System and method for ultrasonic measurement of material level
First Claim
1. A system for monitoring level of material that comprises:
- transducer means for transmitting ultrasonic signals toward and receiving an echo signals from a surface of the material,switch means for selectively connecting and disconnecting said transducer means to and from a source of electrical power for energizing and de-energizing said transducer means, andmicroprocessor-based control means having an output coupled to said switch means for controlling operation thereof, said output providing a pulsed periodic signal at variable frequency, duty cycle and total time duration to operate said switch means at an ultrasonic frequency that corresponds to said periodic signal frequency, at a duty cycle that corresponds to said periodic signal duty cycle and/or a time duration that corresponds to said periodic signal time duration,said control means including means for discriminating between false echo signals and true echo signals from the material surface comprising means operatively coupled to said transducer means for sampling and storing said echo signals, means for identifying an echo signal having greatest amplitude, means for examining duration of all echo signals having an amplitude at least equal to a predetermined percentage of said greatest amplitude, and means for identifying a said true echo signal as the echo signal among those so examined having greatest time duration.
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Accused Products
Abstract
A system for monitoring level of material in a vessel that includes a transducer for transmitting an ultrasonic signal toward and receiving an echo signal from a surface of the material, and a power switch coupled to the transducer for energizing the transducer to transmit the ultrasonic signal. A microprocessor-based controller has an output coupled to the power switch for controlling operation thereof. The output of the microprocessor provides a pulsed periodic signal to the power switch at controllably variable frequency, duty cycle and/or total burst duration to operate the transducer at an ultrasonic frequency that corresponds to the periodic signal frequency, duty cycle and burst duration. The echo signals are compared to successive thresholds between the transmission bursts, and echo signal data is sampled and stored in the microprocessor over a measurement cycle that includes multiple transmission bursts. The true echo signal from the material surface is distinguished from pulse echo signals as a combined function of amplitude and time duration data so stored.
59 Citations
23 Claims
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1. A system for monitoring level of material that comprises:
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transducer means for transmitting ultrasonic signals toward and receiving an echo signals from a surface of the material, switch means for selectively connecting and disconnecting said transducer means to and from a source of electrical power for energizing and de-energizing said transducer means, and microprocessor-based control means having an output coupled to said switch means for controlling operation thereof, said output providing a pulsed periodic signal at variable frequency, duty cycle and total time duration to operate said switch means at an ultrasonic frequency that corresponds to said periodic signal frequency, at a duty cycle that corresponds to said periodic signal duty cycle and/or a time duration that corresponds to said periodic signal time duration, said control means including means for discriminating between false echo signals and true echo signals from the material surface comprising means operatively coupled to said transducer means for sampling and storing said echo signals, means for identifying an echo signal having greatest amplitude, means for examining duration of all echo signals having an amplitude at least equal to a predetermined percentage of said greatest amplitude, and means for identifying a said true echo signal as the echo signal among those so examined having greatest time duration. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9)
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7. A system for monitoring level of material that comprises:
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transducer means for transmitting ultrasonic signals toward and receiving echo signals from a surface of the material, switch means for selectively connecting and disconnecting said transducer means to and from a source of electrical power for energizing and de-energizing said transducer means, microprocessor-based control means having an output coupled to said switch means for controlling operation thereof, said output providing a pulsed periodic signal at variable frequency, duty cycle and total time duration to operate said switch means at an ultrasonic frequency that corresponds to said periodic signal frequency, at a duty cycle that corresponds to said periodic signal duty cycle and/or a time duration that corresponds to said periodic signal time duration, receiver circuit means coupled to said transducer means for receiving signals from said transducer means corresponding to echo signals from the material surface and providing said signals to said microprocessor-based control means, said receiver circuit means having an input for controlling gain of said receiver circuit means, and means coupled to said input and responsive to said control means for increasing gain of said receiver circuit means with time between each burst transmission at said transducer means, and means coupled to said control means for determining system range between minimum and maximum material levels, said gain-increasing means being responsive to said control means for increasing gain of said receiver circuit means in a predetermined number of discrete steps over a total time duration that corresponds to said minimum and maximum material levels. - View Dependent Claims (15)
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10. A method of determining level of material as a function of round-trip transit time of ultrasonic signals between a transducer and a surface of the material comprising the steps of:
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(a) transmitting a series of ultrasonic signals toward the material surface, (b) monitoring for echo signals from the material surface between each ultrasonic signal transmitted in said step (a), (c) comparing amplitude of the echo signals to a plurality of differing amplitude thresholds, and (d) distinguishing between a true echo signal from the material surface and false echo signals as a function of echo signals whose amplitudes exceed a higher threshold than other of said echo signals. - View Dependent Claims (11, 12, 13, 14)
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16. A system for monitoring level of material that comprises:
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transducer means for transmitting ultrasonic signals toward and receiving echo signals from a surface of the material, microprocessor-based control means including means coupled to said transducer means for controlling operation thereof, receiver circuit means coupled to said transducer means for receiving signals from said transducer means corresponding to echo signals from the material surface and providing said signals to said microprocessor-based control means, said receiver circuit means having an input for controlling gain of said receiver circuit means, and means coupled to said input and responsive to said control means for increasing gain of said receiver circuit means with time between each burst transmission at said transducer means, and means coupled to said control means for determining system range between minimum and maximum material levels, said gain-increasing means being responsive to said control circuit means for increasing gain of said receiver circuit means in a predetermined number of discrete steps over a total time duration that corresponds to said minimum and maximum material levels. - View Dependent Claims (17)
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18. A system for monitoring level of material that comprises:
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transducer means for transmitting a series of ultrasonic signals toward a surface of the material and receiving echo signals in response to each said ultrasonic signal, means coupled to said transducer means for comparing amplitude of said echo signals to a plurality of amplitude thresholds, means for distinguishing a true echo signal from the material surface from false echo signals as a function of echo signals whose amplitude exceed said thresholds, and means for determining the level of said material surface as a function of round-trip transit time of said time signal from and to said transducer means. - View Dependent Claims (19, 20)
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21. A system for monitoring level of material that comprises:
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transducer means for transmitting ultrasonic signals toward and receiving echo signals from a surface of the material, microprocessor-based control means including means coupled to said transducer means for controlling operation thereof and receiving said echo signals, and means for discriminating between false echo signals and true echo signals from the material surface comprising means for sampling and storing said echo signals, means for identifying an echo signal having greatest amplitude, means for examining duration of all echo signals having am amplitude at least equal to a predetermined percentage of said greatest amplitude, and means for identifying a said true echo signal as the echo signal among those so examined having greatest time duration. - View Dependent Claims (22, 23)
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Specification