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<?xml version="1.0" encoding="UTF-8"?>
<!--
*
* This help file was generated from pburg.sci using help_from_sci().
*
-->
<refentry version="5.0-subset Scilab" xml:id="pburg" xml:lang="en"
xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:svg="http://www.w3.org/2000/svg"
xmlns:ns3="http://www.w3.org/1999/xhtml"
xmlns:mml="http://www.w3.org/1998/Math/MathML"
xmlns:scilab="http://www.scilab.org"
xmlns:db="http://docbook.org/ns/docbook">
<refnamediv>
<refname>pburg</refname>
<refpurpose>Calculate Burg maximum-entropy power spectral density.</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Calling Sequence</title>
<synopsis>
[psd,f_out] = pburg(x,poles,freq,Fs,range,method,plot_type,criterion)
All but the first two arguments are optional and may be empty.
</synopsis>
</refsynopsisdiv>
<refsection>
<title>Parameters</title>
<variablelist>
<varlistentry><term>x:</term>
<listitem><para> [vector] sampled data</para></listitem></varlistentry>
<varlistentry><term>poles:</term>
<listitem><para> [integer scalar] required number of poles of the AR model</para></listitem></varlistentry>
<varlistentry><term>freq:</term>
<listitem><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]</para></listitem></varlistentry>
<varlistentry><term>Fs:</term>
<listitem><para> [real scalar] sampling frequency (Hertz) [default=1]</para></listitem></varlistentry>
<varlistentry><term>range:</term>
<listitem><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'.</para></listitem></varlistentry>
<varlistentry><term>method:</term>
<listitem><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.</para></listitem></varlistentry>
<varlistentry><term>plot_type:</term>
<listitem><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.</para></listitem></varlistentry>
<varlistentry><term>criterion:</term>
<listitem><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.</para></listitem></varlistentry>
</variablelist>
</refsection>
<refsection>
<title>Description</title>
<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.
</para>
</refsection>
<refsection>
<title>Examples</title>
<programlisting role="example"><![CDATA[
a = [1.0 -1.6216505 1.1102795 -0.4621741 0.2075552 -0.018756746];
[psd,f_out] = pburg(a,2);
]]></programlisting>
</refsection>
</refentry>
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