Waveguide invariant and range estimation based on phase-shift-compensation of underwater acoustic spectrograms.

The waveguide invariant is an important concept in ocean acoustics. It describes the interference striations of the spectral structure of acoustic signals at different ranges. This paper proposes a sound intensity based method for estimating the waveguide invariant and source range by using phase-shift-compensation of the underwater acoustic spectrum obtained by different receivers. When one of the waveguide invariant and the source range is known, this method can be used to estimate the other. With this method, waveguide invariants at different ranges are estimated experimentally using LFM signals radiated by one towed sound source and received by one sea-floor located horizontal-line-array. Data was collected in the North Yellow Sea in December 2011. It is shown that the waveguide invariant varies from 0.8 to 1.2, and that its mean value is near the theoretical value. On the other hand, ranges are estimated using the theoretical value of the waveguide invariant, and these are in good agreement with the ranges measured by GPS. [ABSTRACT FROM AUTHOR]