| 摘要 |
A method of obtaining a measure of flow from an electromagnetic flow meter (3) having at least one field generating coil and potential sensing electrodes. A composite excitation waveform (1) is applied to the field-generating coil. The waveform comprises at least two frequency components and a plurality of frequency components are simultaneously present for at least a portion of the waveform. The potential sensed by the potential sensing electrodes is sampled to produce a sampled output (5) and the sampled output is correlated (6) with a composite waveform based on the composite excitation waveform. The result of the correlating is used to derive a measure of flow. A measure of trend may be established in the measurements.
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