Error in plotting the Histogram of Multi-taper estimate

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Soham 2013-7-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/82214-error-in-plotting-the-histogram-of-multi-taper-estimate

Hello, I am trying to plot the histogram of the power estimate obtained using the Multi-taper method. When 1 taper is used the histogram shows the expected exponential distribution ; on increasing the number of tapers it is expected that the distribution should show Gamma distribution (as seen when shape parameter = 2 and scaling parameter = 2.0 ). However the the plot still shows exponential distribution as seen when single taper is used. Following is the code that I have used.

{

Fs = 2000;
T1 = [];
S1 = [];
for i =1: length(timeVals)
      if (-0.3000<= timeVals(i)) && (timeVals(i)<= -0.1000 );
          T1 = [T1,timeVals(i)];
          S1 = [S1,signal(:,i)];
      end
  end
Ta =(max(T1)) - (min(T1));
f1 = 0:1/Ta :Fs;
C1=S1';
params.Fs = Fs;
params.tapers = [2 3];
params.trialave = 0;
params.pad = 1;
[S,f1] = mtspectrumc(C1, params);
S1 = 10*log10(S/max(S));
semilogy(f1,S1,'k');
grid on;
% xlim([0 50])
xlabel('Frequency [Hz]')
ylabel('Power [dB]')
title ('multi-taper spectrum')
hold on;
T2 = [];
S2 = [];
for j = 1: length(timeVals)
      if (0.2000<= timeVals(j)) && (timeVals(j)<= 0.4000 )
          T2 = [T2,timeVals(j)];
          S2 = [S2,signal(:,j)];
      end
  end
Tb =(max(T2)) - (min(T2));
f2 = 0:1/Tb :Fs;
C2 = S2';
params.Fs = Fs;
params.tapers = [2 3];
params.trialave = 0;
params.pad = 1;
[W,f2] = mtspectrumc(C2, params);
W1 = 10*log10(W/max(W));
semilogy(f2,W1,'r');
grid on;
% xlim([0 50])
xlabel('Frequency [Hz]')
ylabel('Power [dB]')
title ('multi-taper spectrum')
% for plotting the histogram
figure (3);
H =  hist(W(:),100);
plot(H);
xlim ([0 100]);