Recently, a method using multisine excitation was proposed for estimating the frequency response, the nonlinear distortions and the distrubin noise of weakly nonlinear time-invariant 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 time-invariant 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 time-invariant system (high-quality microphone membrane). Next, it is demonstrated that the new methods clearly give an improved estimate of the noise level on time-varying systems. As an application example results for the vibration response of an eardrum are shown.
|Number of pages||10|
|Journal||Measurement Science and Technology|
|Publication status||Published - 1 Aug 2008|
- heterodyne interferometry
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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 time-varying systems", Measurement Science and Technology, Vol. 19, No. 10
Lataire, John (Recipient), 1 Mar 2009
Prize: Prize (including medals and awards)