MSK.zip_MSK解调_modulation_msk_msk调制解调

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_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 %-------------------------------------------------------------------------- %差分编码 [data_diff] = difference(data); %************************************************************************** %-------------------------------------------------------------------------- %并串转换，延时 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) = 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');xlabel('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(πt/(2Tb))');xlabel('时间');ylabel('幅度') % subplot(222) % plot(sin(pi*t/2/Tb),'.-');title('加权函数sin(πt/(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 % sample_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:sample_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); %************************************************************************** %-------------------------------------------------------------------------- %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); %************************************************************************** %-------------------------------------------------------------------------- %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 = awgn(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_dem(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; %************************************************************************** %------------------------------------------------