
Accession Number : ADA116105
Title : Frequency Dispersion of Sound in Undersea Propagation.
Descriptive Note : Interim rept.,
Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC
Personal Author(s) : Gerlach,A A ; Flowers,K D ; Johnson,R B , Jr ; Anderson,W L ; Kunz,E L
PDF Url : ADA116105
Report Date : 17 Jun 1982
Pagination or Media Count : 53
Abstract : Acoustic dispersion in a deep ocean channel is characterized by the dependence of sound propagation speed on signal frequency along the axial propagation path. A model normalmode solution of the wave equation is employed to compute the acoustic field for sinusoidal signals as a function of both axial range and frequency. A virtual propagation time is defined, which reflects the rangedependent phase of the acoustic field. When signals of different frequency are transmitted, the remotely observed frequency ratio (for a given rangerate) will fluctuate about the true frequency ratio of the transmitted signals. The magnitude of the fluctuation is directly proportional to the true frequency ratio. A measure of the spectral dispersion is defined as the difference between the observed and true frequency ratios. The dependence of this measure on range and signal frequencies (for a given frequency ratio) is determined to be relatively insignificant. It is concluded that spectral acoustic dispersion in a deep ocean channel is microscopic, but it can be significant for applications involving the phase correlation of broadband (or spectrally separated) signals over long time intervals. (Author)
Descriptors : *Underwater sound signals, *Wave propagation, Acoustic fields, Dispersions, Deep oceans, Broadband, Wave equations, Sound transmission
Subject Categories : Acoustics
Radiofrequency Wave Propagation
Distribution Statement : APPROVED FOR PUBLIC RELEASE