How does location function in Google Maps work with WiFi?

Discussion in 'iPod touch' started by iwannamac, Apr 3, 2009.

  1. iwannamac macrumors member

    Nov 15, 2007
    When I press the location feature in the Google Maps app on my 1st gen touch while at home, it is able to pinpoint my location correctly at an accuracy down to my address (based on the "sight" that appears). How does this feature work? I've traced my IP before, and it's only accurate to the city next door. Just curious.
  2. edesignuk Moderator emeritus


    Mar 25, 2002
    London, England
    It "knows" the location of fixed public wifi points and figures it out from there....I think.
  3. iwannamac thread starter macrumors member

    Nov 15, 2007
    Interesting. I'm not aware of any public wifi areas near me. It works like a charm, though.
  4. goosnarrggh macrumors 68000

    May 16, 2006
    The service used by the iPod touch is powered by a company called SkyHook.

    SkyHook does not restrict itself to "official" public WiFi hotspots. Instead, it sends a fleet of vehicles down every navigable street within a covered area, scanning ALL of the WiFi access points in the vicinity (both private and public) and recording their unique signatures (called a MAC address, but it has no relation to the popular computer platform) along with their signal strength at various latitudes and longitudes.

    Whenever the WiFi radio is turned on and CoreLocation is in use, the iPod touch continually scans the MAC addresses and relative signal strengths of all the WiFi access points in the vicinity (not just the one it happens to be connected to), and queries those MAC addresses in SkyHook's database. It can then use those results to triangulate your approximate location.

    If SkyHook's database doesn't contain an entry for the WiFi access points nearest you, or if the WiFi access point has moved since the last time SkyHook refreshed its database, then the iPod touch will provide incorrect location information. In that case, it is also possible for operators of WiFi access points (including owners of private home networks) to submit new information to SkyHook in order to help them improve their coverage.
  5. sandman42 macrumors 6502a


    Oct 23, 2003
    This is the best and most accurate explanation I've seen. Well done.
  6. indy42 macrumors newbie

    Jul 13, 2008

    SkyHook? Hey, me and Batman got something in common!
  7. Brewerpaul macrumors regular

    Nov 25, 2008
    Clifton Park,NY
    Pretty cool, but note that keeping location ON uses up battery power more quickly, so you may want to keep it OFF unless you really need that feature.
  8. iwannamac thread starter macrumors member

    Nov 15, 2007
    Wow, awesome reply. Thanks much!
  9. cmichaelb macrumors 68020


    Aug 6, 2008
    Thanks for the info...I knew some of this but still learned something.

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