EP0262990A2
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EP
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Acoustic range finding system
Assignee: Siemens Canada Ltd
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Filing: 1987-10-02
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Granted: —
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Expires: 2007-10-02
Abstract
Abstract 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, various techniques of analysis of the digital data so produced are disclosed, so as variously to detect echoes more reliably, to enable echoes to be detected at shorter ranges, and so as to detect open or short circuited transducers, based on extending digitization of the electrical output of the transducer so as to include an initial portion of the transducer response during which the transducer is ringing at high amplitude as a result of excitation of the transducer during transmission.
Inventors
- 👤 Steven J. Woodward
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 21:09
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/296; G01F23/2962; G01S; G01S15/00; G01S15/88; G01S7/00; G01S7/003; G01S7/52; G01S7/523; G01S7/524; G01N; G01N2291/00; G01N2291/02; G01N2291/028; G01N2291/02836
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
287 words
An acoustic ranging system comprising at least one electro-acoustic transducer directed towards the surface of material whose level is to be determined, a transmitter to transmit pulses of high frequency electrical energy to energize selectively each said transducer whereby to cause it to emit at least one shot of high frequency sound, a receiver receiving and amplifying electrical energy from said at least on shot regenerated by said transducer over a subsequent period, the time lapse after a shot before receipt by said receiver of energy regenerated from an echo from said surface being proportional to the distance of the origin of the echo, signal processing means comprising analog to digital converter means to sample repeatedly the output amplitude of the signal from the receiver at defined intervals and to digitize the samples; memory means to store an extended sequence of digitized samples so produced in respect of at least one shot and form therefrom a digital data base depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; means to utilize the amplitude profile depicted by the data in said data base to help isolate relative to a time axis a portion of the output signal produced by at least one shot deemed most probable to correspond to a wanted echo; and means to determine a range represented by an echo within said portion of the time axis; characterized in that the memory means (8) is adapted to store a sequence of digitized samples such as to form a digital data base depicting an amplitude/time profile (206) fo the received signal, including an initial portion normally mainly comprised by electrical signals generated by high amplitude ringing of the transducer (20).
Claim 2
Dependent Claim
287 words
An acoustic ranging system comprising at least one electro-acoustic transducer directed towards the surface of material whose level is to be determined, a transmitter to transmit pulses of high frequency electrical energy to energize selectively each said transducer whereby to cause it to emit at least one shot of high frequency sound, a receiver receiving and amplifying electrical energy from said at least on shot regenerated by said transducer over a subsequent period, the time lapse after a shot before receipt by said receiver of energy regenerated from an echo from said surface being proportional to the distance of the origin of the echo, signal processing means comprising analog to digital converter means to sample repeatedly the output amplitude of the signal from the receiver at defined intervals and to digitize the samples; memory means to store an extended sequence of digitized samples so produced in respect of at least one shot and form therefrom a digital data base depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; means to utilize the amplitude profile depicted by the data in said data base to help isolate relative to a time axis a portion of the output signal produced by at least one shot deemed most probable to correspond to a wanted echo; and means to determine a range represented by an echo within said portion of the time axis; characterized in that the memory means (8) is adapted to store a sequence of digitized samples such as to form a digital data base depicting an amplitude/time profile (206) fo the received signal, including an initial portion normally mainly comprised by electrical signals generated by high amplitude ringing of the transducer (20).
Claim 3
Dependent Claim
39 words
A system according to Claim 1, characterised by means (RING) to test the amplitude of a sample derived from said initial portion a predetermined interval after a shot, whereby to verify the presence of ringing of the transducer (20).
Claim 4
Dependent Claim
36 words
A system according to Claim 1, characterised in that said memory means (8) is adapted to store samples of the receiver output occurring during said shot, and the receiver (26) is saturable by the transmitter (28).
Claim 5
Dependent Claim
67 words
A system according to Claim 1, characterised in that the transmitter (28) is adapted to transmit both shorter pulses and longer pulses, and means (24) are provided to derive samples of said initial portion from energy regenerated by said transducer (20) from a short pulse, and to derive samples of the remainder of the receiver response from energy regenerated by said transducer (20) from a longer pulse.
Claim 6
Independent Claim
100 words
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 the variation of the output of the transducer with time following the pulses is stored and examined in order to detect the echo, characterized in that the profile includes a period immediately following the transmission of the pulse during which the transducer is ringing at a high amplitude as a result of transmission of said pulse.
Claim 7
Independent Claim
100 words
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 the variation of the output of the transducer with time following the pulses is stored and examined in order to detect the echo, characterized in that the profile includes a period immediately following the transmission of the pulse during which the transducer is ringing at a high amplitude as a result of transmission of said pulse.
Claim 8
Dependent Claim
52 words
A method according to Claim 5, characterized in that the transducer output is amplified by a receiver prior to examination, the dynamic range of the receiver being such that its output is saturated during transmission of each pulse, this level providing a starting point for examining the echo profile for echo anomalies.
Claim 9
Dependent Claim
81 words
A method according to Claim 5 or 6, characterized in that a 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 echo 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.
Claim 10
Dependent Claim
30 words
A method according to Claim 7, characterized in that the transducer output following the narrow pulse is examined by searching the echo profile for an upturn of predetermined minimum amplitude.
Claim 11
Dependent Claim
101 words
A method according to Claim 7, characterized in that the transducer output is amplified by a receiver having a logarithmic transfer characteristic, the receiver output is digitized to form a file of data samples, the further 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 to intersect the largest echo anomaly, and the first echo anomaly in the echo response which intersects the reference curve is deemed the wanted echo.
Claim 12
Dependent Claim
40 words
A method according to Claim 7, characterized in that the difference in amplitude between the selected anomaly and the next largest anomaly is stored as a parameter representing the degree of confidence that the correct echo anomaly has been selected.
Claim 13
Dependent Claim
104 words
A method according to Claim 7, characterized in that 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, and that 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 to intersect the largest echo anomaly, and the first echo anomaly in the echo response which intersects the reference curve is deemed the wanted echo.
Claim 14
Dependent Claim
41 words
A method according to Claim 5, characterized in that 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.
Claim 15
Dependent Claim
73 words
A method according to Claim 12, characterized in that a sequence of samples of signals from the transducer are digitized and stored, and wherein a samples from a specific position in said sequence is tested to verify the amplitude of ringing of the transducer at that point in the sequence, the sample being selected so that the amplitude of ringing of a functional transducer will be high compared to any anticipated noise signal.
Claim 16
Dependent Claim
50 words
A method according to Claim 13, characterized in that signals from a plurality of transducer inputs are monitored, the presence or absence of ringing of predetermined amplitude in the selected sample of signals received from a particular input being utilized to determine whether a transducer is present at that input.
References Cited (Backward Citations)
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