AN INNOVATIVE APPLICATION OF THE HILBERT TRANSFORM TO TIME-DELAY ESTIMATION OF OVERLAPPED ULTRASONIC ECHOES

In many areas, the estimation of time delay between two received signa ls is desired. An innovative process is proposed based on using the Hi lbert transform of the impulse response evaluated from the two signals . A pure delay is thus transformed in a hyperbola whose vertical asymp tote is located at a time yielding to the unknown shift in time. The p recision, and resolution in overlapping are investigated from simulate d signals. The measurement is also studied for an impulse response dif fering from the delta function. It is then demonstrated that when disp ersive effects are sensitive, the technique leads to the asymptotic lo w frequency value of the phase delay. From the point of view of ultras onic applications, these advantages are illustrated in comparison with classical input-output cross-correlation.