Ipad GPS question

Discussion in 'iPad' started by aduteau, Mar 13, 2010.

  1. aduteau macrumors 6502a

    Joined:
    Oct 14, 2007
    #1
    Just to be clear on something Ive read on the forums ...

    I really want my Ipad to sometimes be used as a GPS device (with some apps), and I see that from what people are saying, that the only Ipad models with GPS ... are the 3G ones ...

    Now even with the 3G models it seems that the Ipad uses Assisted GPS ... witch you need the 3G service in order for it to work ???

    It does not have a dedicated GPS chip like car dash board GPS ?

    Im from Canada ... so if I subcribe to a 3G service from a Canadian carier ... I guess Im screwed if I want to take a road trip to the US ??

    Anyways anyone could just clarify all these questions for me ?
    Thanks a lot guys :)
     
  2. ThatsMeRight macrumors 68020

    Joined:
    Sep 12, 2009
    #2
    No GPS in the WiFi-only version. Although TomTom might release another carkit thingy, which will have a GPS chip (just like for the iPod Touch and iPhone).
     
  3. aduteau thread starter macrumors 6502a

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    Oct 14, 2007
    #3
    can I use the GPS function without a 3G service on the 3G model of the Ipad ?
     
  4. ThatsMeRight macrumors 68020

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    Sep 12, 2009
    #4
    Yes, you can. You don't need the 3G service to use the GPS.
     
  5. Chundles macrumors G4

    Chundles

    Joined:
    Jul 4, 2005
    #5
    Ergh, why do people STILL have this issue with the GPS terms.

    OK, once more with feeling:

    IF 3G COVERAGE IS AVAILABLE -

    1. iPad will get rough location using cell tower triangulation.
    2. iPad uses that rough location and compares it with the satellite almanac.
    3. iPad uses it's GPS antenna to access specific location from those nearby satellites.

    IF 3G COVERAGE IS NOT AVAILABLE -

    1. iPad will go straight to the satellites, this takes much longer but will eventually return the same results.

    A-GPS does not require cell phone coverage, but if coverage is available it makes it quicker and uses less power to get your location.
     
  6. aduteau thread starter macrumors 6502a

    Joined:
    Oct 14, 2007
    #6
    Cool !!! :)
    So why do they call it Assisted GPS ??
    And where does it say that the 3G Ipad model has a GPS chip on the spec page (apple web site)
     
  7. aduteau thread starter macrumors 6502a

    Joined:
    Oct 14, 2007
    #7

    Thx for the answer ! (Ive replied to quickly before your post)

    This is exactly what I was looking for as an answer.
     
  8. Chundles macrumors G4

    Chundles

    Joined:
    Jul 4, 2005
    #8
    Did you not read my post?

    The iPad has a GPS chip/antenna. It's called A-GPS because the regular GPS chip is ASSISTED when it can by cell tower triangulation which makes getting your location easier and using less power.

    Instead of firing a location request into the sky and waiting to get a response from whatever GPS satellites happen to be around, A-GPS is able to get a rough location first which allows it to target specific satellites and makes the whole process faster.

    Re-read my post.


    EDIT: SNAP! Looks like we're playing post-tag! :)
     
  9. goobot macrumors 603

    goobot

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    Jun 26, 2009
    Location:
    long island NY
    #9
    cause it gets assisted by towers and will only go to the satellite if needed
     
  10. avaloncourt macrumors 65816

    Joined:
    Oct 18, 2007
    #10
    And there you would have a problem. The iPad uses a microSIM. They're almost non-existent in the GSM world so far.

    There are no Canadian carriers on that list so you can't get a microSIM card to run the iPad in Canada.
     
  11. kdarling macrumors demi-god

    kdarling

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    Jun 9, 2007
    Location:
    Cabin by a lake
    #11
    There is no "firing" into the sky. GPS devices are receive only.

    That's one form of A-GPS, but in ATT's case, the network assists the device by telling it which satellites to listen to, based on the current cell id.

    A-GPS always uses satellites. Without satellites it's not GPS, but a different method. Or sometimes a hybrid of several.
     
  12. goobot macrumors 603

    goobot

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    Jun 26, 2009
    Location:
    long island NY
    #12
    thats what i meant. it goes through the tower to the satellites
     
  13. avaloncourt macrumors 65816

    Joined:
    Oct 18, 2007
    #13
    No, you need a better understanding of GPS. GPS is passive. NOTHING is ever transmitted to a satellite. The signals come down from the visible GPS satellites and the receiver makes its mathematical determination about where the location is.

    Here is a location where you can learn more: http://www.nasm.si.edu/gps/work.html

    If a GPS receiver doesn't have a hint as to where it's located it takes a long time for the receiver to gather the information and compare it against the almanac, as Chundles said, to determine its location. Personal/car GPS units usually save their last known position to make the determination easier but if you turn it off, fly to a much more distant place, and turn it back on again it will go through a slow process to figure out its location. The iPhone/iPad GPS receiver doesn't run very often. If you've ever tried using a navigation app on battery you'd see that your battery depletes very quickly. The phone GPS chip is only polled when necessary by location aware applications to get a snapshot of where you are. Assisted GPS means that the initial location hint comes from available cell towers and then the exact location determination is much quicker.
     
  14. justinfreid macrumors 6502

    justinfreid

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    Nov 24, 2009
    Location:
    NEW Jersey / USA
    #14
    What's in a name?

    Yes, people who care enough to post to a forum about GPS should be bothered to Google AGPS first.

    I see this confusion time and time again, and I suppose the word "assisted" has a connotation that diminishes the noun it modifies when certain people interpret it. Or maybe it's the vestiges of cell tower triangulation on devices like the first generation iPhone that people think of when reading "assisted" GPS.
    Assisted GPS does a lot to overcome the problems with regular GPS and manufactures and their sales teams haven't done enough to educate the public about that, and the name does little to help.
    Further, GPS RECEIVER should connote that it does not transmit anything to GPS satellites.
     

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