Patent EP0340953A2 successfully refreshed from Google Patents.
EP0340953A2
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EP
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Acoustic range finding system
Assignee: Siemens Canada Ltd
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Filing: 1989-04-24
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Granted: —
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Expires: 2009-04-24
Abstract
Abstract Acoustic level sensing apparatus is provided, 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 received by a receiver is digitized and analyzed by a programmed microprocessor 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 (REMOVE_NARROW_ECHOES_F0), and narrow valleys which may represent fragmentation of a wanted echo (REFORM_FRAGMENTED_ECHOES_F0). Echoes are identified by comparing the profile with a time varying threshold generated derived from a linear regression performed on part of the echo profile (TVT_IN_F2), various different types of comparison being performed and their results combined (ALF_ALGORITHM) prior to selecting the most likely true echo on the basis of the combined results (SELECT_BEST_ECHO_FROM_FILE_3).
Inventors
- 👤 Steven James Woodward
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 11:41
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/296; G01F23/2962; G01S; G01S15/00; G01S15/88; G01S7/00; G01S7/52; G01S7/523; G01S7/526; G01S7/527; G01S7/5273; Y; Y10; Y10S; Y10S367/00; Y10S367/901; Y10S367/908
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
361 words
An acoustic ranging system comprising at least one electro-acoustic transducer (20) directed towards the surface of material whose level is to be determined, a transmitter (18) to transmit pulses of electrical energy to energize selectively each said transducer whereby to cause it to emit at least one shot of acoustic energy at a predetermined frequency, a receiver (26) receiving and amplifying electrical energy from said at least one shot regenerated by said transducer from acoustic energy at the same frequency received by the 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 (24) to sample repeatedly the output amplitude of the signal from the receiver at defined intervals and to digitize the samples; memory means (8) to store an extended sequence of digitized samples so produced in respect of at least one shot and form therefrom a digital data base file (F0) depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and computing means (12) programmed 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 said at least one shot deemed most probable to correspond to a wanted echo, and to determine a range represented by an echo within said portion of the time axis; characterized in that the computing means (12) is programmed to generate a time varying threshold file (F3) derived from said digital database file (F0, F1), to compare said files to produce a comparison file (F3) of data relating to peaks in the echo profile, and to manipulate the data in at least one of said database file (F0, F1) and said threshold file (F2) prior to or during said comparison to reduce the likelihood that spurious features of the profile of the received signal representing the database file will affect recognition of a true echo from the data in said comparison file (F3).
Claim 2
Dependent Claim
361 words
An acoustic ranging system comprising at least one electro-acoustic transducer (20) directed towards the surface of material whose level is to be determined, a transmitter (18) to transmit pulses of electrical energy to energize selectively each said transducer whereby to cause it to emit at least one shot of acoustic energy at a predetermined frequency, a receiver (26) receiving and amplifying electrical energy from said at least one shot regenerated by said transducer from acoustic energy at the same frequency received by the 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 (24) to sample repeatedly the output amplitude of the signal from the receiver at defined intervals and to digitize the samples; memory means (8) to store an extended sequence of digitized samples so produced in respect of at least one shot and form therefrom a digital data base file (F0) depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and computing means (12) programmed 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 said at least one shot deemed most probable to correspond to a wanted echo, and to determine a range represented by an echo within said portion of the time axis; characterized in that the computing means (12) is programmed to generate a time varying threshold file (F3) derived from said digital database file (F0, F1), to compare said files to produce a comparison file (F3) of data relating to peaks in the echo profile, and to manipulate the data in at least one of said database file (F0, F1) and said threshold file (F2) prior to or during said comparison to reduce the likelihood that spurious features of the profile of the received signal representing the database file will affect recognition of a true echo from the data in said comparison file (F3).
Claim 3
Dependent Claim
80 words
An acoustic ranging system as claimed in claim 1, characterized in that the computing means is programmed (Figure 3) to examine the digital data base file (F0) depicting the profile of the received signal to measure the height and width of peaks in the profile, and to modify the profile by removing peaks (UE) whose height to width ratio exceeds a predetermined threshold beyond which the ratio is deemed too great for the peak to represent a true echo (TE).
Claim 4
Dependent Claim
73 words
An acoustic ranging system as claimed in claim 1 or 2, characterized in that the computing means is programmed (Figure 4) to examine the digital data base file (F0) depicting the profile of the received signal to measure the width of valleys in the profile, and to remove valleys whose width is less than a predetermined threshold such that peaks which the valleys separate could represent fragmented echoes (FE) from a common target.
Claim 5
Dependent Claim
75 words
An acoustic ranging system as claimed in claim 1, 2 or 3, characterized in that the computing means is programmed (Figure 5) to perform a linear regression upon at least a portion of the database file (F1) to generate a file (F2) containing a linear time varying threshold (TVT), and to compare the database file (F1) depicting the signal profile with the linear time varying threshold file (F3) to identify peaks in the signal profile.
Claim 6
Dependent Claim
95 words
An acoustic ranging system as claimed in claim 4, characterized in that the computing means (12) is programmed to perform the steps (Figure 5) of removing a first portion of the database file (F2) corresponding to a ringdown period of the transducer, removing a latter part of the file (F2) following a breakpoint at which the mean amplitude of the signal samples has become substantially constant, performing a linear regression upon the remaining portion to obtain a slope, and inserting an extrapolation of this slope to replace the removed first portion of this file (302).
Claim 7
Dependent Claim
71 words
An acoustic ranging system as claimed in claim 5, characterized in that the computing means is programmed to perform a further linear regression (304) upon the database file (F2) as modified by replacement of its first portion, to construct a first portion of the time varying threshold file from the slope thus obtained (304), and to construct a remaining portion from a horizontal line intersecting the slope at the breakpoint (305).
Claim 8
Dependent Claim
109 words
An acoustic ranging system as claimed in any of the preceding claims, characterized in that the computing means is programmed to generate a file (F2) containing a time varying threshold (TVT), and to compare this file repeatedly (403-405) with a database file (F1) depicting the signal profile both to identify peaks in the latter and the magnitude of such peaks, utilizing successively different criteria, to generate a file (F3) containing the summed magnitudes of the peaks located by said repeated comparisons at different locations on the profile, and to select the largest of said summed magnitudes (409) as identifying a peak in the echo profile representing a true echo.
Claim 9
Dependent Claim
50 words
An acoustic ranging system as claimed in claim 7, characterized in that the different criteria for assessing the magnitudes of the peaks are the areas of the peaks (403), the height of the peaks (404), and the height by which each successive peak exceeds that of a preceding peak (405).
Claim 10
Dependent Claim
56 words
An acoustic ranging system as claimed in claim 8, characterized in that the computing means (12) is programmed (409) to compare the largest of said summed magnitudes with the next largest of said summed magnitudes which corresponds to a peak more than a predetermined distance from the peak corresponding to the largest of said summed magnitudes.
Claim 11
Dependent Claim
79 words
An acoustic ranging system as claimed in any of the preceding claims, characterized in that the computing means is programmed (306) to introduce a selected local upward adjustment into a time varying threshold file (F2) generated for comparison with the digital database file (F1) depicting the profile of the received signal, the adjustment being selected as to location and magnitude such as to prevent detection of a spurious echo of known location and magnitude when the files are compared.
References Cited (Backward Citations)
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