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');
