A transionospheric communication channel model

This report presents the final results of a three-year contract to develop a signal-statistical model of the transionospheric radio communication channel, building on a previously existing model for first-order signal statistics. The objectives of the contract work were as follows: (1) to test and improve the first-order statistical model; (2) to extend the model to second-order statistical quantities in the temporal, spatial, and spectral domains; (3) to free the model from restriction to cases of weak, single scatter; and (4) to calibrate and iteratively test the morphological description of ionospheric structure that underlies the model. The foregoing objectives have been met, and the research results have been committed to two computer codes for performing systems-oriented, signal-statistical calculations. The more extensive of the two codes, IONSCNT, contains the morphological model and a two-component propagation routine that permits calculation of both focusing and diffractive-scatter effects. Mode 1 of IONSCNT provides calculation of intensity and phase scintillation indices and other first-order, signal-statistical parameters as functions of frequency, observing geometry, or other relevant variables from a user-selected set of ionospheric state parameters. Mode 2 of IONSCNT extends the Mode 1 results to second-order statistics for cases to be selected by the user.