Trace, 5

This view gives a graphic representation of the idea which has been described : is the model. is a short signal with a duration which is a little less than the pause between the reflections; the corresponding received signal. It is possible to interpret this as the reflections do not interfere with one another and it is easy to distinguish them separately. is a long signal. is the corresponding received signal (the longer term is always the sum of the model and the input signal). Here the different echoes interfere like the cacophony resulting from the musical canon of “Freres Jacques” : on the trace obtained it is not possible to distinguish between the reflections from the different reflectors of the model. In this state the trace is uninterpretable… is the processing which consists of a correlation of (4) and (5)…