Abstract
Recently, a method using multisine excitation was proposed for estimating the frequency response, the nonlinear distortions and the distrubin noise of weakly nonlinear timeinvariant systems. This method has been demonstrated on the measurement of nonlinear distortions in the vibration of acoustically driven systems such as a latex membrane, which is a good example of a timeinvariant system. However, not all systems are perfectly time invariant, e.g. biomechanical systems. This time variation can be misinterpreted as an elevated noise floor, and the classical noise estimation method gives a wrong result. Two improved methods to retrieve the correct noise information from the measurements are presented. Both of them make use of multisine excitations. First, it is demonstrated that the improved methods give the same results as the classical noise estimation method when applied to a timeinvariant system (highquality microphone membrane). Next, it is demonstrated that the new methods clearly give an improved estimate of the noise level on timevarying systems. As an application example results for the vibration response of an eardrum are shown.
Original language  English 

Number of pages  10 
Journal  Measurement Science and Technology 
Volume  19 
Publication status  Published  1 Aug 2008 
Keywords
 Noise
 timevarying
 nonstationary
 multisine
 nonlinear
 heterodyne interferometry
 vibrometry
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Dive into the research topics of 'Noise level estimation in weakly nonlinear slowly timevarying systems'. Together they form a unique fingerprint.Prizes

2008 Award Winner  Measurement Science is presented to J.R.M Aerts, J. Lataire, R. Pintelon and J.J.J. Dirckx for the article: "Noise level estimation in weakly nonlinear slowly timevarying systems", Measurement Science and Technology, Vol. 19, No. 10
Lataire, John (Recipient), 1 Mar 2009
Prize: Prize (including medals and awards)