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%?FUNCTION:?music.m
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%?AUTHOR:?Steve?Kogon
%?
%?DATE:?January?18?1999
%
%?DEscriptION:?This?file?forms?an?estimate?of?the?frequency?spectrum?using?
%??????????????MUSIC?algorithm?（spectral?version）?（Schmidt?1986）.
%
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%-----------------------------------------------------------
%?Copyright?2000?by?Dimitris?G.?Manolakis?Vinay?K.?Ingle
%?and?Stephen?M.?Kogon.??For?use?with?the?book
%?“Statistical?and?Adaptive?Signal?Processing“
%?McGraw-Hill?Higher?Education.
%-----------------------------------------------------------


function?[festRbar]?=?music（xPMNfft）
%?x?=?signal
%?P?=?number?of?complex?exponentials
%?M?=?time-window?length
%?Nfft?=?number?of?FFT?frequencies

%?Generate?data?matrix
N?=?length（x）?-?M?+?1;
X?=?zeros（NM）;
for?n?=?1:M
???X（:n）?=?x（（1:N）+?（M-n））;
end
R?=?（1/N）*X‘*X;????????????????%?estimate?correlation?matrix

%?Compute?eigendecomposition?and?order?by?descending?eigenvalues
[Q0D]?=?eig（R）;
[lambdaindex]?=?sort（abs（diag（D）））;
lambda?=?lambda（M:-1:1）;
Q=Q0（:index（M:-1:1））;

%?Compute?pseudo-spectrum
f?=?（-Nfft/2:（Nfft/2-1））/Nfft;????????????????%?FFT?frequencies
Qbar?=?zeros（Nfft1）;
for?n?=?1:（M-P）
???Qbar?=?Qbar?+?abs（fftshift（fft（Q（:M-（n-1））Nfft）））.^2;
end
Rbar?=?1./Qbar;

%?Find?local?maxima?（values?of?Rbar?that?are?larger?than?their?neighbors）
z1?=?Rbar（2:（Nfft-1））?-?Rbar（1:（Nfft-2））;
z2?=?Rbar（2:（Nfft-1））?-?Rbar（3:Nfft）;
peak_index?=?find（（z1?>?0）?&?（z2?>?0））?+?1;
if?Rbar（1）?>?Rbar（2）
???peak_index?=?[1?
??????peak_index];
end
if?Rbar（Nfft）?>?Rbar（Nfft-1）
???peak_index?=?[peak_index
?????????????????Nfft];
end
Npeaks?=?length（peak_index）;
f_peaks?=?f（peak_index）;

%?Determine?the?P?largest?peaks?（taken?from?local?maxima）
[dummyfest_index]?=?sort（Rbar（peak_index））;
fest?=?f_peaks（fest_index（Npeaks:-1:（Npeaks-P+1）））.‘;

?屬性????????????大小?????日期????時間???名稱
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?????文件???????2024??2011-09-11?15:28??music.m

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?????????????????2024????????????????????1