Continuous Mapping of Broadband VHF Lightning Sources by Real-Valued MUSIC

Abstract

To improve the mapping quality of lightning discharge processes at a reduced computational complexity, broadband implementation of the real-valued MUSIC (RV-MUSIC) direction of arrival (DOA) method is proposed and evaluated. A very high frequency (VHF) broadband high-speed continuous acquisition system consisting of three omnidirectional “L” shaped antennae array is implemented to acquire lightning radio emissions in a 20–80-MHz frequency band. The cost function of RV-MUSIC for the broadband lightning signal is derived. Monte-Carlo simulations are carried out to demonstrate functionality and to evaluate the robustness of the proposed method. Further, the proposed method is validated by generating lightning maps using observational data. Simulation and observational results are compared with the conventional incoherent MUSIC (IMUSIC) and interferometric DOA methods. The computational costs of all three methods are derived, and their respective estimated execution times are also presented. Results show that the proposed method can generate lightning maps of similar quality to that of IMUSIC at a significantly lower computational load.