iPhone GPS Without Cell Phone Service

I don't have an iPhone, so I'm not familiar with all its features. So please bear with me. Basically, I'd like an iPod touch with GPS capability. I'm thinking of getting an iPhone but not subscribing to cellular service, since I get an very weak AT&T signal at my home location. Is this possible?

I understand that the iPhone has a built-in GPS receiver chip set and can receive and process the C/A (coarse acquisition) prn code from the constellation of GPS satellites. I'm under the impression that the iPhone doesn't have the capability to process the low bit rate almanac and ephemeris data that is modulo-2 added to the C/A code to make up the SPS (Standard Positioning Service) signal.

My understanding is that the iPhone depends on assisted GPS to obtain the required low rate data, but I'm unclear whether it gets it from cell tower signals or WiFi (Skyhook). If it's WiFi, then I can process the GPS signals and plot location on WiFi downloaded Google maps. I think this would work. Am I mistaken? If the low rate data is obtained via cell tower signal, I guess I'm out of luck. Can anyone clarify this for me?
Thanks
Ray

G4 Powerbook, Mac OS X (10.5.8)

Posted on Sep 29, 2009 6:38 PM

Reply
18 replies

Sep 29, 2009 6:45 PM in response to rayfel

You would be better off spending the money on a GPS.

To buy the iPhone, you will need to activate it with an ATT account for any of the features to work. Even if you cancel the account and pay the ETF, the GPS needs an active data connection to display your location on a map. If you're outside of a wifi zone, the maps won't load and show a position.

Sep 29, 2009 6:50 PM in response to rayfel

You don't say where you're from. All IP's in the US come with 2 year contracts which include a $30 monthly charge for internet access.

If you're looking for a GPS receiver, even if you could do what you describe, you can find a much better GPS for less money. IF you were to buy the IP without a contract, it would cost you around $600.

Sep 29, 2009 7:08 PM in response to Tamara

Tamara
I already have two GPS receivers but would like to combine GPS with all the other features such as Apps, internet WiFi connectivity, iTunes etc, in one device. You have answered at least one of my questions, ie: you must activate the At&T account when you purchase the iPhone. I understand that you must be within the reach of a WiFi signal to download maps, or anything else.

Macaby
I'm in Palo Alto CA, so there are lots of WiFi hot spots around. From what you say, I'd have to pay for WiFi internet access. Is that also true with iPod touch, which has WiFi connectivity?
Thanks for both of your replies.

Sep 29, 2009 7:37 PM in response to rayfel

Count me in as another victim. I've had it happen four times over the last couple weeks. I have a 3G iPhone that's less than a year old. No problems until the 3.1 update. I was fine on 3.0.

After reading this whole thread, there's no way I'm going to Apple or AT&T to report my problem. They'll just ask me to change my SIM card and/or replace my phone. That's the kind of solution you offer to one of a kind problems rather than widespread, clearly diagnosed issues that directly follow a software update. The best way to get Apple's attention is to voice our complaints together. (But perhaps having them replace your iPhone again and again is a good way to get them to realize how expensive this problem will get if they ignore that it's software-related.)

I'd also like to mention that upon rebooting my phone, I get the 20% battery warning. I wonder if the 3G connection issue is causing it to overutilize the antenna, going into an infinite loop, and draining the battery very quickly.

I'm going to try to restore my phone as new, and see if that actually works. The trouble is that I might not experience the problem for a couple days anyway. I guess that makes me "lucky".

Cheers,
James

P.S. I also had a hard crash upon trying to send my very first photo message. The phone pretended to be a brick for at least an hour. After charging it some, I was able to get it to reboot.

Sep 29, 2009 9:20 PM in response to rayfel

The $30 data charge is to use the IP on ATT's 3G network. No, there is NO charge to use WiFi EXCEPT for maybe some hot spots. However, if you don't sign up for ATT's 2 year contract, you also can't use WiFi as I understand the system. In almost all cases, a WiFi connection is faster than the 3G network. However, the 3G network works almost everywhere while the WiFi only works in hot spots or in your home IF you have a WiFi signal (could be your neighbor's or your wireless router).

My advise, buy an iTouch and forget about the GPS. Maybe down the road Apple with come out with a Touch that does WiFi.

Sep 29, 2009 9:31 PM in response to rayfel

Its easy; I am pretty sure that you can not find a non-hacked smartphone form any carrier with out that carrier charging you for the bandwith you are going to use on their service.

do you have an internet connection at home ?? is it a free wifi connection that just comes out of the atmosphere ?? are you connecting thru your poor unsuspecting neighbor who does not know enough to secure their net ? or are you on a cable connection and paying an ISP ? it is the same thing.

The various wireless services charge for your ablility to reach the internet utilizing their bandwith on either the Edge or 3G nets NOT for being able to access the internet on a WiFi radio. You can get free internet service (sort of ) at Starbucks, for example, simply by meeting their requirements and having a WiFi enabled laptop and hooking into their private net; but you can not use that laptop in the middle of nowhere utah on I-70 with out having a radio to to pick up on someones Edge or 3G service as that comes only on a wireless service.

Sep 29, 2009 10:20 PM in response to Macaby

Macaby wrote:
rayfel wrote:
Macaby wrote:


My advise, buy an iTouch and forget about the GPS. Maybe down the road Apple with come out with a Touch that does WiFi.


iPod Touch already has WiFi. Did you mean to say: a Touch that does GPS?


I give up and am leaving the building. This is starting to smell like some kind of game. Adios


I'm sorry you took offense. I'm not playing any games. I am honestly confused by your statement "Maybe down the road Apple with come out with a Touch that does WiFi." I assumed you might have made a typo and meant to write GPS instead of WiFi. In any event, I appreciate everyone's response to my initial query and follow up questions.

Sep 30, 2009 11:21 AM in response to Tamara

Tamara wrote:
The $30 data charge is for 3G/Edge service which is how you access data when you are away from your home/office wifi networks.

To be honest, the IPhone is not the right device for you since you don't want to use it the way it's meant to be used.


Thanks for clarifying what the $30 charge is for. I suppose it would have been fully explained when I was in the process of subscribing to an AT&T contract.

You're probably right, but I'd use it the way it was meant to, if AT&T would fill in the coverage gap at my home location. I really rather not carry around two devices to do the job that iPhone could, if I could get a decent signal.

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iPhone GPS Without Cell Phone Service

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