Patent ID: 8144544

Claim:
A method of processing an echo profile in a pulse-echo ranging system, comprising: providing and using a tank containing a material, wherein the tank comprises an ultrasonic transducer; providing and using a microprocessor which is coupled to the ultrasonic transducer via a transmitter; generating ultrasonic pulses using the ultrasonic transducer, wherein the ultrasonic pulses are reflected by a top surface of the material in the tank; receiving reflected pulses by the transducer and converting the reflected pulses into electrical signals; generating a digital echo profile based on the electrical signals, wherein the digital echo profile is processed by the microprocessor, comprising: forming the digital echo profile into a succession of digital values at spaced points in time; determining a relative slope at each of the spaced points; identifying regions of positive slope within the echo profile; determining a relative area of the region or each region of positive slope; identifying, within the region having the largest relative area, a point of greatest relative slope as a leading edge reference point; identifying one or more peaks within the echo profile by detecting points where the relative slope transitions from positive to negative; and using either said leading edge reference point or said peak(s) as an echo timing measurement point.