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Owing to the inhomogeneities in the atmosphere,an infrasonic wave during its propagtiondecomposes into normal modes,each will have its own phase-and group-velocity.When theinfrasonic wave is received by an acoustic array,at a distance from source,the time delays of differentmodes at the array are also different.According to the fact that the main energy of each mode isdistributed in different frequency regions,a method for computing the average amplitude and azimuthof the phase velocity for each normal mode is proposed in this paper,and the spectrum of each modeis estimated by velocity filtering,and the waveform of any mode at any position in space can beestimated by Weiner-Hopf filtering from the data received in an acoustic array.Finally the computersimulation is given,and it is shown that the estimated waveform is very close to what is assumed.
Owing to the inhomogeneities in the atmosphere, an infrasonic wave during its propagtion decomposes into normal modes, each will have its own phase-and group-velocity. Whilst the infrasonic wave is received by an acoustic array, at a distance from source, the time delays of differentmodes at the fact that the main energy of each mode isdistributed in different frequency regions, a method for computing the average amplitude and azimuthof the phase velocity for each normal mode is proposed in this paper, and the spectrum of each modeis estimated by velocity filtering, and the waveform of any mode at any position in space can beestimated by Weiner-Hopf filtering from the data received in an acoustic array. Finaally the computersimulation is given, and it is shown that the estimated waveform is is very close to what is assumed.