GPS in iPad 2, performance questions

Discussion in 'iPad' started by PracticalMac, Oct 18, 2011.

  1. PracticalMac macrumors 68030

    PracticalMac

    Joined:
    Jan 22, 2009
    Location:
    Houston, TX
    #1
    Simple question to start off with:

    1. Is the iPad 2 GPS using the Cellular Network for GPS?
    (I think no, but cannot find confirmation (don't confuse with AGPS, this is about GPS only))

    2. Is the GPS antenna and Cellular Network antenna the same, or 2 separate antennas (since GPS only comes with network)?

    3. Does the GPS work without a cellular carrier?
    (I read it does, then I read it does not, which is it?)


    The not so simple question is: How good is the iPad's GPS?
    I have read a lot of various reports on the accuracy and speed of the GPS.
    Of course within a cell network one can use AGPS to better triangulate location, but how good is it in areas of poor cellular coverage?

    Naturally I expect the size of antenna be a major factor in reception, however I did not see ay GPS antenna.

    See iFixIt's tear down of iPad 2 for the antennas.


    (and no, I am not planning to go into jungle with iPad.)

    Thanks!
     
  2. poloponies macrumors 68030

    Joined:
    May 3, 2010
    #2
    It uses AGPS where possible to lock in before the GPS acquires a satellite, but then it's GPS all the way.

    The GPS and 3G antennas are separate.

    You can use GPS without 3G only if you have maps downloaded to the device (otherwise the iPad may know where it is but you won't).
     
  3. PracticalMac thread starter macrumors 68030

    PracticalMac

    Joined:
    Jan 22, 2009
    Location:
    Houston, TX
    #3
    I am not asking about AGPS, I am ONLY talking about the GPS portion.

    AGPS takes advantage of cellular or WiFi connections to download satellite directory faster. iPad can d/l the information from the satellites themselves, takes longer, so it is not useful in my questions.

    So you are saying it is a separate antenna. Where is it located? Why is it part of the wireless module?
     
  4. AirForceOne macrumors member

    Joined:
    Jan 16, 2011
    #4
    I have the Verizon 3G iPad 2 with the GPS chip and I DO NOT have cellular service activated, so no you do not need cellular service at all for the GPS to work since I use it all the time. I use wifi at home and I connect the iPad to my HTC Thunderbolt via it's wifi hotspot when out and driving. The GPS works fantastic...I get a sat lock within ten seconds.

    the only reason I bought the Verizon 3G model was because I wanted that GPS chip and I have not been disappointed.

    There is a free iPhone app you can download that gives you great info about your GPS status. I just fired it up to give you an example:

    GPS Status: (mine always says excellent fix within ten seconds)

    Horizontal accuracy: 5M

    vertical accuracy: 4M

    Speed: 0MPH

    Lattitude: secret :)

    Longitude: secret :)

    address of your current location: secret :)

    The only thing it doesn't tell you is how many satellites you are currently locked onto...I miss that from an Android version of the app.
     
  5. takeshi74, Oct 18, 2011
    Last edited: Oct 18, 2011

    takeshi74 macrumors 601

    Joined:
    Feb 9, 2011
    #5
    The GPS receiver does not use the cellular network. It uses the GPS satellites. Now, your GPS app, on the other hand, may or may not require data coverage to function. It depends on the specific app you're referring to.

    aGPS is GPS. That's why there's "GPS" in aGPS. A lot of people confuse aGPS with tower triangulation. They're not the same thing. The only difference between aGPS and standalone GPS is that aGPS receivers use assistance data for a faster initial fix. That's it. Location is still determined using the GPS satellites.

    There's only one GPS receiver in the iPad 2. It uses aGPS if possible. If not possible, it falls back on standalone GPS mode.

    That is an incorrect statement. Otherwise dedicated GPS devices would be totally useless since they don't operate on any wireless carrier's network. Though, now that I think about it some more, are you trying to say that GPS only comes on the 3G models?

    Again, the GPS receiver doesn't care if you have coverage or not. The app may or may not. Again, depends on whether the app requires data. Some do. Some do not. It's important to understand the distinction between the GPS receiver (hardware) and the GPS apps (software) and this applies to all devices with GPS receivers -- not just the iPad. It's the same on any smartphone out there, Apple or otherwise. A lot of people don't get the distinction and seem to assume that they're one and the same which is why you're seeing conflicting information.

    Again, aGPS is not tower triangulation. It doesn't improve GPS accuracy. It just provides a faster GPS fix when aGPS ephemeris data is available. Standalone GPS fixes take longer.

    Granted, Wikipedia isn't the best resource but you might want to refer to:
    http://en.wikipedia.org/wiki/Assisted_GPS

    Cellular coverage doesn't matter unless you have an app that requires data. An initial fix may take longer without coverage since aGPS data won't be available but how long depends on a number of factors and there's no one-size-fits-all answer despite your assumption.

    In my experience it's similar to the the iPhone's. It's weaker than GPS receivers I've used on other smartphones but it's certainly usable. My iPhone and iPad occasionally lose their GPS fix. The receivers on my other smartphones never lose their fix. How exactly do you want this quantified in a way that's meaningful to you?

    It can help but it's not the only deciding factor. Bigger isn't always better with antennas. GPS receivers don't always have separate antennas. I can't speak specifically to the design of the iPad 2's GPS antenna.
     
  6. PracticalMac, Oct 19, 2011
    Last edited: Oct 19, 2011

    PracticalMac thread starter macrumors 68030

    PracticalMac

    Joined:
    Jan 22, 2009
    Location:
    Houston, TX
    #6
    Thank you poloponies, AirForceOne, and Takeshi74 (ありがとう)

    I was seeking to confirm what I thought was correct.

    So, recap is:

    1. iPad does have a true GPS, which is Augmented (thus AGPS) to take advantage of the networks to download the satellite positional logs for faster acquisition.
    2. Is fast and accurate, however is prone to loose position.
    3. iPad (or iPhone) does NOT use cell network triangulation (and may be less accurate to use triangulation).
    4. The GPS Receiver is installed on the network card (GSM and CDMA), so it is needed if one wants GPS.
    5. The GPS antenna might be a separate antenna from cellular, however is not confirmed.
    6. The App is critical to getting useful information. Default "Maps" downloads map information as needed from the internet, but with out internet you have a blank map with blue dot.
    7. A good GPS App will show location regardless of cellular data plan or not.

    It may be that GPS receiving ability is built into the Qualcomms cellular network chip, perhaps that's the reason why the GPS feature is only added if you get the GSM / CDMA version.

    So, a new question:
    Recommended GPS Apps?
    I think I saw a topic on that somewhere.
     
  7. davegoody macrumors 6502

    davegoody

    Joined:
    Apr 9, 2003
    Location:
    Reading, Berkshire, England
    #7
    3G / GPS is on the same chip

    The 3G chipset that the iPad uses has built-in GPS as standard. This is why when you get the 3G version it has the GPS, and not otherwise. My old DELL laptop that I used to lug around for work had 3G capabilities built-in, and COMPLETELY undocumented GPS support too, only found out when I checked Windows 7's Control Panel and noticed it listed.... not that I ever used it on that piece of junk, but better (I suppose) to have it than not.
     
  8. PracticalMac, Oct 19, 2011
    Last edited: Oct 19, 2011

    PracticalMac thread starter macrumors 68030

    PracticalMac

    Joined:
    Jan 22, 2009
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    Houston, TX
    #8
    Thanks!
    Pretty much proves the hypothesis.


    BTW, another tread on reception quality of iPad
     
  9. mikespence macrumors newbie

    Joined:
    Oct 19, 2011
    #9
    gps on ipad 2 w/o 3g

    The Ipad2, Ipod touch, and Iphone w/o data can all be used for mapping and navigation apps if you get a bluetooth gps receiver such as the one made by Dual (xgps150, about $90) This may be irrelevant if all you want is in-car navigation. In that instance a stand-alone gps like the Garmin Nuvi 1100 ($89) will still outperform the Ipod/Ipad/Iphone, especially if you travel to far away places. If you are contemplating Marine use, as I have, the bluetooth gps is the answer if you are going offshore or to foreign countries in particular. Isailor by Transas, used on the Ipad2, is hands-down the best value for marine navigation that currently exists, with maps in foreign countries going for hundreds of dollars less than other chart programs. The savings in foreign charts will pay for the Ipad2 and the bluetooth receiver...
     
  10. PracticalMac thread starter macrumors 68030

    PracticalMac

    Joined:
    Jan 22, 2009
    Location:
    Houston, TX
    #10
    Yes, for serious GPS needs a stand alone is best.


    Thanks for those pointers.
     
  11. fricotin macrumors regular

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    Sep 26, 2011
    Location:
    Puerto Escondido, Oaxaca, Mexico
    #11
    I use the Garmin GLO Bluetooth with my iPod touch, it uses both GPS and Glonass satellites, worked great all over South East Asia.
     

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