WiFi based Mapping

Hi, as some of you know, I am not really into Apple stuff, but my daughter got an ipod touch for her b day recently. In addition to the normal ipod stuff, it has email, web browser, wifi, and a mapping application.

I am familiar with GPS from sats, and aGPS from cell phone tower triangulation, but I was very surprised that this thing provides a remarkably accurate position based on the WiFi router / DSL it is connected to. Not GPS accurate, and of course fixed position, but still, pretty decent.

We tried a few locations around town - when it was near "secured" wifi connections, there was no position value on the map, but anytime we were near a wifi connection that was open, we could get a reasonable fix.

The only thing I could come up with is that it is using the IP adr. to find the location, or it is somehow able to connect to an IP adr. vs location database from the phone company. In some ways, it was a bit un-settling to imagine that anyone in the world with my IP adr could so easily show up at my house. (yes, I am a privacy advocate)

Any ideas on how this is implemented ?

It's based on SkyHook's Wifi location technology, here is some info on it:

"Every Wi-Fi access point, whether public or private, sends out a signal every second or so, like a lighthouse. We pick up those signals and use our technology to calculate your exact location."
http://www.macrumors.com/2008/01/23/skyhooks-wi-fi-location-technology-for-iphone-ipod-touch/

Interesting stuff I've never heard of before. You got me to read more about in on the Skyhook website: http://www.skyhookwireless.com/howitworks/

That's an interesting setup. They appear to be monitoring SSID broadcasts by driving around in cars.

If you want to be stealthy, turn off the SSID and they will not see a radio signal except when you are actively connected.

Of course, they mention that the database is 'self healing', and hint that as users use it, the info those users have will be uploaded. So if you use a wi-fi enabled phone with skyhook installed, it might actually report your access point back to skyhook.

I'm not too worried about it. Any frequent poster will have little nuggets of information spread all over the net. Enough of those nuggets and anyone can be found.

And, of course, there is no legal prohibition against your ISP giving your location to anyone who asks.

Daniel

Hi, thanks for all of the info.

Hi Daniel. :wave:

The part that I am still not clear on, is which part of the signal they are working from. The web sites indicate that it would obtain sufficient information just from the "heart beat" signal of a router, be it secure or unsecure, to make the concept work.

The company takes some pain to point this out, as they don't want to be accused of using any actual data gleaned over the signal and internet connection.

Nonetheless, in our very simple testing, the "mini mac" as we call it, was not able to find its position from secured routers, but easily able to find it from "open" routers. Is the SSID, IP adr, or MAC adr hidden on a normally "secured" home router ? I know you can turn off this ping signal from (some) routers to make it harder to tap into, but we were clearly able to see the router ID names, so this "ping" was on.

A good case in point, is we were at the jamba juice (yes, another bday gift from her friends) and could pick up starbucks (att and t mobile) along with apple bakery, etc. Only Apple Bakery's signal was "open", so it found the location. Even though the T mobile and ATT signal were not secured (behind a walled garden / re-rout server), we could not get the position from them.

In any event, it is an interesting application for around town use by teens.

I will stay with my Nokia pad, but this is an interesting gadget. I have to give Apple credit for making the sync function on this remarkably simple and fast. In less than 5 minutes, my daughter plugged it into her mac, told it to sync, and had all of her pictures, music, and 2 IMAP email account settings transferred with no interaction.

She tapped out a couple of emails at dinner in the rest, and sent them from our DSL when she got home. Pretty handy.

Well another thing...

The data the iPod Touch is pulling for the Google Maps application is also through WiFi, so it's entirely possible that part/all of the reason it can't find your location when you can only see secured WiFi bases is because...the iPod Touch (Sorry, there's already a Mini Mac) can not connect into the internet at those times.

My iPhone can find my location just about anywhere, but it's using WiFi + Cell Tower triangulation, and if I'm not in WiFi range it's able to pull data through the cell network.

SkyHook also has a way that you can help it 'heal' it's database. It had a pretty good estimation of where I was when I was at home, but once I told it the exact location of my home WiFi router, it started locating me a lot more accurately when I am at home.

Thanks for the extra info everyone. I looked at using a cell tower based service for location, but there is a little nagging thing that keeps me away from it - dead zones.

In CA, we have large areas with no cell phone coverage (GSM at least), esp. in the remoter areas where you need it. The local state parks also seem to have no service, even in the areas just outside of town. No cell tower = no location info. If you are hiking in a camp area, you are pretty much SOL without a "real" GPS".

Interestingly, even with sat based GPS, it is still easy to be far from your intended goal. I rented a car with a GPS shortly after 911, knowing the GPS system was "reduced accuracy". What I did not expect, is that I would end up in the wrong town. :laughing:

I was lucky to know more or less how to get to the customer site, so it was fixable, but it was interesting explaining this to my boss, who was riding shotgun for the meeting.

For sure, that's why I'm still a big advocate of people owning a TomTom or Garmin Nuvi, especially now that they've come down in price so much. Murphy's law will dictate that the cell phone network will start acting up when you really need directions from your phone the most!

That said, my 1st Generation iPhone, even without GPS, has greatly reduced my need to take my Garmin GPSMap 60CS *everywhere* with me. (I am totally directionally challenged.)

I remember seeing some discussion that the touch may be using the accelerometer built into it to do basic tracking once it leaves a wifi spot.

For more info, there's a pretty active ipod touch user forum here: http://forums.macrumors.com/forumdisplay.php?f=103 Yes, macrumors is mainly a rumor site, but they tend to talk about the existing products as much as folks talk about lights here.

So it figures - now my wife wants an ipod touch. I need to figure out if I can get ahold of an old rev 1 or the new rev 2 - and figure out what the difference is.

Shame I missed this when I was going through some trouble with my iTouch awhile ago, but I was eventually pointed to Skyhookwireless. Skyhook has mapped out some parts of the country, mainly highly populated areas, but a lot of the country isn't mapped. My iTouch had no idea where I was, unless I was by a public Wifi that was in Skyhook's database. So I submitted my router to their database and about a week later I was in business! It works by reading the router's MAC address, then seeing if Skyhook has that MAC address in the database. If the MAC address is there it sends the router's coordinates to the iTouch, iPhone, etc. I used Google Earth to get accurate coordinates on my router's location.

I believe the iPhone can use XPS, which is GPS, cell tower location, and Wifi location. So if it can pick up on all of these it can be very accurate with your position. I have found my iPhone's GPS to be highly accurate.