Operating LORAN-C Position Fix with Nonhyperbolic Position Lines

Document Type : Original Article

Authors

Staff member of Avionics Dept ,MTC.

Abstract

Hyperbolic navigation systems ( LORAN-C, DECCA Navigator and OMEGA ) represent a widely used class of position fixing
syst.ems.Most of their incorporated traditional receivers display position fihyperbolic position lines and geometrical factors relevant to these lines. Avionics applications as well as automatic vehicle location systems entails low-cost receivers which operate wholly or largely automatically and which display position measurements in geographical coordinates (latitude -longitude) or as headings and distances to given waypoints and/or integrated with readings from dead-reckoning sensors.
Solution issues to some of these problems have been addressed in two published papers by the authors.The underlying idea is to involve modifications in the processing algorithms of on-board receivers.In essence ,that modification was based on generating non-hyperbolic position lines :circles and/or ellipses out of the originally designed hyperbolic systems. Theoretical evaluation of that proposal was the subject of one the authors papers. In the present paper ,the proposed modification is applied to a real ON--EARTH LORAN-C station to confirm the obtained results. Moreover,an algorithm as well as an implementation proposals are presented .The case of short base-length as in the DECCA chains is presented with its algorithm and the proposal for implementation is highlighted.