Wideband processing and analysis of lightning in the earth-ionosphere waveguide

Abstract

A new vertical electric field antenna has been installed at our West Greenwich, RI Schumann resonance field station, coupled to a high-bandwidth charge amp and a computerized sampling system. Techniques are given for the processing of lightning transients. Digital signal processing techniques for the removal of power line harmonic noise are presented and evaluated. Additionally, a wideband (3 Hz - 24 kHz) simulation model has been developed. This model gives evidence that slow tail waveforms are generated primarily due to the variation of waveguide phase velocity with frequency and the depletion of spectral energy in the waveguide cutoff region. Preliminary formulas for distance estimation have been developed from the simulations, based on slow tail separation time and spectral ratios. These methods are evaluated for consistency against real events.