Process control equipment for adverse environments
First Claim
1. A method for adjusting a transducer in an acoustic ranging system comprising said transducer, means to cause said transducer to transmit pulses of sonic energy, and means to detect and analyze energy received from the transducer to detect an echo from a surface whose range is to be determined by the system;
- the method including reiteratively transmitting a pulse, detecting and analyzing the ref lected energy to determine whether an anomaly in the variation of reflected energy with time represents a wanted echo, measuring a parameter indicative of the degree of assurance that the wanted echo has been correctly identified, and adjusting the transducer prior to the transmission of a further pulse, the effect of successive adjustments of the transducer on said parameter being noted so as to find an adjustment such as to maximize said parameter.
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Accused Products
Abstract
Microprocessor controlled industrial monitoring equipment uses a separate portable keypad which can be applied to a sealed casing containing a control unit to transmit commands and calibration to the equipment, which normally operates and provides a display of information in the absence of the keypad. The equipment is usually acoustic level sensing apparatus, in which pulses of acoustic energy are transmitted by an electrically energized transducer towards a surface to be sensed, and the electrical output from the transducer following the pulse is digitized and analyzed to detect a return echo from the surface. Various techniques of analysis of the digital data so produced are disclosed, so as variously to detect echoes more reliably, to assist in aligning the transducer during installation, and so as to detect open or short circuited transducers
58 Citations
12 Claims
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1. A method for adjusting a transducer in an acoustic ranging system comprising said transducer, means to cause said transducer to transmit pulses of sonic energy, and means to detect and analyze energy received from the transducer to detect an echo from a surface whose range is to be determined by the system;
- the method including reiteratively transmitting a pulse, detecting and analyzing the ref lected energy to determine whether an anomaly in the variation of reflected energy with time represents a wanted echo, measuring a parameter indicative of the degree of assurance that the wanted echo has been correctly identified, and adjusting the transducer prior to the transmission of a further pulse, the effect of successive adjustments of the transducer on said parameter being noted so as to find an adjustment such as to maximize said parameter.
- View Dependent Claims (2, 3)
- 4. In a method of acoustic ranging in which a pulse of acoustic energy is transmitted from a transducer which is also utilized to receive an echo reflected from the surface of material whose level it is desired to detect, and in which a profile of a variation of the output of the transducer with time following a pulse is examined in order to detect the echo, the improvement wherein a first profile is obtained using a narrow transmitted pulse, and a first portion of that profile is examined for the presence of an anomaly representing the echo, and if no such an anomaly is detected in said first portion, a further profile is obtained using a broader transmitted pulse, a first portion of the echo profile is discarded, and the remainder is examined for the presence of an anomaly representing the echo.
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9. In a method of acoustic ranging in which a pulse of acoustic energy is transmitted from a transducer which is also utilized to receive an echo reflected from the surface of material whose surface it is desired to detect, and in which a profile of the variation of output of the transducer with time following the pulse is examined in order to detect the echo, and in which the transducer output is amplified by a receiver having a logarithmic transfer characteristic and the receiver output is digitized to form a profile of data samples, the improvement wherein the echo profile as represented by the samples is examined by forming a reference curve by digital filtering of the digitized data samples, the reference curve is shifted, by addition of a constant to its samples, above the echo response so as intersect the largest echo anomaly, and the first echo anomaly in the echo response which intersects the reference curve is deemed the wanted echo.
- 10. In a method of acoustic ranging in which a transducer of relatively high Q is electrically energized to transmit a pulse of acoustic energy towards a surface whose level is to be measured, and electrical signals from said transducer are monitored to detect the temporal location of an echo formed by energy reflected by said surface, the improvement wherein the amplitude of ringing of an electrical signal generated by the transducer excited by said transmit pulse is tested following termination of the transmit pulse to verify normal operation of the transducer.
Specification