General Find my friend question regarding the size of the circle.

Discussion in 'iOS 9' started by slowanimal, Jul 13, 2016.

  1. slowanimal macrumors newbie

    Joined:
    Jul 13, 2016
    #1
    I'm not sure if it's been addressed in prior threads but I can't seem to find any. I'm curious to see if anyone knows what affects the size of the circle. Sometimes I've noticed the person can have an exact location in the same spot, then later that day/night, it becomes larger. Does the amount of people in proximity have something to do with it? how about features like do not disturb?
     
  2. slowanimal thread starter macrumors newbie

    Joined:
    Jul 13, 2016
    #2
    anything? does the proximity of 2 people with find my friends possibly make their circle larger? or possibly low power mode?
     
  3. Mlrollin91 macrumors G4

    Mlrollin91

    Joined:
    Nov 20, 2008
    Location:
    Ventura County
    #3
    The size of the circle depends on the accuracy of the GPS. If you the person is connected to WiFi its going to be more precise quicker. If its cellular, it will eventually zoom in closer, but will always start with a larger circle as it tries to determine the exact location.
     
  4. rigormortis, Jul 14, 2016
    Last edited: Jul 14, 2016

    rigormortis macrumors 68000

    rigormortis

    Joined:
    Jun 11, 2009
    #4
    The size of the circle is the degree of certainty

    GPS is accurate within 30 feet of you, as long as you have clear line of sight. But what you have realize is that a lot of times the iphone just fakes your location, because it wants to save power.

    Real gps locks can take several minutes

    When an app wants to know your location, at first the iphone sends the MAC addresses of your local wifi neighborhood to one of three sources ( apple , wigle & skyhook ). This is used as a temporary placeholder until the real GPS lock has been established. This saves power.

    If you iphone is constantly connected to your home or work wifi networks, its a waste of time and battery power to keep getting GPS coordinates for 30 different apps from the satellites. So it just uses wifi instead.

    AGPS means the device has a real GPS receiver but it uses Assistive Technologies to either SPOOF or to CHEAT and get the GPS lock sooner.


    I've been wondering if ' frequent locations ' is used to cache wifi networking. If this is true, then internet connection may not be needed.

    Please see this apple support article, it says it does not use the GPS to get an exact location every single time. Approximate is good enough. If the circle is small then it is exact. If the circle is big then it is approximate.

    I recently tested this by taking my iPod touch out for a walk while tethered playing "Pokemon go" and saw obvious signs that it was the wifi networks in the neighborhood that caused my avatar to "walk", my avatar would walk, sometimes in a circle, and when I walked in front of a house, my avatar moved on the map

    https://support.apple.com/en-us/HT203033

    The way gps works is its basically impossible to get your location in a split second from a cold start. It could take anywhere from 90 seconds to 25 minutes to get a gps lock. Thats 90 seconds to 25 minutes of battery power your consuming. So instead. The iPhone just scans your wifi networks around you, fires up the cellular radio, sends in the scan results to either apple, skyhook, or wigle and uses that as your location while you are waiting for the circle to get smaller
    --- Post Merged, Jul 14, 2016 ---
    Gps is a system of satellites. They are not in geosynchronous orbits like Westar 5. They are not constantly broadcasting non stop 24/7 like GALAXY 1/ They only send out a ping every 90 seconds or so. And because they are constantly orbiting in a different trajectory you have to know where to look. TomTom used to download constellation tables to predict where the satellites are of the next 7 days, and its a good guess that apple does this too. The other way to speed up is to scan more then one channel at once. So even you are scanning all 24 satellites at once, you might have to wait 90 seconds for an occasional ping. And you need 3 to 5 pings to get your true location.
     
  5. slowanimal thread starter macrumors newbie

    Joined:
    Jul 13, 2016
    #5
    awesome, so two people can't cause an issue where it pushes someone out of a location, thanks!
     

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