高斯调幅信号amgauss

 AMGAUSS Generate gaussian amplitude modulation.
     Y=AMGAUSS(N,T0,T) generates a gaussian amplitude modulation
     centered on a time T0, and with a spread proportional to T.
     This modulation is scaled such that Y(T0)=1
     and Y(T0+T/2) and Y(T0-T/2) are approximately equal to 0.5 .
 
     N  : number of points. 序列点数
     T0 : time center        (default : N/2).中心坐标
     T  : time spreading        (default : 2*sqrt(N)). 拐点
     Y  : signal.返回信号
 
     Examples:
      z=amgauss(160); plot(z);
      z=amgauss(160,90,40); plot(z);
      z=amgauss(160,180,50); plot(z);