JohnPacheco
Level 1 (0 points)

Q: iPhone 5 and Satellite GPS

Everyone, for a long time I have been wanting to move to the iPhone, however due to the lack of Satellite and WAAS based GPS, i have not.  So I am wondering... Oh, please, oh please, oh please, does the iPhone 5 have Satellite based GPS?

 

If not, does anyone know why Apple will not add this feature to their radios.

 

thanks

Posted on Sep 12, 2012 1:08 PM

by MeplatMasher,Solvedanswer
MeplatMasher MeplatMasher
Level 1 (10 points)
A:

As rominggnome showed, the iPhone does have a GPS receiver, and has since the iPhone 3G.  And as Rudegar pointed out, the iPhone also has A-GPS capability, which lets the GPS receiver determine its current location much faster than normal.  Without A-GPS, the GPS receiver has to wait -- sometimes multiple minutes -- before it can determine its location, because it doesn't know where the satellites are.  A-GPS allows the phone to download satellite almanac data over the cellular network, so the GPS receiver can immediately know where all the satellites are.  A-GPS is not necessary, however, for GPS operation -- even if you have no cellular service, you can still use the GPS receiver in the iPhone.  I have done this many times, so I have no idea why your friends have had trouble.  I recommend the MotionX GPS app, and it works really well out in the woods.  You can even download offline map data.

 

But what the iPhone does NOT have is WAAS capability.  The GPS receiver works by measuring how long it takes for the radio signals to propagate between the satellites and the receiver.  The propagation time varies based on the current density of the atmosphere between each satellite and the receiver.  Because of the density flucuations, a standard GPS receiver can only get a fix that is accurate to about 10 meters.  However, some geostationary satellites transmit atmospheric density information that lets GPS receivers compensate for current atmospheric conditions, and this enables accuracies in the neighborhood of about 1 meter.  Garmin has had WAAS capable receivers for years, as have other hand-held and aviation-based GPS receivers, so it is a bit surprising that Apple has not incorporated WAAS into their GPS radio -- especially since WAAS density data can be downloaded via the Internet, eliminating the need for increased radio weight.  I and others have submitted requests for a WAAS capable GPS receiver in the iPhone, but Apple has not delivered.  Perhaps it is because WAAS is only available in North America.  However, according to the specs for the iPhone 4S and 5, it now supports GLONASS, which provides near-WAAS accuracy when combined with standard GPS, and is available worldwide.  At least that is the next best thing to WAAS.

 

Now, the CoreLocation service on the iPhone combines 3 completely separate technologies: GPS, cell tower triangulation, and Wifi-based location.  I don't know the algorithm they use, but I presume that they use whatever service is currently providing the most accurate location information. 

Note that cell tower triangulation has nothing to do with GPS.

Posted on Sep 13, 2012 9:10 PM

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JohnPacheco

Q: iPhone 5 and Satellite GPS

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  • by austinfromtulsa,

    austinfromtulsa austinfromtulsa Mar 25, 2013 9:56 PM in response to JohnPacheco
    Level 1 (0 points)
    Mar 25, 2013 9:56 PM in response to JohnPacheco

    I just spent a week in the Grand Canyon with, of course, no cell service. I was able to track my location on a Pre-downloaded map for the duration of my trip. If I turned airplane mode on, my tracking would disappear. For the GPS to work you need airplane mode off.

  • by hadtomakeupaname,

    hadtomakeupaname hadtomakeupaname Mar 26, 2013 5:03 AM in response to JohnPacheco
    Level 1 (0 points)
    Mar 26, 2013 5:03 AM in response to JohnPacheco

    Austin, Sounds like a nice trip, but cold.  I bet that really ran down your battery fast since the phone was constantly trying to find cellular service.  You might try the technique I described in this thread, posted Oct. 5, 2012, and see if that works. 

  • by earlc13,

    earlc13 earlc13 Jun 21, 2013 5:52 PM in response to JohnPacheco
    Level 1 (0 points)
    Jun 21, 2013 5:52 PM in response to JohnPacheco

    I have a Garmin GPS receiver and to determine if the iPhone 5 really does have a GPS receiver capable of satellite reception and computaion, I went outside in my backyard with my Garmin and obtained it's coordinates.

     

    I then obtained my coordinates from my iPhone for correlation and both were a match.

     

    I then put my iPhone 5 in the AIRPLANE MODE and turned-OFF my WIFI.

     

    I cycled power on the iPhone 5 and when it came up and I checked my GPS coordinates on the phone...the only thing that registered was my COMPASS direction with the LAT LONG coordinates a few HUNDRED MILES OFF and also the phone DID NOT indicate any tracking of my movement at all, as my Garmin did so very resolutly...

     

    Summary

    The iPhone 5 uses the cell site and/or WIFI location data for your LAT/LONG coordinates/presentation.  What else can I conclude from this experiment...?

     

    Perhaps the AIRPLANE MODE turns OFF the GPS receiver...?  A radio receiver has to have at least 1 LOCAL OSCILLATOR for the basic superheterodyne functionality and LOCAL OSCILLATORS can be a source of RF radiation.  So then if the iPhone 5 has a full blown GPS receiver/computational feature then this must be what is happening; that is, the AIRPLANE MODE disables the GPS receiver....

  • by MeplatMasher2,

    MeplatMasher2 MeplatMasher2 Jun 21, 2013 10:37 PM in response to earlc13
    Level 1 (0 points)
    Jun 21, 2013 10:37 PM in response to earlc13

    Your last paragraph is correct.  Airplane mode turns off the GPS receiver.  It's required by the FAA.  You can also verfy that the iPhone 5 has a GPS receiver by looking at the official hardware stats:

    http://www.apple.com/iphone/specs.html

     

    You are also correct that the iPhone uses the cell site and/or WiFi location data for positioning.  The CoreLocation API allows app developers to get the current device location.  CoreLocation uses the available data from the 3 radios and determines the position to an accuracy specified by the developer. 

    http://developer.apple.com/library/ios/#documentation/CoreLocation/Reference/Cor eLocation_Framework/_index.html

     

    Finally, you can verify that the iPhone has a GPS by driving down most any road.  Cell tower triangulation is accurate to maybe a few city blocks, depending on the cell density.  WiFi triangulation only helps when there are WiFi signals nearby.  Download an app like MotionX GPS and start recording your route.  You will notice that your route matches the road you're driving on almost exactly, with position information every few meters.  If it was only using cell tower triangulation, it would be jumping all over the map.  If it was only using WiFi, you would jump from one WiFi location to another, with no updates when no WiFi signals were available.  Even the combination of cell tower and WiFi would produce a scatter-plot of positions, rather than a linear, equally spaced set of positions that line up with the road you're on.

     

    The WiFi location feature is especially effective for iOS devices without GPS when you are staying in one spot or walking down a sidewalk in a downtown area where there are many wifi signals.  Even then, it is only accurate to a few hundred feet.  GPS (without WAAS) is accurate to about 10 meters in good conditions.

  • by earlc13,

    earlc13 earlc13 Jun 23, 2013 6:49 PM in response to MeplatMasher2
    Level 1 (0 points)
    Jun 23, 2013 6:49 PM in response to MeplatMasher2

    Excellent summary !

  • by VinceRN,

    VinceRN VinceRN Sep 10, 2013 4:57 PM in response to MeplatMasher2
    Level 1 (0 points)
    Sep 10, 2013 4:57 PM in response to MeplatMasher2

    Interesting thread.  I got here beasue I am considering changing from an Android phone to a 5s, and the GPS is one of the major concerns for me.  My research today shows that the GPS is jsut as good on the iPhone as on my Android for my needs.

     

    I think the problem comes from people thinking that GPS and mapping are the same thing.  The map you see is not GPS and has nothing to do with GPS.  The GPS signal is just a set of numbers that software finds on map and displays on your screen.  The Compass app will give you your actual GPS coordinates, and will do so when there is no map available, no wifi, and no cellular.  The GPS Staus App will give you slightly more detailed info.  Seeing a non moving dot on the map is a problem with the mapping software or the data connection it uses, not with the GPS.

     

    In my experience most people seem to think that GPS and Map mean the same thing, and it is often difficult to convince them otherwise.

     

    The only problem with Apple's GPS is that it does not use WAAS data.  As far as I know no smartphone uses WAAS from the GPS signal.  In urban areas with lots of cell towers and WiFi, and using GLONASS it can come close to WAAS accuracy, but away from Cellular and WiFi, when it is using jsut standard GPS and GLONASS, it is less accurate than a GPS that uses WAAS.  I have noticed this when Geocaching in remote areas.  It is a difference between a few meters of accuracy and a few tens of meters of accuracy, so for most applications it doesn't matter much.

     

    If you are trying to use the iPhone for actual navigation this can be a problem.  There are external WAAS capable GPS modules that can be used though, I have seen pilots using them.

     

    Message was edited by: VinceRN

  • by VinceRN,

    VinceRN VinceRN Sep 10, 2013 5:10 PM in response to VinceRN
    Level 1 (0 points)
    Sep 10, 2013 5:10 PM in response to VinceRN

    Also, if you really want to verify the presence of a real GPS receiver, I found an App called GPS2IP that can export the NMEA data, including how many sattelites are  fixed.  It costs money and can only export the data to other devices like your computer, for some reason Apple does not want you to be able to access this data on the device.  It is not quick and simple, and requires some technical knowlegde, but can absolutley verify the real GPS receiver if used away from WiFi and Cell service.  Seems a bit extreme, but it is one way to verify it if you question the published specs.

  • by mrmopar5287,

    mrmopar5287 mrmopar5287 Sep 16, 2013 7:01 PM in response to hadtomakeupaname
    Level 1 (1 points)
    Sep 16, 2013 7:01 PM in response to hadtomakeupaname

    Can you or anyone here give advice on how to use just GPS input on a Sprint iPhone 4s?  I want to turn the CDMA and GSM radios off so the battery isn't draining while searching for signal, and just use the GPS receiver in the phone.  I can see how if I had a GSM iPhone I could get that done with the steps listed, but how do I get this done with a Sprint phone?

  • by steve.cerrato,

    steve.cerrato steve.cerrato Sep 27, 2013 2:09 AM in response to JohnPacheco
    Level 1 (0 points)
    Sep 27, 2013 2:09 AM in response to JohnPacheco

    ok so the other day i downloaded an app for training its called "nike running" and after i used the app it will show me the place where i ran or the street.I dont have cellular data on my iphone so how is this happening ?

    it will be cool that i can use my phone as a gps some time

     

    I'm from Nicaragua so i dont know if this feature could be use worldwide

     

    regardsss !!

  • by Harbin96,

    Harbin96 Harbin96 Oct 7, 2013 6:10 PM in response to mrmopar5287
    Level 1 (0 points)
    Oct 7, 2013 6:10 PM in response to mrmopar5287

    Okay, I have an iPhone 4S and if you turn off cellular data and wifi, it can find your location and track it. I use myTracks for hiking and stuff. If only there was a way to turn on the GPS alone... I know you can put airplane mode on and then turn on wifi and Bluetooth but I'm not sure about a GPS. Too bad Apple didn't include a GPS widget in the new Control Center...

  • by andelew,

    andelew andelew Nov 13, 2013 1:01 PM in response to hadtomakeupaname
    Level 1 (0 points)
    Nov 13, 2013 1:01 PM in response to hadtomakeupaname

    I noticed you can turn cellular date and wifi off in settings, do you need to place a sim lock on the phone also to make this work?

     

    thank you

  • by ramsesvi,

    ramsesvi ramsesvi Nov 18, 2013 7:50 AM in response to JohnPacheco
    Level 1 (0 points)
    Nov 18, 2013 7:50 AM in response to JohnPacheco

    Hello speaking on this topic to ask a question:
    There is an app for Iphone 5s to see the FIX satellites?
    I'm interested to see how many satellites hooked my iphone at a precise moment.
    For years, I'm looking for
    thanks

  • by VinceRN,

    VinceRN VinceRN Nov 18, 2013 11:16 AM in response to ramsesvi
    Level 1 (0 points)
    Nov 18, 2013 11:16 AM in response to ramsesvi

    Nope, for some reason no one seems to know Apple prevents access to that information, they feel that users should not know what satellites they are connected to. Since access to that info is standard on all GPS chips Apple has to actually have taken extra steps to hide the info.

     

    It's the one thing that is keeping me from switching to iPhone even though I have an iPad and a Macbook.

  • by Chris CA,

    Chris CA Chris CA Nov 18, 2013 11:36 AM in response to ramsesvi
    Level 9 (79,670 points)
    iTunes
    Nov 18, 2013 11:36 AM in response to ramsesvi

    Developers have access to Location Services, which is the interface between apps and GPS and other location information.

    They don't have access directly to the GPS info.

  • by Chris CA,

    Chris CA Chris CA Nov 18, 2013 11:44 AM in response to VinceRN
    Level 9 (79,670 points)
    iTunes
    Nov 18, 2013 11:44 AM in response to VinceRN

    VinceRN wrote:

     

    Nope, for some reason no one seems to know Apple prevents access to that information, they feel that users should not know what satellites they are connected to.

    Really?

    That's why it's not accessible?

    They didn't do it to make a simpler I/O for developers to get all location data, not only GPS?

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