Three direction finding methods of thunder source using microphone array

In this paper, we have investigated three methods, namely Generalized Cross-Correlation (GCC), Frequency Domain Beam-forming and Approximated Maximum Likelihood (AML), for estimating the direction of thunders measured with a microphone array. The performances of these methods are compared by simulations in terms of the error of angle estimation and also by signal experiments in terms of bi-dimensional representation, coherence measure and error point number for lightning channels measured simultaneously by a high-speed video camera. Comparison results show that both Beam-forming and AML obtain more accurate and complete direction finding than GCC, which is extremely consistent with the reconstructed lightning channel from the camera data. Moreover, Beam-forming and AML obtain additional information regarding thunder sources on top of the lightning channel, which cannot be observed in the camera data due to obstruction. However, the computation of AML is in general much more complicated than the other two methods. Therefore, we conclude that the Frequency Domain Beam-forming based technique suits future practical applications.