The use of both time-of-arrival and direction finder techniques to locate the sources of VLF radiation from distant lightning is well established. The accuracy of the locations, especially for distances beyond several hundred kilometers, has been limited by error sources such as polarization errors, instrumental errors, and errors due to interference between flashes. The last is believed to be the predominant source of error at distances greater than 1000 km. In this context, Nova Technology Systems is proposing a Phase 1 study to design a system for measuring, recording, and locating VLF radiation from distant lightning, as well as developing the algorithms required to discriminate among multiple overlapping, although spatially separated, VLF radiation sources. The innovation is based on the use of time-of-arrival techniques to determine the direction of arrival of the VLF waveform, the use of digital signal processing techniques to extract nanosecond-scale information from the VLF signatures, and the combination of results obtained by several receiving stations to accurately determine the location of the lightning strike. Innovative DSP algorithms will be developed for the identification and location of simultaneous sources while minimizing the effect of polarization and instrumental errors.Potential Commercial ApplicationsThe VLF Lightning Location System is expected to generate interest from the commercial community, given the information it can provide while using a relatively small number of receiving stations. A unique competitive advantage is obtained as a result of lower operating costs, which are significantly reduced since receiving stations can be placed on a 2000 km grid instead of 200~300 km apart. The system can be designed to track developing thunderstorms and produce statistics on lightning activity over vast regions, including transoceanic lightning activity. The VLF Lightning Location System has numerous potential commercial applications, including: - Fire fighting crews could respond quicker to a fire started by lightning before it spreads out of control. - Manufacturers of explosive material can postpone dangerous activities until the thunderstorm activity has terminated. - Golf courses could advise players of incoming thunderstorm activity. - Airline pilots can use the information to avoid potentially dangerous thunderstorms, thus increasing public safety. - Cruise and cargo ships away from the mainland could receive information about the location of thunderstorms hundreds of kilometers away from the coastline in locations where local, shorter baseline systems, do not provide coverage.
