Abstract
The normal modes cannot be extracted even in the Pekeris waveguide when
the source-receiver distance is very close. This paper introduces a normal
mode extraction method based on a dedispersion transform (DDT) to solve
this problem. The method presented here takes advantage of DDT, which is
based on the waveguide invariant such that the dispersion associated with
all of the normal modes is removed at the same time. After performing DDT
on a signal received in the Pekeris waveguide, the waveform of resulting
normal modes is very close to the source signal, each with different
position and amplitude. Each normal mode can be extracted by determining
its position and amplitude parameters by applying particle swarm
optimization (PSO). The waveform of the extracted normal mode is simply
the waveform of the source signal; the real waveform of the received
normal mode can then be recovered by applying dispersion compensation to
the source signal. The method presented needs only one receiver and is
verified with experimental data
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