Envelope-accumulation demodulation of low-SNR Loran-C data with ≥ 5 dB sensitivity gain

Abstract To enhance the demodulation performance of Loran-C signals and improve the autonomous timing capability of Loran-C receivers, we propose an Envelope Conjugate Multiplication Accumulation (ECMA) demodulation scheme based on envelope accumulation. Theoretical analysis demonstrates that the proposed ECMA scheme provides a stable signal-to-noise ratio (SNR) gain and exhibits greater robustness to skywave interference than conventional demodulation methods. Numerical simulations under additive Gaussian noise and skywave-interference conditions show that the proposed scheme achieves a demodulation sensitivity improvement of at least 5 dB, thereby reducing performance degradation under severe interference. Field experiments using real received signals further demonstrate the feasibility and practical effectiveness of the proposed ECMA scheme.