# Detecting multi-path propagation when one acoustic signal is dominant

I am sending an acoustic signal from a source to a receiver where there are limited number of paths the signal can travel. I want to detect if there has been multipath propagation or not when one path is the dominant line of sight path. Based on this link - Cross-correlation peaks in acoustic multi-path conditions , it seems like cross-correlation and checking for multiple peaks is an option, but it does not work when there is Fading (one dominant signal and others being attenuated).

It seems like this sort of Fading is called Rician Fading - however, I am not sure how to use this to detect if their has been multipath propagation or not. How to use the source and receiver signals to know if multipath propagation happened or not. (Also, I cannot use time of arrival of chirp pulses since the difference between time of arrivals of different paths is less than the chirp width)

It seems to me that, in the conditions you describe, the most you will see is flat fading. One indication that flat fading is occuring is that a change in the positions of transmitter and receiver, and/or the reflectors causing the multipath, produce a significant change in the received power. Usually the change has to be of the order of $$\lambda/2$$ meters, so this may be unfeasible in your case.