Observed spectral broadening of acoustic pulse in an underwater channel

Boundaries of oceans viz. surface and bottom form a channel for the propagation of underwater sound. Sound propagation in this channel is subjected to random fluctuations due to the presence of in-homogeneities in water column and interaction with rough sea surface and sea bed. The inhomogeneities in the water column are caused by density microstructures and dynamics of the ocean. As a result of multi-path propagation, underwater sound experiences dispersion, Doppler and amplitude fluctuations. In this scenario, conventional signal detection algorithms do not perform well. This leads to the development of new signal processing algorithms to take care of fluctuations in acoustic signals. The current trend is to use channel factors caused by the ocean environmental variability to derive optimum performance of systems. One of the factors is the Doppler spread. In this paper, estimation of Doppler spread for a CW signal is attempted.