Ionospheric sounding using signal of opportunity

Numerical modeling has demonstrated that signals of opportunity, such as Automatic Dependent Surveillance Broadcast (ADS-B), Automatic Identification System (AIS) and amateur radio signals are subject to Faraday rotation (FR) as they pass through the ionosphere and may be useful for ionospheric sounding in addition to their intended operational purpose. In this work, a ray-tracing model was used to determine the characteristics of individual linearly polarized waves transmit by ships to a satellite in a circular orbit at 1000 km altitude, including the wave path and the state of polarization at the satellite receiver. The modeled FR was computed and used to calculate the total electron content (TEC) along the ray paths. Mobile ground-based transmitters such as those discussed in this work offer more flexibility for deployment than stationary receivers.