Counteraction of Constant Modulus Demodulation Scheme for Mixing Space Borne AIS Signals
Shou Zhong Zhu, Zheng Liu, Wen Li Jiang · Applied Mechanics and Materials · 2013
Demodulation scheme was proposed in satellite systems to received Automatic Identification Systems (AIS) signals, with the potential presence of other interfering signals. The counteraction of constant modulus demodulation scheme, referred to as CCMDS, yields a set of single short signals based on the prior information of AIS after estimating the frequency, code rate and modulation index. It demodulates the corresponding short codes according to the constant modulus characters of GMSK signals. The proposed demodulation scheme is simple and easy to implement. Simulations show the satisfying performance and engineering value in demodulating the mixing AIS signals.