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A few months ago the GPS in my 3G has become really unreliable. The blue circle in google maps looks to be about 2 miles in diameter, and never shrinks to a pinpoint. Apps like RunKeeper can never get a strong enough GPS signal. This may have coincided with the iPhone not picking up wifi unless almost on top of the access point, but that could have been a coincidence.

Things I've tried that haven't worked:

  • Trying to lock on to a satillite when outside with clear skys for >30 minutes
  • General Settings -> Network -> Cellular Data -> Reset Settings
  • Restoring the iPhone from a back-up
  • Giving the phone a prelonged stern look

Any ideas greatly appreciated.

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3 Answers 3

The prelonged stern look didn't work??? Lol

I see that you tried restoring from a backup. Try restoring to stock software instead of your saved backup and see how it works. I've noticed that sometimes erratic behavior is caused by corrupted files within the actual backup image.

If that doesn't work, try taking it in for service...I really don't think that's necessary though.

Hope this helps!

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That would by definition remove all my apps and data, wouldn't it? How could I restore them after the reset? –  tenpn Aug 13 '10 at 15:16
    
That's the down side - you'd have to do it manually. You could selectively add some stuff back in the iTunes options before you sync. Like you could only sync address book instead of all apps or something. –  Thomas Aug 13 '10 at 15:58

It sounds like the receiver chip is malfunctioning. If your 3G is still under warranty, return it to the store for service!

Something similar happened to my 3G: it would no longer find any Bluetooth devices, and no wifi networks even when I entered the network settings manually. I tried hard for weeks to make this work again, even restoring/upgrading etc. but in the end it turned out that the radio chip had died... After a long and phoneless week, I received a brand new replacement 3G from the store.

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Bear in mind that A-GPS is by no means less precise than GPS. The A(ssisted) technology consists of the phone using the Radio (phone) network to query about the Satellites’ information, the GPS receiver only has to care for the “time” information from each satellite, instead of the full pack of information (which is usually lost in poor reception areas like cities anyway). So, A-GPS, by combining info coming from the Cell antenna about the Satellites, and squeezing what it can from the real GPSs messages, can pinpoint your more or less accurate location. In a perfect world, you’d have 6 or more satellites telling you all the information…

If you’re not getting a good location, then I suggest you do what has been suggested, try a fresh “install” (you can later try to restore) or take the phone for service, the GPS Receiver may be failing.

Apart from the cell radio to obtain the info, the iPhone also uses wi-fi (if available).

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