Effects of Lightning on Low-Frequency Navigation Systems
Low Frequency (LF) navigation systems operate in the frequency band from 30 to 300 kHz. In this frequency band, the effect of atmospheric noise caused by lightning is one of the primary contributors to the noise floor as observed by a receiver.
This Thesis investigates the effects of lightning on the Long Range Navigation (Loran-C) system which operates at 100 kHz with a 20-kHz bandwidth. Flight test data were collected and analyzed for both normal and lightning conditions for electric field (E-field) and magnetic field (H-field) antennas.
It was found that both the E-field and H-field antennas are affected similarly by lightning-induced noise. Pulse durations due to lightning discharges are on the order of 0.l to 0.6 ms, both during normal and thunderstorm flight test conditions. The average number of noise pulses per second during normal conditions was approx. 111 pulses for both antennas. During thunderstorm conditions, the average number of noise pulses per second increased by a factor of three for both antennas compared to the number during normal conditions. By discarding Loran pulses affected by lightning, an improvement in SNR was achieved for both E-field and H-field antennas.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:loran c low frequency navigation systems
Date of Publication:01/01/2008