Hey "kornellred" that was a great explanation. That educated me. I sorta new how the GPS system worked, but you helped fill in the blanks.

 

I think that a physicist, mathematician, or electrical engineer could look at my explanation of the GPS system and say that it is so oversimplified that it could be considered wrong. The Pythagorean Theorem is A^2 + B^2 = C^2 when dealing exclusively with right triangles. Since the surface the GPS transponder is traveling on is rarely ever flat, the height of a right triangle is almost never being computed; it is, rather, the short side of a scalene - and one GPS satellite and one transponder could never compute the difference with deadly accuracy. You need more than one satellite. So I guess it's not 7th grade math after all.....but the fact remains that all that is being measured is the amount of time it takes for an RF signal to get from a transponder to a satellite.

 

You also forgot to mention how the clocks run faster on the satellites than on the ground due to thier speed and Einstein's relativity.

 

I saw the thread title: Speedo Off.......and had to look with one hand over my eyes. I was nervous for a bit....

 

If it happened more 3 times ,maybe the lemon law is your only course of action.