iPhone Turn off everything but GPS

Discussion in 'Jailbreaks and iOS Hacks' started by jjk454ss, Jun 8, 2014.

  1. jjk454ss macrumors 601

    jjk454ss

    Joined:
    Jul 10, 2008
    #1
    Maybe I don't need a jb for this, bug I'd also like a quick easy way. Can I turn off everything except GPS, basically airplane mode while leaving GPS on? I'd like to use an app while hiking to track my route, but I want to save battery as much as possible.
     
  2. alkalifly, Jun 8, 2014
    Last edited: Jun 8, 2014

    alkalifly macrumors regular

    alkalifly

    Joined:
    Apr 13, 2004
    #2
    I looked into this a while ago, and am not sure if anything has changed since then, but at the time it was determined that the only way to use the GPS without the phone searching for a signal is to pop out the sim card.

    It is really too bad that the GPS cannot be activated in airplane mode the way wifi can be.

    Edit: it turns out that a LOT has changed since I last looked into it, and the short answer is, it depends not only on what phone model you have, but who your carrier is. The best information is on the page that I originally used to get the info http://adventurealan.com/iphone4gps.htm don't be fooled by the webpage name referring to iPhone 4, it has been updated to include information on the 4S and 5 (though not the 5S yet)
     
  3. jjk454ss thread starter macrumors 601

    jjk454ss

    Joined:
    Jul 10, 2008
    #3
    Thanks, I'll check out that page. I have a 5s but I'm sure it will be helpful.
     
  4. heycal macrumors 6502a

    Joined:
    Jul 25, 2013
    #4
    How accurate is GPS in terms of measuring the distance you walk or run? I notice when I use apps like "Map My Walk" or "Moves", the map created by my walk doesn't quite match where I actually walked.

    For example, if go for an hour walk along a road, the map created by the GPS will show me as sort of zig zagging back and forth down the street, when in reality I'm walking in a fairly straight line. If I were to truly walk where the map shows I did, I would we walking a further distance than I actually walked due to all the zig zagging.

    So I'm concerned that if these apps say "you walked 4 miles" in reality I've only walked 3.2 miles or whatever.

    Anyone have any insight on this issue?
     
  5. jjk454ss thread starter macrumors 601

    jjk454ss

    Joined:
    Jul 10, 2008
    #5
    I use Runkeeper, the map it makes is very accurate. So I can only assume the distance is very close
     
  6. zorinlynx macrumors 601

    zorinlynx

    Joined:
    May 31, 2007
    Location:
    Florida, USA
    #6
    This is what I do:

    Set a PIN on your SIM card. Go to settings -> phone -> sim pin and set a pin. It can be something easy to remember like 5555.

    Then, turn your phone off and back on, but when prompted for the pin, don't enter it. Then turn off Wi-Fi and Bluetooth. Now your phone will leave the cellular radio off, because the SIM is locked, but GPS will still work.

    When you decide to use the phone again, just open the phone app and when you make a call or try to send a text it'll give you a prompt to unlock the SIM. Just enter the number you set and you're all set!

    ----------

    The reason for this is two fold:

    First of all, GPS positioning isn't perfectly accurate down to the foot. You can have some amount of error, possibly even 30 feet even with a clear sky! It all depends on how many satellites are visible and how fast you're moving. So your position won't always be precise. This gets worse in urban areas where less of the sky is visible.

    Second, these GPS apps don't take your position continuously. They take a reading from every second or to even 10-20 seconds between readings, to save battery life.

    When you combine a low sample rate with errors, you will often get the zig zag effect you see. Better apps employ smoothing to fix this.

    I use Cyclemeter to track my bike rides, and find that the distance it calculates is never off from what it says on my odometer by more than a few percent over a typical ten mile ride. I highly recommend this app; it also supports running, walking, hiking, etc. all in one app.
     
  7. heycal, Jun 12, 2014
    Last edited: Jun 12, 2014

    heycal macrumors 6502a

    Joined:
    Jul 25, 2013
    #7
    Thanks. I will check out these alternate apps.

    But is it safe to conclude that my current apps are over-estimating the amount of walking and running I'm doing?
     
  8. zorinlynx macrumors 601

    zorinlynx

    Joined:
    May 31, 2007
    Location:
    Florida, USA
    #8
    You can find out fairly easily.

    Walk a route for which you know the exact distance, and compare.

    You can generate a route in Google Maps to get the exact walking distance between two points.
     
  9. heycal macrumors 6502a

    Joined:
    Jul 25, 2013
    #9
    Really? Interesting. I might do that. Is this guaranteed to be accurate?

    And for that matter, are car odometers accurate?

    ----------

    Tried both these apps on some short drives today, about 3 miles each. Unfortunately they both overestimated the distance compared to the car odometer.
     
  10. zorinlynx macrumors 601

    zorinlynx

    Joined:
    May 31, 2007
    Location:
    Florida, USA
    #10
    I meant my bicycle odometer, which I have actually calibrated to be extremely accurate by measuring my tire circumference.

    Car odometers are usually off by a few percent. They start reading even higher as tire tread wears down, too.
     
  11. heycal macrumors 6502a

    Joined:
    Jul 25, 2013
    #11
    Then who or what can we trust to measure distances in the 3 to 5 mile range, be they through woods, suburban streets, or New York City? (The three places I walk or run.)
     
  12. zorinlynx macrumors 601

    zorinlynx

    Joined:
    May 31, 2007
    Location:
    Florida, USA
    #12
    New York City is easy. There are 20 streets per mile going north or south, once you're out of lower Manhattan. Also note that your GPS will be less accurate in New York because tall buildings play havoc with it.
     
  13. heycal macrumors 6502a

    Joined:
    Jul 25, 2013
    #13
    Not sure how much I trust the old "20 streets per mile" thing. Plus I rarely walk in a straight line from 23rd to 68th street or such.

    So the tall buildings are messing with the GPS in the city, and trees are messing with the GPS in the woods? Where does the GPS work? On the Great Plains?
     

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