Satellite-borne AIS signal demodulation method

The invention provides a satellite-borne AIS (Automatic Identification System) signal demodulation method, which comprises the following steps of: performing band-pass sampling on an AIS intermediate frequency signal at a preset sampling rate through an AD (Analog to Digital) converter, and performing down-conversion and filtering extraction to obtain two paths of baseband sampling data of two frequency points; performing frame header detection on the baseband sampling data, and extracting a frame of complete AIS signal; performing frequency offset estimation and frequency offset compensation on the AIS signal through the code element information of the GMSK signal; aIS signal timing synchronization is completed on the signal sampling data subjected to frequency offset compensation; and carrying out matched filtering on the AIS baseband signal which finishes timing synchronization, sampling at an integer code element moment to obtain an output signal, and carrying out Viterbi decoding on the output signal to