On the Possibility of Coherent Addition of Low-Frequency Multiharmonic Communication Signals in the Deep Sea

Interference patterns of the amplitude and phase of the sound pressure generated by a broadband source of multiharmonic signal (MHS) have been studied in the insonification and shadow zones of the deep sea. The structure of the interference patterns of these signals in the frequency–distance plane depends on the source and detector coordinates. It is shown that the MHS components can be coherently added at distances for which the Fourier component phases coincide. Incoherent addition of powers is performed at other distances. It is found that the coherent addition of components is most efficient in the interference maxima of near and far insonification zones (NIZ and FIZ, respectively), where weakly dispersed water modes dominate, whereas in the shadow-zone interference maxima, where the contribution of highly dispersed modes is decisive, their addition efficiency is significantly reduced.