Acoustic range finding system
First Claim
1. In 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 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 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 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
computing means 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;
the improvement wherein the computing means is programmed to examine the digital data base file 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 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.
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Accused Products
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, 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.
49 Citations
16 Claims
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1. In 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 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 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 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
computing means 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;the improvement wherein the computing means is programmed to examine the digital data base file 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 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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
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8. In 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 pluses 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 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 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
computing means 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;wherein the computing means is programmed to examine the digital data base file 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 from a common target.
- 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
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9. In 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 pluses 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 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 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
computing means 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;the improvement wherein the computing means is programmed to perform a linear regression upon at least a portion of the data base file to generate a file containing a linear time varying threshold, and to compare the data base file depicting the signal profile with the linear time varying threshold file to identify peaks in the signal profile. - View Dependent Claims (10, 11, 12)
- 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
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13. In 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 pluses 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 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 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
computing means 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;the improvement wherein the computing means is programmed to generate a file containing a time varying threshold, and to compare this file repeatedly with the data base file 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 containing the summed magnitudes of the peaks located by said comparisons at different locations on the profile, and to select the largest of said summed magnitudes as identifying a peak in the echo profile representing a true echo. - View Dependent Claims (14, 15)
- 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
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16. In 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 pluses 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 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 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
computing means 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;the improvement wherein the computing means is programmed to introduce a predetermined local upward adjustment into a time varying threshold file generated for comparison with the digital data base file depicting the profile of the received signal, the adjustment being at a location and of a magnitude such as to prevent detection of a spurious echo of known location and magnitude when the files are compared.
- 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 file depicting an amplitude/time profile of the received signal with a resolution dependent on the sampling intervals; and
Specification