Continuous broadband lightning VHF mapping array using MUSIC algorithm

Abstract In order to improve the mapping quality of lightning discharge processes, a mapping approach by applying multiple signal classification (MUSIC) algorithm to direction-of-arrival (DOA) estimation of lightning very high frequency (VHF) radiation sources is proposed (MUSIC-VHF method) and validated. Based on the principles of the eigen decomposition of the spatial covariance matrix, broadband MUSIC algorithm operating in lightning VHF ranges, on arbitrary planar array, is derived. To verify this method, numerical simulations were conducted for testing its performance in localization accuracy, spatial resolution and sidelobe suppression. Field experiments were designed to validate the proposed method, with an unmanned aerial vehicle (UAV) and a portable radiation source. The proposed method was further applied to map two classical triggered flashes. Temporal and spatial development of the discharge channels from the two flashes could be well depicted, including the upward positive leaders (UPLs), K-events, dart leaders and VHF radiations in subsequent return stroke (SRS). Additionally, comparisons among the proposed method and EMTR-VHF method, interferometer (INTF) technology are conducted. Comparison results show that the MUSIC-VHF method performs better in spatial resolution, sidelobe narrowband interference suppression. Moreover, the phenomena of multi-source radiations occurring simultaneously within a single observation window are reported, and their localization results are presented.