Nearby wont find my location

Same problem, and I'm in Dallas.

It's very strange. I moved 2 years ago to Vancouver BC and somehow my ipod touch thinks I am still back in Pittsburgh PA. Maps, Urbanspoon and nearby all do this. Where does it get my location and how do I change it? I tried updating contacts, default location on google maps, etc. What can I do?

Problem Solved! I changed my default location on my google maps account and YAY, now all my ipod touch apps know where I live!

...wait a minute

...this is kinda scary

(it amazes me how these apps and services are integrated)

For anyone else who stumbles across this issue while using Platial, here are some related links and some basic information.

Links:

1. Website for Skyhook Wireless


2. Info about how the WiFi positioning system works at skyhookwireless.com


3. Skyhook's FAQ has information about the WiFi positioning system


4. Coverage map at Skyhook's website


5. Skyhook allows anyone to submit a WiFi access point. There is some debate about whether this is a good idea or not. For their part, Skyhook claims that their algorithms can weed out bad information


6. A USA Today article about Skyhook Wireless from Jan 2008 at usatoday.com


7. A short explanation of a iPhone iPod location spoofing attack that provides some info about how the service works (and fails)


8. Skyhook Wireless has a forum with Get Satisfaction

The iPod Touch has exactly one option for attempting to find your location, and that is WiFi. By comparison the iPhone 3G has 3 (WiFi, the cellular radio, and GPS), and the original iPhone had 2 (WiFi, and the cellular radio). Combining multiple technologies, as the 1st and 2nd gen iPhones do, is sometimes referred to as a 'hybrid positioning system' (or 'hybrid location services'). By combining different location technologies we can hope to overcome the limitations of any one of the methods.

For example, GPS is accurate but often unavailable; cell (i.e. determining location by distance and relative position from reachable cell towers) is often available when GPS isn't but is less accurate; WiFi is really a last resort and is the best option only when GPS is unavailable and cell triangulation fails (where there is no cell coverage and also there is no clear line of sight to the sky for GPS).

I'll limit myself to talking about WiFi location because that is the only service that applies to the iPod Touch (which lacks a cell radio or GPS hardware).

How does it work? A company called Skyhook Wireless maintains a reference database of access point locations (public WiFi network access points). This database is created through a data collection process which involves sending out a fleet of vehicles to targeted areas to record information about WiFi devices they find (SSID, MAC addresses, and signal strength). This is essentially a form of wardriving except that the purpose isn't to connect to the networks (which is why Skyhook doesn't worry too much about the legal issues involved in mapping open WiFi networks for the purposes of connecting to someone else's network).

Skyhook does a very thorough job of those areas they choose to target. They claim to have 70% coverage in North America and are aggressively expanding (particularly in Europe). For these areas, they literally drive "every passable road". You can see a map for the data for San Francisco on their website (look for the San Francisco coverage area map on this page).

With this data in place, the service can begin operating. It's capable of making adjustments on its own. Let's say I'm near an access point that the service doesn't know about because it didn't exist when they mapped the area, but my new access point is near several others that they do know about. It can fix the location of the new access point by determining its position relative to the others. In this way, the service can deal with changes within an area, but it can't expand in any good way outside of the known regions (well in theory it can slowly expand this way).