Canadian Corporate Management Company Limited

Federal Industries Industrial Group Inc.

Milltronics Ltd.

Siemens Milltronics Process Instruments, Inc.

Steven J Woodward

Quinton Lyon

Stanley Panton

Thomas Mike Bednarchuk

A method of measuring the position of a target feature in a pulse-echo ranging system including transmitting at least one pulse of high frequency energy from a transducer towards the target feature, receiving energy reflected back from the direction of the target feature to the transducer to provide at least one return signal, repeatedly sampling the amplitude of the return signal(s) at intervals to form a digital database relating signal amplitude to elapsed time, and searching the database for at least one target zone in which a greater than background rate of fall of the return signal amplitude is sustained.

Pulse-echo system for mediums having varying densities

A method for processing an echo amplitude profile generated by an echo ranging system with reference to a temporal axis to identify return echoes comprised by the profile by identifying amplitude peaks in the profile above with respect to an amplitude axis, a threshold curve on the same temporal axis, wherein the threshold curve is generated by identifying rising edges of echoes in the profile, and generating curve segments extending on the temporal axis from points at or above said leading edges to intersections with descending edges of echoes in the profile, whereby to trace echo base lines delimiting access of the echoes. The invention also extends to a method for processing an echo amplitude profile. According to a further feature of the invention, there is provided a method for processing an echo amplitude profile generated by an echo ranging system with reference to a temporal axis to identify return echoes comprised by the profile by identifying amplitude peaks in the profile above with respect to an amplitude axis, threshold curve on the same temporal axis, whereby to define echo base lines delimiting areas of the echoes, comprising identifying the position of at least a selected echo on the temporal axis by determining the temporal position of the center of area of at least the selected one of the areas so delimited.

Echo detection in pulse-echo ranging systems

In an acoustic pulse-echo ranging system, a high impedance piezoelectric transducer element is connected via a transformer to a transmitter, and also directly to a high impedance input of a receiver through a network, in parallel with the transducer element which includes a limiting resistor having a value which is low compared with the impedance of the transducer and a pair of oppositely connected diodes connected across the receiver input, the diodes being in series with the resistor and conducting to complete a damping circuit for large amplitude signals during transmission, and to limit the amplitude of signals applied to the receiver. When the signals are not of sufficient amplitude to cause the diodes to conduct, the damping circuit is normally rendered ineffective, but a further circuit is provided in parallel with the diodes to selectively switch into the network a further smaller resistance which acts both to form an attenuator at the receiver input in conjunction with the damping resistor, and to restore the damping effect. By this means, the dynamic range required by the receiver is much reduced, and effective damping can be applied selectively during reception to reduce the effect of ringing at short ranges. A tuned circuit formed with the transducer by the transformer through which the transmitter drives the transducer is tuned by means of an air gap in the transformer core, which may be adjustable.

Acoustic range-finding system

In an acoustic pulse-echo ranging system, the transmitter and receiver, which respectively generate pulses of acoustic energy and receive reflections of the same, are electronically tuned to determine their operating frequency, the electronic tuning being controlled responsive to stored data relating to a particular transducer being utilized to transmit and receive a pulse. A single transmitter and receiver can be utilized to service a number of different transducers, being automatically tuned to an appropriate frequency for each transducer as it is used to transmit and receive a pulse. The system can verify the nominal operating frequency of each transducer, and can also adjust the operating frequency used with any particular transducer to optimize its performance.

Acoustic ranging systems

In 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, so as to produce a digitized echo profile. The digitzed echo profile is enhanced by removing narrow peaks likely to correspond with certain types of spurious echo, and narrow valleys which may represent fragmentation of a wanted echo. Echoes are identified by comparing the profile with a time varying threshold generated derived from a linear regression performed on part of the threshold, various different types of comparison being performed and their results combined prior to selecting the most likely true echo on the basis of the combined results.

Acoustic range finding system

In 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, so as to produce a digitized echo profile. The digitized echo profile is enhanced by removing narrow peaks likely to correspond with certain types of spurious echo, and narrow valleys which may represent fragmentation of a wanted echo. Echoes are identified by comparing the profile with a time varying threshold generated derived from a linear regression performed on part of the threshold, various different types of comparison being performed and their results combined prior to selecting the most likely true echo on the basis of the combined results.

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

Process control equipment for adverse environments

Programmable apparatus for monitoring an industrial installation, such as for measuring the depth of material in bins or silos, utilizes a computer having a hermetically sealed case, with an externally visible display and necessary connections to the installation being monitored. The computer includes non-volatile random access memory for the storage of operating parameters which is written to under control of a portable external programming unit which can temporarily access the computer via an infrared or equivalent communications link. The case of the computer has provision for temporary docking of the programming unit, which has a keypad for the selection of calibration and diagnostic routines, and the entry of data or commands to be transmitted to the computer.

Monitoring equipment for adverse environments

In an acoustic ranging system, an echo signal received following a shot is repeatedly sampled and the samples digitized to produce a statistical data base representing the received echo profile which can be analyzed by various methods to determine the point on the time axis of the profile which corresponds to a wanted echo, and the degree of confidence with which the wanted echo has been identified. The number of shots taken depends upon the conditions at the site being monitored and upon the degree of confidence with which the wanted echo has been determined, and the order in which points in a multipoint system are monitored is determined by an adaptive scanning system which directs shots to different points following a system determined by a predetermined hierarchy, by the results provided by previous shots, by the conditions existing at different points, and by the receipt of outside signals. In order to improve resolution beyond that permitted by the sampling rate selected, the data base produced may be used as an adjunct to an analog determination of the actual elapsed time before receipt of a wanted echo, either by using the data base to determine a temporal 'window' within which a wanted echo may be expected, and the expected amplitude of that echo, so that an accurate analog determination of the receipt of a wanted echo becomes possible, or by using the data base to provide an adaptive time variant gain control signal for the echo signal receiver so as to facilitate analog detection of the wanted echo.

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Port Hope, Canada

Steven J Woodward