Loran-C operates based on the principle wherein the arrival time difference of a signal that can be provided by two synchronized transmission stations and a hyperbolic LOP is measured.

Line of Position (LoP) is determined by the arrival time difference between two trajectories, which have a constant distance difference on the map from two transmission stations, from the two stations.

Positioning can be done with the intersection of two or more LOPs. Measurement of time difference in each LOP is determined through the pulse envelope comparison that is synchronized between the master station and secondary stations, and is received by measuring their elapsed time.

Among transmission stations, the master station launches a pulse first; other transmission stations then act as secondary stations, become synchronized with the master station, and then launch a pulse in turn with a set time difference. The locations of all points that have the same time difference from a hyperbola is as shown in the picture. To find one position (two LOPs), which means at least three transmission stations including one master station (M) and two secondary stations (X, Y), are required.

In the picture, the pulse arrival time difference from M and X and the M-Y time difference are indicated as TDx and TDy, respectively.