Transionospheric propagation and detection of broadband electromagnetic waveforms

The ability to observe RF emissions through the ionosphere and the degree to which useful information about the source may be gleaned from such measurements is highly dependant upon the type of source, frequency ranges of interest, the state of the ionospheric medium, detector sensitivity and reliability of recovery algorithms used.

This paper analyzes the propagation, detection and discrimination aspects of this observables problem as modeled by the Transionospheric Propagation Code (TIPC). Covered first are several typical theoretical broadband source waveforms. Second, the physics of deterministic dispersion is discussed along with the ionospheric transfer function. Next, results from the TIPC for deterministic and disturbed propagation are presented as well as white noise effects. Results are then presented from a simple detection algorithm utilizing a Gaussian filter function, and finally, a discussion on two methods of source discrimination: spectrum reconstruction and quadrature filtering.

Generally, the TIPC is very useful as a baseline propagation code. The ionospheric transfer function has been validated analytically and provided an accurate representation of the source is used, the higher order corruptive effects of noise and both deterministic and non-deterministic dispersion may be modeled to gain insight to the detectability and usefulness of the transionospheric pulse.