Based On Software Radio Qpsk Signal Modulation And Demodulation

Software Radio (SWR) is a new design ideas proposed in the late 20th Century, which breaks through the hardware radio design patterns in the traditional radio. The central idea of Software Radio is to build an open, standardized, modularized communication hardware platform, and achieve communication with software. In wireless communication, the digital modulation and demodulation is a key technology. Digital phase shift keying (PSK), because of its high spectrum efficiency, BER performance, flexible, is especially suitable for high data transmission and fast fading channels. It has become the main modulation in the current mobile communication systems.This paper, establishes a system ofπ/4-DQPSK differential modulation and demodulation, based on the studying of theπ/4-DQPSK theory Then, the paper program all the models of this system in the Xilinx Company's ISE software platform, and simulate the entire system combining with the software of ModelSim The models of the modulation system include differential encoding of baseband signal,CORDIC algorithm for DDS,π/4-DQPSK modulation, and improved the CORDIC algorithm in the aspect of reducing the pipeline stages.The models of the demodulation system include FIR filters, LP loop filter, carrier frequency recovery base on COSTAS loop, and so on Meanwhile, this paper research the analog band pass filter and achieved a four-order switched-capacitor bandpass filter,which locate in the SWR's analog part.All function modules of the digital modulation and demodulation system, programmed by the hardware description language verilog,and the entire systems simulate by System Generator of the Xilinx Company's system modeling tool under the simulink environment. According to the result of simulation, we can finally verify the correctness of system design. The last part is the summary and outlook.