"In the event of a GPS failure." which probably means that either the world is at war again, or we've finally crossed the tipping point on space junk and everything in medium earth orbit (MEO or 12,500 miles) is now just a cloud of parts working its way into LEO as the orbits decay.

Or that you're in a location where GPS reception is difficult, like a city core, like eLoran proponents would likely remind you. Unfortunately, I think the ship sailed when the US decided to decommission its chain. Another weakness of Loran is that it's only available near the coasts (where precise navigation is a necessity for ships), so it won't help you in the middle of the ocean or in Las Vegas.

... or there's a hostile attack on your location that somehow manages to disturb GPS signals.

or a big solar flare or some other kind of space weather...

Or the US deactivates GPS in your location. Which they can do.

GPS is a one way system. Receivers do not communicate back to the satellites, thus they do not tell the US government where you are.

Thanks, did not know that.

If theses little cheap device could communicate to a satellite, it would be amazing. Currently if you want to connect to a satellite, you need a big antenna and a bunch of time.

Don't these handheld devices, $79.99 on Amazon, connect to satellites to send their location? https://en.wikipedia.org/wiki/SPOT_Satellite_Messenger

"Satellite service is wireless and requires a clear line of sight toward the satellite" http://faq.findmespot.com/index.php?action=showEntry&data=11...

> Any time one of your devices contacts a GPS satellite, it's telling a system of satellites owned and maintained by the US government exactly where you are.

GPS receivers are just that. They do not transmit anything to the satellite.

While the satellites are US-controlled, the communication is strictly in one direction; your GPS listens, it doesn't broadcast. I mean, do you think that news anchors can watch you through your TV?

Yes? https://news.ycombinator.com/item?id=8537039

Also, GPS has become a generic term, just like aspirin. There are quite a few alternative systems that provide the same functionality (http://en.m.wikipedia.org/wiki/Global_Positioning_System#Oth...). Most aren't global, but the Russian one is, and the Chinese and EU ones are planned to be one.

Many phones can use GLONASS, the Russian system, so, for example, the 'GPS' in your iPhone or Lumia may not always be using the GPS system to compute your location.

People, even allegedly technical ones, get amazingly confused.