Robust VLF Navigation via Short and Long Path Propagation

The prevalence and reliance upon GPS for geo-location has proven invaluable to defense efforts. However, GPS signals have also proven to be easily interfered, blocked, and spoofed creating a very large vulnerability in a time of conflict. Methods for mitigating these risks have renewed interest in old technologies such as OMEGA to support localization efforts in GPS constrained environments. OMEGA is a ground-based navigation system using VLF band waveforms to allow for any receiver on the globe to ascertain their geo-location. Note, that VLF is such a large waveform that the earth’s surface and the ionosphere form a wave guide for the waveform to propagate completely around the world. With such a large wavelength producing an interferer requires intractable power and blocking the signal would require a mountain. Thus, VLF signals present a compelling choice for GPS denied navigation. Toyon intends to improve upon OMEGA systems by integrating the latest in ionospheric modeling and novel short and long path exploitation to achieve improved localization estimates. When the short path and long path of a VLF signal is exploited, more robust navigation solutions are possible. Toyon proposes to demonstrate feasibility on hardware in the Phase I effort.