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iPhone-iPad Wifi Tethering: Location info passed on as well.

P

puercaeli

macrumors regular
Original poster
I got 4.3GM and did little test driving around with iPhone-iPad tethered by WiFi. Surpisingly, location on iPad Map application changed(although very delayed) as the car moved around. And this was not like urban area where it was completely covered by WIFI signals.

So it looks like iPhone might be passing on location info as well as internet connections to iPad...
 
puercaeli said:
I got 4.3GM and did little test driving around with iPhone-iPad tethered by WiFi. Surpisingly, location on iPad Map application changed(although very delayed) as the car moved around. And this was not like urban area where it was completely covered by WIFI signals.

So it looks like iPhone might be passing on location info as well as internet connections to iPad...
Click to expand...

Are you sure it was passing location data? If it was you would get an exact location (a GPS ping icon would appear on the map) and not just a circle around the area you are in.

Remember that the Skyhook Wi-Fi location stuff does not require an active internet connection for it to work. It is pretty crazy how awesome it works at times considering it's just using some cool math to figure out triangulation.
 
puercaeli said:
I got 4.3GM and did little test driving around with iPhone-iPad tethered by WiFi. Surpisingly, location on iPad Map application changed(although very delayed) as the car moved around. And this was not like urban area where it was completely covered by WIFI signals.

So it looks like iPhone might be passing on location info as well as internet connections to iPad...
Click to expand...

iPhone does no such thing. As you drive by WiFi hotspots - iPad determines its location via the usual WiFi hotspot triangulation, by using Apple's WiFi hotspot location database.
 
ovrlrd said:
Remember that the Skyhook Wi-Fi location stuff does not require an active internet connection for it to work. It is pretty crazy how awesome it works at times considering it's just using some cool math to figure out triangulation.
Click to expand...

Now I'm curious. If there's no active Internet connection, how is the data to map the wifi signal(s) to a geolocation acquired? It would seem that would require a somewhat significant local database. AFAIK, wifi signals do not encode any geolocation information.

Note -- I'm not challenging your statement, I just don't see how it would work and am curious to know more. According to Skyhook there's client-server communication required. If there's no data connection, how does that communication occur?
 
hitekalex said:
iPhone does no such thing. As you drive by WiFi hotspots - iPad determines its location via the usual WiFi hotspot triangulation, by using Apple's WiFi hotspot location database.
Click to expand...

To be fair to the OP, there is a special icon that replaces the WiFi icon on the iPad when you connect to the hotspot on the iPhone. I don't know if that is just for fun or if there is a bigger reason for that. Since it detects the iPhone hotspot, there is no reason why Apple couldn't implement some special features that communicate between the two devices. I would love it if it could share GPS data, but you are right it's probably not doing that at the moment.
 
deeddawg said:
Now I'm curious. If there's no active Internet connection, how is the data to map the wifi signal(s) to a geolocation acquired? It would seem that would require a somewhat significant local database. AFAIK, wifi signals do not encode any geolocation information.

Note -- I'm not challenging your statement, I just don't see how it would work and am curious to know more. According to Skyhook there's client-server communication required. If there's no data connection, how does that communication occur?
Click to expand...

I'm wondering this too. And even if it does acquire the location somehow, how does the map app load the map if there is no data coming through?
 
deeddawg said:
Now I'm curious. If there's no active Internet connection, how is the data to map the wifi signal(s) to a geolocation acquired? It would seem that would require a somewhat significant local database. AFAIK, wifi signals do not encode any geolocation information.

Note -- I'm not challenging your statement, I just don't see how it would work and am curious to know more. According to Skyhook there's client-server communication required. If there's no data connection, how does that communication occur?
Click to expand...

iPad accesses Apple's geolocation database via tethered Internet connection. If there is no working Internet connection - WiFi iPad cannot do any location mapping.

Also for the record.. iOS devices no longer use Skyhook's services. Apple switched to its own location services sometime in 2010.
 
Does Skyhook work if there is no Wifi nearby whatsoever?
Also this was like in suburbs surrounded by national park in Northern Sydney... so unless there is like other algorithm I am aware of, I am not so sure how iPad Wifi is retrieving location info.


And that special icon does look suspicious to me too.
 
puercaeli said:
Does Skyhook work if there is no Wifi nearby whatsoever?
Click to expand...

Nope. And it's not Skyhook, as per my post above (although Apple's own geo services work similarly).

puercaeli said:
Also this was like in suburbs surrounded by national park in Northern Sydney... so unless there is like other algorithm I am aware of, I am not so sure how iPad Wifi is retrieving location info..
Click to expand...

I am sure there were WiFi hotspots nearby - there is no magic to this. I used to tether my iPad to an Android phone (no special iPhone-to-IPad GPS protocol there right?), and the iPad location mapping worked exact same way.
 
Last edited:
I am also interested in finding out whether ipad (2) can receive gps information via the new iphone 4 hotspot feature. I have an iphone 4 and am considering buying wifi ipad2.

I have looked at the various posts where people think this is happening including the link above, but I think none of them are conclusive. I was wondering if anyone with the devices is willing to run some tests please? I think the following steps should be more conclusive in telling us what is going on:

1) Go to a spot where you know there aren't any wifi signals around. You can check by making sure ipad is not picking up any signals in settings->wifi menu.
2) Confirm by going to the ipad maps application. It shouldn't be able to find your location.
3) Turn on iphone 4 hotspot feature and get your ipad to connect to it.
4) Go again to the ipad maps application and it should now be able to find you.
5) Disconnect ipad from the iphone 4 hotspot and see that the ipad maps again cannot find your location. This step is important for the next step 6 I think.
6) As a final step, turn off cellular data under settings->general->network on your iphone 4, reconnect ipad to the hotspot and see if the ipad maps application can again find your location. Move around to see if it tracks your movement.

I think steps 5 and 6 are interesting because they tell us whether you need an active data connection on the iphone 4 for this to work. It shouldn't need it if direct GPS data is being passed to the ipad. On the other hand if it does need it it would suggest (maybe) iphone 4 is sending its mac address with location info to the apple database and then ipad is using plain "old" wifi location service via apple database and treating the iphone 4 as just another wifi (if it is true it might explain the 1min update interval reported on the other site).

This can of course be repeated with mywi instead of iphone 4 hotspot feature, but I am personally interested in the iphone 4 hotspot (which I think has more of a chance of working as it is apple tech).

Thanks to anyone willing to run the test 🙂
 
I did this for a 2.5 hour trip on Saturday and it tracked correctly the entire way (with bits of expected jitter along the way). It works. Not sure what people have to gain by denying it. Maybe they just haven't tried it? I had my iPad 2 tethered via WiFi (MyWi) to my iPhone 4 for the drive.
 
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