the probability of detection of an underwater moving target is enhanced by the selective summing of a multiplicity of reverberation suppressed , moving target detections , each appearing in a different and non - overlapping , narrow frequency band of a unitary , broadband transmission . the motion - sensitive target echoes are the result of a multiple - pulse broadband transmission . these broadband received echoes are bandpass filtered to form a set of narrow frequency bands extending over the full bandwidth of the transmission . these narrow band returns are then matched - filtered against a set of moving target replicas . selected ones of these band - limited , matched - filtered returns are then summed together . the summed result can contribute to an enhanced probability that a unitary , moving target has been detected .