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)?

  • $\begingroup$ This sounds like measuring the differences in the impedance of the sensor when it is simply driven versus being driven while it receives a signal at its peak frequency and I am not sure if you would be able to observe any differences there. The "load" variation would be very small to observe anything meaningful :/ In Continuous Wave Radar applications, the Transmitter is distinct from the Receiver. $\endgroup$ – A_A Feb 15 '19 at 15:10
  • $\begingroup$ I would either: (1) transmit, then listen, and repeat; or (2) use two transducers, one to transmit and one to receive. $\endgroup$ – MBaz Feb 15 '19 at 15:14
  • $\begingroup$ there are some papers on “full duplex” acoustic systems. there was a DARPA program for radio. I’ve never looked closely at it. people seem to be working on the problem but I have no idea if there is tangible progress $\endgroup$ – user28715 Feb 15 '19 at 20:14

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