Assessment of GDOP calculating methods in Loran ground-based system and determining the optimum configuration of transmitters

LORAN land-based system is a radio navigation system using land-based radio transmitters and receivers to allow mariners, aviators, and those interested in terrestrial navigation to determine their position. The accuracy of Loran land-based system is affected by various factors that one of most important factors is the geometry of transmitters relative to receiver position. This effect is calculated with a non-dimensional parameter called Dilution Of Precision (DOP). There are various methods for calculating GDOP that are: particular bisector method, general azimuthal method and Torrieri method. The aim of this research is calculating of DOP base on these methods for triple Labrador chain and comparing the results together. Then a new algorithm is represented for calculating GDOP based on distance between receiver and transmitter similar to using existing GPS algorithm that based on results of Labrador chain, this method in comparison with other methods presented optimistic results. Also, this paper introduces an algorithm for finding the best geometry of transmitters according to position of the receiver. This algorithm is used for Labrador chain and results indicates that this geometry in comparison with existing geometry of this chain, prepare the minimum values of GDOP for the receivers of this region.