Method of processing echo profile, and pulse-echo system for use with the method

1. 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.

2. The method according to claim 1 , wherein the echo profile contains multiple peaks, and one of the peaks is selected in the following manner:

the first peak is selected if it is of greater amplitude than the subsequent peaks; and

otherwise, the peak which follows said leading edge reference point is selected.

3. The method according to claim 1 , further comprising:

detecting a peak by expanding back and forward from the detected slope transition to a predefined amplitude level; and

selecting the mid-point of the expanded area.

4. The method according to claim 2 , further comprising:

detecting a peak by expanding back and forward from the detected slope transition to a predefined amplitude level; and

selecting the mid-point of the expanded area.

5. The method according to claim 3 , wherein the peak is expended to points where the echo amplitude is 20% of the maximum peak amplitude.

6. The method according to claim 4 , wherein the peak is expended to points where the echo amplitude is 20% of the maximum peak amplitude.

7. A pulse echo ranging system, comprising:

an ultrasonic transducer;

a transmitter for supplying energy pulses to the transducer;

a receiver for receiving energy pulses from the transducer, wherein the receiver comprises an amplifier and an envelope detector; and

a processing unit, wherein the processing unit is configured to

select echoes from a received signal,

perform an analog-to-digital conversion to produce an echo profile in form of a succession of digital values at spaced points in time, and

process the echo profile,

wherein processing the echo profile comprises:

forming the 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.

8. The system according to claim 7 , wherein the echo profile contains multiple peaks, and one of the peaks is selected in the following manner:

the first peak is selected if it is of greater amplitude than the subsequent peaks; and

otherwise, the peak which follows said leading edge reference point is selected.

9. The system according to claim 7 , the processing further comprising:

detecting a peak by expanding back and forward from the detected slope transition to a predefined amplitude level; and

selecting the mid-point of the expanded area.

10. The system according to claim 9 , wherein the peak is expended to points where the echo amplitude is 20% of the maximum peak amplitude.