二进制调制团圆饭

源代码

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 单极性归零NRZ码、双极性非归零NRZ码、2ASK、2FSK、2PSK、2DPSK的产生% 观察二进制数字信号码元速率和它的带宽的关系%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%clc; clear all;close all;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%参数设置 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%fs = 8000;% 采样频率fc1 = 200;% 载波频率fc2 = 800;% 载波频率RB = 1e2;% 码元速率my_count=fs/RB;% 一个码元的采样点数M = 2; % 二进制调制N = 100; % 码元数count=my_count*N; % 总的采样点数t = 0:1/fs:(count-1)/fs; % 信号持续时间%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 产生原始信号%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% randi函数：生成0 1的单极性序列% 第一个参数：生成随机序列的最大值 第2个参数：行数 第3个参数：列数s = randi([0,1],N,1); % 基带序列y1 = zeros(1,count); % 单极性不归零信号（ 0和+1表示数字信息）y2 = zeros(1,count); % 双极性不归零信号（-1和+1表示数字信息）y3 = zeros(1,count); % 差分信号% 1对应π，0对应0last_bit = -1; % 初始值为-1for n = 0:N-1y1((n*my_count+1):((n+1)*my_count)) = s(n+1); % 内插 if s(n+1) == 1y2((n*my_count+1):((n+1)*my_count)) = 1; % 双极性不归零信号last_bit = -last_bit;% 取反y3((n*my_count+1):((n+1)*my_count)) = last_bit; % 如果基带信号为1，y3=1else % s(n+1) == 0y2((n*my_count+1):((n+1)*my_count)) = -1;y3((n*my_count+1):((n+1)*my_count)) = last_bit; % 如果之前s的值有过1，那么last_bit的值就会取一次反endend%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%单极性归零信号（ 0和+1表示数字信息）%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%S = fftshift(fft(y1));L=length(y1);P=abs(S)/L;f=(0:L-1)*fs/L-fs/2;figure(1)subplot(2,1,1);stem(t,y1);grid minor;title('单极性归零基带信号时域波形');subplot(2,1,2);plot(f,P);grid minor;xlabel('f/Hz');ylabel('频谱');title('单极性归零基带信号频谱');%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 2ASK调制% 当幅度=1时，与载波相乘 当幅度=0时，0%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%s_ask = y1.*cos(2*pi*fc2*t);S_ask = fftshift(fft(s_ask));P_ask=abs(S_ask)/L;figure(2)subplot(2,1,1);plot(t,s_ask);grid minor;title('2ASK信号时域波形');subplot(2,1,2);plot(f,P_ask);grid minor;xlabel('f/Hz');ylabel('频谱');title('2ASK信号频谱');%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 2FSK调制% 当幅度=1时，与载波f1相乘;当幅度=0时，与载波f2相乘%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%s_fsk = y1.*cos(2*pi*fc1*t) + (~y1).*sin(2*pi*fc2*t);S_fsk = fftshift(fft(s_fsk));P_fsk=abs(S_fsk)/L;figure(3)subplot(2,1,1);plot(t,s_fsk);grid minor;title('2FSK信号时域波形');subplot(2,1,2);plot(f,P_fsk);grid minor;xlabel('f/Hz');ylabel('频谱');title('2FSK信号频谱');%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%双极性归零信号（-1和+1表示数字信息）%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%S = fftshift(fft(y2));P=abs(S)/L;figure(4);subplot(2,1,1);stem(t,y2);grid minor;title('双极性归零基带信号时域波形');subplot(2,1,2);plot(f,P);grid minor;xlabel('f/Hz');ylabel('频谱');title('双极性归零基带信号频谱');%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%BPSK信号 % 相移键控利用载波的变化来传递数字信息%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%s_psk = y2.*cos(2*pi*fc2*t);S_psk = fftshift(fft(s_psk));P_BPSK=abs(S_psk)/L;figure(5);subplot(2,1,1);plot(t,s_psk);grid minor;title('BPSK信号时域波形');subplot(2,1,2);plot(f,P_BPSK);grid minor;xlabel('f/Hz');ylabel('频谱');title('BPSK信号频谱');%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%2DPSK信号 % 2DPSK是利用前后相邻码元的载波相对相位变化来传递数字信息%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%s_2dpsk = y3.*cos(2*pi*fc2*t);S_2dpsk = fftshift(fft(s_2dpsk));P_2DPSK=abs(S_2dpsk)/L;figure(6);subplot(2,1,1);plot(t,s_2dpsk);grid minor;title('2DPSK信号时域波形');subplot(2,1,2);plot(f,P_2DPSK);grid minor;xlabel('f/Hz');ylabel('频谱');title('2DPSK信号频谱');

仿真结果