How Does a GPS
Determine Elevation?

The satellites are situated at a height of about 20000 km and situated at orbits with an inclination of 55 degrees and a distance of 60 degrees. The satellites transmission period is about 12 hours. Each of these satellites uses two radio frequencies for the transmission of its time and position coordinates.

So How Does a GPS Determine Elevation?

GPS receivers calculate variants like elevation, longitude and latitude using these satellite signals. These radio signals are then received by the receiver. The time taken to reach the receiver is calculated which allows it to understand the exact distance from the satellite. The more satellites your GPS receiver can lock on to, the more accurate the calculations.

For example if there are four satellites being used to determine the coordinates, then you can imagine four spheres emerging from the earth to each of the satellites. The point where these spheres meet is your position.

The GPS system uses the 3 D geometry for the calculation of the exact position. The calculation method known as trialteration is similar to triangulation but uses lines and not angles from any three given points to determine the location of the GPS receiver.

In the technical parlance, it uses the Pythagoras method in geometry and algebra to solve simultaneous equations which gives us the three coordinates. These days the advanced technology has eliminated all kinds of errors and it's easy to get the exact latitude, longitude and the elevation of the place.

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