Matlab 功率谱图

Question

我想绘制特定 .wav 声音文件的功率谱图，频率范围为 -2000 到 +2000 Hz。

尝试：

到目前为止，这是我的代码：

[s, Fs] = wavread('chord.wav');
Hs=spectrum.periodogram;
psd(Hs,s,'Fs',Fs)

我尝试使用周期图算法。但结果 plot 的范围是 0 到 20,000 Hz。那么，我该如何修改代码，使其在 -2000 到 +2000 Hz 范围内绘制？

如有任何帮助，我们将不胜感激。

Answer 1

我修改了这个支持中的一个例子page

    Fs = 32e3;   
    t = 0:1/Fs:2.96;
    x = cos(2*pi*t*1.24e3)+ cos(2*pi*t*10e3)+ randn(size(t));
    nfft = 2^nextpow2(length(x));
    Pxx = abs(fft(x,nfft)).^2/length(x)/Fs;
    Hpsd = dspdata.psd(Pxx(1:length(Pxx)/2),'Fs',Fs);  
    plot(Hpsd)

figure
plot(Hpsd)
axis([9.8 10.2 -90 0])  %change axis range

Answer 2

我编写此代码是为了对任何时间历史向量进行 FFT，其中 T 是时间步长向量，S 是相关位移或您希望绘制其频谱的任何给定量。 ps:STfile 是所有自由度的模型位移时间历史，我将其保存为 .mat 文件

    clc
clear

load STfile

% is your starting vector of time

data = S(:,12); % vector of data you want to resample 

N = length(T);

for ii=1:(N-1)
    DT(ii) = T(ii+1)-T(ii);
end

DTS = mean(DT);


data_TS = timeseries(data,T); % define the data as a timeseries 

new_T = T(1):DTS:T(end); % new vector of time with fixed dt=1/fs

data_res = resample(data_TS,new_T); % data resampled at constant fs

plot(data_res)

y=getdatasamples(data_res,1:N);

Fs=1./DTS;
NFFT = 2^nextpow2(N);
Y = fft(y,NFFT)/N; % the division by N is to scale the amplitude

freq = Fs/2*linspace(0,1,NFFT/2+1); % vector of frequencies for the plot
figure()
plot(freq,2*abs(Y(1:NFFT/2+1)),'r') % multiplicated by 2 to recover the energy related
% to the negative frequencies since in this way only half spectrum is plotted
xlabel('Frequency(rad/sec)')
xlim([0 0.05])

example result for this code(time history of heave velocity)

Matlab 功率谱图

Matlab Power Spectrum Plot

matlab

signal-processing

fft