How GPS Works

Video Transcript

"O.k. so how does a GPS work? Let's exit out of here and come down here. Now, what we're looking at here, these are satellites, all these green bars are satellites that are watching, actually we're watching at the moment, because this is a receiver, so it's watching those which are transmitters. All the green bars are indicating a solid signal so, currently we have, looks like about seven or eight, maybe nine satellites that we're locked in on. And, on this one we have dead reckoning which you probably cannot see but at the very bottom of these there is a D, which means it's locked in for dead reckoning which makes it more accurate. Our current elevation is eight hundred and seventy six feet above sea level. And, we are, you only really need two satellites to lock in to get good positioning, so we are well within, and then over on the left of the screen if you can see it, it's actually showing by number the satellites up in the sky. These are defense satellites. You've already paid for it, the defense department maintains them, so when you purchase a GPS unit like this after market, it does not come with a card, there should be no monthly charge for that. You've already paid for it, there is no expense, added expense monthly charge, so you're good to go as far as expenses."