yule walker psd

hi i m working on a speech recognition project with command 'pyulear' when i use command

 Duration = 1; % Duration (sec)

 Fs = 8000; % Sampling Freq (Hz)

 z1 = wavrecord(Duration*Fs,Fs);

 pyulear(z1,12,512,8000);

i get the yule walker psd plotted in a graph with frequency on one axes and db/frequency on the other. but when i use

k1= pyulear(z1,12,512,8000);

i have 256 values in k1. i want to know how to relate the coordinates in the graph with those in k1.

any inputs would be helpful.

thanks in advance

Answer 1

[Wayne King]

The k1 are the power estimates as a function of frequency. If you enter

    10*log10(k1)

You will see that those values agree with the plotted values.

256 is the default NFFT length. So

    x = randn(100,1);
    y = filter(1,[1 1/2 1/3 1/4 1/5],x);
    pyulear(y,4,[],1000);   
    % compare with
    k1 = pyulear(y,4,[],1000);
    figure;
    plot(10*log10(k1)); grid on;

[777]

thanks a lot...