A method of operating an acoustic pulse echo ranging system is provided. A series of acoustic energy pulses of successively increasing or decreasing burst frequencies are transmitted through a transducer assembly. For each transmitted energy pulse associated echoes are received and converted into an echo function over time. The obtained echo function is stored in a two-dimensional pattern whose first dimension is the burst frequency and whose second dimension is the time. Based upon the two-dimensional pattern a frequency response function is evaluated as a function of echo function values over burst frequency at a selected point of time.