A structure is presented for passive estimation of range and bearing as well as velocity of a source from a linear array. It uses a quasi-optimal post processor of the time delays, which are obtained from a generalized correlator with finite observation time. The post processor ultimately maps the sequential time-delay observations onto invariant source trajectory parameters over which smoothing is performed to reduce, jointly, the variance and the bias in the estimate of the source kinematics. The present approach remains viable for moving sources at long ranges, off-broadside source directions and high time-delay variances. Analysis and simulation results are presented to justify its usefulness under the stated stringent conditions. Review of and comparison to existing approaches are made to highlight the viability of present approach in the estimation of source trajectory.
In a recent paper [ 11, Theriault and Zeskind evaluate an approximate form for the bias encountered in conventional wavefront curvature ranging. We would like to point out that this result has been given previously by Hassab, Guimond, and Nardone [2].Theriault, and Zeskind note that reduction of this bias through increase in processing time exacerbates the problem; then they conclude that this bias represents a fundamental limitation on the performance of systems which employ the ranging equation.In [ 2 J , Hassab, Guimond, and Nardone present an approach that allows for removal of this limitation. It is demonstrated that the bias as well as the variance on the range estimates can be asymptotically reduced to negligible levels. The noisy time delays from a correlator output with short time average are mapped in a postprocessor onto the invariant source trajeo tory parameters over which smoothing is performed to reduce jointly the variance and the bias in the estimate of source range, course, and speed. This mapping imparts stationarity to the problem, thus allowing an effective increase in the averaging time of the localization systems beyond that permitted in a correlator.It is shown in [2] that theaddition of the proposed structure improves ,substantially on the techniques that process inappropriately mapped time delays or those that. transform directly the best time delays available into source motion estimates.
A structure is presented for passive estination of range, bearing as well as velocity of a source from a linear array. It uses a quasioptimal post-processor of the time delays, which are obtained from a generalized correlator with finite observation time. The postprocessor ultimately naps the sequential time delay observations onto invariant source trajectory parameters over which smoothing is performed to reduce, jointly, the variance and the bias in the estimate of the source kinematics. The present approach remains viable for moving sources at long ranges, off-broadside source directions and high time delay variances. -Lal'-ysis and simulation results are presented to justify its usefulness under the stated stringent conditions. Review of and comparison to existing approaches are made to highlight the viability of present approach in the estimation of source trajectory.
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