QAM的FPGA实现

电子通信论文编号:TX206 附外文翻译,原理图及PCB,论文字数:20278,页数:40

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目录

引言………………………………………………………………………………………………1
1  Quartus软件介绍……………………………………………………………………2
2  数字调制技术…………………………………………………………………………5
3  QAM原理…………………………………………………………………………………10
4  DDS介绍…………………………………………………………………………………25
5 16QAM调制的FPGA实现……………………………………………………………32 
6  结论………………………………………………………………………………………36
谢辞……………………………………………………………………………………………37
参考文献……………………………………………………………………………………38
附录……………………………………………………………………………………………39

摘  要
 
    正交幅度调制解调QAM(quadrature amplitude modulation and emodulation)频谱利用率，功率利用率高以增强抗干扰性能，是一种高效的数字调制解调方式。他在中、大容量数字微波通信系统、有线电视网络高数据传输、卫星通信等领域被广泛应用。DDS技术的实现依赖于高速、高性能的数字器件。，根据需要方便地实现各种比较复杂的调频、调相和调幅功能。DDS 是从相位的概念出发进行频率合成的一项新型技术。本文简要介绍了DDS 的工作原理，提出了一种选用Altera 公司新发布崭新体系的大容量Cyclone系列FPGA来实现DDS 系统的核心部分的设计方案。并用QUARTUSⅡ6.0 波形仿真。实验结果表明，通过各种优化措施，设计开发的DDS 系统，达到了预期的目的，具有较高的性价化。AD9761是完成双通道，高速，10bit CMOS DAC。AD9761主要应用于超带宽通信，I和Q路信息在传输时处理。该论文是基于FPGA的QAM实现，用VHDL语言对QAM调制过程进行编程，主要是QAM星座图映射和DDS信号源模块。对输入信息先经过星座图映射来控制DDS来产生相应幅度，相位的数字已调信号。该过程要使用Quartus II这软件，和下载芯片Cyclone。由芯片输出的信号通过D/A转换，该电路使用AD9761芯片。然后通过低通输出就是我们想得到的已调的QAM信号。

关键词：QAM；VHDL；DDS；QAM星座图；Quartus II；AD9761；数字调制解调；Cyclone；D/A转换

Abstract

The quadrature amplitude modulation and demodulation QAM(quadrature amplitude modulation and demodulation) frequency  utilization ratio and the power utilization ratio is a high efficiency digitized modulation and demodulation  solution to strengthen the anti- interference function. In the medium  and big capacity digital microwave correspondence system,the high  cable TV networks  data transmission  and  the satellite correspondence etc was extensively applied. DDS  technical realization depend on digitized spare part of the high speed,high performance. According to the need to carry out various more complicated frequency complicated phase complicated range function expediently. The DDS(Direct Digital Synthesis) is a new digital frequency synthesis technique based on theconcept of phase. This paper presents the work principle of DDS. And by using the big capacity FPGA (Cyclone)which is the latest product declared by the Altera company, here brings up a design project to realize thecore of the DDS system. And we also use the QUARTUSⅡ6.0’simulation to wave form. By making use of some optimizing measure, the performance of the DDSsystem designed comes to our anticipant purpose, finally, the experiment result demonstrate that the proposed method has relatively high cost performance ratio. The AD9761 is a complete dual channel, high speed, 10-bit CMOS DAC. The AD9761 has been developed specifically for use in wide bandwidth communication applications where digital I and Q information is being processed during transmit operations. This paper is depended on  FPGA for QAM realization, Use the VHDL language to make process of the QAM modulation，Mainly is the reflection of QAM constellation and  the DDS signal source module. Through the reflection of QAM constellation of the input  information to control DDS to produce to correspond range, phase already modulated digital signal. That process need the Quartus II software and  the download chip Cyclone.  the chip export   pass the D/A conversion, which  use AD9761 chip electric circuit . Then pass a low pass filter are the already modulated of QAM signal we want to get.

Key words: QAM；VHDL；DDS；QAM constellation；Quartus II；AD9761；
digitized modulation and demodulation；Cyclone；D/A conversion