Patent ID: 8374292
Filing Date: 2013-02-12
Classification: G08G,H04B

Abstract:
1. A method for producing validated decoded Automatic Identification System (AIS) message segments from a plurality of AIS signals wherein a plurality of AIS signals are received at one or more satellites in space and pre-processed to produce digital input data corresponding to the received plurality of AIS signals, the method comprising: processing the digital input data by correlating the digital input data with a plurality of predefined signals having different Doppler offsets to compute a plurality of corresponding correlation signals, wherein the plurality of predefined signals are generated by applying the different Doppler offsets to a predetermined AIS code sequence, and scanning the plurality of correlation signals for amplitude peaks exceeding neighbouring amplitude peaks by a predetermined amount in order to identify one or more candidate AIS message signals; determining corresponding Doppler offset estimates and arrival time estimates for the one or more candidate AIS message signals; decoding the one or more candidate AIS message signals in the digital input data to obtain corresponding message segments; and validating the decoded message segments for proper AIS formatting to produce validated decoded AIS message segments.