sh2_1_jt.rar_am matlab_jt_sh2_1_jt_通信系统仿真

clear; t0=0.15; ts=0.001; Fc=200; Fs=1/ts; Kf=50; df=0.3; t=[0:ts:t0]; m=[ones(1,t0/(3*ts)),-2*ones(1,t0/(3*ts)),zeros(1,t0/(3*ts)+1)]; c=cos(2*pi*Fc.*t); %FM调制 int_m(1)=0; for i=1:length(t)-1 int_m(i+1)=int_m(i)+m(i)*ts; end u=cos(2*pi*Fc.*t+2*pi*Kf*int_m); [M,m,df1]=fft_seq(m,ts,df); M=M/Fs; [U,u,df1]=fft_seq(u,ts,df); U=U/Fs; %////////////////////////////////////////// %FM解调(包络检波法) [v,phase]=env_phas(u,ts,Fc); phi=unwrap(phase); dem=(1/(2*pi*Kf))*(diff(phi)/ts); %调制信号功率 W=1*t0/3+4*t0/3; P=W/(2*t0/3) %////////////////////////////////////////// [C,c,df1]=fft_seq(c,ts,df); f=[0:df1:df1*(length(m)-1)]-Fs/2; clf subplot(2,2,1);plot(t,m(1:length(t))); title('未调制信号'); subplot(2,2,2);plot(t,u(1:length(t))); title('已调制信号'); subplot(2,2,3);plot(t,dem(1:length(t))); title('解调波形'); subplot(2,2,4);plot(f,abs(fftshift(U))); title('已调制信号频谱');