Patent ID: 6626048
Filing Date: 2003-09-30
Classification: G01F

Abstract:
A magnetic flow meter comprising:a conduit operable to guide a flow along a flow path; a magnetic field generator operable to generate an alternating magnetic field at a drive frequency across the flow path; a flow sensor operable to sense electromagnetic fields generated across the flow path and to output a corresponding flow sensor signal including: (a) an electric field component at the drive frequency and at a first phase, which electric field component varies with an electric field generated by the interaction of the magnetic field generated by said magnetic field generator and said flow; and (b) an interfering component at the drive frequency and at a second different phase; a magnetic field sensor operable to sense the magnetic field generated by said magnetic field generator and to output a corresponding magnetic field sensor signal at said drive frequency at a phase related to said second phase; a calibration processor operable to process said magnetic field sensor signal to generate an alternating calibration control signal at said drive frequency whose phase depends upon the phase of said magnetic field sensor signal; a first processing circuit responsive to the calibration control signal and operable to process the flow sensor signal to determine a measure of the strength of the electric field component thereof; a second processing circuit operable to process the magnetic field sensor signal to determine a measure of the strength of the magnetic field sensor signal; and a measurement processor operable to determine a measure of the flow in said conduit in dependence upon the determined measure of strength of said electric field component and the determined measure of strength of said magnetic field sensor signal.