Tell/Ask HN: My Location is different on iPod touch vs Laptop Google Map

by code_devil on 12/29/2009, 7:22 AM with 2 comments

I used the "Show my Location" feature to find out my current location using my laptop and my iPOD touch device's built in Maps. Apparently, the iPOD touch is showing that I am about 1 mile away. (It used to show the accurate location before)

I am using the same WiFi network for both(my home Comcast cable) and they are in the same internal private subnet effectively having the same public facing IP. I am curious how this is possible as I thought the IP is resolved to the location.

  • by colonelxc on 12/29/2009, 7:47 AM

    You are correct about how it works. Companies have (or buy) geo-ip data to correlate ip addresses with real world locations. These databases change frequently (IP's bought and sold, people's residential IP's changing).

    There's a couple possibilities about why it is different. Maybe the maps app actually goes through Apple first, and there is a slight flaw in the most recent version of Apple's geo-IP database. Even if they both query Google for the location, it's possible that different sets of servers serve the mobile maps versus the web maps, and they are slightly out of sync with which databases they use.

  • by gojomo on 12/29/2009, 9:58 AM

    It's not just IPs; visible wifi base stations with known locations are also used, if that info is shared by the client (as I believe both the Google Maps app and Firefox 3.5+ offer). So any difference in the devices' signal reception could result in different location guesstimates.