The use of meteor scatter and extended range VHF for vehicle tracking and communication

A wide coverage area, terrestrial radio system is described for vehicle tracking and communication by exploiting the great variety of mechanisms which propagate in the lower VHF band. Using the ionized trails of meteors entering the ionosphere provides wide area communication (regional coverage out to 800 km) from a single base station at a fraction of the cost of satellite-based systems. The small ground illumination footprints of individual meteor trails combined with random access protocols and high-gain sectored antennas provide inherent spatial multiplexing or space division multiplexing (SDMA) allowing for large numbers of vehicles to be supported by a single base station. While the arrival of meteor trails is stochastic, reliable service to a large fleet of vehicles is realizable through proper system design. For coverage in urban areas where the noise is higher, local base stations provide extended ground wave coverage within a 75-100 km radius, making use of a variety of line of sight/diffraction modes that propagate well in the 40-50 MHz frequency band.