热噪声由于其随机和不相关的特性,在时域中累加无法将其加强;脉冲信号由于相关性,即使低于热噪声,也可以通过长时间的累加,将其加强;
clear
close all
a=randn(10^4,1024);
for cntx=1:10^4
for cnty=1:1024
if(mod(cnty,128) == 0)
a(cntx,cnty)=0.1+randn;
end
end
end
a_s=sum(a);
a_s0=sum(abs(a));
a_avg=a_s0./10^4;
snr_db=20*log10(0.1/mean(a_avg))
stem(a_avg,'r*')
hold on
stem(a_s,'b')