Google Latitude Produces Inaccurate Location Based on Wifi Location

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Here is something that is a bit of shame. I’ve been using Google Latitude for over 2 years, maybe 3, to record my location and then serve it up on this blog to show the general location I’m in. This has been really useful whilst I’ve been travelling, and now I’m mobile again, it would be useful again.

Except its not working reliably. I’ve figured out why though. It’s because I’ve brought my Apple Time Capsule with me which used to be my Wifi access point when I was at home. Google, Apple and a number of other companies have built databases of Wifi access points geolocation so that mobile devices without a GPS can be more accurately tracked to a location.

For example, Google does (or did) part of this mapping as an adjunct to Google Street View. As the Street View camera car travels around the countryside, it listens out for Wifi networks and through triangulation of signal strength they can work out a pretty accurate position (they also got into trouble over capturing too much wifi information in the process). Also, if you own a mobile device with a GPS, (most smartphones and some tablets) that can be used to generate and even more specific location for your wifi router or access point.

Because the wifi access point is tracked using its hardware identifier (mac address), it doesn’t matter what name (SSID) you use (i.e. NETGEAR, DAVEHOME or some such), so reconfiguring that won’t change things. Basically, they are working on the assumption that a wifi access point doesn’t move about.

Except of course, mine now does. If I switch off wifi on my phone, which is what runs Latitude all the time to track me, the position becomes accurate, but if I switch wifi back on, then the position reverts to the old location of the access point. Interestingly though, whilst we spent three weeks on a friends driveway about half a mile from the old house, the position started out as the home location, and gradually over that period crept closer and closer to the driveway location, so it was starting to learn. Maybe over the coming weeks it will start to work out that the constantly changing location will suggest that the access points location is unreliable and it will stop using it, but I don’t hold out much hope.

As a result, the map showing my location may well be inaccurate depending on where I am in the country. As we are off to the midlands next week, it will be interesting to see what it thinks.

If anyone has a better suggestion for a location tracker app that runs on the iPhone, and allows for a map to be embedded on a website, please let me know via the comments.

Update: I’m testing an app called FollowMee for the iPhone which does the tracking and allows me to embed a map. I’m going to leave that alongside the Latitude maps on this site for the time being to see if its any more or less accurate.




One thought on “Google Latitude Produces Inaccurate Location Based on Wifi Location

  1. Jared

    Interesting – I always wondered how Google would handle this kind of scenario. I would be curious to learn the outcome on how Google categorizes the location of your access point over time as you continue to move about.

    Reply

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