Is it just my phone or does GPS really suck?

Discussion in 'iPhone Tips, Help and Troubleshooting' started by andrewwg94, Aug 28, 2009.

  1. andrewwg94 macrumors member

    Aug 5, 2009
    it never constantly updates. on the maps app, it never keeps the dot updated. it just "jumps" from place to place. usually that's not a problem, but most of the time i'm on a curved road, the dot would keep going off the map. i bought the tomtom app expecting it to actually work like real gps. Tomtom as an app is really amazing. When I was on I-95 ( a straight highway), tomtom was very accurate. it calculated the speed precisely and updated well. when i went on another interstate that's shaped like a circle, it simply couldn't realize i was still on the highway. every second it would go off the road, or onto an exit. i'm not trying to criticize the iphone, just wondering if this is normal or should i get it replaced.
  2. Michael CM1 macrumors 603

    Feb 4, 2008
    How is your signal at these times? I'm 99 percent sure that the Maps app is dependent on the Internet to update the maps since it's not stored in flash memory like a normal GPS. Therefore, your dot may jump in such a case. That happened to me as I was down near Panama City this week in multiple dead zones. But when I had at least a 2-bar signal, the dot went right along with me.
  3. andrewwg94 thread starter macrumors member

    Aug 5, 2009
    well the tomtom app has 1.2 GB of of maps in it, so i doubt that's a problem...
  4. Templex macrumors regular

    Jul 12, 2007
    Los Angeles, CA
    I believe I have the same problem as you. The GPS is pretty much useless for turn by turn, it's hardly accurate and takes a while to update. A lot of people seem to have issues with the iPhone's GPS-- I hope that this is a software and not a hardware related problem.
  5. Michael CM1 macrumors 603

    Feb 4, 2008
    I thought you were mostly referring to Maps. If TomTom is doing that, maybe you're losing your signal. I haven't tried to constantly keep my GPS on, so I'm betting I'm a horrible adviser on this.
  6. Pjoseph macrumors member

    Mar 9, 2009
    I have the 3G and my works great. I can basically watch the dot and not read street signs to get around.
  7. jav6454 macrumors P6


    Nov 14, 2007
    1 Geostationary Tower Plaza
    GPS also depends on how many satellites you pull info from. If you have 3 satellites then you will have a fairly accurate positioning (albeit it could be inaccurate at times if you are moving a lot; eg, a car). To get the best positioning it takes 4+ satellites to pin point you.
  8. iHateMacs macrumors 6502a


    Aug 13, 2008
    Coventry, UK
    Mine works great. I've used it in the car a few times with copilot and it's never missed a turn. The turn warnings always come at the same distance from the turn.

    In my case I had it on the dashboard with the iPhone screen facing upwards. I couldn't see the screen from the driving position, but it had a good view of the sky.

    I think a lot of people these days expect too mush of GPS. When GPS was new I always believed(was told and believed it) the receiver needed a unobstructed view of the sky. Now people moan that the reception is not very good indoors, or when holding the phone low down. These GPS signals are so weak what do you expect. Give the receiver a fair go and it'll work.
  9. alent1234 macrumors 603

    Jun 19, 2009
    Maybe dod changed it but I think all civilian gps units are only accurate to a few hundred feet. The military ones need a special encryption key and are accurate to a few feet
  10. Pull Up Now! macrumors newbie

    Mar 8, 2010
    Poor iphone gps reception

    I can't believe the number of folks on here who add useless information to this post. Yes, GPS signals are weak, we all know that. And no, it's not the cell network reception not updating the maps. Apple, KNOWING that GPS signals are weak should have provided an external gps antenna jack. They could have sold more accessories that way. But they didn't. This has little to do with software either. I notice a lot of these posts are combined with the Tom Tom ap, but I have problems just using Google Maps on the phone (which uses the gps). By the way, Google Maps is bad enough, sometimes not accepting an address, or converting it to a wrong location. Mapquest is much better in this regard.

    OK, so I had a Chevy Suburban with relatively good GPS reception and then got a new Suburban that DIDN'T have a sunroof. horrible reception . I have to hold the phone out the window when travelling north. In a Mn winter, that can be cold.

    Anyone have a solution to this GPS reception issue?
  11. -aggie- macrumors P6


    Jun 19, 2009
    Where bunnies are welcome.
    Mine works inside a bus, so IDK what the issue is. Can you take it back to Apple?
  12. Ward macrumors newbie


    Jul 5, 2009
    Piloting a miniature submarine in your brain.
    The problem is both hardware and software.

    The iPhone's GPS is utter crap. It tricks you into thinking it's on par with dedicated units by combining the tower triangulation (a misnomer, but that's another thread), wifi MAC address lookup and GPS. It lacks the sensitivity that many GPS units have, meaning that good fixes take longer and are more likely to be lost once achieved.

    The software (OS3.0) hides most of the raw processing, so no app can actually access the GPS in the same way as it is on other devices, ie, using NMEA standard. This means that apps are restricted to the limited data the API makes available and can only update at the sampling rate the same API allows - which is p*ss poor for vehicles, fine for pedestrians.

    TL;DR: The iPhone's GPS is for pedestrians and other location services. Driving use will dissappoint most people.
  13. Pull Up Now! macrumors newbie

    Mar 8, 2010
    #13 inside a bus

    Aggie, there could be several reasons why your iphone gps works inside a bus vs mine not working well in a Suburban. More windows? Sitting lower in relationship to the windows giving a slightly better angle to the sky? Or even more disturbing, are the hidden changes/improvements iphone made to the GPS without letting people know? THAT would be huge.

    Ward, thanks for the information. What is API? From your context, I'd imagine that is the underlying firmware that is not available from the SDK? As for the ibone GPS being only good for pedestrians...yes I agree at this point based on functionality. HOWEVER, is that Apple's intent? AT&T charges $9.95 per month for their turn-by-turn service. And there's Tom Tom. Both of these are clearly for driving. I can just imagine how ripped off those users feel. Especially AT&T.

    Someone should open up the iphone and do a hack for an external antenna jack. Maybe I'll do it. I've had two apart and replaced broken screens sucessfully.
  14. chris975d macrumors 68000


    Sep 21, 2008
    Georgia, USA
    I've noticed that the GPS seems to vary greatly between individual handsets. On my 3G, the GPS worked very accurately, and could lock on just about anywhere. With my first 3GS, the GPS was utter crap. Navigon would take up to 20 minutes to lock on, and quite often wouldn't lock on at all. After replacing that 3GS with another (different warranty issue), the GPS is back to being very accurate, and can even lock on inside my apartment, which is brick, with very few windows. In satellite view, the dot will actually be on top of the corner of the building I live in, whereas the previous 3GS would place the dot several streets over (I'm assuming that was cell tower triangulation, as it probably never locked on to satellite signals). So in my experience, the GPS modules inside these phones varies. I've seen this with friends units (both 3G and 3GS's) as well.
  15. iceterminal macrumors 68000


    May 25, 2008
    Dallas Tx.
    I've had a couple of iPhones and they've both worked fine on GPS. Inside and outside of a car. On EDGE and 3G. So I'm not sure what the issue might be.
    Maybe I'm not expecting perfection or exact second by second updates. I realize that it will be behind or lag a few seconds.
    At most, my update might be about 20 seconds behind, at most. Usually it lags about 5-10 seconds. Thats expected for a phone.

    I pretty much know where north is no matter which way I'm facing.
    Turn by turn, same thing. I guess I look at the phone as a phone, not as a GPS receiver.
    My father was looking for the iPhone to do that but he wanted to use it mainly for GPS for golf. I told him to get a GPS receiver.
  16. Ward macrumors newbie


    Jul 5, 2009
    Piloting a miniature submarine in your brain.
    The API is the Application Programming Interface, it's a layer of code which provides apps with the means to use the underlying hardware without actually having to know how the hardware works precisely. The app simply makes a call to the right API function and lets it take it from there.

    The API in the iPhone allows apps to access location services but the application itself is unaware of how the API uses the GPS, just the coordinates that it receives back. Information such as the number of satellites, the quality of each, etc. is not provided.

    I'm not sure how the iPhone API works precisely, (I'm a programmer, but not for Mac/iPhones), but it appears that it updates location fix fairly slowly. For pedestrian use, this is fine and uses the least battery power. For vehicles, the updates aren't fast enough, meaning changes in direction aren't noticed and applications which use software tricks to 'guessimate' the position often go awry.

    One of the main tricks dedicated GPSes use is averaging - they observe the 'jitter' in position values and average them to smooth out the motion. They can do this and still give a good refresh rate because they sample many times faster than the iPhone.

    Of course, they generally have the same battery life, *without* the phone, fast processor, camera, etc. That's why the iPhone's GPS is so so. It's to save power.
  17. Pull Up Now! macrumors newbie

    Mar 8, 2010
    Iceterminal, that's fine that yours are working. The issue is that a phone that updates the GPS every 10 seconds (mine can be much longer than that) can send you off on the wrong turn, or keep you going straight when you SHOULD have turned. Imagine approaching an intersection or a turnoff, and your green dot hasn't updated it's location. You drive past the turn because the screen doesn't look like you've arrived at that turn yet (because it hasn't updated). Suddenly the green bubble moves a lot, past the turn. Now you realize you've missed the turn. It sux and should work better. It's also dangerous because it can distract the driver trying to get the phone to work. I think there is actual legal Apple liabilty here due to hardware that can't possibly live up to the advertised expectations of the GPS aps.
  18. thelatinist macrumors 603


    Aug 15, 2009
    Connecticut, USA
    I think you're talking about Selective Availability, which was the intentional degradation of the civilian GPS signals. This policy was ended May 1, 2000.

    As far as I am aware, the iPhone 3G and 3GS have always used the same Infineon Hammerhead II aGPS chipset. There may have been changes in the Antenna design betweent the 3G and the 3GS, and there may have been changes to the firmware, but I wouldn't classify either of these as "disturbing."

    I have an early (week 30) iPhone 3GS which I have used with both Maps and Navigon. Maps updated position smoothly for the most part, although there were occasional mistakes with roads running in close parallel...usually just after starting the application and before a sufficient fix had been established.

    Navigon has worked fine for me for turn-by-turn directions, with the one caveat that, again, position accuracy improves over the first couple of minutes, as the phone locks onto more satellites. As with any turn-by-turn GPS device, one has to use common sense. My wife's TomTom once instructed me to drive off a 20 foot clip because of inaccurate map data (seems that the dead-end road wasn't connected to the road at the foot of the cliff after all).
  19. jutte64 macrumors regular


    Apr 28, 2009
    Fort Recovery , OH
    i am having problems with mine lately as weel. on the google maps app it finds me sometimes sometimes it doesnt. it used to find me just fine sitting in my house showing off how great it worked to my friends. now i have to be outside and as soon as i start moving its jumps around two to three blocks away or just freezes. then with tomtom i just went on vaction and it was pointless even having it.. 95% of the time i had it on i just said poor GPS reception. last vacation i went on i had it mounted in the same place and not a single problem. dont know if it had something to do with the last tomtom update, but it shouldnt affect my google maps. i have restarted reset and rebooted my phone nothing has fixed it. guess its time to go see an apple store.. the nearest one is only an hour away it so easy to get to!
  20. MorganK macrumors regular

    Apr 13, 2010
    Mobile, AL
    I've had problems with mine lately. It will tell me to go 6.3 miles will take 7 hours 40 minutes. Or to go to my parent's house (used to say about 5hrs 8min) will tell me it is going to take 4 days or something ridiculous. :confused:
  21. kernkraft macrumors 68020


    Jun 25, 2009
    The iPhone 3G has a very very poor GPS chip. My years old Garmin unit beats the hell out of it. The 3GS is supposed to be better, I haven't tried that.

    But in Central London and in Hampshire too, the 3G is often miles off. It's pathetic.

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