The way they triangulate from your cell phone in relation to the nearest cell phone towers is the strength of the signal coming from your phone to the tower. Your phone is giving a signal all the time and is registered by the towers. The closest one reads that you are nearest to it and services your call, the others simply register the strength of the signal and that is how they find people, but, like I said, it’s vague tracking.
Now, listen carefully…. I get sick of seeing this on TV.. Cell phones transmit. GPS equipment doesn’t. (or at least it doesn’t need to for it’s most basic use) It only receives the signal from the satellites. It doesn’t send a signal registering your whereabouts to the satellite and the satellite is a honey badger… it don’t care. What does transmit is when you’re using it in relation to an app on your cell phone. The cell phone can take that information and other searches you’ve done on your phone and transmit it to a tower and that information can (and has been) collected. I’m sure there will be an upgrade soon so that the car GPS information you use is transmitted and downloaded into some ‘big brother’ collection point so they can sell you more fast food, designer shoes and tell you where to get your hair done, and,of course, so the police can follow your every move.
Welcome to the 21st century and you can thank the people at Apple. The collection of GPS location searches and data was their idea first.
We don’t need anything on land. It would extremely redundant. GPS is only one of the several global satellite networks buzzing around. Here’s a link of some of the latest info.
http://en.wikipedia.org/wiki/Satellite_navigation
Also, basing the stuff on land is very problematic. Signal interference would be a big problem, as would finding decent surveyors to place them and set them up correctly (you wouldn’t believe the problems….). The things would also be struck by lightening and they’d have to be completely replaced.