摘 要：π/4-DQPSK能够进行有效鉴频器解调和差分解调，是一种线性窄带数字相位调制技术，频谱特征好，抗多径机能强，频谱利用率高，广泛应用于移动通信、卫星通信中。本论文讨论π/4-DQPSK调制解调系统的仿真问题。介绍了π/4-DQPSK调制解调基带差分解调原理，可以解决比特定时恢复，插值，脉冲整形和其他重要的问题,在此基础上对整个通信系统进行matlab仿真。研究调制解调中脉冲整形滤波器降低因子α对通信系统的误码率（BER）性能的滚动效果和位定时恢复算法的M值对该通信系统误码性能的影响,为实际系统的设计的一个有效的提供依据。61528

毕业论文关键词：π/4-DQPSK，调制解调，误码率  

Abstract：π/ 4-DQPSK is able to have effectively discriminator demodulation and differential demodulation. It is a linear narrowband digital phase modulation technique, the feature of good frate spectrum, resistance to many ways of function which is strong and above the average of spectrum productivity.π/ 4-DQPSK is diffusely invested in variable communications and satellite communications. This design discusses π/ 4-DQPSK modem system of simulation. This paper briefly introduces theπ/ 4-DQPSK modem baseband differential demodulation principle,which can solve the bit definite time regression, manipulation, impulse moulding and other important problems. The matlab simulation has based on the whole communication system. Research in modem pulse shaping filter to reduce the factor alpha of the communication system BER (BER) performance of the rolling effect and a timing recovery algorithm M value affect the performance of the communication system error. So it affords a very effective element in the case of practical system design.

Keywords：π/4-DQPSK，modulation and demodulation，error rate 

1 引言 4

1.1 研究的背景 4

1.2 研究的意义 4

1.3 软件简介 5

2 π／4一DQPSK 6

2.1 π／4一DQPSK的基本概念 6

2.2 数据与相位关系 6

2.3 π／4一DQPSK的性质 6

3 π/4-DQPSK调制原理 8

3.1 输入数据的产生 8

3.2 串／并变换 8

3.3 差分编码 9

3.4 发送端基带成形技术 9

3.5 正交上变频及得到π/4一DQPSK信号 11

4 π/4-DQPSK解调原理 12

4.1 基带差分解调的原理 12

4.2 位同步信号恢复的实现 12

5 仿真结果及其分析 13

5.1 仿真过程 13

5.2 仿真结果和分析 13

结 论 18

参考文献 19

致 谢 20

附 录 20

附录A： 21

附录B： 21

附录C: 22

附录D: 22

1 引言

1.1 研究的背景[1]

    第一代（1G）被称为第一代移动通信标准。这也是一个模拟移动电话系统，然后调用形式大多数蜂窝电话标准。