Simulation of wide bandwidth signals that have propagated through random media

A numerical technique is described to generate realizations of the received signal after propagation of a wide bandwidth waveform through a layer of strongly turbulent media. These signal realizations are generated to have Rayleigh amplitude statistics and to have spatial and frequency correlation properties which obey the parabolic wave equation in the strong scatter limit. This technique is based upon the solution for the two-frequency mutual coherence function Γ for spherical wave propagation with transmitter and receiver located on opposite sides of a finite layer of ionized electron density irregularities. An analytic solution may be obtained for Γ in the strong scatter regime by use of the quadratic approximation for the phase structure function. The thin phase screen approximation to the thick layer is then utilized, and great simplification to the analytic expression for Γ is obtained. The relationship between the impulse response function of the propagation channel and the two-frequency mutual coherence function and its Fourier transform is then used to directly obtain statistical realizations of wide bandwidth signals. These statistical realizations may be used as direct input to digital receiver modems to represent the effect of propagation through an ionospheric environment disturbed by barium releases or other sources of enhanced ionization. Although these statistical signal realizations apply only to the case of strong scattering, their generation requires only a fraction of the computer resources required for signal generation by wide bandwidth multiple phase screen calculations.

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