Message Extraction for 9th Pulse Standard of eLoran Navigation System
Subject Areas : electrical and computer engineeringMehri Lotfalizade 1 , Morteza Shafiee Neyestanak 2 , Mohammad Bagher Nezafati 3
1 - Maalek Ashtar University of Technology
2 -
3 - Institute for Research in Fundamental Sciences (IPM)
Keywords: 9th pulse eLoran, envelope shift, phase shift, enhanced Loran (eLoran), Pulse Position Modulation (PPM).,
Abstract :
In the Standard of 9th pulse enhanced Loran (eLoran) system, an additional pulse is incorporated into the navigation pulse group for data transmission. The process of extracting messages from the Loran signal involves two stages: first, determining time delay of the data pulse relative to its original position, and second, decoding the data. This paper proposes a method for message extraction using the 9th pulse standard. Time delay of the data pulse is calculated in two steps, involving envelope shift and phase shift utilizing matched and fractional filters, respectively. Following this, Reed-Solomon (RS) decoding is applied, leading to final message extraction. Furthermore, to enhance pulse delay estimation, particularly in noisy and interference conditions, the reference pulse is chosen as average of the eight pulses preceding the data pulse, resulting in a unique reference pulse for each symbol extraction. Evaluation results show that the error rate before decoding decreases from 0.08 to 0.003 as the signal-to-noise ratio increases from 7 to 15 dB, with a significant reduction in errors after RS correction.