N=2000;?????????????????????????%?simulation?length
fs=1000*10;?????????????????????%?sampling?rate
ts=1/fs;
t=-N/2*ts:ts:（N/2-1）*ts;????????????????%?N?points
T=N*ts;

%?To?generate?a?tri-pulse:?s3（t）
A3=1.0;?????????????????????????%?Parameters?of?the?square
W3=0.02;????????????????????????%?width?of?the?pulse
T3=0.03;
m_t=A3*（tripuls（tW3）-tripuls（t-1.5*W3W3））;?????????
%?m_t=A3*cos（2*pi*20*t）;?????????
B0=5*1/W3;???????????????????????%?帶寬
Pm=mean（（m_t）.^2）;
index=Pm/（1+Pm）;

A=1;?????????????????????????????%?Parameters?of?cos
f0=1000;?????????????????????????%?freq
sAM_t=A*（1+m_t）.*cos（2*pi*f0*t）;?????????

%?CHANNEL
%?To?generate?white?gausian?noise
N0=0.000001;????????????????????????%?Parameters?of?cos
sigma=sqrt（N0*fs/2）;
w=normrnd（0sigma[1N]）;????????%?正態分布隨機數

hbpf=fir1（100[f0-B0f0+B0]/（fs/2））;???????%?考慮101階
%?delay?line
%?hbpf=zeros（1101）;???hbpf（51）=1;????????????????%?考慮101階

sAM_ti=filter（hbpf1sAM_t）;
wi=filter（hbpf1w）;
sAM_t=sAM_ti+wi;
Psi=（std（sAM_ti））^2;
Pni=（std（wi））^2;
SNRi=10*log10（Psi/Pni）;

%?LPF
h=fir1（40[B0]/（fs/2））;??????????%?B0-Hz低通濾波器，考慮41階
sAMabs_t=sAM_t.*（sAM_t>0）;???????%?***?Envelope?detector?=?abs（）?+?LPF（）
sAMdem_t=filter（h1sAMabs_t）;??%?demodulated?wave