基于软件无线电的QPSK信号调制解调的研究与实现

【作者】 陈立功；

【导师】 宋学瑞；

【作者基本信息】 中南大学 ， 电子科学与技术， 2010， 硕士

【摘要】 软件无线电是20世纪末提出的一种新的设计思想,它突破了传统的无线电台以硬件为核心的设计模式。其中心思想是构建一个开放的、标准的、模块化的通信硬件平台,用软件的方式来实现各种通信功能。在无线通信中,数字调制与解调技术是一项关键技术,他的好坏直接决定了通信系统的好坏。数字相移键控(PSK)由于其具有频谱利用率高、误码性能好、技术灵活、特别适应于高数据传输与快速衰落信道等突出优势,已经成为了当前各种移动通信的主要调制方式。本文在对数字相移键控中的π/4-DQPSK的调制与解调进行理论研究的基础上,建立了π/4-DQPSK的差分调制解调的数字通信模型。之后在Xilinx公司ISE软件平台上通过对整个系统模型中的模块进行编程设计,并结合ModelSim对整个通信系统进行了仿真验证。本课题中,在调制发送端完成了基带信号的差分编码、CORDIC算法实现的DDS、π/4-DQPSK调制,并对CORDIC算法进行改进,减少了传统CORDIC算法在流水线处理结构的级数,缩短了系统计算所用时间；在解调接收端完成FIR滤波器、LP环路滤波器、COSTAS环载波恢复等功能模块的设计。同时对软件无线电结构中的模拟前端中的模拟带通滤波器做了一定的研究,设计并实现了一个四阶的中心频率可调开关电容带通滤波器。所有数字信号调制与解调系统功能模块利用Verilog硬件描述语言进行编写,利用Xinlinx公司System Generator系统建模工具,在Simulink下联合仿真,从而验证了系统设计的正确性。最后是对论文工作的一些总结和对今后工作的展望。更多还原

【Abstract】 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.更多还原