Computationally efficient estimation of the azimuth and elevation of multiple sources with planar sensor arrays

The use of ESPRIT as a direction-finding algorithm requires a pair of identical array structures, where one is merely translated with respect to the other. For the case in which the individual arrays are not linear, it is proposed that a scheme referred to as pseudo-forward-backward averaging (PFBAVG) be incorporated. In contrast to conventional forward-backward averaging, the use of PFBAVG does not effect source decorrelation. Rather, the use of PFBAVG in conjunction with ESPRIT effects a substantial reduction in the attendant computational burden and at the same time a significant improvement in performance. In addition, the use of PFBAVG gives rise to a simple scheme for estimating the number of sources. This scheme may be used either as an alternative to AIC and MDL, or as a means of verification. Finally, PFBAVG also facilitates a simple preprocessing measure for counteracting the pejorative effects of ill-conditioning arising when sources are closely spaced. The penalty paid for these benefits is a reduction in the maximum number of sources the algorithm is able to handle by a factor of one-half