iPod touch iPod Touch tracking location as I drive

[tukey-kramer]

So occasionally I will use the maps app on my iPod touch 3g (32GB) to get to places I am not familiar with. I will input the starting and ending addresses and go through all of the steps on my route while I am at home and have access to my home WiFi network. I do this in order to make sure that the maps get cached into my device so I can access them once I don't have internet access. The other day, I was stopped at a light and I opened the maps app to see where I needed to turn next to get to my destination.

To my surprise, the location pin dropped exactly at the intersection where I was waiting. Today, I decided to test out the location tracking on the device, and so I had my wife look at it as we ran an errand, traveling about 7 miles away from my home. Over the entire journey, the location pin tracked our progress and was fairly accurate (I don't think it ever got more than 300 meters behind).

Can someone explain to me how this works? I know my device doesn't have a GPS chip, and I am aware of the location triangulation feature that works using wireless hotspots and MAC addresses of local wireless networks, but I thought you had to have an internet connection for the device to check the hotspot or MAC address against the database of locations. Is it possible that my device cached all the MAC addresses I could encounter along my route? I live in Champaign, Illinois and my route included two private neighborhoods. Any ideas?

 

[pilotrtc]

Wow! My guess would be the cache theory. Another test you could do is load up your device with the maps, turn off the WiFi and then go for a drive.

 

[Tikker]

everytime the wifi latches onto an accesspoint that's been submitted to skyhook it will update your location

no wifi, no updates

 

[PaperQueen]

I will input the starting and ending addresses and go through all of the steps on my route while I am at home and have access to my home WiFi network. I do this in order to make sure that the maps get cached into my device so I can access them once I don't have internet access.

Forgive me if this is a stupid question, but “maps” plural? How do you cache (then later access) more than whatever map is most recent?

I’m going to feel like a real bozo if the answer is obvious.......

 

[kungfumonkey]

Forgive me if this is a stupid question, but “maps” plural? How do you cache (then later access) more than whatever map is most recent?

I’m going to feel like a real bozo if the answer is obvious.......

Maps and map are different here. There is one map that gets updated and stored. I think the maps referred to are just locations on the map or routes that someone had recorded on the map - no different than scribbling on a paper map with a sharpie pen.

Unless you are time-traveling or doing military operations, or both, you don't need to have more than one map file. If you do, you need to store your maps on a backup device and then load them to the map system as needed, but only one will accessible at a time from within the map software.

 

[tukey-kramer]

...I think the maps referred to are just locations on the map or routes that someone had recorded on the map..

kungfumonkey has it right--by maps I was referring to steps along the overall route.

 

[tukey-kramer]

everytime the wifi latches onto an accesspoint that's been submitted to skyhook it will update your location

no wifi, no updates

This is correct--if I turn my wifi off, I get a message stating that my location cannot be determined.

 

[Skyhigh223]

This is correct--if I turn my wifi off, I get a message stating that my location cannot be determined.

So what was your iPod connecting to when you were on your route?

Unlocked WiFi hotspots?

If your iPod wasn't connected to some sort of WiFi whilst you were on your route then:

1. You have an iPhone.
2. You have a mysterious GPS-enabled iPod touch.
3. The martians are getting intelligent.

 

[newt2mac]

it doesnt have to connect to them, it just needs to "see" them. I noticed this too and it freaked me out. Still pretty cool. Skyhook.

 

[a sandwhich]

Yep, the app can look for wifi and retrieve the ip address of the spot without connecting. Then it can easily run through a database the location of that ip address. Immagine it sort of like spider man swinging through the city. He sends out a web, latches on, swings, detaches, and repeats.

 

[tukey-kramer]

Yep, the app can look for wifi and retrieve the ip address of the spot without connecting. Then it can easily run through a database the location of that ip address. Immagine it sort of like spider man swinging through the city. He sends out a web, latches on, swings, detaches, and repeats.

How much of that database is mobile though? In subsequent tests, I don't seem to get location tracking if I deviate from the route I have pre-programmed into the maps app. After this conversation and further testing, I am more inclined to believe my initial hunch--that the iPod caches the MAC addresses of hotspots and other wireless networks along the planned route, and then uses that cached database to pinpoint your location.

 

[PaperQueen]

Maps and map are different here. There is one map that gets updated and stored. I think the maps referred to are just locations on the map or routes that someone had recorded on the map - no different than scribbling on a paper map with a sharpie pen.

Unless you are time-traveling or doing military operations, or both, you don't need to have more than one map file. If you do, you need to store your maps on a backup device and then load them to the map system as needed, but only one will accessible at a time from within the map software.

Ahhhh....got it.

The appeal to multiple maps was that I travel heavily for work (ex: five cities in the next nine days). Thought it would be cool to load up on walking maps for several of them so I didn’t have to also tote around my Garmin unit.