To enable selecting and using of the effective results of outputs by a method wherein a time domain reflection(TDR) measuring signal by a plurality of techniques to calculate independent results and a weighted coefficient is applied to the individual results to compare the weighted results.
A sensor device 10 is used for the measuring of the level of a process variable such as interface 26 of mediums 11 (air) and 12 (liquid) within a storage container to determine a reflection position of an impedance pulse generated at the interface 26 in contact with a probe element 18. Detection methods of changes in impedance include the detection of a peak amplitude for a TDR signal hourly matched, the initial zero-cross detection after the positive peak of the primary derivative function signal and the like. Also available are the utilization of a base line signal or a primary derivative function signal thereof and the like. When the results of outputs determined by a microprocessor 46 are different as obtained by the above mentioned methods, weighted coefficients are given to the respective output results and the weighted output results are compared with each other to select and use the most effective output results based on the results of the comparison.
CUMMINGS DONALD D (US)
PERDUE KENNETH L (US)
SWAGER RICHARD B (US)
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