Patent ID: 11906335
Assignee: ENDRESS+HAUSER FLOWTEC AG
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 14:
15. A method for measuring at least one measurement variable, changeable as a function of time, of a fluid flowing along a flow path with a predetermined flow direction, the method comprising:
providing the flow path, which includes a first portion, a second portion disposed in the flow direction downstream of the first portion, and a third portion disposed in the flow direction downstream of the second portion, wherein within the second portion a flow obstruction is configured to effect a disturbance in the flowing fluid dependent on the at least one measurement variable and/or a measurable effect dependent on the at least one measurement variable;
enabling the fluid to flow along the flow path such that volume portions of the fluid flow from the first portion to the second portion and then to the third portion, wherein the flow obstruction of the second portion effects the disturbance;
generating a first sensor signal having a first frequency spectrum influenced by the fluid flowing within the first portion;
converting the first sensor signal into a first sensor signal sampling sequence of digital sampled values approximating the first sensor signal obtained from the first sensor signal at different, time-equidistant sampling points in time at a constant sampling rate;
generating a second sensor signal having a second frequency spectrum influenced by the fluid flowing within the second portion and/or within the third portion, wherein the second frequency spectrum deviating from the first frequency spectrum and/or includes at least one wanted spectral signal component influenced by the at least one measurement variable or the disturbance with respect to at least one signal parameter;
converting the second sensor signal into a second sensor signal sampling sequence of digital sampled values approximating the second sensor signal obtained from the second sensor signal at different, time-equidistant sampling points in time at a constant sampling rate, wherein the second sensor signal sampling sequence approximates at least one wanted spectral signal component of the second sensor signal influenced by the at least one measurement variable;
using the first sensor signal sampling sequence and a digital adaptive filter to determine from the first sensor signal sampling sequence at least one wanted signal filter coefficients set, including at least five filter coefficients and/or filter coefficients at least partially differing from one another;
using the wanted signal filter coefficients set to define a first z-transfer function of a wanted signal filter, the first z-transfer function defined as:, G
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wherein the wanted signal filter is a digital filter configured to filter the second sensor signal sampling sequence such that the first z-transfer function of the wanted signal filter is determined by the wanted signal filter coefficients set, wherein N is the number of filter coefficients, wk, and Ts2 is the sampling period of the second sensor signal;
using the second sensor signal sampling sequence and the wanted signal filter to generate a wanted signal sequence, wherein the wanted signal sequence is a sequence of digital function values calculated from the second sensor signal sampling sequence using the wanted signal filter, the wanted signal sequence; and
generating a measured values sequence from the wanted signal sequence, wherein the measured values sequence is a sequence of digital measured values representing the at least one measurement variable and following one after the other in time.