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I can imagine the scene...

Shuttle Crew: Hey guys we've brought some iPhones for you guys to do some testing on, and have some fun!
ISS Crew: Awesome! Thanks guys, we'll get on it straight away!
*Swipes Finger*
**Please Connect To iTunes**
Shuttle Crew: Houston, We Have A Problem.
 
There was a Federal requirement that GPS sold in the US cannot display or output info above the limits I quoted, even if they know that info perfectly.

I suppose the prohibition made a lot more sense 15 years ago before GPS chips were commonplace. It might even be gone now... not sure.

Keep in mind that if anything goes down, the big switch for GPS can be pulled as needed. This is why there are two other GPS systems in orbit; the EU Galileo and the Russian GLONASS.
 
Keep in mind that if anything goes down, the big switch for GPS can be pulled as needed. This is why there are two other GPS systems in orbit; the EU Galileo and the Russian GLONASS.

Galilleo's in orbit? Last I'd heard, there was just the Giove satellites, so the big brass could strut around saying, "And over here, gentlemen, we have the satellite that goes 'ping'." I don't think they have anything suitable for navigation.

The Chinese are much further along with Beidou.

I think the Big Switch has been upgraded now so they can deny GPS only in specific areas-- preventing use in hostile areas while still letting Americans find the nearest Walmart at home.
 
Galilleo's in orbit? Last I'd heard, there was just the Giove satellites, so the big brass could strut around saying, "And over here, gentlemen, we have the satellite that goes 'ping'." I don't think they have anything suitable for navigation.

Yes and no. Galileo is trying to do a subscription service where it is intentionally encrypted with decryption done on units with the right software keys installed and accuracy based on the class of key that you have. This model came from satellite TV.

The Chinese are much further along with Beidou.

China has some serious problems with launch capacity. Beidou has promise but the big problem is infighting defining exactly what the product is going to be. The classic socialist military vs. civillian fight is happening there.

I think the Big Switch has been upgraded now so they can deny GPS only in specific areas-- preventing use in hostile areas while still letting Americans find the nearest Walmart at home.

Not only that but like I mentioned before Big Switch can encrypt regionally so boxes with keys can only work. So yes, Mrs. Mid-West can find Walmart while Abdul can't use it to track in Iraq.
 
Keep in mind that if anything goes down, the big switch for GPS can be pulled as needed. This is why there are two other GPS systems in orbit; the EU Galileo and the Russian GLONASS.

Yep, GPS could be either turned off, or jammed by the enemy. Or even spoof the signal so that receivers calculate incorrect positions.

Which is why the military has became so keen on using location methods of opportunity as a backup.

E.g. The idea is that, just as with smartphones, if a cruise missile's GPS fails, it can switch to using pre-mapped radio or cell towers as guide points. Basically, use whatever it can find.

--

On a thread related note, I read that the Android phones that went up were the first totally STOCK smartphones to be NASA certified for space. The iPhones are, as mentioned, modified. If I had to guess, I'd bet the modification was to allow easy removal or replacement of the battery. Anyone know for sure?
 
Yep, GPS could be either turned off, or jammed by the enemy. Or even spoof the signal so that receivers calculate incorrect positions.

Which is why the military has became so keen on using location methods of opportunity as a backup.

E.g. The idea is that, just as with smartphones, if a cruise missile's GPS fails, it can switch to using pre-mapped radio or cell towers as guide points. Basically, use whatever it can find.

Yup and the declassified data shows that most cruse missiles work via the old "bobsled driver" method of having a series of images programmed into it. When the terrain matches a specific image it changes trajectory.

My fave of that was a CNN reporter during the Second Gulf War. He was in Baghdad seeing a Tomahawk headed right at him, the camera crew was right on it, the missile nosed up, stalled a bit and turned a corner down another street missing them.

The reporter was in shock for a second and then screamed "It turned the ********* corner!!"
 
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