文档介绍：基于FPGA的MSK调制器设计与实现
谢丽君1 谭立志2
( 410003; 412001)
摘要:介绍了MSK信号的优点,并分析了其实现原理,提出一种MSK高性能数字调制器的FPGA实现方案;采用自顶向下的设计思想,将系统分成串/并变换器、差分编码器、数控振荡器、移相器、乘法电路和加法电路等六大模块,重点论述了串/并变换、差分编码、数控振荡器的实现,用原理图输入、VHDL语言设计相结合的多种设计方法,分别实现了各模块的具体设计,并给出了其在QuartusII环境下的仿真结果。结果表明,基于FPGA的MSK调制器,设计简单,便于修改和调试,性能稳定。
关键词:MSK,FPGA,差分编码器,数控振荡器
中图分类号: TP29 文献标志码:A 文章编号:
Design and Realization of MSK Modulation Based on FPGA Technique
XIE Lijun1 TAN Lizhi2
( Professional Technology college, Changsha,410003,china; Professional Technology college,zhu zhou,412001,china;)
Abstract: This article introduced the advantage of MSK,and analyzed the implementation proposed a high-preformance MSK digital modulator’s implementation method based on FPGA;The system is divied into serial / parallel conversion、differential encoding、 NCO、phase shifter、 multiplication circuit and adder using Top-to-Down design; And achieved the specific design of each module by schematic and VHDL; The simulation and experiment of FPGA design were given with QuartusII. Result shows,the MSK modulator based on FPGA,simple in design,convenient to modify or debug,and it operates stable.
Key words: MSK,FPGA, Differential Encoding .NCO
0 引言
在QPSK调制技术中,假定每个符号的包络都是矩形,已调信号的包络是恒定的,此时无论基带信号还是已调信号其频谱都是无限的。但是实际的信道总是有一定的带宽的,因此在发送QPSK信号时通常要通过带通滤波器进行限带。限带后的信号已经不能再保持包络恒定,相邻符号间发生相移时,限带后包络会明显变小,甚至出现包络为