Multilateration (MLAT) is a well-known and proven method in aviation. The position of a flying object is calculated by measuring the different arrival times of the same radio signal at different receivers. The light:guard system for Aircraft Detection Lighting System works at most locations by means of multilateration and can therefore achieve particularly accurate results. Multilateration requires the following elements:
Transponder receiver (Light:Guard receiver): There are several transponder receivers at known locations with synchronized clocks. These receivers receive the transponder signals transmitted by airplanes.
Time measurement: When an aircraft transmits a transponder signal, this is received by the various transponder receivers. Each transponder receiver measures the time it takes for the signal to reach it.
Triangulation: Positions can be calculated using the time differences in the transponder signals between the various transponder receivers. This is done by triangulation. The position of the aircraft is determined by the intersection of the time measurements from different receivers.
Error correction: As the transponder signals require a certain amount of time to reach the receivers, a number of factors must be taken into account. These factors are the transit time of the signal, possible reflections and atmospheric conditions. Algorithms correct the errors and calculate the exact position of the aircraft.