直扩MSK调制解调和差错控制技术研究

【作者】 邓涛；

【导师】 吕明；

【作者基本信息】 电子科技大学 ， 信号与信息处理， 2006， 硕士

【摘要】 本文阐述和分析了一个带有差错控制的直扩序列MSK调制系统的设计原理与方法,详细分析和推导了系统的建模过程并给出基于MATLAB的仿真结果与性能分析。文章中还讨论了RS纠错码的编译码原理和算法,总结了基于FPGA实现一个RS(31,15)编码和译码器的设计经验和调试经验。最后给出了相应的功能仿真和时序仿真结果。文中第一章介绍了该系统的设计背景和设计要求。第二章介绍了MSK调制解调原理,给出调制和解调的结构。随后讨论了带通采样技术的原理,说明可以使用不满足奈奎斯特低通采样定理但大于信号带宽两倍的采样速率进行中频数字化,减轻基带处理负担。接下来讨论了伪随机扩频码的捕获和跟踪方法,包括相干的方法和非相干的方法,其中非相干的方法更适合用于无线通信中。最后介绍了科斯塔斯环的特点、原理以及实现结构。第三章分析讨论了RS码的特点,给出了伽罗华有限域的定义与运算规则,推导和分析了基于对偶基的有限域乘法器实现方法。在此基础上进一步讨论了RS编码的实现原理和具体的实现电路结构。最后阐述RS译码器的实现算法,给出时域译码迭代过程和迭代的流程图。第四章中构建了一个直扩MSK调制解调模型。通过对该模型中几个主要模块进行详细的推导和分析,从理论上证明了该模型的合理性和可行性。随后讨论了接收机设计的几个主要参数。最后给出使用MATLAB对该系统模型进行仿真的结果。第五章给出了基于FPGA实现的RS编码器和译码器设计说明,RS(31,15)纠错码设计实现的综合结果,有限域乘法器、除法器、RS编码器、RS译码器的功能仿真和布局布线后仿真结果,最后总结主要的调试经验。最后一章对论文工作进行了总结,指出尚需完善的工作。更多还原

【Abstract】 This dissertation analyses the design idea and method for the direct spreading sequence MSK modulate system with an error control function. It gives the MATLAB simulate result and the performance analysis through the modeling process. It also discusses the code and decode theory for RS error-correcting codes, then summarizing the design and debug experience for the RS(31,15) coder and decoder through FPGA. At last, it gives the corresponding functional simulation result and timing simulation result. Chapter 1 introduces the background of this system, and its design requirement. Chapter 2 introduces the principle of the MSK modulation and demodulation system and gives the corresponding structure. After that, it discusses the principle of the band-pass technology, illuminating the feasibility of the digital intermediate frequency system based on the sampling speed which is two times lager than the signal band but unsatisfying the Nyquist theorem. After that, it discusses the capture and tailing method for the false random code spreading code, including correlation and non-correlation method. Between the two method, the correlation method is fit for the wireless communication. At last, it discusses the characteristic and theory of Costas loop and its realization structure. Chapter 3 introduces the correcting ability of the RS code. Then it particularly states the definition and algorithm of Galois field, and analyses the realization of the limited field multiplier based on the dual basis. After that it illustrates the realization arithmetic for the RS decoder. Furthermore it gives the detail time domain iterative decoding process and its flowchart. Chapter 4 makes up a modulate and demodulate system based on direct spread MSK. It theoretically proves the reasonability and feasibility of the system through analyzing the mainly modules. Furthermore, it discusses the main parameters of the receiver. At last it gives the simulation results based on MATLAB of the system. Chapter 5 gives the design illumination of the RS coder and decoder based on FPGA. Then it gives the integrated results for realization design of the RS(31,15) error-correcting code. After that, it gives the functional and layout simulation results for the limited field multiplier, divider, RS coder and RS de-coder. Finally, it summarizes the debug experience. The last chapter summarizes the dissertation and points out the further work needed to be done.更多还原