Unterdrückung stationärer Interferenzsignale bei Ultraschalllaufzeitmessungen mithilfe der Hauptkomponentenanalyse / Suppression of stationary interference signals in ultrasonic transit-time measurements using the principle component analysis

For the transit-time measurement of ultrasonic signals, as used for flow measurements, superimposed interfering signals impair the accuracy of the measurement. These signal components are caused, among other things, by a dispersive multipath propagation across the pipe wall, which leads to a interference in the same frequency and time domain, preventing the use of conventional filtering. In this paper, a methodology is presented which specifically employs and models the process influence of the temperature change to allow a disturbance-invariant estimation of the transit-time. The model uses the Hilbert transform in combination with the principal component analysis in order to suppress the influence of temperature-independent signal components. Finally, the methodology is validated using measurement data from a flow measurement system and compared to the conventional method of zero-crossing determination.