GPS is the oldest one from the frameworks available to the large audience. It isn't the first positioning system, but it is the one with the most success and longevity. It started as a military project in 1957. Because of the cold war, once the Russians sent to space the first man-made satellite, a team of scientists started monitoring its radio transmissions. The crucial discovery was that, because of the Doppler Effect, the signal transmitted frequency increases as the satellite approached, and lowers as it continued moved away from them.