Investigation and Implementation of Spread Spectrum QPSK-CPM Demodulation Algorithm for Satellite-Based VDE

The utilization of satellite-based VDE facilitates efficient, precise, and instantaneous communication between vessels and between vessels and the shore, thereby ensuring the safeguarding of maritime navigation. Its extensive adoption in non-coastal regions is evident. Continuous Phase Modulation (CPM), characterized by its continuous phase and unvarying envelope, presents noteworthy benefits, including heightened spectral and power efficiency, and has garnered widespread employment within wireless communication. This research delves into the exploration of a non-coherent demodulation algorithm for QPSK-CPM spread spectrum systems employed in satellite-based VDE. A non-coherent demodulation technique, rooted in the Viterbi algorithm, is devised and implemented through the utilization of FPGA technology.