Long Range Navigation (LORAN)
- Joseph Lo
The Long Range Navigation system (LORAN) has been the primary navigation tool for sea and air traffic. It is mostly replaced by GPS nowadays. The location of a navigator is determined by receiving LORAN signals from a primary station and two or more secondary stations. Since the distance from each of the stations to the receiver is different, it takes a different amount of time for each station to transmit the time information to the receiver. These time differences allows the navigator to calculate distance differences between primary and secondary stations and draw corresponding hyperbolas on the map. The intersection of all these hyperbolas represents the location of the navigator. The following diagram shows how LORAN works. Each distance difference is measured by the LORAN signals from a primary-secondary station pair and determines a hyperbola on the map. Two of these hyperbolas will produce at most two intersection points and three will produce only one. The point \(Y\) represents the position of the navigator in a map. The points \(A\) to \(D\) represent LORAN stations. You can move \(Y\) and see how the hyperbolas change.