（2）、修正的周期图法1、N=256，M=3200.511.522.533.544.55x104-15-10-50510N=256M=32改进的谱估计，2、N=256，M=12800.511.522.533.544.55x104-20-15-10-5051015N=256M=128改进的谱估计，3、N=512，M=12800.511.522.533.544.55x104-20-15-10-5051015N=512M=128改进的谱估计，程序：1.functionPer1N=256；fs=100000；f=0.02；n=1:N；s(n)=sin(2*pi*f*n)；x=awgn(s,10)；window1=hamming(32)；overlap=10；[Pxx1,f1]=psd(x,N,fs,window1,overlap)；log_Pxx1=10*log10(Pxx1)；n1=0:round(N/2-1)；f1=n1*fs/N；plot(f1,log_Pxx1(n1+1))；title('改进的谱估计N=256，M=32')；2.functionPer2N=256；fs=100000；f=0.02；n=1:N；s(n)=sin(2*pi*f*n)；x=awgn(s,10)；window1=hamming(128)；overlap=10；[Pxx1,f1]=psd(x,N,fs,window1,overlap)；log_Pxx1=10*log10(Pxx1)；n1=0:round(N/2-1)；f1=n1*fs/N；plot(f1,log_Pxx1(n1+1))；title('改进的谱估计N=256，M=128')；3.functionPer3N=512；fs=100000；f=0.02；n=1:N；s(n)=sin(2*pi*f*n)；x=awgn(s,10)；window1=hamming(128)；overlap=10；[Pxx1,f1]=psd(x,N,fs,window1,overlap)；log_Pxx1=10*log10(Pxx1)；n1=0:round(N/2-1)；f1=n1*fs/N；plot(f1,log_Pxx1(n1+1))；title('改进的谱估计N=512，M=128')；
