GPS Chip ?

Discussion in 'iPhone' started by Bob, Dec 24, 2014.

  1. Bob

    Bob Guest

    Hello,

    Is there a full GPS receiver chip in the iPhone 6, or is position
    detrmined solely by triangulation from towers ?

    B.
     
    Bob, Dec 24, 2014
    #1
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  2. Bob

    Guest Guest

    every iphone other than the first model back in 2007 has a full gps.

    cellphone towers and wifi help the gps get a fix.
     
    Guest, Dec 24, 2014
    #2
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  3. Bob

    David Empson Guest

    There is a full GPS receiver.

    All iPhone models apart from the original one have "Assisted GPS". This
    includes receiving signals from GPS satellites to determine accurate
    position. The iPhone 4S and later also support the Russian GLONASS
    satellite system.

    The "assisted" aspect allows the iPhone to get a much faster initial
    fix, by determining its approximate position based on nearby Wi-Fi base
    stations and cell towers, and downloading some of the GPS satellite
    positional data via the Internet rather than having to get it slowly via
    GPS. The position is then fine tuned via GPS/GLONASS, which typically
    takes a few seconds (assuming good signals).

    If there are no cell towers or Wi-Fi networks in range, the initial
    position can be determined using GPS/GLONASS alone, but it takes much
    longer. I haven't tried timing this, but I gather it is in the order of
    a minute rather than seconds.
     
    David Empson, Dec 24, 2014
    #3
  4. Bob

    JF Mezei Guest

    This assumes that there is a data path to the internet, for both Wi-Fi
    triangulation and for downloading the current ephemeris updates.

    If you have data turned off while roaming (to prevent bankruptcy), the
    "assisted" portion offers reduced advantages. You would still get
    location of the tower to which you are connected.


    What is interesting is that turning off Wi-Fi sets off the "reduced GPS
    accuracy" warning when in fact, assisted GPS relies far more on a
    cellular data path to work.
     
    JF Mezei, Dec 24, 2014
    #4
  5. Bob

    Guest Guest

    no it doesn't.
     
    Guest, Dec 24, 2014
    #5
  6. Bob

    Rod Speed Guest

    Corse there is.
    Nope.
     
    Rod Speed, Dec 24, 2014
    #6
  7. Bob

    Rod Speed Guest

    No it does not.
     
    Rod Speed, Dec 24, 2014
    #7
  8. Bob

    JF Mezei Guest



    So, you are traveling on a road. You turn on an app that needs location.
    Pray tell how the phone gets its "assisted" information ?

    How does the phone translate the WiFI SSIDs it sees into lat/long ?
    Just because it ses nearby Wi-Fi system doesn't mean it can use them to
    access the internet.
     
    JF Mezei, Dec 24, 2014
    #8
  9. Bob

    Rod Speed Guest

    It does without it and just takes a little longer to get a
    useful GPS lock when its been moved quite a bit while
    turned off.
    It doesn’t need to do that.
    Sure, in fact it doesn’t use them to access the net at all.

    It doesn’t use cellular data either and I know that because
    I pay for it by the MB and can see that it doesn’t use that
    if I say use the GPS to log where I have been.
     
    Rod Speed, Dec 24, 2014
    #9
  10. Bob

    JF Mezei Guest


    Your claim was that assisted GPS didn't need access to a data link. What
    you arte now saying is that without a data link, you don't get assisted
    GPS and you just let the GPS get its bearings all by itself.
    (aka: non assisted).
     
    JF Mezei, Dec 24, 2014
    #10
  11. Bob

    Rod Speed Guest

    It clearly doesn’t when it JUST takes longer to get a fix.
    Nope.
     
    Rod Speed, Dec 24, 2014
    #11
  12. Bob

    JF Mezei Guest

    Which is why I stated that the cellular data connection was key to
    assisted GPS. Without it, there isn't much "assist".

    The only assist you get without a data link and lat/long of the tower
    serving you (even if data turned off). However, unless you travel at
    great speeds, the previous location your phone had would be more than
    enough to know which satellites to listen to first.

    If you have traveled 30km from last place your GPS had a fix, you GPS
    may not yet be aware of it, but using the last location will yield it
    the same visibility on the same satellites in the sky that should be
    overhead at the moment. So having a cell tower give you a closer
    approximation of your location doesn't change much.

    If, however, you have traveled by airplane from New York to LAX, then
    yeah, different satellites will be in the sky than the GPS would expect
    to be over New York , so getting localised lat/lon will help the GPS get
    started and know which satelites to look for overhead.

    To give you an idea, second generation GPS units would prompt for
    location where the whole province of Québec was broken (IIRC) in 2
    zones. This was more than enough to get idea who what satellites should
    be overhead at this time.
     
    JF Mezei, Dec 24, 2014
    #12
  13. Bob

    Rod Speed Guest

    You're wrong.
    There doesn’t need to be much assist. The only time that is
    useful is when the phone is moved a considerable distance
    when its turned off completely and that is **** all of the time.
    That isnt even a viable sentence.
    With the phone turned off or the GPS turned off.
    Yep, so assisted gps isnt actually used that much.
    And the only effect that will have is getting a fix a bit quicker.
    The Frog Zone and where the white men live.
    And you don’t need cellular data access to do that auto.
     
    Rod Speed, Dec 24, 2014
    #13
  14. Bob

    Guest Guest

    by using cellular and wifi in addition to gps.
    it has a cached database.
    yes it does.
     
    Guest, Dec 24, 2014
    #14
  15. Bob

    Guest Guest

    it doesn't need a data connection.
     
    Guest, Dec 24, 2014
    #15
  16. Bob

    Pat Guest

    In this whole thread, no one has mentioned that GPS signals don't
    penetrate into buildings very well. Most people spend a lot of time
    inside buildings so the "assist" features are used most of the time
    for location services. Both cell tower locations (with triangulation
    if multiple towers are within rangle) and known wifi network locations
    are used to help.
     
    Pat, Dec 24, 2014
    #16
  17. Bob

    Guest Guest

    it depends on the building. i can get a fix on my garmin gps inside my
    house, as well as with a couple of other devices that have gps, and
    that's *without* assist.
    sometimes. it depends what level of accuracy is needed. plus, wifi
    might be enough to get a precise location without the gps at all.
    yes.
     
    Guest, Dec 24, 2014
    #17
  18. Bob

    Rod Speed Guest

    Its more complicated than that with modern GPS receivers.
    But don't spend all their time in those with no satellites visible.
    He wasn't talking about helping.
     
    Rod Speed, Dec 24, 2014
    #18
  19. Bob

    JF Mezei Guest

    ached database is for recently seen wi-fi SSIDs that got translated when
    there was data access. It does not have the full database of worldwide
    Wi-Fi SSIDs.

    If you are traveling, chances are the "Recently visited" are behind you
    and useless because you care about new SSIDs you have never seen before.
     
    JF Mezei, Dec 24, 2014
    #19
  20. Bob

    JF Mezei Guest


    Please explain how the phone can translate a Wi-Fi SSID into lat/long
    coordinated without a data connection.
     
    JF Mezei, Dec 24, 2014
    #20
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