New principle of array processing in underwater passive listening

One of the main function of an underwater passive listening system is the reckoning of the number of present sources as well as the characteristic parameters of everyone. To do so, the noises transmitted by the sources are used when recorded on the sensors of an array. The basic tool is the spatial processing. The traditional tool is the classical beamforming. Then, in view of improving the performance, one came to adaptive beamforming of a sensor array. As a result, this method brings an improvement - an array gain - which is asymptotically bound by the signal to noise ratio of the source noises, when measured on a particular sensor. More recently have appeared more powerful methods called high resolution. The improvement in performance as compared to previous processing is at the cost of one more assumption on the medium. Nevertheless, these methods carry the possibility to include free parameters in the medium model, and that make more flexible the assumptions to be accepted.