%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%生成bpsk調制信號
fs=100;
%采樣頻率
fc=40;
%載頻
fo=fs/20;
%碼率
a=2*fo;
%循環周期
T=40;
%信號樣本
x=rand(40,1);
y=round(x);
a1=y*2-1;
z=ones(200,1);
for i=1:40
    for j=1:5
        an(5*i-5+j)=z(5*i-5+j)*a1(i);
    end
end
t=1/fs:1/fs:2;
xn=an.*cos(4*pi*fc*t);
%生成bpsk調制信號,第一用戶使用情況下
figure(1)
plot(t,xn);
axis([0 2 -1.5 1.5]);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%進行周期圖檢測
window=kaiser(length(xn),0.5);
%矩形窗
nfft=512;
%512fft
[Pxx,f]=periodogram(xn,window,nfft,fs);
%周期圖檢測

figure(2)
plot(f,-10*log10(Pxx));
window=kaiser(length(xn),0.5);
nfft=1024;
%%%%%%%%%%%%%%%%%%%%%%%%%%%%1024fft
[Pxx,f]=periodogram(xn,window,nfft,fs);
%周期圖檢測
figure(3)
plot(f,10*log10(Pxx));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%對不同類型窗函數進行檢測興性能分析
window1=boxcar(length(xn));
%矩形窗
window2=hamming(length(xn));
%海明窗
window3=blackman(length(xn));
%blackman窗
[Pxx1,f]=periodogram(xn,window1,nfft,fs);
[Pxx2,f]=periodogram(xn,window2,nfft,fs);
[Pxx3,f]=periodogram(xn,window3,nfft,fs);
figure(4)
subplot(221)
plot(f,-10*log10(Pxx));
subplot(222)
plot(f,-10*log10(Pxx1));
subplot(223)
plot(f,-10*log10(Pxx2));
subplot(224)
plot(f,-10*log10(Pxx3));