不同方式解调下FSK、PSK、DPSK的误码率比较

不同方式解调下FSK、PSK、DPSK

的误码率比较

摘要一般来说，数字解调与模拟调制的基本原理相同，但是数字信号有离散取值的特点。因此数字调制技术有两种方法：1 利用模拟调制的方法去实现数字式调制，即数字调制看成是模拟调制的一个特例，把数字基带信号当做模拟信号的特殊情况处理；2 利用数字信号的离散取值特点通过开关键控载波，从而实现数字调制。这种方法通常称为键控法，比如对载波的振幅，频率和相位进行键控，便可获得振幅键控、频移键控、和相移键控三种基本的数字调制方式。这次为期一周的通信传输课程设计的实习,就是通过MATLAB编程仿真,来更好的理解FSK、PSK、DPSK的调制和解调过程。在这次的实习中，主要是应用MATLAB 进行编程仿真并显示结果。仿真的是

FSK的相干、非相干和过零解调，PSK 的相干解调及DPSK的相干和差分解调。并比较相同调制后的信号不同的解调方式和不同调制后的信号相同的解调方式。关键字：频移键控，相移键控，误码率，信噪比ABSTRACT Generally speaking, digital demodulation and analog modulation of the basic principles of the same, but the digital signal has the characteristics of discrete values. Therefore, digital modulation techniques, there are two methods: one using analog modulation methods to achieve digital modulation, digital modulation that is seen as a special case of analog modulation to digital baseband signal as an analog signal a special case; 2 using digital signal characteristics of discrete values by keying switch carrier in order to achieve digital modulation. This method is usually referred to as keying method, such as the

right carrier amplitude, frequency and the phase shift keying, can receive amplitude shift keying (Ampolitude shift keying, ASK), frequency shift keying (Frequency shift keying, FSK), and the phase shift keying (Phase shift keying, PSK) digital modulation of three basic ways. The week-long internship curriculum design communication transmission is through MATLAB simulation program, to a better understanding of FSK, PSK, DPSK modulation and demodulation process. In this attachment, the main is the application programming MATLAB simulation and displays the results. Simulation is the FSK coherent, non-coherent and zero-crossing demodulation, PSK and DPSK coherent 2 demodulation of coherent and differential demodulation. And compare the same modulated signal demodulation in different ways and different modulated signal demodulation the same way.

Keywords: Frequency shift keying, phase shift keying, the bit error rate, signal to noise ratio 3 目录摘要 (2)

ABSTRACT………………………………………………………………3 绪论……………………………………………………………………….5 第一章FSK……………………………………………………………….6 产生原理信号的解调相关仿真第二章PSK……………………………………………………………….8 产生原理信号的与解调相关仿真第三章DPSK………………………………………………………………10 产生的原理信号的解调相关仿真第四章FSK、PSK、DPSK误码率的比较…………………………………12 第五章结论和心得体

会 (15)

2FSK信号的产生方法主要有两种。一种可以采用模拟调频电路来实现；另一种可以采用键控法来实现，即在二进制基带矩形脉冲序列的控制下通过开关电路对两个不同的独立频率源进行选通，使其在每一个码元Ts 期间输出f1或f2两个载波之一。这两种方法产生2FSK信号的差异在于：有调频法产生的2FSK信号在相邻码元之间的相位是连续变化的，而键控法产生的2FSK信号，是电子开关在两个独立的频率源之间转换形成，故相邻码元之间的相位不一定连续。信号的解调2FSK信号的常用解调方法是采用如同所示的非相干解调、相干解调和过零检测法。相干解调和非相干解调的原理是：将2FSK信号分解为上下两路2ASK信号分别进行解调，然后进行抽样判决。这里的抽样判决时直接比较两路信号抽样值的大小，可以不设置专门的门限。