The Implementation Of Digital Processing Module Of QDPSK Radio In FPGA

The software radio (SWR) is a new developing technology with the progress of micro-electronics technique in recent years. It was first presented in the field of military communication, and later introduced to personal communications and permeated through the technological field of other electronics. Its nucleus is: make A/D and D/A commutator close to the antenna as far as possible, and realize the wireless communication function by software as far as possible based on the basic hardware platform.With the development of VLSI and FPGA are designed and manufactured successively. So Software Defined Radio(SDR) on basic of digital signal processing technique can be implemented at present. So digital receiver of DFH radio is to be designed based on SDR, in order to make preparation for implementation of QDPSK system with great agility and expansibility.In the paper, the current status of the domestic and international research on software radio is introduced, and the principle of sampling, multi-rate signal processing, digital modulation and demodulation is discussed. A software radio experimental platform on FPGA is set up in the paper, which focuses on the digital down converter (DDC) and the digital orthogonal demodulation. The receiver adopts the digital structure of IF to sample and quantize the IF signal. And the signal processing units such as DDC, the software, goes deep into the study on the modulation and demodulation arithmetic of QDPSK. We also carry on simulation on the arithmetic by MATLAB, so that we can prove its correctness and feasibility, which can be downloaded into FPGA for their realization, defines digital demodulation and so on. The structure reduces the rate of sampling and the speed of digital processing, and requires low-performance hardware, which can be realized easily. Finally, the simulation of system grades about the receiver is carried on with System View, and different function units are described with HDL to emulate, synthesize, download and debug. Finally,the test results shows that the design target is obtained. The project accomplishes the general platform software of communication signal modulation and demodulation based on the software radio, so that we validate the correctness of the general structure of the software radio modulation and demodulation, and realize the compatibility of multi-mode modulation and demodulation. We also introduce a hardware structure of the software radio general platform, in order to establish the foundation of the deeper research of the software radio.The paper shows that the software radio system has the flexibility, openness and compatibility in processing the digital signal, and indicates that FPGA is especially suitable for the standardized designing of SWR with its advantage of reconfiguration and parallel processing.