How GPS works in iPhone ?

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gps
iphone

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208

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+1 Q:

How GPS works in iPhone ?

Hi Friends,

I am using a iPhone 3g. I am in India(I got it in India). I just tried to check my location using the Google Maps. My location was spotted when I had sim in my phone. But when I took out the SIM from iPhone, I did not get my location. I tried the same with the Locate me Sample Application . So can someone explain how GPS works in iPhone, and how to fix my problem(to get my location when there is no SIM).

Thanks and Regards, krishnan

I know the iPhone uses assisted GPS: it first looks for the rough location by cell tower, knows the GPS satellites to expect for that rough location, and then finds a more precise location. Maybe when the first step fails (no SIM means no cell tower fix), the API's do not work?

Henno Brandsma 2010-06-11 09:36:26

Hi Henno,thanks For your response. The reason you specify may be true reason. I am hoping it would work.

Krishnan 2010-06-11 10:26:08

Try going outdoors or holding your iPhone near the window where it can see the sky. You may be able to get a GPS fix (it will take a while to lock on)

nolim1t 2010-06-11 11:26:18

Nolim1t , I tried the same you have specified. It worked like a charm. Thanks Nolim1t

Krishnan 2010-06-11 15:52:07

Hi Friends(Emil, NOlim1t, Plumentaor), Thanks all for your time. The only problem I facing is like, The service does not work (if sim is removed), when I am inside my office. When I take my phone outside of my office, it works . Any way thanks all.

Krishnan 2010-06-11 15:55:07

The iPhone uses many things, including cell ID and WiFi SSID. It communicates these to a server, which returns an estimated location and (possibly) a list of nearby satellites.I'm pretty sure the GPS also works standalone, but you need much stronger signal; non-assisted GPS generally doesn't work indoors.

tc. 2010-06-11 20:25:49

+1 A:

The iPhone uses AGPS, or Assisted Global Positioning System. That means that the iPhone uses both GPS and internet information to get your location. If you are not connected to a WiFi network or your phone doesn't have a SIM-card in it, it won't be able to locate you.

You can't get the location of an iPhone if you have no internet, so I suggest you check wether the phone is connected to any type of internet, and show a warning if it isn't. But the GPS will still work if you are connected to a WiFi Hotspot.

Emil 2010-06-11 09:36:35

Hi Emil,I am connected to a wi-fi Hotspot in my office Space. but even then I don't get my current Location....

Krishnan 2010-06-11 10:10:08

I think the WiFi Hotspot you use must be registered with the service that Apple uses to get the location.

Plumenator 2010-06-11 10:26:10

@Plumenatorm Correct.

Emil 2010-06-11 10:48:41

Go to http://www.skyhookwireless.com/howitworks/submit_ap.php and add the wifi hotspot and then wait

nolim1t 2010-06-11 11:23:08

Hi Plumenator/Emil,I think the Wifi must be registered with some Server to get them detected. I found a link which many had suggested. http://www.skyhookwireless.com/howitworks/FindMyAP.php. Does it mean that when I travel to a place, where there is no signal, I will not be able to find my location.

Krishnan 2010-06-11 11:40:02

I did not try this option, Nolim1t.

Krishnan 2010-06-11 15:55:42

@Krishnan: Yes, unfortunately.

Emil 2010-06-11 21:20:14

As Nolim suggested, I tried checking in outdoors and it worked. If you are checking within your office space or home, get out of it completely and go to a open space and check there. It should work, irrespective of whether you have SIM or not.( Usually when you have SIM, it A-GPS would work).If it is not working immediately, wait for some time, for around 2-3 minutes and it would work.

Krishnan 2010-07-14 05:06:35

ansaurus

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How GPS works in iPhone ?

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