短时傅里叶变换matlab程序.

function [Spec,Freq]=STFT(Sig,nLevel,WinLen,SampFreq %计算离散信号的短时傅里叶变换；

% Sig 待分析信号；

% nLevel 频率轴长度划分（默认值512）；

% WinLen 汉宁窗长度（默认值 64）；

% SampFreq 信号的采样频率（默认值1）；

if (nargin <1,

error('At least one parameter required!';

end;

Sig=real(Sig;

SigLen=length(Sig;

if (nargin <4,

SampFreq=1;

end

if (nargin <3,

WinLen=64;

end

if (nargin <2,

nLevel=513;

end

nLevel=ceil(nLevel/2*2+1;

WinLen=ceil(WinLen/2*2+1;

WinFun=exp(-6*linspace(-1,1,WinLen.^2;

WinFun=WinFun/norm(WinFun;

Lh=(WinLen-1/2;

Ln=(nLevel-1/2;

Spec=zeros(nLevel,SigLen;

wait=waitbar(0,'Under calculation,please wait...';

for iLoop=1:SigLen,

waitbar(iLoop/SigLen,wait;

iLeft=min([iLoop-1,Lh,Ln];

iRight=min([SigLen-iLoop,Lh,Ln];

iIndex=-iLeft:iRight;

iIndex1=iIndex+iLoop;

iIndex2=iIndex+Lh+1;

Index=iIndex+Ln+1;

Spec(Index,iLoop=Sig(iIndex1.*conj(WinFun(iIndex2; end; close(wait;

Spec=fft(Spec;

Spec=abs(Spec(1:(end-1/2,:;

Freq=linspace(0,0.5,(nLevel-1/2*SampFreq; t=(0:(SigLen-1/SampFreq;

clf

set(gcf,'Position',[20 100 500 430]; set(gcf,'Color','w';

axes('Position',[0.1 0.45 0.53 0.5]; mesh(t,Freq,Spec;

axis([min(t max(t 0 max(Freq]; colorbar

xlabel('t/s';

ylabel('f/Hz';

title('STFT时频谱图';

axes('Position',[0.1 0.1 0.55 0.25]; plot(t,Sig;

axis tight

ylabel('x(t';

title('时域波形';

axes('Position',[0.73 0.45 0.24 0.5]; PSP=abs(fft(Sig;

Freq=linspace(0,1,SigLen*SampFreq; plot(PSP(1:end/2,Freq(1:end/2; title('频谱';