High accuracy signal processing for magnetic flowmeter
First Claim
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1. A magnetic flowmeter providing high accuracy signal processing for measuring flow of a conductive process fluid, comprising:
- a flow tube assembly disposed to receive a fluid flow;
a coil configured to apply a magnetic field to the fluid flow;
an electromotive force (EMF) sensor coupled to the fluid flow having an EMF signal output related to an EMF generated in the fluid flow due to the applied magnetic field, velocity of the fluid and noise;
an isolated signal output related to the velocity of the fluid; and
a signal processor coupled to the EMF signal output, the signal processor including a wavelet transformer and providing the isolated signal output.
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Abstract
A magnetic flowmeter for measuring flow of a conductive fluid includes a flow tube assembly adapted to receive a fluid flow and a coil configured to apply a magnetic field in the fluid flow through the flow tube. An EMF sensor coupled to the flow tube provides an EMF output related to an EMF generated in the fluid flow due to the applied magnetic field, velocity of the fluid and noise. A signal processor includes a wavelet transformer that performs a wavelet transformation on the EMF output and provides a decomposition signal related to velocity of the fluid.
311 Citations
38 Claims
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1. A magnetic flowmeter providing high accuracy signal processing for measuring flow of a conductive process fluid, comprising:
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a flow tube assembly disposed to receive a fluid flow;
a coil configured to apply a magnetic field to the fluid flow;
an electromotive force (EMF) sensor coupled to the fluid flow having an EMF signal output related to an EMF generated in the fluid flow due to the applied magnetic field, velocity of the fluid and noise;
an isolated signal output related to the velocity of the fluid; and
a signal processor coupled to the EMF signal output, the signal processor including a wavelet transformer and providing the isolated signal output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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8. A magnetic flowmeter providing high accuracy signal processing for measuring flow of a conductive process fluid, comprising:
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a flow tube assembly disposed to receive a fluid flow;
a coil configured to apply a magnetic field to the fluid flow;
an electromotive force (EMF) sensor coupled to the fluid flow having an EMF signal output related to an EMF generated in the fluid flow due to the applied magnetic field, velocity of the fluid and noise; and
a signal processor coupled to the EMF signal output and including a wavelet transformer, an isolated signal output related to velocity of the fluid and a spike remover configured to remove spikes from the EMF signal output, the spike remover including a delay to delay the EMF signal by one period and a summer to sum the delayed EMF signal with the EMF signal to thereby generate a spike signal. - View Dependent Claims (9)
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12. A magnetic flowmeter providing high accuracy signal processing for measuring flow of a conductive process fluid, comprising:
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a flow tube assembly disposed to receive a fluid flow;
a coil configured to apply a magnetic field to the fluid flow;
an electromotive force (EMF) sensor coupled to the fluid flow having an EMF signal output related to an EMF generated in the fluid flow due to the applied magnetic field, velocity of the fluid and noise; and
a signal processor coupled to the EMF signal output and including a wavelet transformer and an isolated signal output related to the velocity of the fluid and a change follower coupled to the EMF signal output, the change follower including an averager and a bypass switch configured to bypass the change follower and the change detector is configured to actuate the bypass switch in response to rapid changes in the EMF output signal.
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22. A method for high accuracy signal processing in a magnetic flowmeter for processing an electromotive force (EMF) signal generated in response to a magnetic field and velocity of a process fluid, comprising:
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digitizing the electromotive force EMF signal;
wavelet transforming the digitized signal and providing a signal output;
isolating the signal output to provide an isolated signal output; and
converting the isolated signal output to a signal related to velocity of the process fluid. - View Dependent Claims (23, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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24. A method for high accuracy signal processing in a magnetic flowmeter for processing an electromotive force (EMF) signal generated in response to a magnetic field and velocity of a process fluid, comprising:
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digitizing the EMF signal;
wavelet transforming the digitized signal and providing an isolated signal output;
converting the isolated signal output to a signal related to velocity of the process fluid; and
removing spikes from the digitized EMF signal prior to wavelet transforming the digitized EMF signal, wherein removing spikes comprises shifting the digitized EMF signal by at least one period and summing the time shift in the EMF signal to generate a spike signal. - View Dependent Claims (25)
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27. A method for high accuracy signal processing in a magnetic flowmeter for processing an electromotive force (EMF) signal generated in response to a magnetic field and velocity of a process fluid, comprising:
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digitizing the EMF signal;
wavelet transforming the digitized signal and providing an isolated signal output;
converting the isolated signal output to a signal related to velocity of the process fluid;
averaging the digitized EMF signal prior to wavelet transforming the digitized EMF signal; and
bypassing the averaging by detecting rapid changes in the EMF signal.
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38. A magnetic flowmeter having high accuracy signal processing for measuring flow of a conductive process fluid, comprising:
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a flow tube assembly disposed to receive a fluid flow;
means for applying a magnetic field which extends in the fluid flow;
EMF sensing means for sensing an EMF signal generated in the fluid flow due to the applied magnetic field, the velocity of the fluid and noise and responsively providing an EMF output;
an isolated signal output related to the velocity of the fluid; and
wavelet transforming means for wavelet transforming the EMF signal output to provide the isolated signal output.
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Specification