All-digital Qpsk Communication System, The Fpga-based Study

QPSK digital modulating technique has features of high-spectrum utilization ratio, better spectrum specification, stronger anti-interference performance and faster baudrate. So the modem method has been applied widely in mobile communication system and satellite communication system. But all-digital QPSK modem based on FPGA is searching and developing.An all-digital communicating system of QPSK based on FPGA has been researched and designed in this dissertation. Firstly, the rationales of a FPGA-Based QPSK modem are introduced in the dissertation. After that, author complete simulation of EBR. Secondly, under the ISE 6.1 of XILINX, VHDL has been adopted for designing and implementing the system. The designing mainly included NCO, shaping-filter, matching-filter, carrier synchronization of Costas and bit synchronization. According to these designing results, the functional simulation of system is completed. Via observing timing wave, program can implement right modem. Lastly, the method of designing and debugging circuit is presented in this dissertation.The QPSK modem basing on FPGA is designed with high integration, great flexibility and upgrade in software. The design in this dissertation will provide for the further design with more high integration and more great flexibility in the modern communication system in the future.