| Abstract: | This paper proposes a method to distinguish the normal modes in shallow water under near field.The method,which is based on frequency-wavenumber(F-K) transform,employs the 2D matrix comprising near field horizontal multi-channel signals.These signals are transformed from the time-space domain to the frequency-wavenumber domain,and the normal modes in the signals are distinguished by extracting the wavenumbers component at each frequency for each order in the frequency-wavenumber domain.The practical reliability and validity of this method are verified by performing numerical simulation and a tank experiment,and the results showed that the normal modes in the Pekeris waveguide below 200 Hz could be obtained reliably at 500 m by using this method. |
