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CVS Update
author | Daniele Nicolodi <nicolodi@science.unitn.it> |
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date | Tue, 06 Dec 2011 11:09:25 +0100 |
parents | f0afece42f48 |
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd"> <html lang="en"> <head> <meta name="generator" content= "HTML Tidy for Mac OS X (vers 1st December 2004), see www.w3.org"> <meta http-equiv="Content-Type" content= "text/html; charset=us-ascii"> <title>Generating model noise (LTPDA Toolbox)</title> <link rel="stylesheet" href="docstyle.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.52.2"> <meta name="description" content= "Presents an overview of the features, system requirements, and starting the toolbox."> </head> <body> <a name="top_of_page" id="top_of_page"></a> <p style="font-size:1px;"> </p> <table class="nav" summary="Navigation aid" border="0" width= "100%" cellpadding="0" cellspacing="0"> <tr> <td valign="baseline"><b>LTPDA Toolbox</b></td><td><a href="../helptoc.html">contents</a></td> <td valign="baseline" align="right"><a href= "builtin_models.html"><img src="b_prev.gif" border="0" align= "bottom" alt="Built-in models of LTPDA"></a> <a href= "franklin_ng.html"><img src="b_next.gif" border="0" align= "bottom" alt="Franklin noise-generator"></a></td> </tr> </table> <h1 class="title"><a name="f3-12899" id="f3-12899"></a>Generating model noise</h1> <hr> <p> <p> Generating non-white random noise means producing arbitrary long time series with a given spectral density. Such time series are needed for example for the following purposes: </p> <p> <ul> <li> To generate test data sets for programs that compute spectral densities, </li> <li> as inputs for various simulations.</li> </ul> </p> <p> One way of doing this is to apply digital filters (FIR or IIR) to white input noise.<br/> This approach is effectively implemented for the generation of <a href="ndim_ng.html"> multichannel noise </a> with a given cross spectral density. <br/> Multichannel transfer functions are identified by an automatic fit procedure based on a modified version of the vector-fitting algorithm (see <a href="zdomainfit.html"> Z-Domain Fit </a> for further details on the algorithm). <br/> Partial fraction expansion of multichannel transfer functions and the implementation of <a href="sigproc_dfilt.html">filter</a> state initialization avoid the presence of unwanted 'warm-up period'. </p> <p> A different approach is implemented in LTPDA as <a href="franklin_ng.html">Franklin noise-generator</a>.<br/> It produces spectral densities according to a given pole zero model (see <a href="pzmodel.html">Pole/Zero Modeling</a>) and does not require any warm-up period. <br/> </p> </p> <br> <br> <table class="nav" summary="Navigation aid" border="0" width= "100%" cellpadding="0" cellspacing="0"> <tr valign="top"> <td align="left" width="20"><a href="builtin_models.html"><img src= "b_prev.gif" border="0" align="bottom" alt= "Built-in models of LTPDA"></a> </td> <td align="left">Built-in models of LTPDA</td> <td> </td> <td align="right">Franklin noise-generator</td> <td align="right" width="20"><a href= "franklin_ng.html"><img src="b_next.gif" border="0" align= "bottom" alt="Franklin noise-generator"></a></td> </tr> </table><br> <p class="copy">©LTP Team</p> </body> </html>