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<span class="path"><a href="index.html">FOSSEE Signal Processing Toolbox</a> >> <a href="section_e54aa8aac34aa55341e8b4b782fe1a74.html">FOSSEE Signal Processing Toolbox</a> > pburg</span>
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<div class="refnamediv"><h1 class="refname">pburg</h1>
<p class="refpurpose">Calculate Burg maximum-entropy power spectral density.</p></div>
<div class="refsynopsisdiv"><h3 class="title">Calling Sequence</h3>
<div class="synopsis"><pre><span class="default">[</span><span class="default">psd</span><span class="default">,</span><span class="default">f_out</span><span class="default">] = </span><span class="functionid">pburg</span><span class="default">(</span><span class="default">x</span><span class="default">,</span><span class="default">poles</span><span class="default">,</span><span class="default">freq</span><span class="default">,</span><span class="default">Fs</span><span class="default">,</span><span class="default">range</span><span class="default">,</span><span class="default">method</span><span class="default">,</span><span class="default">plot_type</span><span class="default">,</span><span class="default">criterion</span><span class="default">)</span>
<span class="default">All</span> <span class="default">but</span> <span class="default">the</span> <span class="default">first</span> <span class="default">two</span> <span class="default">arguments</span> <span class="default">are</span> <span class="default">optional</span> <span class="default">and</span> <span class="default">may</span> <span class="default">be</span> <span class="default">empty</span><span class="default">.</span></pre></div></div>
<div class="refsection"><h3 class="title">Parameters</h3>
<dl><dt><span class="term">x:</span>
<dd><p class="para">[vector] sampled data</p></dd></dt>
<dt><span class="term">poles:</span>
<dd><p class="para">[integer scalar] required number of poles of the AR model</p></dd></dt>
<dt><span class="term">freq:</span>
<dd><p class="para">[real vector] frequencies at which power spectral density is calculated [integer scalar] number of uniformly distributed frequency values at which spectral density is calculated. [default=256]</p></dd></dt>
<dt><span class="term">Fs:</span>
<dd><p class="para">[real scalar] sampling frequency (Hertz) [default=1]</p></dd></dt>
<dt><span class="term">range:</span>
<dd><p class="para">'half', 'onesided' : frequency range of the spectrum is from zero up to but not including sample_f/2. Power from negative frequencies is added to the positive side of the spectrum. 'whole', 'twosided' : frequency range of the spectrum is -sample_f/2 to sample_f/2, with negative frequencies stored in "wrap around" order after the positive frequencies; e.g. frequencies for a 10-point 'twosided' spectrum are 0 0.1 0.2 0.3 0.4 0.5 -0.4 -0.3 -0.2 -0.1 'shift', 'centerdc' : same as 'whole' but with the first half of the spectrum swapped with second half to put the zero-frequency value in the middle. (See "help fftshift". If "freq" is vector, 'shift' is ignored. If model coefficients "ar_coeffs" are real, the default range is 'half', otherwise default range is 'whole'.</p></dd></dt>
<dt><span class="term">method:</span>
<dd><p class="para">'fft': use FFT to calculate power spectral density. 'poly': calculate spectral density as a polynomial of 1/z N.B. this argument is ignored if the "freq" argument is a vector. The default is 'poly' unless the "freq" argument is an integer power of 2.</p></dd></dt>
<dt><span class="term">plot_type:</span>
<dd><p class="para">'plot', 'semilogx', 'semilogy', 'loglog', 'squared' or 'db' specifies the type of plot. The default is 'plot', which means linear-linear axes. 'squared' is the same as 'plot'. 'dB' plots "10*log10(psd)". This argument is ignored and a spectrum is not plotted if the caller requires a returned value.</p></dd></dt>
<dt><span class="term">criterion:</span>
<dd><p class="para">[optional string arg] model-selection criterion. Limits the number of poles so that spurious poles are not added when the whitened data has no more information in it (see Kay & Marple, 1981). Recognized values are 'AKICc' -- approximate corrected Kullback information criterion (recommended), 'KIC' -- Kullback information criterion 'AICc' -- corrected Akaike information criterion 'AIC' -- Akaike information criterion 'FPE' -- final prediction error" criterion The default is to NOT use a model-selection criterion.</p></dd></dt></dl></div>
<div class="refsection"><h3 class="title">Description</h3>
<p class="para">This function is being called from Octave
This function is a wrapper for arburg and ar_psd.
The functions "arburg" and "ar_psd" do all the work.
See "help arburg" and "help ar_psd" for further details.</p></div>
<div class="refsection"><h3 class="title">Examples</h3>
<div class="programlisting"><table border="0" width="100%"><tr><td width="98%"><pre class="scilabcode"><span class="scilabid">a</span> <span class="scilaboperator">=</span> <span class="scilabopenclose">[</span><span class="scilabnumber">1.0</span> <span class="scilaboperator">-</span><span class="scilabnumber">1.6216505</span> <span class="scilabnumber">1.1102795</span> <span class="scilaboperator">-</span><span class="scilabnumber">0.4621741</span> <span class="scilabnumber">0.2075552</span> <span class="scilaboperator">-</span><span class="scilabnumber">0.018756746</span><span class="scilabopenclose">]</span><span class="scilabdefault">;</span>
<span class="scilabopenclose">[</span><span class="scilabid">psd</span><span class="scilabdefault">,</span><span class="scilabid">f_out</span><span class="scilabopenclose">]</span> <span class="scilaboperator">=</span> <span class="scilabid">pburg</span><span class="scilabopenclose">(</span><span class="scilabid">a</span><span class="scilabdefault">,</span><span class="scilabnumber">2</span><span class="scilabopenclose">)</span><span class="scilabdefault">;</span></pre></td><td valign="top"><a href="scilab://scilab.execexample/"><img src="ScilabExecute.png" border="0"/></a></td><td valign="top"><a href="scilab://scilab.editexample/"><img src="ScilabEdit.png" border="0"/></a></td><td></td></tr></table></div></div>
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