A ray-based blind channel estimation method in ocean sound channels. Application to high-frequency underwater telecommunications

Abstract

A signal that travels through a sound channel is typically distorted when recorded by a remote listener because of interference arising from multiple propagation paths. We developed a ray-based blind channel estimation technique in ocean sound channels, i.e., using only records of the distorted signal along a transducer array. The technique yields broadband estimates of the source-to-array impulse response (or Green’s functions) synthesized directly from the recorded distorted signals. The technique relies on separating out the contribution of a propagating ray path having a phase that depends linearly on frequency. This technique was used to decode high-frequency underwater telecommunications sequences collected in 2005 off the West Coast of Italy, without any a priori knowledge of the channel impulse response. [Work supported by ONR.]