside my house? If so, that is absurd!
Click to expand...
Click to collapse
Well i suggest you to go out and test it.. well also i suggest you to always keep your quick gps application updated so you'll get a quick fix locked to sattelites.. my Raphael locks on around 20-30 seconds and sometimes even less....
no problem here!
i've tested head to head with my old Asus P535 SirfIII (wich is pretty good as gps) on a 300km trip and they react in the same way.
no lag, no errors.
i use iGO8!
Well i found this on youtube: omnia vs HD in gps...
i am aware of that greek clip
what can i say? they have their experience, i have mine.
from my experience i say the gps of hd is good enough, as long as i don't make maps and i don't need precision on cm level
GPS works great on HD. Tested with IGO8 and latest TomTom, as well as Google Maps - all have accuracy within 5m range, wich is more then enough for normal navigation use.
I also tested my HD along side with Garmin car navigation unit - they were literary synchronized to the very second, even the voice instructions came at the same time, it was actually very funny
If you're having problems, I suggest you look up here on the forum for HTC GPS tool.
Well just to say, I agree with you guys eventhough i have a Raphael.. well i guess the gps chipset are the same.. (correct me if im wrong though) .. well many people in the Raphael community is talking about 50 - 100 yards lag but i only experience 5m, the most ive experienced was 10m but that was just once..
GPS doesn't work inside. Not just on the Touch HD but on any GPS device.
At the most, my lag is a car's length. I think my Trinity was slightly more accurated but not by much.
As far as getting a lock from inside, I can occaisionally get a lock if I am sat by my West facing window, but otherwise not a chance!
Ok, I got it working! I guess it just takes a couple minutes without touching any keys to acquire the satellites.
So in conclusion, to impatient people like me, don't touch any keys for a good minute or two. Thanks, guys!
HandGrip said:
GPS doesn't work inside. Not just on the Touch HD but on any GPS device.
Click to expand...
Click to collapse
Mine does. Can take about a minute/minute and a half to lock to the satalites, usually finds about 9 of them, and from google maps when zoomed in to max you can see roughly where abouts in the house the handset is.
The cell tower lock is useless. I'm in the north west of england. The cell lock feature keeps telling me I'm in Russia!!
like all gps i have used, sometimes getting a fix is hard work, regardless of apparent sky conditions.... i guess thats what happens when technology (the gps sats) are made by the lowest bidder
if you have a "your postion within 300-500m" message displayed, then that is using the cell mast to get your position, you never see this message when using GPS
some progs and some roms prefer to have the gps ports mapped, i do it manually for all my gps progs using com4 and bit rate of 9600k... seems to offer best situation
afaik, no civilian GPS can assure an accuracy of greater then 15m, although some units some of the time seem to be more precise
i dont see lag, i see the limitations of GPS (outside of military application... but then again, we've seen how accurate smart bombs are not!!)
Hi,
i need a Tool to calculate the distance of two devices with an accuracy of about 1 meter by a distance of 0-3 meter.
GPS doesn't suite this needs, but i guess bluetooth signal-strength does.
I was looking up the android bluetooth api but can't find anything to read signal strength. Anyone any tips how to get on the strength of the bluetooth signal?
thanks, exec
Cool idea
That is a pretty cool idea. I'm not a developer but I like it.
Another way is to use sound along with a tcp/ip or bluetooth connection
1) keep track of each phone's clock (or difference between)
2) make the second phone chirp/beep and record
a)the time the second phone started the beep
b)the time the first phone heard the beep.
3) calculate the distance using the amount of time it took to hear the beep.
note: the speed of sound may differ slightly but should be within your accuracy range
see http://www.sengpielaudio.com/calculator-soundpath.htm for an example.
nice idea, i'll keep this in mind. But for the moment it doens't fit my needs, cause it can be a loud enviorment with a lot of phones where i have to find the nearest one
exec87 said:
nice idea, i'll keep this in mind. But for the moment it doens't fit my needs, cause it can be a loud enviorment with a lot of phones where i have to find the nearest one
Click to expand...
Click to collapse
A pure tone at an agreed upon frequency will be hard to miss. If you have the service installed on all the phones you can query each one in turn and then figure out which one is nearest.
do you know any example how to analyse the frequenze of the current recorded tone?
exec87 said:
do you know any example how to analyse the frequenze of the current recorded tone?
Click to expand...
Click to collapse
This looks promising
http://code.google.com/p/moonblink/wiki/Audalyzer
sry but if you want to measure distances of up to 3 metres with the help of sound speed, that wont work
sonic speed is 343m/s, that means it takes 0,002.9sec for one meter to pass.
or otherwise, it would pass the 3 meters in 0,008.7 sec for 3m
to compare it, a nexus one would do a clock cycle every 0,000.000.01 seconds, and in that time, the sound weave moves 0,000.000.343 metres.
So if you're optimistic and it takes "only" 100.000 to 500.000 cycles to sample the sound AND compare it to the clock, your diffrence of that two cases would be 3cm to 15cm, so you got a standard "uncorrectness" of about 12cm.
but thats if it takes 100.000 to 500.000 cyles, and it would be worse if it takes more time or if the clock is not 100% correct (this example is with a 100% exact clock)
if the clock is only correct for 1ms, you must add another 30cm of "uncorrectness"
arthofer said:
So if you're optimistic and it takes "only" 100.000 to 500.000 cycles to sample the sound AND compare it to the clock, your diffrence of that two cases would be 3cm to 15cm, so you got a standard "uncorrectness" of about 12cm.
but thats if it takes 100.000 to 500.000 cyles, and it would be worse if it takes more time or if the clock is not 100% correct (this example is with a 100% exact clock)
if the clock is only correct for 1ms, you must add another 30cm of "uncorrectness"
Click to expand...
Click to collapse
Dont think sampling and processing cpu-time matters so much as to make this method unusable.
a)The sample time does not matter. It will be:
system time when the recording started + time within the sample where the frequency is found (comparison is part of post-processing). The sample window can be fixed at 0.5 seconds (or less) as 343/2= 171.5m is huge.
The phone emitting the frequency can be triggered over wifi/radio and that will be very very quick (speed of light+message processing time)
b)the time taken for the comparison will not matter as its done after the event has occurred. (post-processing)
The 1ms clock problem can possibly be overcome by using System.nanoTime()
exec87 said:
Hi,
i need a Tool to calculate the distance of two devices with an accuracy of about 1 meter by a distance of 0-3 meter.
GPS doesn't suite this needs, but i guess bluetooth signal-strength does.
I was looking up the android bluetooth api but can't find anything to read signal strength. Anyone any tips how to get on the strength of the bluetooth signal?
thanks, exec
Click to expand...
Click to collapse
Maybe use a ruler?
Sorry that I can't stop myself doing this after reading your question
ok, to a more serious side, if bluetooth don't work, then maybe use wi-fi. don't know if they have the api for wi-fi to measure signal strength neither.
What if you had one phone act as a Wi-fi hot spot, then the other connect to it. Then someone write an app that will use GPS to determine the distance between the two. IDK, just a shot in the dark. I really dont have a lot of knowledge about that stuff.
You could use a PRF (pulse repitition frequency) but I have no idea what these would be for bluetooth or even the radios. Honestly I think using the GPS coordinates and distance equation would be the easiest.
Unfortunately our consumer gps's rarely go down to 1m, and that the max... And it will likely not work indoors
britoso is right... i'll keep the hint with wlan strength in mind, but atm i'm working at the audio idea... it's a little bit hard, and first tests show that an accuracy of 1-2 meters is possible... i'll reply if i'm done.
however i'm thankful for EVERY input
edit: i think i will give up... the delay of analyzing the sound is between 150ms and 250ms... and i can't see in code where this 100ms difference come from... i think i need a kind of realtime system to build this...
exec87 said:
britoso is right... i'll keep the hint with wlan strength in mind, but atm i'm working at the audio idea... it's a little bit hard, and first tests show that an accuracy of 1-2 meters is possible... i'll reply if i'm done.
Click to expand...
Click to collapse
however i'm thankful for EVERY input
exec87 said:
edit: i think i will give up... the delay of analyzing the sound is between 150ms and 250ms... and i can't see in code where this 100ms difference come from... i think i need a kind of realtime system to build this...
Click to expand...
Click to collapse
If you can PM me the code I can take a look.
I didn't want to start coding this because
a) I only have one phone
b) havent used the bluetooth API.
I'm comfortable using tcp/ip though
i don't know if this is impossible.. but i think its worth the try.. i'm horrible at development nor i have taken any advanced math courses... so heres the concept:
how about getting two people hold a phone facing each other.... they both have to hold the phone upright and straight...(using Spirit Leveler)
with one of the phones... the app takes a picture of the other phone... and asks you to point out the phone's height in the picture...
and given the real height of the phone (this should be a dropdown box for known phone types.. and custom if you want to use a credit card... or anything else u find) it should tell you the height..
possible?
oh and one more thing.. u can have the phone's screen facing the camera with white background and black DOT... if that helps to do live tracking of the phone's size...??
britoso said:
If you can PM me the code I can take a look.
I didn't want to start coding this because
a) I only have one phone
b) havent used the bluetooth API.
I'm comfortable using tcp/ip though
Click to expand...
Click to collapse
This is what i first thought of when i saw this thread. Why not establish an ad-hoc network and send over a series of pings, each one send over one packet of info from phone A to phone B. have phone B process the information and show its good then send it back to A and have it verify it also. Then based of this data(and experiments to see hwo long it takes to process the information. you the time from a-b-a to calculate the distance.
This is all hoping that the speed of travel of the packet is not to fast to calculate the distance lol.
Any results?
This is the exact answer I'm looking for, which method produce better accuracy, is it the sound (measuring time difference) or the signal strength test (measuring the RSSI)
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.
Click to expand...
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.
Click to expand...
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).
tl;dr version:
1) Switch data on. (not wifi, data. Has to be data.)
2) ? ? ?
3) PROFIT.
looong version:
I kept wondering why GPS would find many satellites, but would often not lock onto them, or would take a very very long time to lock (around 10 mins or so). Then I noticed that it works fine when data is switched on, and locks within a few seconds.
You should get a lock as soon as you're "fully connected to Google", and "go green" for people who have that enabled.
This is the a part in agps at work Assisted GPS. Click to check the wikipedia article on it.
Accuracy is still a problem, and testing with a friend's DHD, I was getting around 10-6m accuracy, and he generally got 2-4m.
And Samsung's GPS software sucks too. glgps daemon's internal smoothing algorithms are still there, and it's annoying.
~Rawat
Rawat said:
tl;dr version:
1) Switch data on. (not wifi, data. Has to be data.)
2) ? ? ?
3) PROFIT.
looong version:
I kept wondering why GPS would find many satellites, but would often not lock onto them, or would take a very very long time to lock (around 10 mins or so). Then I noticed that it works fine when data is switched on, and locks within a few seconds.
You should get a lock as soon as you're "fully connected to Google", and "go green" for people who have that enabled.
This is the a part in agps at work Assisted GPS. Click to check the wikipedia article on it.
Accuracy is still a problem, and testing with a friend's DHD, I was getting around 10-6m accuracy, and he generally got 2-4m.
And Samsung's GPS software sucks too. glgps daemon's internal smoothing algorithms are still there, and it's annoying.
~Rawat
Click to expand...
Click to collapse
If you go to the Location Settings, and Untick "Use wireless networks" and Untick "Use sensor aiding"
You will get a GPS lock even without DATA. BUT, it will take longer.
Not on my Sgs... with those unchecked and cold start I still get a lock within 10 secs. So something funky in Sgs ii his stuff.
Sent from my GT-I9000 using Tapatalk
So does the SGS2 have similar GPS issues to the original? I'm currently on the Samsung Captivate and have a preorder in for the SGS2. One of the big reasons I'm looking to spend 800 bucks to upgrade is to be done with GPS issues on my phone. If this won't be the case maybe I need to give up on Samsung and wait for HTC to release a dual core beast on AT&T bands...
TheSopranos16 said:
So does the SGS2 have similar GPS issues to the original?
Click to expand...
Click to collapse
I have no experience with the earlier Galaxy's but I can compare it to a G2 and G2X. There are three GPS settings: Use wireless networks (cell and Wi-Fi), use GPS satellites, and use sensor aiding. With "use wireless networks" checked and Wi-Fi off it just locked and loaded for me in Google maps in less than a minute from a poor location. With only "GPS satellites" checked it took closer to 2 minutes. It was accurate down to my street address both times. In order of speed from "activation" to "usable" I'd rank the phones in this order: G2, G2X, SGS2. While a bit slower to lock than the others it's fine (accuracy, holding lock) for me. Someone from the EU uses Tracks to measure his walks and was complaining about the street-level accuracy. You might want to check out that thread.
I personally never ever would use the WiFi- and Sensor functions as GPS replacement.
Why?
1) It is responsible for the collection of the location data and sending it to Google.
2) It costs battery power.
3) Why using when the GPS fixes fast enough? What's the problem with waiting for 10 seconds for a fix?
The fix can be made quicker by DL'ing the "GPS Status & Toolbox" app and using it for DL'ing the actual valid GPS sat vectors. That helps the GPS to fix quicker.
Cheers
Zap
Mine is very slow to lock, despite having plenty of sats visible with good strength.
This is compared to 4 different ZTE Blades that showed me how quick locking can be, even indoors.
There is a tool on the market called GPS Aids which was developed for the Galaxy and I'm keen to discover whether this can improve the SGS2.
However, it requires rooting and I'm reluctant to do so as I may decide to replace my phone if it can't be sorted.
Is anyone who is rooted willing to carry out some tests using that or other tools to see whether performance can be improved? I'd really appreciate it.
TheSopranos16 said:
So does the SGS2 have similar GPS issues to the original? I'm currently on the Samsung Captivate and have a preorder in for the SGS2. One of the big reasons I'm looking to spend 800 bucks to upgrade is to be done with GPS issues on my phone. If this won't be the case maybe I need to give up on Samsung and wait for HTC to release a dual core beast on AT&T bands...
Click to expand...
Click to collapse
I've used GPS a few times, and it works fine. Accuracy is a bit weak sometimes (compared to other phones) but it's fine for navigation, and even using mytracks or similar. (although when it goes off on mytracks it'll take a while to get back due to Samsung's inane smoothing)
prusling said:
Mine is very slow to lock, despite having plenty of sats visible with good strength.
This is compared to 4 different ZTE Blades that showed me how quick locking can be, even indoors.
Click to expand...
Click to collapse
Not sure why it's like this, but you have to have data enabled for it to get a quick lock on SGS II, otherwise it'll take a few mins.
I'll give GPS AIDS a test later on. Maybe.
My gps has been spot on from day one-locks in seconds and google maps always puts me in right room of house or parking space etc. The blue accuacy circle is bigger on sgs2 then sgs1 but the reall accuacy is tons better.
--deleted--
Hi everybody.. i have downloaded an app called GPS aids v 2.0 and this has helped me in getting a lock in under 15 secs after which i fire up Sygic and it hardly takes 10 secs to lock my position.
Do put in a thanks if it helps somebody
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..
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..
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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)
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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.
---------- 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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