suijixinhao.rar_periodic noise_信号提取matlab_音频周期_音频周期噪声_频谱 功率谱

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %巴特沃思数字低通滤波器 %数字滤波器指标 wp=1000*2*pi;ws=2000*2*pi; %滤波器通带和阻带截止频率(Hz) rp=2;as=35;fs=44100;t=1/fs; %模拟巴特沃思原型滤波器计算 [N,wc]=buttord(wp,ws,rp,as,'s'); %原型的阶数和边缘频率计算 [ba,aa]=butter(N,wc,'s'); %原型的分子分母系数向量 [bd,ad]=impinvar(ba,aa,fs); %调用脉冲响应不变法函数使成为数字信号 [H,W]=freqz(bd,ad); %计算数字低通滤波器频率响应 figure(10); plot(W*fs/(2*pi),abs(H));grid on; %画幅频响应图 title('巴特沃思数字低通滤波器幅频响应曲线');ylabel('幅度');xlabel('频率/Hz');%标题设置 axis([0 3000 0 1.2]); %设置坐标范围 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %四种信号 x=0:1/44100:2047/44100; %横坐标取值 sgn=wavrecord(2048,44100,1,'double'); %从声卡取得信号 sgn=sgn'; %信号转置 %sgn=square(1000*2*pi*x); %sgn=sin(1000*2*pi*x); hnoise=wgn(1,2048,-10); %高斯白噪声信号,强度为-10dBW noisesgn=sgn+hnoise; %加有高斯白噪声的信号 lpfnoisesgn=filter(bd,ad,noisesgn); %通过低通滤波器的噪声信号 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %计算信号(sgn)的的统计特性 figure(1); plot(x,sgn);grid on; %画信号波形 axis([0,0.015,-2,2]); title('信号波形曲线'); disp('信号均值'); mxsgn=mean(sgn); %信号均值 fprintf('%f\n',mxsgn); disp('信号方差值'); dsgn=var(sgn); %信号方差值 fprintf('%f\n',dsgn); disp('信号标准差'); ssgn=std(sgn); %信号标准差 fprintf('%f\n',ssgn); disp('信号均方值'); ex2sgn=mxsgn^2+dsgn; %信号均方值 fprintf('%f\n',ex2sgn); rsgn=xcorr(sgn,'unbiased'); %信号的自相关函数 figure(2); plot(rsgn);grid on; %画自相关函数曲线 title('信号自相关函数曲线'); axis([1000,1500,-1,1]); fxsgn=fftshift(fft(sgn)); %频谱函数数值 figure(3); g = floor((-length(fxsgn)/2+0.5):(length(fxsgn)/2-0.5)); d=g*44100/length(fxsgn); plot(d,abs(fxsgn)); title('信号频谱函数'); axis([0,3000,0,1000]); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% figure(5); plot(x,hnoise);grid on; title('高斯白噪声波形曲线'); axis([0,0.015,-2,2]); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %加有噪声信号的统计特性 figure(7); plot(x,noisesgn);grid on; %画加有噪声信号波形 axis([0,0.015,-2,2]); title('加有噪声信号波形曲线'); disp('加有噪声信号均值'); mxnoisesgn=mean(noisesgn); %加有噪声信号均值 fprintf('%f\n',mxnoisesgn); disp('加有噪声信号方差值'); dnoisesgn=var(noisesgn); %加有噪声信号方差值 fprintf('%f\n',dnoisesgn); disp('加有噪声信号标准差'); snoisesgn=std(noisesgn); %加有噪声信号标准差 fprintf('%f\n',snoisesgn); disp('加有噪声信号均方值'); ex2noisesgn=mxnoisesgn^2+dnoisesgn; %加有噪声信号均方值 fprintf('%f\n',ex2noisesgn); rnoisesgn=xcorr(noisesgn,'unbiased'); %加有噪声信号的自相关函数 figure(8); plot(rnoisesgn);grid on; %画自相关函数曲线 title('加有噪声信号自相关函数曲线'); axis([1000,1500,-1,1]); fxnoisesgn=fftshift(fft(noisesgn)); %频谱函数数值 figure(9); g = floor((-length(fxnoisesgn)/2+0.5):(length(fxnoisesgn)/2-0.5)); d=g*44100/length(fxnoisesgn); plot(d,abs(fxnoisesgn)); title('加有噪声信号频谱函数'); axis([0,3000,0,1000]); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %通过低通滤波器的加噪声信号 figure(11); plot(x,lpfnoisesgn);grid on; %画通过低通滤波器的加噪声信号波形 axis([0,0.015,-2,2]); title('通过低通滤波器的加噪声信号波形曲线'); disp('通过低通滤波器的加噪声信号均值'); mxlpfnoisesgn=mean(lpfnoisesgn); %通过低通滤波器的加噪声信号均值 fprintf('%f\n',mxlpfnoisesgn); disp('通过低通滤波器的加噪声信号方差值'); dlpfnoisesgn=var(lpfnoisesgn); %通过低通滤波器的加噪声信号方差值 fprintf('%f\n',dlpfnoisesgn); disp('通过低通滤波器的加噪声信号标准差'); slpfnoisesgn=std(lpfnoisesgn); %通过低通滤波器的加噪声信号标准差 fprintf('%f\n',slpfnoisesgn); disp('通过低通滤波器的加噪声信号均方值'); ex2lpfnoisesgn=mxlpfnoisesgn^2+dlpfnoisesgn; %通过低通滤波器的加噪声信号均方值 fprintf('%f\n',ex2lpfnoisesgn); rlpfnoisesgn=xcorr(lpfnoisesgn,'unbiased'); %通过低通滤波器的加噪声信号的自相关函数 figure(12); plot(rlpfnoisesgn);grid on; %画自相关函数曲线 title('通过低通滤波器的加噪声信号自相关函数曲线'); axis([1000,1500,-1,1]); fxlpfnoisesgn=fftshift(fft(lpfnoisesgn)); %频谱函数数值 figure(13); g = floor((-length(fxlpfnoisesgn)/2+0.5):(length(fxlpfnoisesgn)/2-0.5)); d=g*44100/length(fxlpfnoisesgn); plot(d,abs(fxlpfnoisesgn)); title('通过低通滤波器的加噪声信号频谱函数'); axis([0,3000,0,1000]); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%