Application of the Z-transform on the deconvolution of lightning electric field waveforms obtained from single-station measurements

Abstract

Fast electric field measurement systems used in the field of atmospheric electricity often have decay time constants of the order of 1 ms, which means that slower processes – such as long continuing currents – are not visible in the raw electric field records. This paper presents a practical approach to compensate for the time decay caused by the system response and regain the original lightning electric field waveforms. To accomplish this task, the transfer function of the measurement system is modeled in the Z-domain. Then, from the inverse Z-transform of the transfer function, the compensated electric field is obtained in discrete time domain. Based on data obtained at Nova Gameleira campus of CEFET-MG (Belo Horizonte, Brazil), we present and discuss results of typical electric field waveforms that include some slower lightning processes, which are not readily observable in the raw data.