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The flight parameters of a nonmaneuvering aircraft can be determined from the closest points of approach (cpa) time registrations in a field of acoustic sensors. In plane geometry, and with four sensors, the problem has a (nearly) closed-form solution. Monte Carlo simulation is applied to demonstrate that the solution behaves in a stable manner against a deviation from the hypothesis of zero target height, in the order of the distance between sensors, as long as the target velocity is not too high. Application to real data has demonstrated the feasibility of the procedure. [ABSTRACT FROM AUTHOR]

Acoustical tracking of maneuvering aircraft based on bearing measurements from distributed sensors is not directly accessible to conventional techniques because of the retardation between emission and reception of sound. To overcome this complication, the following two-step strategy is proposed: (1) Estimate the aircraft location at an arbitrary time and repeat this procedure to obtain a sequence of position estimates; (2) combine these estimates by conventional filtering methods. Focusing on the first step, the localization problem is treated on the basis of at least two separated sensors that measure the direction of arrival of the incident sound wave. An assessment of the accuracy of the resulting position estimates is provided, as well. The procedure is illustrated both with simulated and real data. [ABSTRACT FROM AUTHOR]

The flight parameter of an aircraft moving without acceleration can be estimated by exploiting the target-generated noise received by a directional sensor consisting of three or four microphones. The Cramér-Rao lower bound is calculated to investigate the theoretical accuracy of estimates. Moreover, an algorithm is proposed which computes the maximum-likelihood estimate. Extended simulations prove the algorithm to work reliably and fast, and the estimate to be nearly unbiased and efficient when averaged over a large region of flight parameters. Results obtained with real data are included. [ABSTRACT FROM AUTHOR]

In a planar multistatic sonar system employing omnidirectional source and receivers, two receivers generally do not suffice to permit localizing a target unambiguously. Whether three receivers are sufficient depends on the geometrical configuration of source and receivers. This note provides a necessary and sufficient condition for unambiguous localization. [ABSTRACT FROM AUTHOR]