Data demodulation algorithm of enhanced Loran system

Enhanced Loran (eLoran) system plays an important role in the national positioning, navigation, and timing (PNT) fields. The information demodulation capability of its user receiving end also directly affects the application coverage of the system. Using the existing arctangent and matched filter demodulation algorithms, we propose a novel algorithm based on log likelihood ratio (LLR) information, and then analyzing the implementation process of these three algorithms in detail and simulating the system performance difference in an additive white Gaussian noise (AWGN) environment. The results showed that the performance difference of the three algorithms was between 0.5 dB and 1 dB, and the proposed algorithm was 0.5 dB better than the arctangent demodulation which is more widely used in engineering practice. Simultaneously, the proposed algorithm can be used to provide an algorithm basis for the study of the eLoran system to switch to modern channel coding methods with LLR information as the decoding input.