A transducer is acting as a transmitter and a receiver. It keeps on sending pulses which can hit an object placed at 5cm. Echo comes back and hits the transducer while it is continuously sending pulses. That is there is no way to detect echo signals explicitly (as the line is being driven by input signal). How do we detect whether object is present at 5cm? I was thinking of extracting beats/lag from the distorted input signal (my intuition: when the echo hits the transducer, it tries to generate a signal which oppose the input signal) when the object is present and compare it with a case when the object is not present. What's the best technique to use here (any Adaptive Signal Processing)?