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From: | Rudolf Widmer-Schnidrig |
Subject: | Re: System identification... |
Date: | Wed, 19 Jan 2011 19:10:59 +0100 |
User-agent: | Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.13) Gecko/20101207 Lightning/1.0b2 Thunderbird/3.1.7 |
On 19.01.11 16:00, Doug Stewart wrote:
Dear Doug, Since my input sweep has constant amplitude the amplitude variation with frequency of the output signal shows immediately how the gain of the instrument varies with frequency. From a comparison of input and output signals in the time domain one can - at least qualitatively - also see the phase delay and how it varies with frequency. What I am after is a precise estimation of the poles and zeros to within hopefully 1% or better.
The random telegraph signal is band limited white noise. My seismometer can be modeled as a band-pass filter. I also have a good idea on the number of poles and zeros (nA and nB) needed for a description in the s- or z-plane. So maybe I'll just have to do a grid search and perturb the locations of the A and B values until norm(output - H(z)*input) is minimal. Fortunately in the case of the z-transform the serach is limited to the real axis. -Ruedi -- +---------------------------------------------------------------+ Rudolf Widmer-Schnidrig |
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