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navxguy
133 Posts |
 Posted - 08 févr. 2010 : 21:26:08
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GPS INFO TOOL : Here is the link for the nifty GPS Info application that shows what type of positioning the iPhone is using : Cell, WiFi or GPS with the respective accuracy. Cell and WiFi (in urban areas) are nice because they are instant but as you've found not very accurate (~300m and ~100m)
I did a quick search to see if this was discussed previous, but didn't see it. Does A-GPS use data service for "assisted" processing? ... or does it use cellular minutes?
And if you don't have a "data plan" (in fact turned off at cellular provider system - like i do w/ my kids), will the 'assist' work? or will GPS default to non-assisted GPS? I passed along my prior 3G iPhone to my son who has data service turned off (by provider), the 3G iPhone still gets a GPS lock, just wasn't sure if it was using 'assited' or not.
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gpspassion
93427 Posts |
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navxguy
133 Posts |
Posted - 09 févr. 2010 : 04:09:05
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| thanks! ... i did a quick read through and didn't see confirmation as to whether the "Assist" part of A-GPS comes from data service/triangulation (data plan) or cellular triangulation (minutes) or some other antenna triangulation ... just curious about getting more details on 'assisted' processing. Thx! |
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ELEGEND_YVR
Canada
454 Posts |
Posted - 09 févr. 2010 : 07:21:40
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| It definitely works. It's accuracy can be a big issue. The iPhone will use wifi and cellular towers to get a fix if not using A-GPS. While in my apartment, my iPhone incorrectly reported my position as being across the river. Enabling A-GPS gave me an accurate fix of my true location. |
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gpspassion
93427 Posts |
Posted - 09 févr. 2010 : 08:50:05
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What you describe is not "A-GPS" it's cell and/or wifi positioning, "A" stands for Assisted as in assistance brought to the hardware chip for the initial fix as was explained in the article.
Here is the link again for the nifty GPS Info application that shows what type of positioning the iPhone is using : Cell, WiFi or GPS with the respective accuracy. Cell and WiFi (in urban areas) are nice because they are instant but as you've found not very accurate (~300m and ~100m) |
Discounts and Assistance/Réductions et Assistance (Club GpsPasSion) / Où commencer? |
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danham
USA
7347 Posts |
Posted - 09 févr. 2010 : 13:45:39
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WiFi can potentially be quite accurate, but to the extent it depends on self-reported position data can be unreliable. There have been some truly wild errors observed, such as someone moving to another state and forgetting to tell the database that their router went with them [g].
I'm not in an urban area, but if you're on my street you will get a very good position fix near my router. If it's on [g].
And to answer the OP, WiFi data use is free and not counted by the phone. Cell data is part of the so-called "unlimited" data, which is only capped or restricted when you are on an AT&T partner network.
-dan |
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Edited by - danham on 09 févr. 2010 13:47:50 |
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Assisted GPS on the iPhone - Cell/WiFi/Data
