msk的调制解调MATLAB源代码讲课教案.docx

1、msk的调制解调MATLAB源代码讲课教案msk的调制解调MATLAB源代码msk的调制解调MATLAB源代码 function out = delay(data,n,sample_number) %data:延迟的数据 %n:延迟码元个数 %sample_number:码元采样个数 out = zeros(1,length(data); out(n*sample_number+1:length(data) = data(1:length(data)-n*sample_number);function data_diff = difference(data) %差分编码 %* %data 输入

2、信号 %data_diff 差分编码后信号 %* %- data_diff = zeros(1,length(data); data_diff(1) = 1 * data(1); %1为差分编码的初始参考值 for i = 2:length(data) data_diff(i) = data_diff(i-1) * data(i); end %*function signal_out,I_out,Q_out = mod_msk(data,data_len,sample_number,Rb) %MSK基带调制 %* % data 调制信号 % data_len 码元个数 % sample_num

3、ber 每个码元采样点数 % Rb 码元速率 % signal_out 基带调制输出 % I_out I路输出 % Q_out Q路输出 %* % data_len = 10; %码元个数 % sample_number = 8; %采样点数 % Rb = 16000; %码元速率 % data1 = randint(1,data_len); % data = 2*data1-1; %传输的序列 Tb = 1/Rb; %码元时间 fs = Rb*sample_number; %采样速率 %- %差分编码 data_diff = difference(data); %* %- %并串转换，延时

4、I(1) = 1; %fai0 = 0,cos(fai0) = 1 for i = 1:2:data_len Q(i) = data_diff(i); Q(i+1) = data_diff(i); end for i = 2:2:data_len I(i+1) = data_diff(i); I(i) = data_diff(i); end for i = 1:sample_number I1(i:sample_number:data_len*sample_number) = I(1:data_len); Q1(i:sample_number:data_len*sample_number) =

5、 Q(1:data_len); end %* %- %乘加权函数 t=1/fs:1/fs:data_len*Tb; I_out = I1 .* cos(pi*t/2/Tb); Q_out = Q1 .* sin(pi*t/2/Tb); %* %- %调制信号产生 signal_out = I_out + j*Q_out; %* % %- % %画图 % subplot(221) % plot(data,.-);title(MSK传输的数据);xlabel(时间);ylabel(幅度) % subplot(222) % plot(data_diff,.-);title(差分后的数据);xlabe

6、l(时间);ylabel(幅度) % subplot(223) % plot(I1,.-);title(加权前I路);xlabel(时间);ylabel(幅度); % subplot(224) % plot(Q1,.-);title(加权前Q路);xlabel(时间);ylabel(幅度); % % figure(2) % subplot(221) % plot(cos(pi*t/2/Tb),.-);title(加权函数cos(t/(2Tb);xlabel(时间);ylabel(幅度) % subplot(222) % plot(sin(pi*t/2/Tb),.-);title(加权函数sin

7、(t/(2Tb);xlabel(时间);ylabel(幅度) % subplot(223) % plot(I_out,.-);title(加权后I路);xlabel(时间);ylabel(幅度); % subplot(224) % plot(Q_out,.-);title(加权后Q路);xlabel(时间);ylabel(幅度); % %* function signal_out,I_out,Q_out,phase = mod_msk2(data,data_len,sample_number,Rb) %MSK基带调制 %* % data 调制信号 % data_len 码元个数 % sampl

8、e_number 每个码元采样点数 % Rb 码元速率 % signal_out 基带调制输出 % I_out I路输出 % Q_out Q路输出 %* % data_len = 10; %码元个数 % sample_number = 8; %采样点数 % Rb = 16000; %码元速率 % data1 = randint(1,data_len); % data = 2*data1-1; %传输的序列 Tb = 1/Rb; %码元时间 fs = Rb*sample_number; %采样速率 %- %采样 for i = 1:sample_number data_sample(i:samp

9、le_number:data_len*sample_number) = data; end %* %- %计算相位 phase = zeros(1,data_len*sample_number); phase(1) = data_sample(1) * pi/2/sample_number; for i = 2:data_len*sample_number phase(i) = phase(i-1) + data_sample(i-1) * pi/2/sample_number; end %* %- %I/Q I_out = cos(phase); Q_out = sin(phase); %*

10、 %- %调制信号产生 signal_out = I_out + j*Q_out; %*%MSK调制，差分解调方法一 clear all close all %- %参数设置 data_len = 10000; %码元个数 sample_number = 8; %采样个数 Rb = 24000; %码元速率 fc = 96000; %载波频率 %* %- %随机产生传输信号 data=rand_binary(data_len); %* %- %MSK基带调制 signal_out,I_out,Q_out = mod_msk(data,data_len,sample_number,Rb); %*

11、 %- %中频搬移 multi = fc/Rb; I_temp=interp(I_out,multi); Q_temp=interp(Q_out,multi); Fs=fc*sample_number; t=1/Fs:1/Fs:length(I_temp)*1/Fs; signal_i=I_temp.*cos(2*pi*fc*t); signal_q=Q_temp.*sin(2*pi*fc*t); signal_mod=I_temp.*cos(2*pi*fc*t)-Q_temp.*sin(2*pi*fc*t); %* %- %加噪声 for SNR = 0:8 signal_mod1 = aw

12、gn(signal_mod,SNR); %- %去载波 N=300; % 滤波器的阶数为(N+1) F=0,fc-1000,fc+1000,Fs/2*2/Fs; A=1,1,0,0; lpf=firls(N,F,A); amp_lpf,w=freqz(lpf); I_dem=signal_mod1.*cos(2*pi*fc*t)*2; I_dem=conv(I_dem,lpf); I_dem=I_dem(N/2+1:N/2+length(I_temp); Q_dem=signal_mod1.*sin(2*pi*fc*t)*2; Q_dem=conv(Q_dem,lpf); Q_dem=-Q_d

13、em(N/2+1:N/2+length(I_temp); I_dem_out=zeros(1,length(I_dem)/multi); % 抽取 Q_dem_out=zeros(1,length(Q_dem)/multi); for i=1:length(I_dem_out) I_dem_out(i)=I_dem(multi*(i-1)+1); Q_dem_out(i)=Q_dem(multi*(i-1)+1); end; %* %- %差分解调 demod_data = zeros(1,data_len); demod_data(1) = Q_dem_out(sample_number);

14、 for i = 2:data_len demod_data(i) = Q_dem_out(i*sample_number)*I_dem_out(i-1)*sample_number) - I_dem_out(i*sample_number)*Q_dem_out(i-1)*sample_number); end %* %- %判决 demod_data = demod_data0; demod_data = 2*demod_data-1; %* %- %计算误码率 num,ber(SNR+1)=symerr(demod_data,data); %* end %* %- %误码率曲线 semil

15、ogy(0:8,ber,r*-); %* %- %误码率理论值 snr = 0:0.1:8; for i = 1:length(snr) snr1(1,i) = 10(snr(1,i)/10); ps(1,i) = 1/2 * erfc(sqrt(snr1(1,i); pe(1,i) = 2 * ps(1,i); end hold on semilogy(0:.1:8,pe); %*%MSK调制，差分解调方法二 clear all close all %- %参数设置 data_len = 10000; %码元个数 sample_number = 8; %采样个数 Rb = 24000; %码元速率 fc = 96000; %载波频率 %* %- %随机产生传输信号 data=rand_binary(data_len); %* %- %MSK基带调制 signal_out,I_out,Q_out = mod_msk(data,data_len,sample_number,Rb); %*