초록 ▼

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

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.

대표청구항 ▼

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

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 generate a time varying threshold file derived from said digital database file, to compare said files to produce a comparison file of data relating to peaks in the echo profile, and to manipulate the data in at least one of said database file and said threshold file prior to or during 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.