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WiFi GPS with an Ipod Touch

In honor of the opening of the new Technology forum, here's my favorite tip:

After a lot of trial and error with my Ipod Touch I've finally figured out how to do it. It's an almost unknown feature, Apple doesn't have any documentation on it, and I've been unable to locate any unofficial info about it either. This will only work when walking around in a city, it won't work as well in a car. I've only tested it with my Ipod Touch but it should also work with a WiFi only Ipad. This is what you do:

  1. Before you leave for your trip you'll need to install an offline mapping app like "CityMaps2Go". You need offline maps because you will not actually be connecting to the internet while you are doing your sightseeing.

  2. When you arrive in a new city you'll have to find a hotpot (hotel, Mcdonalds, Starbucks etc) and connect to the internet. This is the one and only time you need an internet connection.

  3. Open either the built-in Apple "Map" app, or the Google Maps app, and open-up the "directions" option. Now enter any two points in the city, like from the train station to your hotel, or between any other two points of interest. After the app gives you directions the device will automatically load a database (from Apple) of all Wifi hotpots in the entire city! That database will now reside in the memory of the Ipod Touch even after you exit Google Maps, and until you reboot the device. Any other app that uses the location service can now access that database.

  4. At this point you no longer need to be connected to the internet, but the device must still be in Wifi mode. As you are walking around the city the device will be detecting Wifi hotpots (but not connecting to them), the device reads the hotpot's MAC serial number and in the background looks up the hotspot's coordinates off the database, and is able to determine and show your exact location anywhere you are in the city with an offline map app like CityMaps2Go.
    I've now used this feature successfully in Budapest, London, the Big Apple, Toronto, Amsterdam, Beijing and Hamburg. It's very accurate, determines your location in milliseconds, and I haven't come across in gaps in coverage.

Posted by
107 posts

What do you mean when you say "It's very accurate"??
I've tried to use my WiFi-ony ipad to measure distance when I'm out walking, and the wifi only ipad, measures walking distance just as you've described, BUT it measured my walking distance as if I walked from hotspot to hotspot. So if the hotspot is 50-100 yards off of my actual walking route, the ipad thinks I walked to the hotspot, and if the next hotspot is 50-100 yards on the OTHER side of my walking route, it jumps me over there.. So what happened is that my walking route that I measured with my car at 3.0 miles, came out to nearly 7.0 miles measured by the ipad.

So if by "very accurate" you mean that it will show you where you are in the city based on the nearest hotspot, AND there are a lot of hotspots in the city, then it is probably "very accurate", but if you are measuring actual distance walked, or want to get the distance between two locations that are not near hotspots, it may not be as accurate..

I think its a great idea, and useful, but I'm not sure I'd say it was "very accurate"..

Posted by
8906 posts

I've never used wifi GPS for step by step walking directions like you describe. Seems like a bit of overkill to me:) But rather I use it from time to time while sightseeing to see how far away I'm from a museum or metro station. It's never given me any kind of false readings. Last month I was in Beijing and it worked like a charm. I've never been in any city that my device didn't detect a minimum of 10 different hotpots at any one time. So In my experience it is indeed very accurate.