Joint coherent demodulation technology for AIS signals

Aiming at the problem of high demodulation error rate of Automatic Identification System (AIS) signals under low signal-to-noise ratio conditions, which leads to information interpretation failure, a joint coherent demodulation technique for AIS signals based on two-dimensional parameter search and cyclic redundancy check (CRC) verification is proposed. On the basis of rough estimation of timing and carrier synchronization parameters, this technology uses smaller steps to perform two-dimensional search on timing and carrier synchronization parameters, and ultimately achieves coherent demodulation performance that approximates ideal synchronization demodulation performance. The experimental results show that this method has a performance improvement of about 2.5dB compared with the two bit differential feedback demodulation and fusion decision algorithm.