Improved Viterbi Algorithm for Automatic Identification System Signal Demodulation

To address the limitations of conventional Automatic Identification System (AIS) signal demodulation algorithms, this paper comparatively analyzes the performance characteristics of differential phase detection and coherent Viterbi demodulation. An improved scheme combining 1-bit differential phase detection with the Viterbi algorithm—termed the enhanced Viterbi demodulation algorithm—is proposed. By incorporating inter-symbol phase differences for path selection and metric accumulation, the algorithm reduces reliance on absolute phase information while optimizing computational complexity and memory requirements. Extensive simulations validate the algorithm’s performance, demonstrating significant improvements over traditional methods in carrier frequency offset tolerance, phase noise robustness, and bit error rate. The proposed solution offers an efficient demodulation approach for AIS signal processing systems.