.¦Ð/4-dqpsk Baseband Differential Demodulator Technology And Data Transmission To Achieve

This project study the all-digital modulation and demodulation ofπ/4 offset differentially encoded quadrature phase shift keying (π/4-DQPSK). Then useπ/4-DQPSK digital modulation and baseband differential demodulation technology to implement digital signal transmission. The bite rate is 500Kb/s and the intermediate frequency is 2MHz.π/4-DQPSK which is a modification of QPSK modulation. It is a linear narrowband technology which has been widely employed in mobile communication system, satellite communication system. It possesses features of high spectrum utilization ratio, better spectrum specification, stronger anti-fading performance and applicability to non-coherent detection.The paper introduces the modulation and demodulation theory ofπ/4-DQPSK. Recommended pulse shaping filter and bit synchronization detailed. Then author use Matlab software to simulate the whole process of modulation and demodulation and use Verilog Hardware Description Language to design the module. To validate the correctness of each module, author use Quartus and ModelSim software to implement software simulation , designed the PCB board based on FPGA chip and finished circuit debug. Through download designed program to FPGA chip and run it ,the modulation and demodulation system ofπ/4-DQPSK proved to be run correctly and the target goal is completed.