Pulse position modulated (PPM) acoustic pulses are difficult to detect exactly in shallow sea channels because of strong multipath interference

large signal fluctuation and high noise level. This paper reports results of analysis on the main characteristics of multipath interference and its adverse effects on detection of pulse position information. Feasible methods to overcome multipath interference are pointed out

and an efficient one is proposed to realize reliable and precise detection of PPM information. The results of this study are of reference value for other modes of signal detection.