Design of a PXIe-Based VHF Lightning Interferometer System and Initial Observations

This article presents a novel development of a very high-frequency (VHF) lightning interferometer system at National Atmospheric Research Laboratory, Gadanki (13.58°E,79.18°N). While similar systems have been developed in the past, this system distinguishes itself due to use of PXIe-based commercial-off-the-shelf (COTS) digitizers and controllers, offering the ease of configuration, scalability, and future upgradability. The system design comprises three broadband RF channels, a trigger generator, and a high-speed digitizer. The RF frontend incorporates discone antennas, bandpass filters, and low-noise amplifiers, ensuring efficient capture of lightning signals in the 20–80-MHz frequency band. The system addresses issues encountered during initial field experiments, such as frequent amplifier failures, by implementing voltage regulation closer to the amplifier. The signal acquisition system utilizes modular PXIe-based technology, enabling high bandwidth and throughput. The system employs two dual-channel Keysight M9203A PXIe digitizer cards mounted in a Keysight M9019A chassis, along with an embedded controller (Keysight M9037A) for seamless control and data acquisition. Its design and scalable architecture hold promise for future enhancements and upgrades. An example observation of a lightning flash recorded during the initial field deployment is presented. The detailed analysis of the flash showcases system’s capabilities in capturing the initiation, progression, and branching of lightning channels and identifying initial breakdown pulses (IBPs) and their characteristics.