"Stupid? Or just Evil?" UCAP #216

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koehn
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"Stupid? Or just Evil?" UCAP #216

Postby koehn » Mon Dec 20, 2010 10:25 am

Wanted to throw my hat into the ring re: how wifi geolocation works.

My guess is that Jeb told Apple his address when he registered his iPad, and it picked up the router's ethernet MAC address, fired up the GPS, grabbed a location, and shipped all that information to Apple, which dutifully updated its Wi-Fi location database.

In short, yes, Skynet now knows where Jeb lives.

Landis
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Re: "Stupid? Or just Evil?" UCAP #216

Postby Landis » Mon Dec 20, 2010 11:26 am

Just listening now and wanted to share a link in regards to using the iPad as an EFB. Turns out some people have experienced inopportune failures. Something to be aware of before throwing away your paper charts. http://www.nafinet.org/APPLE_IPAD_USED_AS_AN_EFB.pdf (PDF - sorry Jack).

-L

hmng
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Re: "Stupid? Or just Evil?" UCAP #216

Postby hmng » Mon Dec 20, 2010 1:27 pm

koehn wrote:Wanted to throw my hat into the ring re: how wifi geolocation works.

My guess is that Jeb told Apple his address when he registered his iPad, and it picked up the router's ethernet MAC address, fired up the GPS, grabbed a location, and shipped all that information to Apple, which dutifully updated its Wi-Fi location database.

In short, yes, Skynet now knows where Jeb lives.


Actually, all that is for the iTouch or iPad WITHOUT 3G; if a unit has cellular connection, the network KNOWS, by definition where you are, it needs to know to what base station (antenna) it must talk to reach the device.

Henrique Gomes

koehn
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Re: "Stupid? Or just Evil?" UCAP #216

Postby koehn » Mon Dec 20, 2010 2:30 pm

The cell network doesn't know where you are to any degree of accuracy. It can get you to within perhaps a few hundred meters, but beyond that you need GPS.

The GPS in an iPhone/iPad 3G is "seeded" by the 3G network by finding the nearest towers and getting the towers' locations and the (approximate) time. From there it can determine imprecise location and use that to determine which GPS satellites are overhead, and start trying to tune in those satellites, which takes a minimum of several seconds. Once it has the satellites tuned it can calculate the precise time (to within a few µs) and location.

One thing that doesn't work well with the built-in GPS is when you activate it at altitude. When it tries to find the nearest towers it often cannot, either because you're out of range or because there are too many in range and it cannot determine where you are to seed the GPS tuner.

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Sven
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Re: "Stupid? Or just Evil?" UCAP #216

Postby Sven » Tue Dec 21, 2010 12:02 am

To fix the airborne GPS problems with the iPhone and the iPad, I use a little $99 device called Bad Elf. It's a very small GPS antenna that plugs into the sync port. You can also charge your device through it. Check it out: http://bad-elf.com/products/gps/

Just so long as you're using an app that caches your charts or info, it will track you as high as FL600 and at speeds in excess of 1,000 mph. My Southwest 737 never hit that altitude but with a 168 kt tailwind we almost hit that speed (almost). It was fun sitting by the window and knowing where I was on the VFR charts. I haven't tried it in the Mooney yet because it won't stop raining here in Northern CA. I wouldn't use it as my primary GPS but I am planning on using it as my backup along with my paper chart. The nice thing about the Bad Elf is that it does not come with a subscription fee. Take that, Garmin.

-Sven
Flying a Mooney M20D. One of only 3 fixed-gear Mooney aircraft still flying.

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jackhodgson
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Re: "Stupid? Or just Evil?" UCAP #216

Postby jackhodgson » Thu Dec 23, 2010 11:17 pm

Very neat looking accessory.

But I've always wondered if any sort of GPS device is an "allowed" device in a cruising airliner?

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ATC_Ben
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Re: "Stupid? Or just Evil?" UCAP #216

Postby ATC_Ben » Fri Dec 24, 2010 12:41 am

Jack, if it doesn't transmit anything I can't see a problem with it. Problem is does 'flight mode' kill the GPS antenna too with all the other stuff?? I certainly don't subscribe to turning flight mode off to gain use of the GPS function!
Caelus latus sursum

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Sven
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Re: "Stupid? Or just Evil?" UCAP #216

Postby Sven » Fri Dec 24, 2010 4:18 am

The Bad Elf worked in flight mode on my iPhone 4. I mean, my friend's iPhone 4. ;)
Flying a Mooney M20D. One of only 3 fixed-gear Mooney aircraft still flying.

Greg Bockelman
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Re: "Stupid? Or just Evil?" UCAP #216

Postby Greg Bockelman » Fri Dec 24, 2010 10:57 am

I used to wonder what the big deal was as far as electronic devices in airplanes goes. I finally got an answer I could understand.

Each airline is required to determine which device will or won't affect the flight. But it isn't that simple. You see, the fuselage acts like a wave guide. So the signal emitted by a device will bounce around inside the fuselage. Now, when you add to it the second device, you have a different set of signals bouncing around. Each device adds its signal to the mix. It isn't possible to test for all the possible combinations, so they ban them all.

Reality is, it isn't likely that any one device will affect the airplane, but it HAS been determined that some will.

randyc
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Re: "Stupid? Or just Evil?" UCAP #216

Postby randyc » Sun Dec 26, 2010 11:09 am

I still have my palm VIIx and the software from cheapbastards.com loaded onto it...it was amazingly effective around here. I could go from Pittsburgh to Savannah and almost always have a decent coverage.


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