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The On-Line Lightning Monitoring System (OLMS) is designed to continuously detect and characterize the effects of lightning-induced electromagnetic transients at a number of spacecraft launch sites in the United States. The OLMS uses broadband sensors, installed at a number of preselected locations at the launch site, to simultaneously measure incident electromagnetic fields, as well as energy coupled to conductors, using a unique combination of analog and digital subsystems. The system allows users to assess the electromagnetic threat to sensitive electronic systems aboard spacecraft, thereby retesting systems only if necessary. All data from OLMS is available in real time and can be accessed by authorized users via the Internet using a standard web browser interface. At the International Conference on Lightning and Static Electricity in 1999 (ICOLSE ‘99), we described the ongoing design and development of OLMS. The system is now installed and fully operational at five launch sites.

This paper provides a technical overview of the on-line lightning monitoring system (OLMS), a sophisticated second-generation system designed to monitor the effects of lightning-induced electromagnetic (EM) transients on ground-based space systems. The potential damage of sensitive electronic systems by lightning-induced EM transients is of concern to system designers, operators, and maintainers. The OLMS uses broadband sensors to measure free-field radiation (electric and magnetic fields), as well as energy coupled to conductors (current and voltage). Characterization of the measured signals is performed by two subsystems in parallel: an analog transient processor (TPM) and conventional state-of-the-art digitizers. While the digitizers are able to provide the actual high-frequency waveforms desired by many users, they have inherent limitations in duty cycle and large data storage requirements.