FPGA design and implementation of pulse shaping filter for coherent underwater communication

Underwater acoustic channel is characterized by strictly limited frequency bandwidth, therefore, pulse shaping filter is often used in the transmitter of underwater acoustic (UWA) communication system for baseband processing in order to reduce the inter-symbol interference (ISI), ensure more effective transmission, reduce bit error rate and improve the communication quality. This paper analyses the basic parameters of the pulse shaping filter for UWA coherent communication system and presents one implementation architecture on field programmable gate array (FPGA). The design adopts polyphase structure based on distributed algorithm (DA) and realizes an adjustable roll-off factor shaping filter with greatly reduced resource usage, which is optimized through approach of look-up table (LUT) partition and symmetry of finite impulse response (FIR). The designed shaping filter has been successfully applied to a real time UWA communication system and the results show that it can meet the shaping requirements well.