What was used before GPS?

Answer 1

Long wave radio signals such as systems like LORAN and OMEGA that operated on Very Low Frequency radio , in the region of 100kHz down to 14kHz , which obviously relied on enormously long wavelenghts to penetrate bad weather, the curvature of the earth and even into the oceans for submarine navigation.

The principle was much the same as GPS in that signals from different locations were received and identified as coming from a particular location (where the transmitter was), although it was a fixed location on the earth's surface rather than a satellite in space. The difference in time where more than one signal came from gave an idea of the distance travelled from the point of origin (because the electromagnetic speed of propagation is pretty constant) so using simple trigonometry and mathematics you could work out, from a receiver, how far you were from each transmitter and therefore as the transmitters were in known fixed locations, you could extrapolate where you must be on the surface of the planet.

Early systems had an accuracy down to the nearest few kms but later versions improved on that to a few hundred metres.

Answer 2

Before GPS, people used traditional methods of navigation such as maps, compasses, and landmarks to find their way. Navigation tools like sextants and chronometers were also used by mariners to determine their position at sea.