The Loran-C Cycle Identification Problem

Current techniques for cycle identification in Loran-C radionavigation receivers are reviewed and compared. A new technique is presented for use in hard-limiting receivers. It is based on the widely used analogue “half-cycle peak ratio” technique, from which it differs by being entirely digital; no additional analogue signal processing or other hardware is required. Drawing on recent advances, the new method makes decisions based on a large number of sample points in each Loran-C pulse, thereby increasing the resilience of the identification process in the presence of noise. Performance of the algorithm in the face of continuous-wave interference is analysed and found to be equal to or better than that of other cycle-identification techniques.