Patent ID: 6856576

Claim:
A method for echo processing in a pulse echo level measurement system, said level measurement system having a transducer for transmitting pulses and receiving echoes and including a receiver for converting the received echoes into corresponding received signals, said method comprising the steps of: (a) transmitting a transmit pulse to a reflective surface; (b) receiving an echo and converting the echo into a receive signal, said receive signal having a plurality of peaks; (c) high-pass filtering said receive signal to create a filtered signal; (d) creating a correlation signal from the addition of said filtered signal to a copy of said filtered signal shifted by a time unit; (e) identifying a correlation indicator of said correlation signal; (f) repeating steps (d) and (e) for a range of time units to generate a set of said correlation signals and correlation indicators; and (g) selecting an echo time based upon a maximum correlation as determined by one of said correlation indicators, said echo time corresponding to the time shift at which said maximum correlation occurs, and said echo time indicating the echo distance travel time.