最佳接收机的systemview仿真

摘要

摘要

通信的一个主要目的就是保证通信质量，而衡量一个数字通信系统质量好坏的主要指标就是错误概率，因此如何良好的设计接收机使错误概率最小是通信工程师追求的一个目标。本文用仿真的方法验证了一种使错误概率最低的接收方式，亦称最佳接收机。

本文首先介绍了一种使错误概率最小的最佳接收机设计依据——最大似然准则。其次，介绍了确知信号的最佳接收原理和实现方式，为仿真做好理论准备。还介绍了用于仿真的2ASK，2FSK，2PSK等输入信号和其用相干（非相干）的解调方法，其目的是与最佳接收方法做比较以彰显最佳接收机的性能优越性。然后利用仿真工具——System View对信号的相干（非相干）解调系统和相关器形式的最佳接收机的各点波形进行了仿真，并将仿真结果和理论情况进行了比较和评述。结果表明，在最大似然准则下的最佳接收机可以使输出总的误码率达到理论最低值，其性能要比相干（非相干）解调的接收机的误码率性能要好，因此最佳接收机可做为最理想的接收机实现形式。本文最后还加入了习题的仿真解答，使最佳接收理论与实际联系的更加紧密。

关键词：最大似然准则 最佳接收机 System view 相干（非相干）解调

ABSTRACT

ABSTRACT

A major purpose of communication is to ensure the quality of communication,the main indicators that measure of the quality of a digital communication system is good or bad is error probability.Therefore,it is a communications engineers to pursue a goal that how to design a receiver which have a minimize error probability.In this paper,there is a simulation method to verify a receiver system which make error probabily minimize,also know as Best Receiver.

This paper introduces a design basis of Best Receiver which make error probabily minimize-- maximum likelihood criterion.Secondly,it introduces the principle and realization of Best Receiver of deterministic signal.It is a good theoretical preparation for the simulation. Also introduce the modulation and the use of coherent(non-coherent) demodulation method of 2ASK, 2FSK, 2PSK other input signal. Its purpose is to compare with the best reception method to highlight the superiority of the best performance of the receiver. Then use simulation tools--System View to simulate waveform points and performance of signal. The simulation results and theoretical situations are compared and reviewed. The results show that maximum likelihood criterion in the optimal receiver allows the output bit error rate of the total theoretical

（non-coherent）minimum，the performace is better than coherentreceiver. Therefore, the

receiver can be used as the best realization of the ideal receiver. finally, the simulation also joined the exercises and answers.It make the best reception of the theory and practice more closely link.

Keywords: maximum likelihood criterion Best Receiver System view Coherent (non-coherent) demodulation

目录

目录

第一章 绪论 .......................................................... 1

1.1 最佳接收机概述 ............................................... 1 1.2 System view ................................................... 2

1.2.1 System view概述 ......................................... 2 1.2.2 System view图幅说明 ................................... 2 1.3研究成果和内容安排 ............................................ 6 第二章 数字信号最佳接收机............................................ 7

2.1 判决准则 ..................................................... 7

2.1.1 最大输出信噪比准则 ...................................... 7 2.1.2最小均方误差准则 ........................................ 7 2.1.3最大后验概率准则 ........................................ 8 2.2 最佳接收 .................................................... 8

2.2.1 最佳接收的概念 .......................................... 8 2.2.2 最大似然比准则 ......................................... 11 2.2.3 接收机结构 ............................................. 12 2.2.4二进制确知信号最佳接收机的抗噪性能 ..................... 15

第三章 数字信号调制与解调........................................... 17

3.1 2ASK信号 ................................................... 17

3.1.1 2ASK信号调制 ......................................... 17 3.1.2 2ASK功率谱密度 ....................................... 18 3.1.3 2ASK信号解调 ......................................... 18 3.2 2FSK信号 ................................................... 19

3.2.1 2FSK概述 ............................................. 19 3.2.2 2FSK数字系统的调制原理 ............................... 20 3.2.3 2FSK系统的解调方式 ................................... 21 3.3 2PSK信号 ................................................... 22

3.3.1 2PSK信号概述 ......................................... 22 3.3.2 2PSK信号调制 ......................................... 22 3.3.3 2PSK信号功率谱 ....................................... 23 3.3.4 2PSK解调 ............................................. 23 3.4 误码率对比 .................................................. 25 3.5 总结 ........................................................ 26 第四章 System view仿真实现 ......................................... 27

4.1 时钟设置 .................................................... 27 4.2 2ASK信号仿真 ............................................... 27

4.2.1 2ASK信号调制 ......................................... 27 4.2.2 信道加噪 ............................................... 28 4.2.3 2ASK信号解调 ......................................... 29 4.2.4 2ASK最佳接收机 ........................................ 31 4.3 2FSK信号仿真 ............................................... 34

4.3.1 2FSK信号调制 ......................................... 34 4.3.2 2FSK信号解调 ......................................... 35 4.3.3 2FSK最佳接收机 ....................................... 39

目录

4.4 2PSK信号仿真 ............................................... 43

4.4.1 2PSK信号调制 .......................................... 43 4.4.2 2PSK信号解调 .......................................... 44 4.2.3 2PSK最佳接收机 ........................................ 46 4.5 本章小结 ..................................................... 49 第五章 总结与展望 ................................................... 51

5.1总结 ......................................................... 51 5.2 展望 ......................................................... 51 感谢 ................................................................ 53 参考文献 ............................................................ 55