Multi-rate digital signal processor for signals from pick-offs on a vibrating conduit
First Claim
1. A method for processing signals received from a first pick-off sensor and a second pick-off sensor measuring vibrations of a conduit using a digital signal processor to output information about a material flowing through said conduit, said method comprising the steps of:
- receiving samples of signals from said first pick-off sensor and said second pick-off sensor at a first sample rate;
decimating said samples from said first sample rate to a desired sample rate;
determining a frequency of vibration for said conduit at said first pick-off and at said second pick-off from said samples of said signals at said desired sample rate;
calculating a normalized frequency of said signals; and
demodulating said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to a center frequency, wherein said step of demodulating comprises the steps of;
calculating a normalized pulsation of said normalized frequency of said signals; and
calculating dot products of said normalized pulsation and said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to said center frequency.
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Abstract
A digital signal processor for determining a property of a material flowing through a conduit. The digital signal processor of this invention receives signals from two pick-off sensor mounted at two different points along a flow tube at a first sample rate. The signals are converted to digital signals. The digital signals are decimated from a first sample rate to a desired sample rate. The frequency of the received signals is then determined from the digital signals at the desired sample rate.
89 Citations
26 Claims
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1. A method for processing signals received from a first pick-off sensor and a second pick-off sensor measuring vibrations of a conduit using a digital signal processor to output information about a material flowing through said conduit, said method comprising the steps of:
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receiving samples of signals from said first pick-off sensor and said second pick-off sensor at a first sample rate;
decimating said samples from said first sample rate to a desired sample rate;
determining a frequency of vibration for said conduit at said first pick-off and at said second pick-off from said samples of said signals at said desired sample rate;
calculating a normalized frequency of said signals; and
demodulating said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to a center frequency, wherein said step of demodulating comprises the steps of;
calculating a normalized pulsation of said normalized frequency of said signals; and
calculating dot products of said normalized pulsation and said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to said center frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
demultiplexing said signals into I components and Q components;
integrating said I components;
integrating said Q components multiplexing said I components and said Q components to produce digitally integrated signals; and
calculating a ratio between an amplitude of said signals and an amplitude of said digitally integrated signals to produce said normalized frequency of said signals.
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3. The method of claim 2 wherein said step of calculating said normalized frequency further comprises the step of:
applying said integrated Q components to a compensator responsive to said step of integrating prior to said step of multiplexing.
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4. The method of claim 2 wherein said step of calculating said normalized frequency further comprises the step of:
applying said integrated I components to a compensator responsive to said step of integrating prior to said step of multiplexing.
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5. The method of claim 1 further comprising the step of:
determining properties of said material flowing through said conduit responsive to determining said frequency of said signals from said first pick-off sensor and said signals from said second pick-off sensor.
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6. The method of claim 5 wherein one of said properties is mass flow rate of said material flowing through said conduit.
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7. The method of claim 5 wherein one of said properties is density of said material flowing through said conduit.
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8. The method of claim 1 wherein said step of determining said frequency of vibration of said conduit comprises the steps of:
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modulating said normalized frequency of said signals; and
performing a complex demodulation of said signals using said modulated normalized frequency to determine said frequency.
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9. The method of claim 8 wherein said step of determining said frequency of vibration of said conduit further comprises the steps of:
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decimating said demodulated signals;
performing a complex correlation of said signals to determine a phase difference between said signals.
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10. The method of claim 1 wherein said step of decimating said samples from said first pick-off sensor and said signals from said second pick-off sensor comprises the step of:
performing a preliminary decimation from said first sample rate to an intermediate sample rate responsive to receiving said signals from said first and said second pickoff sensors.
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11. The method of claim 10 wherein said step of decimating further comprises the steps of:
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demodulating said signals into an I component and a Q component; and
performing a secondary decimation of said samples of said signals from said intermediate sample rate to a final sample rate responsive to said demodulation of said signals.
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12. The method of claim 1 further comprising:
determining a phase difference between said signals from said first pick-off sensor and said signals from said second pick-off sensor.
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13. A product for directing a processor controlling an apparatus that has a vibrating conduit for measuring properties of a material flowing through said conduit to process signals received from a first pick-off sensor and a second pick-off sensor connected to said conduit, said product comprising:
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instructions operational to perform receiving samples of signals from said first and said second pick-off sensors at a first sample rate, decimating said samples from said first sample rate to a desired sample rate, determining a frequency of vibration for said conduit at said first pickoff sensor and at said second pick-off sensor from said samples of said signals at said desired sample rate, calculating a normalized frequency of said signals, and demodulating said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to a center frequency, wherein said step of demodulating comprises the steps of;
calculating a normalized pulsation of said normalized frequency of said signals; and
calculating dot products of said normalized pulsation and said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to said center frequency; and
a processor readable storage media for storing said instructions. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
demultiplexing said signals into an I component and a Q component;
integrating said I component;
integrating said Q component;
multiplexing said I component and said Q component to produce digitally integrated signals; and
calculating a ratio between an amplitude of said signals and said digitally integrated signals to produce said normalized frequency of said signals.
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15. The product of claim 14 wherein said instruction of calculating said normalized frequency comprises instructions to perform:
applying said integrated Q component to a compensator responsive to said step of integrating prior to said step of multiplexing.
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16. The product of claim 14 wherein said instructions of calculating said normalized frequency further comprises instructions to perform:
applying said integrated I component to a compensator responsive to said step of integrating prior to said step of multiplexing.
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17. The product of claim 13 wherein said instructions further comprise instructions to perform:
determining properties of said material flowing through said conduit responsive to determining said frequency of said signals from said first pick-off sensor and said signals from said second pick-off sensor.
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18. The product of claim 17 wherein one of said properties is mass flow rate of said material flowing through said conduit.
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19. The product of claim 17 wherein one of said properties is density of said material flowing through said conduit.
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20. The product of claim 13 wherein said instructions for determining said frequency of vibration of said conduit comprises the instructions to perform:
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modulating said normalized frequency of said signals; and
performing a complex demodulation of said signals using said modulated normalized frequency to determine said frequency.
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21. The product of claim 20, wherein said instructions for determining said frequency of vibration of said conduit further comprise the instructions to perform:
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decimating said demodulated signals;
performing a complex correlation of said signals to determine a phase difference between said signals.
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22. The product of claim 17 wherein one of said properties is mass flow rate of said material flowing through said conduit.
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23. The product of claim 22 wherein said instructions for decimating further comprises instructions for:
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demodulating said signals from an I component and a Q component; and
performing a secondary decimation of said samples of said signals from said intermediate sample rate to a final sampled rate responsive to said demodulation of said signals.
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24. The product of claim 13 wherein said instructions further comprise instructions to perform:
determining a phase difference between said signals from said first pick-off sensor and said signals from said second pick-off sensor.
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25. The product of claim 17 wherein said apparatus is a Coriolis flowmeter.
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26. A transmitter for a Coriolis flowmeter comprising:
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a processing unit;
a memory storage media readable by said processing unit; and
processor readable instructions stored in said storage media for directing said processing unit to perform receiving samples of signals from first and second pick-off sensors at a first sample rate, decimating said samples from said first sample rate to a desired sample rate, determining a frequency of vibration for said conduit at said first pick-off sensor and at said second pick-off sensor from said samples of said signals at said desired sample rate, calculating a normalized frequency of said signals, and demodulating said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to a center frequency, wherein said step of demodulating comprises the steps of;
calculating a normalized pulsation of said normalized frequency of said signals; and
calculating dot products of said normalized pulsation and said signals from said first pick-off sensor and said second pick-off sensor to translate said signals to said center frequency.
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Specification