Is the A-GPS assisted by the datanetwork, or the standard network?

Discussion in 'iOS Apps' started by stofferdk, Mar 24, 2010.

  1. stofferdk macrumors regular

    Joined:
    Jul 22, 2007
    Location:
    Copenhagen, Denmark
    #1
    Dear MacRumours,

    When I use my beloved Navigon app, I suppose it lets the GPS get assisted. So, my question is - does the GPS get assisted by the datanetwork (2G or 3G), or the standard network? Or have I misunderstood how it works?!

    I am asking because I wish to travel with my iPhone and Navigon through Europe. As I will not bring my simcard (no roaming charges for me), I thought about just buying a prepaid simcard in each country, just to get a signal.

    Will this signal be enough for the GPS to be assisted, or will I need to get a prepaid dataplan also?

    Thanks!
     
  2. pauliphone macrumors regular

    Joined:
    Nov 27, 2008
    Location:
    London, UK
    #2
    The iPod Touch gives a rough indication of location without using GPS but by using the cell tower triangulation.... I would assume the iPhone uses the same method and so no sim card would be needed for the A-GPS to work.
     
  3. gdlcjr macrumors regular

    Joined:
    Dec 3, 2009
    #3
    The Iphone GPS does not need data unless you are using the Google maps or any app that needs data. If Navigon has all the maps installed in the iphone you are good to go. You can test it now without going to other country. Removed your sim and try running Navigon if it will work.
     
  4. amorya macrumors 6502

    Joined:
    Jun 17, 2007
    #4
    Cell Tower Triangulation and Assisted GPS are two completely different things.

    Cell Tower Triangulation is where the phone can work out where you are by looking at the relative signal strengths of a few cell towers. This is not GPS.

    GPS uses a network of satellites to work out where you are. This doesn't require any form of network connection, but can be slow (take a couple of minutes until it's up and running).

    A-GPS, or Assisted GPS, uses an internet connection to download information about where the satellites are likely to be (approximately), before using GPS to work out where you are. That internet connection can be wifi, 3G, or anything. If the internet connection is not present, the system falls back on standard GPS.

    One further point: prepaid SIM cards (at least in Britain) will probably allow you to access the 3G data network. For example, Orange charge £2/day, just taken off your normal credit, so no special plan needed. This may be similar in the rest of Europe.

    Amorya
     
  5. stofferdk thread starter macrumors regular

    Joined:
    Jul 22, 2007
    Location:
    Copenhagen, Denmark
    #5
    Thank you for your replies! Most helpful.

    Fact is for me, that Navigon regretfully is almost useless without sim card. The GPS never really seems to get a lock. I tried a few times, and when it finally gets a lock, or loses track fast when driving.

    My concern is I really need those prepaid sim cards with data access
     
  6. funnyboy88 macrumors regular

    Joined:
    Jun 18, 2009
    #6
    Call me crazy, but I noticed having WIFI turned on also improves the GPS accuracy in the turn-by-turn apps.
     
  7. vertigo235 macrumors 6502

    Joined:
    Jun 6, 2009
    #7
    Wirelessly posted (iPhone: Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_1_2 like Mac OS X; en-us) AppleWebKit/528.18 (KHTML, like Gecko) Version/4.0 Mobile/7D11 Safari/528.16)

    No it doesn't.

    It uses wifi hotspot locations.

    The iPod touch has no capability to recieve any kind of cell phone tower signals.
     
  8. stofferdk thread starter macrumors regular

    Joined:
    Jul 22, 2007
    Location:
    Copenhagen, Denmark
    #8
    well, I still seek a definitive answer regarding the dataconnection.

    When I travel Europe, will having a cellconnection be enough for the GPS to get assisted? Or will I need a datacard?

    I really hope I wont need to buy those expensive prepaid datacards
     
  9. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #9

    You do not need a connection at all for gps to work on your Europe trip.

    Also if you have roaming turned off there is no data connection avalible for your iPhone to use.
     
  10. stofferdk thread starter macrumors regular

    Joined:
    Jul 22, 2007
    Location:
    Copenhagen, Denmark
    #10
    but when I have no cellconnection in my home country, the GPS never seems to work properly :/

    Guess ill do some testing with data off
     
  11. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #11
    are you placing it so it has direct line of sight with the sky?
     
  12. stofferdk thread starter macrumors regular

    Joined:
    Jul 22, 2007
    Location:
    Copenhagen, Denmark
    #12
    If placing it in the window in the car counts as direct line to the sky, then yes.
     
  13. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #13
    Does your car have a heated windscreen or a Metallic winscreen coating?
     
  14. Jeffro macrumors newbie

    Joined:
    Aug 20, 2009
    #14

    Same here!
     
  15. amorya macrumors 6502

    Joined:
    Jun 17, 2007
    #15
    To get Assisted GPS, you will need a data card.

    To get Cell Tower Triangulation, I believe you don't need a data card, although I'm not 100% sure.

    Amorya
     
  16. trainguy77 macrumors 68040

    Joined:
    Nov 13, 2003
    #16
    http://www.skyhookwireless.com/flash/loader_howitworks.swf That is how the location services as a whole works for the iPhone.

    But any one piece can work independently.

    So with no data access GPS should still work.
    As well with no sim or cell signal wifi location services should work.

    For best results you would have wifi on, with cell signal data, and a clear view of the sky.
     

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