Azimuth-Only Estimation for TDOA-Based Direction Finding With 3-D Acoustic Array.

This paper focuses on the time-difference-of-arrival (TDOA)-based direction finding for a low-altitude source with an acoustic sensor array. The source bearing in space must be estimated by the joint azimuth-elevation estimation. The azimuth may be the only concern for some scenarios, where the elevation is trivial; however, an extra parameter about elevation needs to be estimated in the joint estimation. When a planar array is introduced to replace the spatial array, the azimuth-only estimation solution with the original TDOA measurements is proposed. This solution is simpler than the joint estimation by excluding the elevation calculation. The mathematical relation between the TDOAs of spatial and planar arrays is derived, and their azimuth Cramer–Rao lower bounds (CRLBs) are compared. The CRLBs together with the pseudo-linear estimation and Taylor series least squares method are evaluated for estimating the source azimuth by simulations as well as real-life data. The results demonstrate that the azimuth-only estimation would create a modest precision improvement over the joint azimuth-elevation estimation. The effect of array altitude variation is also examined, suggesting that the relative heights among sensors have little influence on the estimation of source azimuth. [ABSTRACT FROM AUTHOR]