Current Location In Maps on iPod Touch Changes

[GhostBook Pro]

I noticed today that the iPod Touch Current Location feature in Maps moves as you move around when you are going somewhere. My friends and I were speculating that the change might be calculated several ways.
1. The iPod uses and internal compass and accelerometer to do dead reckoning. Though I argued that the Compass Free app shows that the iPod has no internal compass.
2. It knows all the wireless network names in the world and where they are and uses the wireless card to reference surrounding networks with it's list. (unlikely)
3. It somehow connects to these networks, secure or not, and asks a web resource what it's location is, or the networks are broadcasting their geographical locations with some Skyhook add-on.

We're all looking forward to being enlightened about this feature.

Also, just as a side note, is this the right website to be posting apple hardware questions? If not, what is the correct forum.

Thanks,

GhostBook Pro

[Maruk]

A friend of mine noticed that feature, and I must say it has significantly added to the usefulness of my ipod.

I think it works by downloading a list of the wireless networks near the spot you're looking at when you first download the map. Once it has that list, it doesn't need to use the internet any more in order to locate you, as long as you're near one of those networks.

1) I don't think the ipod has an internal compass, and the accelerometers aren't accurate enough to track the ipod's position, or even horizontal orientation (ie, if you lay it flat on a table, then rotate it around the vertical, it wont know.) You can use GPS in the iphone to act like a compass, but only by travelling far enough that the GPS registers a change. It can then tell you which direction you travelled in.

2) There are a lot of wireless networks in the world - presumably it just caches the ones on your cached map.

3) Secured networks use encryption for all traffic, and don't just make exceptions for individual web services. You either have access to the network or not, there are no half measures. That said, there is an unsecured network (the cloud, I think it's called) in many places in London, which needs a username and password for web access, but allows you to download google maps data even if you don't have an account. However, last I checked Skyhook wireless wasn't accessible through that, so it couldn't find my location. This partial access to the internet only works because the wifi network isn't encrypted, it simply requires you to log into a website before it will let you access websites.

If you're bored, you can convince yourself that the ipod can't track you when you're not in range of wireless networks by walking around in the countryside, or simply by turning the wifi off once you have your location.

All the best!

Maruk