Research on DQPSK Carrier Synchronization based on FPGA

Digital modulation-demodulation technique in modern digital communication system plays a very important role. Carrier synchronization is also one of the key technologies of digital wireless communication. As a kind of four phase shift keying modulation method, QPSK has strong anti-interference ability of the suppressed carrier, which is widely used in digital wireless communications. On this basis, this article describes a Costas-loop coherent carrier extraction algorithm based on Arctangent phase detection. It designs a digital intermediate frequency receiver system based on software radio thought. The system consists of data acquisition module, digital down converter (DDC) and digital demodulation module. And use the differential coding to solve the QPSK carrier phase fuzzy problem. And also illustrate the basic principle of DQPSK in detail. It makes simulation verification by Matlab for DQPSK demodulation. Simulation results show that the simulation model could correctly implement DQPSK signal carrier synchronization.At last, it is implemented on the FPGA platform.Implementation results show that the system can be applied to practical engineering.