Song H C, Cho Chomgun
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0238, USA.
J Acoust Soc Am. 2015 Aug;138(2):899-903. doi: 10.1121/1.4927090.
The waveguide invariant β is based on the dependence of group speed on phase speed and summarizes the robust interference phenomenon in the range-frequency plane. Over the last decade the elegant approach has been utilized for various applications including passive source ranging. Separately, the array invariant approach [Lee and Makris, J. Acoust. Soc. Am. 119, 336-351 (2006)] has been proposed for a robust source-range estimator from beam-time intensity data using either a horizontal or vertical array. In this paper, it is shown that the array invariant can be derived from the waveguide invariant theory assuming β=1.
