Maximum likelihood localization of sources propagating in a random media using intensity measurements

A statistical signal processing solution is proposed for locating a monochr omatic source propagating in a random media. The media is fully parametrize d by the normalized scattering strength gamma and scaled range X, which dep end upon the physics of the media. M independent intensity measurements are observed, each drawn from the generalized gamma distribution. This has bee n shown by Ewart [J. Acoust. Sec. Am. 86, 1490-1498 (1989)] to describe sou rces propagating through internal waves in ocean environments. The paramete rs of the distribution are related to the scattering parameters, gamma and X. Maximum likelihood estimation is used to infer X, given the observations and our knowledge of gamma. The estimation performance is well-characteriz ed by the Cramer-Rao lower bound (CRLB). The results show that we can estim ate range to a precision of about 20%, for ranges up to half the distance t o the focus of the medium. Simulation results verify both the normality of the estimates and the validity of the CRLB as a predictor of the estimator precision at these ranges. The practical value of this method will depend o n our ability to gather enough independent measurements, and on the accurac y of the statistical models we assume, including prior knowledge of gamma. It can be expected to augment other methods such as matched field processin g. (C) 1998 Acoustical Society of America. [S0001-4966(98)02011-6].